GDR INSAR & GDR STRAINSAR
Feigl et al.
2016-02-15
Final Report of GDR STRAINSAR
Bilan scientifique du
GDR INSAR (1997-2000) et du GDR STRAINSAR (2001-2004)
For consideration by section 18 of the CNRS
Number of characters =
162865
Number of words =
28415
Number of pages =
41
File name
Bilan2005GDRstrainsar1.doc
Kurt L. Feigl
Department of Terrestrial and Planetary Dynamics (UMR 5562)
Centre National de la Recherche Scientifique
14 ave. E. Belin
31400 Toulouse
France
feigl@dtp.obs-mip.fr
Fax. +33 5 61 33 29 00
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TABLE OF CONTENTS
Table of contents
2
People
3
Geodetic Techniques For Measuring Deformation Using Satellite Data
GPS
SAR interferometry
Correlation of two optical images acquired by optical satellites such as SPOT
Correlation of two SAR backscatter images acquired by the radar satellites such as ERS
3
3
4
5
7
Advances published between 1997 and 2004
Coseismic deformation for earthquakes
Volcanos
Landslides and subsidence
Glaciers
Interseismic Deformation
Postseismic Deformation
Troposphere
Orbits
Satellite missions
8
8
9
9
9
9
9
10
11
11
Services Provided by GDR INSAR and GDR STRAINSAR
mail list (insar@pontos.cst.cnes.fr)
Catalog of ERS-1 and ERS-2 orbits
Software for selecting interferometrically compatible pairs from ERS-1 and ERS-2 catalog
Software for filtering interferograms
Future Satellite Missions
13
13
13
13
13
15
Subscribers to mail list insar@pontos.cst.cnes.fr (2005)
16
Glossary
19
Acknowledgments
20
Bibliography of GDR INSAR and GDR STRAINSAR
1993-1994
GDR INSAR (1995-1999) – 53 peer-reviewed publications
GDR STRAINSAR (2000-2005) 98 peer-reviewed publications
Theses
Selected conference proceedings 1997- 2000
21
21
21
22
37
38
Other References Cited
39
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PEOPLE
Our community includes:
Over 100 people subscribed to the mail list (insar@pontos.cst.cnes.fr)
See section below entitled “Subscribers to mail list insar@pontos.cst.cnes.fr”.
The authors of over 150 publications in peer-reviewed journals between 1997 and 2005
See section below entitled “Bibliography of GDR INSAR”.
Over a dozen doctoral degrees related to INSAR between 1997 and 2005
See section below entitled “Theses”.
Over 50 people have participated in DIAPASON short courses since 1997
GEODETIC TECHNIQUES FOR MEASURING DEFORMATION USING SATELLITE DATA
Tectonic geodesy took a great leap forward when we published the first coseismic interferogram on the cover
of Nature in the summer of 1993 [Massonnet et al., 1993]. Twelve years later, in 2005, interferometry on
synthetic aperture radar images (INSAR) has become a widely used and widely accepted geophysical technique
for measuring topography and deformation of the Earth’s lithosphere and cryosphere. Confronted with
conventional models, these INSAR measurements have significantly advanced the study of earthquakes,
volcanos, landslides, subsidence and glaciers.
GPS
The Global Positioning System can achieve sub-centimeter estimates of relative position with a relatively
inexpensive and lightweight instrument for less than “10 kg, 10 Watts, and 10 $K”. Since the most precise
solutions involve post-processing data from multiple instruments, it typically requires several days between
acquisition and estimate. The constellation of satellites came into use gradually beginning in 1985 and becoming
fully operational in 1992. Data from this early period are typically more difficult to analyze and may yield less
precise results than more recent surveys. For reviews of geophysical applications, see Dixon [1991], Hager et al.,
[1991], and Segall and Davis [1997]. For earthquake studies, GPS networks tend to operate in one of two endmember modes: Continuous operation of permanently installed, widely-spaced antennas (CGPS), or intermittent
occupation of densely-spaced benchmarks in “campaign” mode. The former offers good temporal resolution (1
measurement/30 seconds = 33 mHz) but poor spatial resolution (> 100 km between stations), while the latter
offers poor temporal resolution (1 measurement/year = 32 nHz) and good spatial resolution (~10 km between
stations). This trade-off between temporal and spatial resolution creates a difficult decision in the face of limited
resources. Although a compromise “hybrid” strategy could rotate expensive receivers on a roughly monthly basis
through several fixed monuments, this approach has yet to be deployed, apparently because it requires more
manpower than permanent installations.
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Figure 1. Left: Map of Izmit region showing GPS sites (4-character, named sites are continuous stations operating before and
after the main shock; two additional continuous stations used in this study are located off the map at 40.61°N, 27.59°E, and
40.97°N, 27.96°E) and observed (including 95% confidence ellipses) and modeled (yellow arrows) horizontal coseismic
displacements relative to a station in Ankara, Turkey (ANKR, located at 39.89°N, 32.76°E). The five segment fault model
used to investigate slip distribution the Izmit earthquake epicenter and focal mechanism from the Harvard CMT Catalog
(http://www.seismology.harvard.edu/CMTsearch.html), and pre-earthquake seismicity (http://quake.geo.berkeley.edu/cnss)
are also shown. Light lines are mapped or inferred faults [Barka, 1997]. MV = Mudurnu Valley fault. Right: Map of
observed postseismic GPS station displacements (black arrows) relative to ANKR (located at 39.89°N, 32.76°E) during the
first 75 days following the earthquake. Error ellipses indicate 95% confidence intervals. Modeled station displacements
(yellow arrows) were computed with the slip distributed dislocation model shown in Fig. 3C. Station names (four-character
ID) indicate continuously operating sites installed within 48 hours following the main shock. Red dots indicate aftershocks
of the first 30 days. The blue dotted line indicates the fault geometry used in the postseismic model inversions (note that the
fault is extended to the east of the coseismic fault model to include the Duzce segment). The "beach ball" shows the location
and focal mechanism of the MW 7.2, 12 November 1999, Düzce earthquake. From Reilinger et al. [2000].
SAR interferometry
This geodetic technique calculates the interference pattern caused by the phase difference between two images
acquired by a spaceborne synthetic aperture radar (SAR) at two distinct times. The resulting interferogram is a
contour map of the change in distance between the ground and the radar instrument. Each fringe represents a
range change of half the wavelength. Thus, the contour interval is 28 mm for C-band radars such as ERS and
RADARSAT and roughly four times larger, 125 mm for the L-band JERS satellite. These maps provide an
unsurpassed spatial sampling density (~100 pixels/km2), a competitive precision (~1 cm) and a useful
observation cadence (1 pass/month), as described in a review article by Massonnet and Feigl [1998], which I
paraphrase here.
To capture an earthquake, INSAR requires three data sets: a SAR image before the earthquake, one after, and
topographic information. The SAR images themselves are rich data sets well documented in the remote sensing
literature [Curlander and McDonough, 1991; Henderson and Lewis, 1998]
The topographic information is necessary to model and remove the interferometric fringes caused by
topographic relief as “seen in stereo” from slightly different points of view. To handle the topographic
contribution, we can choose between the “two-pass” approach, [e.g., Massonnet and Feigl, 1998] and the “threepass” or “double-difference” approach [e.g., Zebker et al., 1994]. For tectonic studies, there is usually a trade-off
between the two-pass approach, which requires a digital elevation model (DEM), and the three-pass approach,
which requires a third SAR acquisition. Further discussion of relative merits of the two- and three-pass
approaches are beyond the scope of this chapter.
To interpret an interferogram, one must understand how different effects contribute to the fringe pattern. Many
instructive examples appear in review papers by Massonnet and Feigl [1998] and Madsen and Zebker [1998].
The mathematical details appear in another review [Bamler and Hartl, 1998]. For earthquake studies, the most
important effects involve topographic relief, orbital trajectories, and tropospheric refraction, usually in
combination.
If the topographic information (a DEM for two-pass, or the “topo pair” in three-pass INSAR) is in error, the
interferogram will contain artifactual fringes. They appear in the same location in every interferogram produced
using that topographic model. To quantify this effect, Massonnet and Rabaute [1993] define the altitude of
ambiguity ha , or the shift in altitude needed to produce one topographic fringe. Indeed, this parameter is
inversely proportional to the perpendicular component of the (“baseline”) vector separating the two orbital
trajectories, conventionally written B, pronounced “B-perp”, and given in meters [Zebker and Goldstein, 1986].
The number of “topographic” fringes is proportional to B and inversely proportional to ha. Thus we seek pairs
of orbital trajectories with a small separation, that is, with small (absolute) values of B and large (absolute)
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values of ha for earthquake studies. It turns out that for the ERS satellites, an acceptably good orbital pair has
both B and ha approximately equal to 100 m.
A topographic error of  meters in the DEM will produce a phase error of  /ha fringes in the resulting
interferogram. Errors in typical DEMs range from 10 to 30 m [Wolf and Wingham, 1992], implying that choosing
a pair of images with |ha | between 20 and 60 m will yield an interferometric measurement with an error better
than  /ha = ± 1/2 cycle, or ± 14 mm for ERS. Small values of |ha | can mask even large signals with artifactual
topographic fringes. In an extreme (and rare) case, Massonnet and Feigl [1995a] uncovered a topographic error
of  ~250 m, roughly 8 times larger than the published precision for the DEM. This artifact resembles the fringe
pattern produced by a small earthquake. Avoiding such confusion requires looking at several interferograms with
different values of ha . For an earthquake, the number of coseismic fringes does not depend on ha.
Atmospheric effects can also complicate the interpretation of an interferogram. Indeed, variations in the
refractive index of the troposphere are the current limiting source of error in the INSAR technique [Delacourt et
al., 1998; Goldstein, 1995; Hanssen, 1998; Massonnet and Feigl, 1995a; Rosen et al., 1996; Tarayre and
Massonnet, 1996; Williams et al., 1998; Zebker et al., 1997]. Potentially, one could confuse a topographic
signature with a displacement, if propagation effects create fringes which "hug" the topography like contour lines,
but which measure the change in tropospheric delay, as first observed as several concentric fringes on a 1-day
interferogram on Mount Etna [Massonnet and Feigl, 1998];. One can recognize this subtle effect by pair-wise
logic [Massonnet and Feigl, 1995a] or using the DEM and local meteorological observations [Delacourt et al.,
1998; Williams et al., 1998]. Yet separating the tropospheric noise from the deformation signal can be
challenging, particularly when the signal is small, e.g. the magnitude 5.2 St. Paul de Fenouillet earthquake [Rigo
and Massonnet, 1999].
Correlation of two optical images acquired by optical satellites such as SPOT
It is also possible to detect (large) coseismic displacements by correlating two optical images. The “lag”
vectors estimated between the corresponding sub-pixel cells of a pre-quake and a post-quake image yields the
horizontal components of the coseismic displacement vector with sub-meter precision and hectometer resolution
[Crippen, 1992; Crippen and Blom, 1992; Vadon and Massonnet, 2000; Van Puymbroeck et al., 2000]. To
capture the Izmit earthquake of August 17, two groups have correlated optical images acquired by the SPOT4
satellite on July 9 and the SPOT2 satellite on September 16, after anti-aliasing resampling [Michel and Avouac,
2000; Vadon and Massonnet, 2000].
The result is a measurement of the offset between the two images at each 20-meter pixel where the correlation
succeeds. In this case, lines of the SPOT images are almost parallel to the fault, we use only the offset in columns
to determine the horizontal component of displacement in the direction S77°E. Although the two images were
acquired in very similar geometric configurations, the correlation map still shows the effects of slight differences
in spacecraft position and sensor attitude. Michel and Avouac [2000] model these explicitly, while Vadon and
Massonnet [2000] model them empirically with a biquadratic polynomial fit. These results are shown in Error!
Reference source not found. and Figure 2, respectively. As Michel and Avouac write, SPOT images can also be
used to map accurately the fault zone and determine the slip distribution by sub-pixel correlation of images
acquired before and after an earthquake. It reveals a less than 100m wide and very linear fault zone that can be
traced for 70km from Gölcük to Akyazi. The obtained slip distribution compares well with the field
measurements, and is consistent with ground deformation measured at some distance from the fault zone using
SAR images. Very little slip was absorbed off the main fault plane.” [Michel and Avouac, 2000].
Both these maps show a discontinuity corresponding to the trace of surface rupture mapped between the east
end of the bay at Izmit and Sapanca Lake. The mean offset between two 5-by-20-km blocks on opposite sides of
the fault is 4.60 ± 0.24 m. After median filtering with a 2-by-2-km window, Feigl et al. [2001] retain 148 values.
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Figure 2. Component at S77°E of the coseismic displacement field measured by correlation of SPOT images. As described
by Vadon and Massonnet (2000), these images were acquired on July 9 and September 16, 1999. These original 20-m pixels
have been filtered using a 2-dimensional median filter on a 100-by-100-m window [Feigl et al., 2001].
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Berthier Izmit Figure
Figure 3. The left panel shows the offsets in longitude determined by correlating two SPOT images acquired on 9 July and 16
September 1999. A clear discontinuity in the offset field indicate the location of the surface rupture. Area where the
correlation failed are displayed in grey. The location and co-sismic deformation recorded at 4 GPS stations are also added.
The right panel represent the slip along the surface rupture as a function of longitude. The blue dots represent the mean slip
every 300 meters; the red dots a running average over 3-km segments [Berthier, 2005].
Correlation of two SAR backscatter images acquired by the radar satellites such as ERS
A similar correlation technique also applies to SAR images. By correlating two Single Look Complex (SLC)
SAR amplitude (“backscatter”) images acquired at different times, Michel et al. [1999a] measured ground
displacements for the Landers earthquake. Their result is “a two-dimensional displacement field with independent
measurements every about 128 m in azimuth and 250 m in range. The accuracy depends on the characteristics of
the images. For the Landers test case discussed in the study, the 1- uncertainty is 0.8 m in range and 0.4 m in
azimuth. [They] show that this measurement provides a map of major surface fault ruptures accurate to better
than 1 km and an information on coseismic deformation comparable to the 92 GPS measurements available.
Although less accurate, this technique is more robust than SAR interferometry and provides a complementary
information since interferograms are only sensitive to the displacement in range.” [Michel et al., 1999a]. Its
greatest potential is for measuring cryospheric deformation, where flow can be sufficiently rapid ( > 10 cm/day)
to allow detection in the short time (1, 3 or 35 days) between ERS acquisitions [Michel, 1997; Michel and
Rignot, 1999].
For the Izmit earthquake, however, Sarti et al. [2000] find less accurate results than at Landers. Using multiple
scales for their correlation cells, they find the range component of the coseismic displacement with a scatter in
excess of a meter. Indeed, it is difficult to discern even the trace of the fault in the map of ERS range offsets
(Figure 4). Consequently, Feigl et al. [2001] do not include these data in their inversion.
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Figure 4. Component at S77°E of the coseismic displacement field measured by correlation of two ERS images, as described
by Sarti et al. (2000). Note that discontinuity in these measurements does not follow the mapped trace of the fault (crosses)
as well as the SPOT correlation map [Feigl et al., 2001].
ADVANCES PUBLISHED BETWEEN 1997 AND 2004
Coseismic deformation for earthquakes
INSAR has now captured over a dozen earthquakes in the act of permanently deforming the Earth’s surface
(Table 1.)
Table 1. Earthquake studies estimating parameters from satellite geodetic measurements using INSAR as compiled from the
literature [Feigl, 2002; Funning, 2005].
Location
Landers,CA,USA
Litle Skull Mountain, CA, USA
Fawnskin, CA,USA
Ngamring County, Tibet
Eureka Valley, CA, USA
Northridge, CA, USA
Double Spring Flat, NV, USA
Kobe, Japan
Grevena, Greece
Neftegorsk, Sakhalin, Russia
Aigion, Greece
Antofagasta, Chile
Dinar, Turkey
Nuweiba, Egypt
St Paul de Fenouillet, France
MW
7.3
5.6
5.4
6.1
6.1
6.7
6.0
6.9
6.6
7.2
6.2
8.1
6.3
7.3
5.0
Date
1992-06-28
1992-06-29
1992-12-02
1993-03-20
1993-05-17
1994-01-17
1994-09-12
1995-01-17
1995-05-13
1995-05-27
1995-06-15
1995-07-20
1995-10-01
1995-11-22
1996-02-26
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InSAR
[Fialko, 2004c]
[Lohman, et al., 2002]
[Feigl, et al., 1995]
[Funning, 2005]
[Massonnet and Feigl,
1995]
[Massonnet,
et al.,
1996]
[Amelung and Bell, 2003]
[Ozawa, et al., 1997]
[Bernard, et al., 1997b]
[Tobita, et al., 1998]
[Bernard, et al., 1997a]
[Pritchard, et al.,
2002b]
[Funning,
2005]
[Shamir, et al., 2003]
[Rigo and Massonnet,
1998]
GDR INSAR & GDR STRAINSAR
Nazca Ridge, Peru
Kagoshima-ken-hokuseibu, Japan
Manyi, Tibet
Zhangbei-Shangyi, China
Fandoqa, Iran
Mt Iwate, Japan
Aiquile, Bolivia
Izmit, Turkey
Athens, Greece
Colfiorito, Italy
Colfiorito, Italy
Hector Mine, CA, USA
Duzce, Turkey
Cankiri, Turkey
S Iceland Seismic Zone, Iceland
S Iceland Seismic Zone, Iceland
Nisqually, WA, USA
Arequipa, Peru
Kokoxili, Tibet
Nenana Mountain, AK, USA
Denali, AK, USA
Bam, Iran
Feigl et al.
7.7
6.1
7.5
6.2
6.6
6.1
6.6
7.4
6.0
5.7
6.0
7.1
7.1
6.0
6.5
6.4
6.8
8.5
7.8
6.7
7.9
6.6
1996-11-12
1997-03-26
1997-11-08
1998-01-10
1998-03-14
1998-09-03
1998-05-22
1999-08-17
1999-09-07
1999-09-26
1999-09-26
1999-10-16
1999-11-12
2000-06-06
2000-06-17
2000-06-21
2001-02-28
2001-06-23
2001-11-14
2002-10-23
2002-11-03
2003-12-26
2016-02-15
[Delouis, et al., 2002]
[Fujiwara, et al., 1998]
[Funning, 2005]
[Zhang, et al., 2002]
[Funning, 2005]
[Nishimura, et al.,
2001]
[Funning, et al., 2005]
[Cakir, et al., 2003]
[Kontoes, et al., 2000]
[Salvi, et al., 2000]
[Salvi, et al., 2000]
[Simons, et al., 2002]
[Bürgmann, et al., 2002]
[Wright, 2000]
[Pedersen, et al., 2003]
[Pedersen, et al., 2003]
[Bustin, et al., 2004]
[Pritchard, et al.,
2002a]
[Lasserre,
et al., 2002]
[Wright, et al., 2003]
[Wright, et al., 2003]
[Funning, 2005]
Volcanos
Volcanos continue to be the most fruitful target for INSAR studies. We know the location of the most active
ones. We know that shield volcanos produce better fringe patterns than stratovolcanos [Massonnet and
Sigmundsson, 2000; Zebker et al., 2000]. We know how to choose images to optimize radar correlation, by
considering ground, weather, and orbit conditions. Techniques for separating tropospheric artifacts from
deformation signals are are particularly useful in this case [e.g., Beauducel et al., 2000a].
For these reasons, INSAR on volcanos is now fully validated. The feasibility studies of the past few years have
proven the concept. It works! Progress in the next few years will come from operational monitoring of many
volcanos. This will require routine acquisitions every time the satellite passes over the volcano. Although some
may argue against the utility of acquiring SAR images during the winter when there is snow on the ground, simple
comparison of SAR images (without interferometry) has already revealed a subglacial eruption [Alsdorf and
Smith, 1999].
Landslides and subsidence
[Carnec, 1996; Carnec and Delacourt, 2000; Carnec and Fabriol, 1999; Carnec et al., 1996; Delacourt,
1997; Delacourt et al., 2000; Fruneau et al., 1996].
Glaciers
[Joughin et al., 1996a; Joughin et al., 1996b; Joughin, 1995; Joughin et al., 1998; Joughin et al., 1995;
Legresy et al., 2000; MacAyeal et al., 1998; Michel and Rignot, 1999; Rignot, 1996a; Rignot, 1996b; Rignot,
1997; Rignot et al., 1996; Rignot et al., 1995; Rignot, 1998].
Interseismic Deformation
Several studies have successfully applied INSAR to measure subtle deformation during the intersesimic
interval between large earthquakes. [Rosen et al., 1998][Bürgmann et al., 2000].
[Peltzer, et al., 2001]
[Wright et al., 2000a].[Wright, et al., 2004a; Wright, et al., 2004b]
Postseismic Deformation
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Studying the postseismic deformation in the months following a large earthquake can help understand
mechanical behavior of the lithosphere. The mainshock provides a known impulse and satellite surveying, the
response. By measuring and modelling these signals, we can construct a mechanical experiment to determine the
relevant rheologic properties. This is one one of the few cases in solid-earth geophysics where we can access the
time dependence of the the phenomenon. The time scales of both the phenomena and the measurements are short
enough to make the problem tractable.
Landers provides a good case study, although earlier examples exist. Here, both GPS and INSAR also
measured postseismic deformation [Bock et al., 1997; Massonnet and Feigl, 1995a; Massonnet et al., 1994;
Massonnet et al., 1996b; Peltzer et al., 1996; Savage and Svarc, 1997; Shen et al., 1994]. See also: [Deng et al.,
1998; Peltzer et al., 1998; Pollitz et al., 2000]. And more recently : [Jacobs, et al., 2002; Fialko, 2004a; 2004b].
The same arid conditions also favor INSAR for measuring postseismic deformation following the M ~ 7
earthquake at Hector Mines in 1999 [Sandwell et al., 2000].
Postseismic deformation involving afterslip down-dip from the coseismic slip was also captured following the
Izmit earthquake using GPS [Ergintav et al., 2000; Reilinger et al., 2000].
Other studies using INSAR have improved our understanding of post-seismic deformation [Jonsson, et al.,
2003; Chlieh, et al., 2004; Arnadottir, et al., 2005].
Troposphere
Atmospheric effects can also complicate the interpretation of an interferogram. Indeed, variations in the
refractive index of the troposphere are the current limiting source of error in the INSAR technique [Delacourt et
al., 1998; Goldstein, 1995; Hanssen, 1998; Massonnet and Feigl, 1995a; Rosen et al., 1996; Tarayre and
Massonnet, 1996; Williams et al., 1998; Zebker et al., 1997]. Potentially, one could confuse a topographic
signature with a displacement, if propagation effects create fringes which “hug” the topography like contour lines,
but which measure the change in tropospheric delay. This effect was first observed as several concentric fringes
in a 1-day interferogram on Mount Etna [Massonnet and Feigl, 1998]. One can recognize this subtle effect using
pair-wise logic [Massonnet and Feigl, 1995a] or using a DEM and local meteorological observations [Delacourt
et al., 1998; Williams et al., 1998]. Yet separating the tropospheric noise from the deformation signal can be
challenging, particularly when the signal is small, e.g., the magnitude 5.2 earthquake near St. Paul de Fenouillet,
France [Rigo and Massonnet, 1999].
The interferograms spanning the Izmit earthquake illustrate the dangers of interpreting tropospheric fringes as
deformation. There, Reilinger et al. [2000] found that “both the ERS-1 and ERS-2 interferograms are
significantly contaminated by tropospheric artifacts”. Accordingly, they chose not to include these INSAR results
in their estimate of coseismic slip. The inversion procedure is particularly sensitive to gradients in the
displacement field, which are in turn sensitive to errors in range along the steep radar lineof sight. In the far field,
at 50 km from the fault, an error of one 28-mm fringe in range can alter the estimate of slip on the fault by several
meters. This may explain why models based on these INSAR observations tend to find more slip on the fault, and
thus a higher total moment, than does the GPS-only solution [Reilinger et al., 2000].
Left uncorrected, the tropospheric artifact appears as a residual of approximately 8 cm in range almost 50 km
north of the fault when Delouis et al. [2001] include the ERS-2 interferogram in their inversion.
To mitigate the correlation of tropospheric delay with topographic elevation, we can estimate additional
parameters in addition to the parameters of geophysical interest in our models. To do this, Feigl et al. [2001]
implicitly assume a uniform troposphere. They then estimate the (negative) correlation between tropospheric
delay along the radar line of site and the topographic elevation. This “tropo-topo” correlation coefficient thus
adds a free “nuisance” parameter in their estimation procedure.This parameterization differs slightly from the
layered tropospheric model employed by Beauducel et al. [2000a] at Etna. The single layer approach adds only
one free parameter, the gradient, to the inversion. The layered model adds one parameter per tropospheric layer.
Reducing the number of nuiscance parameters reduces the trade-off between the nuisance parameters and those of
interest in the geophysical model for deformation.
For the ERS-1 coseismic interferogram at Izmit, Feigl et al. [2001] find a strong correlation between
topographic relief and tropospheric delay, yielding a vertical gradient of –36 ± 6 mm in range per kilometer of
elevation. This value is of the same order of magnitude as the worst cases observed in radiosonde profiles
[Hanssen and Klees, 1999]. The INSAR estimate of the tropospheric gradient may be biased by the non-uniform
distribution of measurements with respect to elevation [Beauducel et al., 2000a].
The strong tropospheric gradient produces over more than three fringes in the valley around Izmit, just as in
the aseismic one-day interferogram (Figure 5). Estimating this nuisance parameter yields a moment of 2 x 1018
N.m lower than the value we find without it. This implies that tropospheric artifacts may have slightly increased
the moment previous inversions using the ERS interferograms
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Figure 5. Interferogram showing the phase difference between an ERS1 image acquired August 12, 1999 (orbit number
42229) and an ERS-2 image acquired August 13, 1999 (orbit number 22556). The altitude of ambiguity is 40 m, but the
DEM used for this calculation has an estimated RMS accuracy of ~ 7 m. Orbital fringes have been modeled empirically with
a linear gradient. As a result, the remaining fringes must be tropospheric in origin [Feigl et al., 2001].
Orbits
In working with interferograms for the Izmit earthquake, we found some unmodeled gradients [Feigl et al.,
2001]. These appear to be at leas partially due to be caused by using the preliminary ORRM estimates of the ERS
orbital trajectories. Indeed, the eastward and northward derivatives of range change are significant. In their
preferred joint inversion of GPS, SPOT and ERS data, these authors find values of ()/x = –0.3 ± 0.05  10–6
and ()/y = 1.73 ± 0.01  10–6 for these quantities, respectively. They imply roughly one north-striking fringe
spread over the 100-km east-west dimension of the interferogram, and over nine east-striking fringes spread over
the 150-km north-south dimension of the interferogram. Left uncorrected, the former error could bias the alongstrike variation of the slip distribution. Similarly, the latter effect would lead to an overestimate of the total
amount of slip across the fault, and thus the moment. Indeed, including the two horizontal gradients as nuisance
parameters reduces the moment by 1.1 x 1019 N.m.
A cleverer approach would be to adjust the orbital parameters using interferometric pairs in which little or no
deformation is expected [Kohlhase et al., 2000].
For future missions, the orbital trajectories should be less of a problem because DORIS and GPS receivers
aboard the satellites will improve orbital knowledge to better than a decimeter, and perhaps even control the
orbits to within tens of meters.
Satellite missions
During the 8 years of GDR INSAR and STRAINSAR between 1997 and 2004, the following SAR missions
operated:
ERS-1.
Launched in July 1991, ERS-1 served faithfully for almost 9 years until she finally failed on March 10, 1999.
ERS-2
Launched in 1995. Doppler frequency began to drift in 2000.
JERS-1.
http://www.eorc.jaxa.jp/JERS-1/user_handbook/index.html
SRTM
Shuttle Radar Topographic Mission. Flew in early 2000. [http://www2.jpl.nasa.gov/srtm]
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RADARSAT
MDA's Geospatial Services (formerly RADARSAT International) holds the exclusive distribution rights to
Canada’s RADARSAT-1 and RADARSAT-2 synthetic aperture radar (SAR) satellites. MDA will operate the
RADARSAT-2 satellite following launch [http://www.rsi.ca]
ENVISAT (2001)
Several members of GDR INSAR were approved by the European Space Agency as investigators for the
following projects, granting them ENVISAT data free of charge, as described by the announcement of
opportunity [ESA, 1997].
More recently, we have obtained ENVISAT data for 25 euros per scene under the Category-I program.
http://eopi.esa.int/esa/esa.
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SERVICES PROVIDED BY GDR INSAR AND GDR STRAINSAR
mail list (insar@pontos.cst.cnes.fr)
The mail list uses a program called "listproc". There are two addresses for two separate functions.
Messages for the entire INSAR working group:
insar@pontos.cst.cnes.fr Messages sent to this address will be sent to all members of the GDR
INSAR working group, currently about 150 members. So, please be polite enough to re-read your message
before sending it!
An automatic secretary to handle the bookkeeping of the address list:
listproc@pontos.cst.cnes.fr This adddress understands only the following instructions in the body
of the message:
help
subscribe insar your_family_name
unsubscribe insa
get insar
review insar
In particular, to subscribe, you should send a message to this address with the instruction:
subscribe insar dupont
where "dupont" is your family name. There is no need to enter your e-mail address because listproc picks that
of your message. Note that you can also obtain all the previous messages with the get function.
Catalog of ERS-1 and ERS-2 orbits
Compiled from the ORRM estimates, with gaps filled by Delft and DLR. In “.orb” format for use with
Diapason. X,Y,Z,XDOT, YDOT, ZDOT every 30 seconds in ASCII. One file per orbit.
scp insar.omp.obs-mip.fr
Software for selecting interferometrically compatible pairs from ERS-1 and ERS-2 catalog
Telnet to insar.omp.obs-mip.fr
Execute orbiscan.csh and follow the instructions. You will need to have run DESCW beforehand to find a
catalog of aquired images.
Software for filtering interferograms
ps_filt2
Solaris executable written by Zhong Lu using a power spectrum algorithm [Goldstein and Werner, 1998]
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Figure 6. Example of power-spectral filtering using ps_filt2, showing unfiltered interferogram (left) and filtered
interferogram using alpha = 0.8. Courtesy Benoit Legresy.
DTOOLS
This set of shell scripts automates the running DIAPASON/PRISME version 3. Written by Kurt Feigl, is in the
public domain and available by request to him.
It reduces data analysis to the following two operations:
Read CD-ROM or DVD
setup_image_slc_envisat
#or
setup_image
then
create_diapason_files
calculate_interferogram
#or
dtool
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Future Satellite Missions
RADARSAT-2 (launch 2006)
Co-funded by Canadian Space Agency (CSA) and MacDonald Dettwiler (MDA). Data continuity from
RADARSAT-1. All RADARSAT-1 imaging modes supported. Plus many additional capabilities. Launch in
2006. Mission duration: 7 years.
Same orbit as RADARSAT-1: 798 km altitude, sun-synchronous orbit, 6 PM ascending node and 6 AM
descending node. Same repeat cycle and ground track as RADARSAT-1: RADARSAT-1 and -2 scenes precisely
aligned.
Image location knowledge: < 300 metres at downlink (c.f. RS1 ~ 1.4 km) and < 100 metres post-processed
RADARSAT-2 Innovations and Improvements3-metre Ultra-Fine resolution
highest-resolution SAR commercially available, Routine left-looking and right-looking mode , more frequent
revisit, faster response to user requests
Fully-polarimetric imaging modes, polarimetry modes (amplitude and phase information), selective
polarization (HH,HV,VH,VV), Choosing between polarizations or using polarimetric parameters increases the
information content and its applicability for various applications such as agriculture, target identification, marine
monitoring, and mapping/geology
GPS receivers on-board. Real-time position knowledge ± 60 m
Delay between imaging modes < 1 s. Compared to RADARSAT-1 ~14 s. This decrease in the switching rates
allows greater flexibility in changing beam positions/modes within adjacent geographic areas.
Higher downlink power. 3-metre minimum size antenna. lower "cost of entry" for new ground stations
Data encryption. encryption for both data downlink and data transfer is critical for military clients.
[http://www.radarsat2.info/rs2_satellite/overview.asp].
ALOS (2005)
Members of GDR INSAR have been approved by NASDA in Japan as investigators for the following projects,
granting them ALOS data free of charge, as described by the announcement of opportunity.
Amelung et al., Monitoring Hawaiian and other hot-spot volcanoes with ALOS radar interferometry (RA-129)
Amelung et al., Monitoring large earthquakes in SE Asia and Central America with PALSAR and PRISM (RA-91)
Feigl and Massonnet, Waiting for the Big One.
Feigl et al., Djibouti
Sigmundsson et al., Dynamicsof the Shangbai Shan (Tianchi) caldera, China, from ALOS PALSAR interferometry
Sigmundsson et al., Monitoring of the Mid-Atlantic Ridge in Iceland with ALOS PALSAR interferometry
This list is not yet complete.
The ALOS will be launched by an H-IIA launch vehicle from the Tanegashima Space Center, Japan in summer
2005 [http://www.eorc.jaxa.jp/ALOS/about/2overview.htm]
HABITAT (2005)
Massonnet describes a genuinely innovative concept for a new mission: “Quasi-simultaneous radar images can
be produced by a low cost system using a set of passive receivers onboard a constellation in a special orbial
configuration. The combination of thes images can improve the final resolution in range and azimuth and
systematically produce across-track and along-track inteferometric data” [Massonnet, 2000]. This concept has
been incorporated into a proposal called HABITAT submitted to ESA’s Earth Explorer Programme.
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SUBSCRIBERS TO MAIL LIST INSAR@PONTOS.CST.CNES.FR (2005)
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50)
51)
Achache
Alberto Refice
Alsdorf
Amelung
Andrea Taramelli
Aoki
Armijo
Arnaud
Avallone
Bawden
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Berthier
Berthod
Blegresy
Briole
Brun
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Burgmann
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Cheminee
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Cking
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Curlander
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Eneva
Fabio Bovenga
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Feurer
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Frederique Remy
Freysteinn Sigmundsson
Froger
Fruneau
Funning
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ALBERTO.REFICE@BA.INFN.IT
ALSDORF@GEOG.UCLA.EDU
AMELUNG@KAHANA.HIGP.HAWAII.EDU
ATARAM@LDEO.COLUMBIA.EDU
AOKI@LDEO.COLUMBIA.EDU
ARMIJO@SPARC.IPGP.JUSSIEU.FR
ALAIN.ARNAUD@ALTAMIRA-INFORMATION.COM
ANTAV@IPGP.JUSSIEU.FR
GBAWDEN@USGS.GOV
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LEGRESY@PINOT.CST.CNES.FR
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DIRGEOSC@UNIV-RENNES1.FR
JEROME.BRUNIQUEL@SPACE.ALCATEL.FR
BURGMANN@SEISMO.BERKELEY.EDU
ECABRAL@TONATIUH.IGEOFCU.UNAM.MX
CAKIRZ@ITU.EDU.TR
C.CARNEC@BRGM.FR
CARNEC@EXCHANGE.BRGM.FR
CAROLINA@HI.IS
CHEMINEE@IPGP.JUSSIEU.FR
JEAN@DSTU.UNIV-MONTP2.FR
DELAC@ALTO.UNIV-LYON1.FR
C.KING@BRGM.FR
COUNIL@CST.CNES.FR
JCC@VEXCEL.COM
OLIVIER.DAUTEUIL@UNIV-RENNES1.FR
DECHABAL@IPGP.JUSSIEU.FR
BENOIT.DEFFONTAINES@EPHE.SORBONNE.FR
DENIS.FEURER@VOILA.FR
DESMOND.DARBY@GNS.CRI.NZ
ALSDORF@GEOLOGY.OHIO-STATE.EDU
THIERRY.DUQUESNOY@IGN.FR
PHILIPPE.DURAND@CNES.FR
DZURISIN@ASOPUS.WR.USGS.GOV
NELASSAD@IRESTE.FR
E.VAN.DALFSEN@OPEN.AC.UK
MENEVA@SAN.RR.COM
FABIO.BOVENGA@BA.INFN.IT
FEIGL@PONTOS.CST.CNES.FR
D.FEURER@BRGM.FR
VIGNON@CLIPPER.ENS.FR
REMY
FS@NORVOL.HI.IS
J.L.FROGER@OPGC.UNIV-BPCLERMONT.FR
FRUNEAU@UNIV-MLV.FR
GARETHF@EARTH.OX.AC.UK
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52)
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83)
84)
85)
Galloway
Gasperi
Gking
Gmascle
Granet
Guerre
Guyot
Hanssen
Hargrove
Herlin
Jackson
Joern Hoffmann
John W. Bell
Jonsson
Jouanne
Kohlhase
Labazuy
Laurent Marinelli
Le Mouelic
Legresy
Lenat
Lesage
Lognonne
Lohman
Louat
Lu
Massonnet
Mazzega
Mcclusky
Meyer
Michael Inggs
Michael Studinger
Michel Peyret
Michel Sebrier
Michel.sebrier@lgs.jussieu.fr
86) Michelle Sneed
87) Michelremi
88) Mohamed Chlieh
89) Mohr
90) Mougin
91) Nicki Stevens
92) Oliver Henriot
93) Oppenheimer
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95) Parsons
96) Pastor
97) Pathier
98) Pavez
99) Peter Clarke
100) Peyret
101) Pinet
102) Podaire
103) Pourthie
104) Pourthie
105) Pritchard
Feigl et al.
DLGALLOW@USGS.GOV
GASPERI@CAHORS.CST.CNES.FR
KING@IPGP.JUSSIEU.FR
GMASCLE@UJF-GRENOBLE.FR
MICHEL@SILMARIE.U-STRASBG.FR
LOUIS-FRANCOIS.GUERRE@SPOTIMAGE.FR
GUYOT@LMCP.JUSSIEU.FR
R.HANSSEN@GEO.TUDELFT.NL
HNW@FIRE.ESD.ORNL.GOV
ISABELLE.HERLIN@INRIA.FR
DJACKSON@UCLA.EDU
JOERN@PANGEA.STANFORD.EDU
JBELL@UNR.EDU
JONSSON@PANGEA.STANFORD.EDU
JOUANNE@UNIV-SAVOIE.FR
ANDREAS.KOHLHASE@DLR.DE
LABAZUY@OPGC.UNIV-BPCLERMONT.FR
DEV@GEOIMAGE.FR
LEMOUELIC@EXCHANGE.BRGM.FR
BENOIT.LEGRESY@NOTOS.CST.CNES.FR
LENAT@OPGC.UNIV-BPCLERMONT.FR
PHILIPPE.LESAGE@UNIV-SAVOIE.FR
LOGNONNE@IPGP.JUSSIEU.FR
FISHEGGS@GPS.CALTECH.EDU
LOUAT@IPGP.JUSSIEU.FR
LU@EDCMAIL.CR.USGS.GOV
DIDIER.MASSONNET@CNES.FR
CIAMP@NOTOS.CST.CNES.FR
SIMON@WEGENER.MIT.EDU
MEYER@SPARC.IPGP.JUSSIEU.FR
MIKINGS@ENG.UCT.AC.ZA
MSTUDING@LDEO.COLUMBIA.EDU
MICHEL.PEYRET@DSTU.UNIV-MONTP2.FR
MICHEL.SEBRIER@LGS.JUSSIEU.FR
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PETER.CLARKE@NEWCASTLE.AC.UK
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PINET@PONTOS.CST.CNES.FR
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NADINE.POURTHIE@CNES.FR
MATT@GPS.CALTECH.EDU
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106) Ramon Hanssen
107) Raucoules
108) Remko Scharroo
109) Remy
110) Remyd
111) Revaux
112) Ribbes
113) Rigo
114) Rikke Pedersen
115) Ritz
116) Romieu
117) Rosenblatt
118) Rudant
119) Rudi Gens
120) Ruegg
121) Sassier
122) Sebrier
123) Simons
124) Smith
125) Sylvia Stork
126) Tapponnier
127) Thierry Souriot
128) Tregoning
129) Ultre-guerard
130) Umberto Fracassi
131) Vadon
132) Villemin
133) Wolfgang Rack
134) Wright
135) Xxuejun Qiao
136) Young
137) Zerubia
138) Zhong Lu
Feigl et al.
R.F.HANSSEN@GEO.TUDELFT.NL
RAUCOULES@EXCHANGE.BRGM.FR
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CHARLES.REVAUX@IFP.FR
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WHGPS1@PUBLIC.WH.HB.CN
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JOSIANE.ZERUBIA@SOPHIA.INRIA.FR
LU@USGS.GOV
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GLOSSARY
2-pass differential interferometry. Approach to calculating interferograms which uses two radar images and a
digital elevation model. Also called DEM-elimination.
3-pass interferometry. Approach to calculating interferograms which uses three radar images but no elevation
model. Also called double differencing.
altitude of ambiguity. The topographic relief (or error) required to create one fringe in an interferogram. Noted
ha and expressed in units of meters. Also called “ambiguity height”. Defined and sketched in Massonnet
and Rabaute [1993] and Massonnet and Feigl [1998].
azimuth. In radar terminology, the along-track component of the vector between the ground and the satellite. The
azimuth direction is parallel to the trajectory of the satellite.
baseline. In triangulation networks, the scalar distance between two bench marks which determines the scale of
the network. In GPS, the same term has come to mean the vector difference in position between two
bench marks. In INSAR, jargon for the (vector ) separation or (scalar) distance between two orbital
trajectories.
C-band. Radar frequency around 5 GHz with wavelength around 6 cm.
CDP. Crustal Dynamics Project, a NASA research program in the 1980s.
CGPS. Continuously operating GPS receivers and networks.
CNES. Centre National d’Etudes Spatiales. French space agency.
cross-track. Component of motion perpendicular to the trajectory of the satellite.
DEM. Digital Elevation Model. An array of topographic values.
displacement vector. Movement of a point on the Earth’s surface. Usually defined in a local (east, north, up)
coordinate system.
DORIS. Détermination d’Orbite et Radiopositionnement Intégré par Satellite. Doppler satellite navigation
system developed by the French Space Agency.
double-difference. In INSAR, this term denotes the difference of two interferograms, each of which is the
difference of two radar images. In GPS, this term describes a linear combination of four signals involving
two satellites and two receivers.
DTED. Digital Terrain Elevation Data.
EDM. Electronic Distance Measurement. The technique and instrument usually used for trilateration [Bomford,
1980].
ERS-1. European Remote Sensing satellite 1. Carries a C-band SAR. Launched in 1991.
ERS-2. Twin of ERS-1, launched in 1995.
ESA. European Space Agency.
GPS. Global Positioning System. Dual-frequency L-band satellite navigation system.
IGS. International GPS Service. An organization responsible for worldwide coordination of continuous GPS
measurements [Zumberge et al., 1996].
INSAR. INterferometric (analysis of) Synthetic Aperture Radar (images). Recent reviews [Bamler and Hartl,
1998; Madsen and Zebker, 1998; Massonnet and Feigl, 1998].
ITRF. International Terrestrial Reference Frame. The geodetic reference frame defined by a combination of VL
BI, SLR, DORIS and GPS currently used to represent absolute coordinates for sub-centimeter geodetic
measurements[Boucher et al., 1992].
JERS-1. Japanese Earth Resource Satellite 1.
JPL. Jet Propulsion Laboratory, Pasadena, California.
Landsat. Series of optical imaging satellites.
L-band. Radar frequency around 1.2 GHz with wavelength around 25 cm.
radar. RAdio Detection And Ranging
RADARSAT. Multi-mode, C-band radar satellite launched by Canada in 1995.
range. Distance along the line of sight between the satellite and the ground.
SAR. Synthetic Aperture Radar.
SEASAT. L-band radar satellite with altimeter which flew only for several months in 1978.
SIR-C. Shuttle Imaging Radar C.
SLC. Single Look Complex. Radar image including both phase and amplitude information, after processing by
the synthetic aperture resolution reconstruction process.
SLR. Satellite Laser Ranging
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SPOT. Satellite Pour l’Observation de la Terre. Series of optical imaging satellites with a resolution of 10 or 20
m for Earth observation.
SRTM. Shuttle Radar Topographic Mission.
VLBI. Very Long Baseline Interferometry. X-band. Radar frequency around 9 GHz with wavelength around 3
cm.
WEGENER. An SLR geodetic network around the Mediterranean.
WGS84. World Geodetic System, 1984. A system of coordinates conventionally used for (coarse) GPS
coordinates. Includes an ellipsoid with inverse flattening 1/f = 298.25722 and semi-major axis =
6378.137 km [DMA, 1987].
ACKNOWLEDGMENTS
I thank Alexis Rigo, Benoit Legresy and Didier Massonnet for helpful discussions. We thank the European
Space Agency for providing most of the ERS data free of charge. GDR INSAR has been financed by l’Institut
National des Sciences de l’Univers and Centre National d’Etudes Spatiales.
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BIBLIOGRAPHY OF GDR INSAR AND GDR STRAINSAR
Peer-reviewed publications with at least one author from our GDR:
1993-1994
Massonnet, D., and T. Rabaute, Radar interferometry: limits and potential, IEEE Trans. Geoscience & Rem. Sensing, 31,
455–464, 1993.
Massonnet, D., M. Rossi, C. Carmona, F. Adragna, G. Peltzer, K. Feigl, and T. Rabaute, The displacement field of the
Landers earthquake mapped by radar interferometry, Nature, 364, 138-142, 1993. [Cover]
Massonnet, D., K. L. Feigl, M. Rossi, and F. Adragna, Radar interferometric mapping of deformation in the year after the
Landers earthquake, Nature, 369, 227–230, 1994.
Massonnet, D., M. Rossi, and F. Adragna, CNES General-purpose SAR correlator, IEEE Trans. Geosci. Rem. Sensing, 32,
636-643, 1994.
Peltzer, G., K. W. Hudnut, and K. L. Feigl, Analysis of surface displacement gradients using radar interferometry: New
insights into the Landers earthquake, J. Geophys. Res., 99, 21,971–21,981, 1994.
GDR INSAR (1995-1999) – 53 peer-reviewed publications
Alsdorf, D. E., and L. C. Smith, Interferometric SAR observations of ice topography and velocity changes related to the
1996, Gjálp subglacial eruption, Iceland, International J. Remote Sensing, 20, 3031-3050, 1999.
Amelung, F., D. Galloway, J. Bell, H. Zebker, and R. Laczniak, Sensing the ups and downs of Las Vegas: InSAR reveals
structural control of land subsidence and aquifer-system deformation, Geology, 27, 483-486, 1999.
Ancey, H., S. Mascle, H. Tarayre, L. Peytavin, J. A. Sirat, and M. Mariton, Valorisation des plateformes RSO: cas
particulier du deroulement des franges interferometriques, Bulletin - Societe Francaise de Photogrammetrie et de
Teledetection, 138, 66-72, 1995.
Avallone, A., P. Briole, C. Delacourt, A. Zollo, and F. Beauducel, Subsidence at Campi Flegrei (Italy) detected by SAR
interferometry, Geophys. Res. Lett., 26, 2303-2306, 1999.
Briole, P., D. Massonnet, and C. Delacourt, Post-eruptive deformation associated with the 1986-87 and 1989 lava flows of
Etna detected by radar interferometry, Geophys. Res. Lett., 24, 37-40, 1997.
Carnec, C., and H. Fabriol, Monitoring and modeling land subsidence at the Cerro Prieto geothermal field, Baja California,
Mexico using SAR interferometry, Geophys. Res. Lett., 26, 1121-1214, 1999.
Cayol, V., and F. H. Cornet, Effects of topography on the interpretation of the deformation field of prominent volcanoes:
Application to Etna, Geophys. Res. Lett., 25, 1979-1982, 1998.
Clarke, P. J., D. Paradissis, P. Briole, P. C. England, B. E. Parsons, H. Billiris, G. Veis, and J.-C. Ruegg, Geodetic
investigation of the 13 May 1995 Kozani-Grevena (Greece) earthquake, Geophys. Res. Lett., 24, 707-710, 1996.
Clarke, P. J., D. Paradissis, P. Briole, P. C. England, B. E. Parsons, H. Billiris, G. Veis, and J.-C. Ruegg, Reply to Comment
by Meyer et al. on"Geodetic investigation of the May 13, 1995 Kozani-Grevena (Greece) earthquake" by P. J. Clarke et
al., Geophys. Res. Lett., 25, 131-134, 1998.
Delacourt, C., P. Briole, and J. Achache, Tropospheric corrections of SAR interferograms with strong topography.
Application to Etna, Geophys. Res. Lett., 25, 2849-2852, 1998.
Feigl, K. L., A. Sergent, and D. Jacq, Estimation of an earthquake focal mechanism from a satellite radar interferogram:
application to the December 4, 1992 Landers aftershock, Geophys. Res. Lett., 22, 1037-1048, 1995. [Cover]
Feigl, K. L., and E. Dupré, RNGCHN: a program to calculate displacement components from dislocations in an elastic halfspace with applications for modeling geodetic measurements of crustal deformation, Computers and Geosciences, 25,
695-704, 1999. [Best Paper Award]
Fielding, E. J., R. G. Blom, and R. M. Goldstein, Rapid subsidence over oil fields measured by SAR interferometry,
Geophys. Res. Lett., 25, 3215-3218, 1998. [Cover]
Fruneau, B., and J. Achache, Détection du glissement de terrain de Saint-Etienne-de-Tinée par interférométrie SAR et
modélisation, Note de l'Académie des Sciences, T.320, série II a, 809-816, 1995.
Fruneau, B., J. Achache, and C. Delacourt, Observation and modelling of the Saint-Etienne-de-Tinee landslide using SAR
interferometry, Tectonophysics, 265, 181-190, 1996.
Galloway, D. L., K. W. Hudnut, S. E. Ingebritsen, S. P. Phillips, G. Peltzer, F. Rogez, and P. A. Rosen, Detection of aquifer
system compaction and land subsidence using interferometric synthetic aperture radar, Antelope Valley, Mojave Desert,
California, Water Resour. Res., 34, 2573-2585, 1998.
Hanssen, R. F., T. M. Weckwerth, H. A. Zebker, and R. Klees, High-resolution water vapor mapping from interferometric
radar measurements, Science, 283, 1295-1297, 1999.
Hanssen, R., and R. Bamler, Evaluation of interpolation kernels for SAR interferometry., IEEE Trans. on Geoscience and
Remote Sensing,, 37, 318-321, 1999.
Hernandez, B., F. Cotton, and M. Campillo, Contribution of radar interferometry to a two step inversion of the kinematic
process of the 1992 Landers earthquake, J. Geophys. Res., 104, 13,083-13,099, 1999.
Ichoku, C., A. Karnieli, Y. Arkin, J. Chorowicz, T. Fleury, and J.-P. Rudant, Exploring the utility potential of SAR
interferometric coherence images, International Journal of Remote Sensing, 19, 1147-1160, 1998.
Lu, Z., and J. Freymueller, Synthetic aperture radar interferometry coherence analysis over Katmai volcano group, Alaska, J.
Geophys. Res, 103, 29887-29894., 1998.
Lu, Z., D. Mann, and J. Freymueller, Satellite radar intererometry measures deformation at Okmok volcano, Eos Trans.
Amer. Geophys. Un., 79, 461-468, 1998.
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Lu, Z., R. Fatland, M. Wyss, S. Li, J. Eichelberger, K. Dean, and J. Freymuller, Deformation of New Trident volcano
measured by ERS-1 SAR interferometry, Geophys. Res. Lett., 24, 695-698, 1997.
Lyuboshenko, I., and H. Maître, Phase Unwrapping for Interferometric SAR Using Helmholtz Equation Eigenfunctions and
the First Green's Identity, Journal of the Optical Society of America A, 16, 378-395, 1999.
Marinelli, L., and L. Laurore, Une méthode simple de déroulement de phase appliquée à la restitution de MNT
interférométrique, Bulletin de la Société Française de Photogrammétrie et Télédétection, 138, 33-38, 1995.
Massonnet, D., and K. L. Feigl, Discriminating geophysical phenomena in satellite radar interferograms, Geophys. Res. Lett.,
22, 1537-1540, 1995.
Massonnet, D., and K. L. Feigl, Radar interferometry and its application to changes in the Earth's surface, Rev. Geophys., 36,
441-500, 1998.
Massonnet, D., and K. L. Feigl, Satellite radar interferometric map of the coseismic deformation field of the M = 6.1 Eureka
Valley, Calfornia earthquake of May 17, 1993., Geophys. Res. Lett., 22, 1541-1544, 1995.
Massonnet, D., H. Vadon, and C. Carmona, ERS-1 Internal clock drift measured by interferometry, IEEE Trans. Geosci.
Rem. Sensing, 33, 401-408, 1995.
Massonnet, D., P. Briole, and A. Arnaud, Deflation of Mount Etna monitored by spaceborne radar interferometry, Nature,
375, 567-570, 1995. [Cover]
Massonnet, D., Satellite radar interferometry, Scientific American, 262, 46-53, 1997.
Massonnet, D., T. Holzer, and H. Vadon, Land subsidence caused by the East Mesa geothermal field, California, observed
using SAR interferometry, Geophys. Res. Lett., 24, 901-904, 1997.
Meyer, B., R. Armijo, D. Massonnet, J. B. de Chabalier, C. Delacourt, J. C. Ruegg, J. Achache, and D. Papanastassiou,
Comment on "Geodetic investigation on the May 13, 1995 Kozani-Grevena (Greece) earthquake" by Clarke et al.,
Geophys. Res. Lett., 25, 129-130, 1998.
Meyer, B., R. Armijo, D. Massonnet, J. B. de Chabalier, C. Delacourt, J. C. Ruegg, J. Achache, P. Briole, and D.
Panastassiou, The 1995 Grevena (Northern Greece) earthquake: fault model constrained with tectonic observations and
SAR interferometry, Geophys. Res. Lett., 23, 2677-2680, 1996.
Michel, R., and E. Rignot, Flow of Glaciar Moreno, Argentina, from repeat-pass Shuttle Imaging Radar images: comparison
of the phase correlation method with radar interferometry, J. Glaciology, 45, 1999.
Michel, R., J. P. Avouac, and J. Taboury, Measuring ground displacements from SAR amplitude images: application to the
Landers earthquake, Geophys. Res. Lett., 26, 875-878, 1999.
Michel, R., J. P. Avouac, and J. Taboury, Measuring near field ground displacements from SAR images: application to the
Landers earthquake, Geophys. Res. Lett., 26, 3017-3020, 1999.
P. Bernard, P. Briole, B. Meyer, H. Lyon Caen, J.-M. Gomez-Gonzalez, C. Tiberi, R. Cattin, D. Hatzfeld, C. Lachet, B.
Lebrun, A. Deschamps, F. Courboulex, C. Larroque, A. Rigo, D. Massonnet, P. Papadimitriou, J. Kassaras, D.
Diagourtas, K. Makropoulos and G. Veis, The Ms=6.2, June 15, 1995 Aigion earthquake (Greece): Evidence for low
normal faulting in the Corinth rift., J. of Seismology, 1, 131-150, 1997.
Perlant, F., Utilisation de l'interférométrie RADAR (RSO) pour la réalisation et l'interpolation d'ortho-images, Societe
Francaise de Photogrammetrie et de Teledetection, 138, 54-65, 1995.
Rigo, A., and D. Massonnet, Investigating the 1996 Pyrenean earthquake (France) with SAR Interferograms heavily distorted
by atmosphere, Geophys. Res. Lett, 26, 3217-3220, 1999.
Rossi, M., B. Rogron, and D. Massonnet, JERS-1 SAR image quality and interferometric potential, IEEE Trans. Geosci.
Rem. Sens., 34, 824-827, 1996.
Scharroo, R., and P. Visser, Precise orbit determination and gravity field improvement for the ERS satellites, J. Geophys.
Res., 103, 8113-8128, 1998.
Shan, X., and H. Ye, The INSAR technique: its principle and applications to mapping the deformation field of earthquake,
Acta Seismologica Sinica, 11, 759-769, 1998.
Sigmundsson, F., H. Vadon, and D. Massonnet, Readjustment of the Krafla spreading center segment to crustal rifting
measured by satellite radar interferometry, Geophys. Res. Lett., 24, 1843-1846, 1997.
Sigmundsson, F., P. Durand, and D. Massonnet, Opening of an eruptive fissure and seaward displacement at Piton de la
Fournaise volcano measured by RADARSAT satellite radar interferometry, Geophys. Res. Lett., 26, 533-536, 1999.
[Cover]
Stramondo, S. Tesauro, M., Briole, P., Sansosti, E., Salvi, S., Lanari, R., Anzidei, M., Baldi, P., Fornaro, G., Avallone, A.,
Buongiorno, M. F., Franceschetti, G. and Boschi, E.The September 26, 1997, Colfiorito, Italy, earthquakes: Modeled
coseismic surface displacement from SAR interferometry and GPS, Geophys. Res. Lett., 26, 883-886, 1999.
Sylvander, S., and P. Gigord, Exploitation tridimensionelle d'images ERS-1, Bulletin de la Société Française de
Photogrammétrie et Télédétection, 40-53, 40-53, 1995.
Trouvé, E., J.-M. Nicolas, and H. Maître, Improving phase unwrapping techniques by the use of local frequency estimates,
IEEE Transactions on Geoscience and Remote Sensing, 36, 1963-1972, 1998.
Vadon, H., and F. Sigmundsson, 1992-1995 Crustal deformation at Mid-Atlantic ridge, SW Iceland, mapped by radar
interferometry, Science, 275, 194-197, 1997.
Wicks, C., W. Thatcher, and D. Dzurisin, Migration of fluids beneath Yellowstone caldera inferred from satellite radar
interferometry, Science, 282, 458-462, 1998.
Williams, C. A., and G. Wadge, The effects of topography on magma chamber inflation models: Application to Mt. Etna and
radar intererometry, Geophys. Res. Lett., 25, 1549-1552, 1998.
Wright, P., and R. Stow, Detecting mining subsidence from space, Int J Remote Sensing, 20, 1183, 1999.
Wright, T. J., B. E. Parsons, J. A. Jackson, M. Haynes, E. J. Fielding, P. C. England, and P. J. Clarke, Source parameters of
the 1 October 1995 Dinar (Turkey) earthquake from SAR interferometry and seismic bodywave modelling, Earth Plan.
Sci. Lett., 172, 23-27, 1999.
GDR STRAINSAR (2000-2005) 98 peer-reviewed publications
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Alsdorf, D. E., J. M. Melack, T. Dunne, L. A. K. Mertes, L. L. Hess, and L. C. Smith, Interferometric radar measurements of
water level changes on the Amazon floodplain, Nature, 404, 174-177,, 2000.
Alsdorf, D. E., L. C. Smith, and J. M. Melack, Amazon water level changes measured with interferometric SIR-C radar, IEEE
Transactions on Geoscience and Remote Sensing, in press, 2000.
Amelung, F., and J. W. Bell (2003), Interferometric synthetic aperture radar observations of the 1994 Double Spring Flat,
Nevada earthquake (M 5.9): Mainshock accompanied by triggered slip on a conjugate fault, J. Geophys. Res., 108,
2433, doi:2410.1029/2002JB001953 .
Amelung, F., C. Oppenheimer, P. Segall, and H. Zebker, Ground deformation near Gada 'Ale Volcano, Afar, observed by
Radar Interferometry, Geophys. Res. Lett., 3093-3096, 27, 2000.
Arnadottir, T., R. Pedersen, S. Jonsson, and G. Gudmundsson (2003), Coulomb stress changes in the South Iceland Seismic
Zone due to two large earthquakes in June 2000, Geophys. Res. Lett., 30, doi:10.1029/2002GL016495. The South
Iceland Seismic Zone experienced the largest earthquakes for 88 years in June 2000, with a MS = 6.6 event on June 17,
followed by another MS = 6.6 earthquake on June 21. These events occurred on two parallel N-S striking, right-lateral
strike slip faults, separated by about 17 km. We calculate the static Coulomb stress change for the June 17 and 21
earthquakes using a distributed slip model derived from joint inversion of InSAR and GPS data. We find that the static
stress change caused by the June 17 event is about 0.1 MPa at the location of the June 21 hypocenter, promoting failure
on the second fault. Locations of aftershocks agree well with areas of increased Coulomb failure stress. Our calculations
indicate that positive stress changes due to the two earthquakes make the area west of the June 21 rupture the most likely
site of the next large earthquake in South Iceland. doi:10.1029/2002GL016495
Árnadóttir, T., H. Geirsson, and P. Einarsson (2004), Coseismic stress changes and crustal deformation on the Reykjanes
Peninsula due to triggered earthquakes on 17 June 2000, Journal of Geophysical Research (Solid Earth), 109, 09307. A
large (Mw = 6.5) earthquake struck the South Iceland Seismic Zone (SISZ) on 17 June 2000. The 17 June main shock
triggered increased seismicity over a large area and significant slip on at least three distinct faults on the Reykjanes
Peninsula, up to 87 km to the west of the event. A second large (Mw = 6.4) earthquake in the SISZ occurred on 21 June
2000, about 17 km west of the 17 June main shock. This event does not appear to have triggered as much activity on the
Reykjanes Peninsula as the 17 June main shock, although the epicenter was closer. Crustal deformation signals due to
the June 2000 earthquakes on the Reykjanes Peninsula were observed with campaign and continuous GPS and synthetic
aperture radar interferometry, with the largest coseismic deformation signal near lake Kleifarvatn. We model the faults
using three uniform slip rectangular dislocations in an elastic half-space. Best fit uniform slip models consistent with
seismic and geodetic data indicate that all three faults trend N-S and the motion on them was primarily right-lateral
strike slip. Our study suggests that the event near Kleifarvatn had a significantly larger moment than seismic estimates,
indicating a component of aseismic slip on the fault lasting no more than several hours. Static Coulomb failure stress
change calculations indicate that the event at Kleifarvatn increased the Coulomb stress at the hypocenter of the
Núpshlídarháls event by 0.1-0.2 MPa as well as loading the Hvalhnúkur fault.
Baumont, D., O. Scotti, F. Courboulex, and N. Melis (2004), Complex kinematic rupture of the Mw 5.9, 1999 Athens
earthquake as revealed by the joint inversion of regional seismological and SAR data, Geophysical Journal International,
158, 1078-1087. Slip distributions of the moderate magnitude (Mw 5.9), 1999 Athens earthquake, inverted from surface
waves and interferometric Synthetic Aperture Radar (SAR) images, show very different characteristics. The robustness
analysis proposed in this study, confirms the discrepancy between the well-constrained features of each individual
solution. Irrespective of the hypotheses we made (data/modeling errors, slow deformation, post- or pre-seismic slip), the
joint inversion of the two data sets led to a complex and heterogeneous rupture model. This model is characterized by a
short rise time (<5 s) slip patch centred on the hypocentre, extending bilaterally up to 4 km depth and down to 17 km
and releasing approximately 70 per cent of the total moment. Located further to the WNW and releasing the remaining
30 per cent of the total moment, a long rise time slip patch extends from 8 to 17 km depth. If the short rise time slip
patch propagated above and below the brittle zone delineated by the aftershocks, the long rise time slip patch (slow
deformation) appears to be mostly confined below the brittle zone. This unified model satisfies the analysis of the
seismic and geodetic slip distributions as well as the location of the aftershock sequence and attests to the diversity of
the crustal response even for moderate size faults.
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004GeoJI.158.1078B&db_key=AST
Bawden, G. W., W. Thatcher, R. S. Stein, K. W. Hudnut, and G. Peltzer (2001), Tectonic contraction across Los Angeles
after removal of groundwater pumping effects, Nature, 412, 812 - 815. After the 1987 Whittier Narrows and 1994
Northridge earthquakes revealed that blind thrust faults represent a significant threat to metropolitan Los Angeles, a
network of 250 continuously recording global positioning system (GPS) stations was deployed to monitor displacements
associated with deep slip on both blind and surface faults. Here we augment this GPS data with interferometric synthetic
aperture radar imagery to take into account the deformation associated with groundwater pumping and strike-slip
faulting. After removing these non-tectonic signals, we are left with 4.4 mm yr-1 of uniaxial contraction across the Los
Angeles basin, oriented N 36° E (perpendicular to the major strike-slip faults in the area). This indicates that the
contraction is primarily accommodated on thrust faults rather than on the northeast-trending strike–slip faults. We have
found that widespread groundwater and oil pumping obscures and in some cases mimics the tectonic signals expected
from the blind thrust faults. In the 40-km-long Santa Ana basin, groundwater withdrawal and re-injection produces 12
mm yr-1 of long-term subsidence, accompanied by an unprecedented seasonal oscillation of 55 mm in the vertical
direction and 7 mm horizontally. http://www.nature.com/nlink/v412/n6849/abs/412812a0_fs.html
Beauducel, F., P. Briole, and J. L. Froger, Volcano wide fringes in ERS synthetic aperture radar interferograms of Etna:
Deformation or tropospheric effect?, J. Geophys. Res., 105, 16,391-16,402, 2000.
Beauducel, F., P. Briole, J.-L. Froger, and D. Rémy, SAR Interferometry studies of Mt Merapi, Java, Indonesia, Report to
ESA 2000.
Berthier, E., H. Vadon, D. Baratoux, Y. Arnaud, C. Vincente, K. L. Feigl, F. Remy, and B. Legresy (2004), Surface motion
of mountain glaciers derived from satellite optical imagery, Remote Sensing of Environment, in press. A complete and
detailed map of the ice-velocity field on mountain glaciers is obtained by cross-correlating SPOT5 optical images. This
approach offers an alternative to SAR interferometry, because no present or planned RADAR satellite mission provides
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data with a temporal separation short enough to derive the displacements of glaciers. The methodology presented in this
study does not require ground control points (GCPs). The key step is a precise relative orientation of the two images
obtained by adjusting the stereo model of one slave image assuming that the other master image is well georeferenced.
It is performed with numerous precisely-located homologous points extracted automatically. The strong ablation
occurring during summer time on the glaciers requires a correction to obtain unbiased displacements. The accuracy of
our measurement is assessed based on a comparison with nearly simultaneous differential GPS surveys performed on
two glaciers of the Mont Blanc area (Alps). If the images have similar incidence angles and correlate well, the accuracy
is on the order of 0.5 m, or 1/5 of the pixel size. Similar results are also obtained without GCPs. An acceleration event,
observed in early August for the Mer de Glace glacier, is interpreted in term of an increase in basal sliding. Our
methodology, applied to SPOT5 images, can potentially be used to derive the displacements of the Earth’s surface
caused by landslides, earthquakes, and volcanoes.
Carnec, C., and C. Delacourt, Three years of mining subsidence monitored by SAR interferometry, Gardanne, France,
Applied Geophysics, 43, 43-54, 2000.
Catita, C., J. Catalão, J. M. Miranda, K. L. Feigl, and L. A. Mendes-Victor (2004), Co-seismic Deformation of the 9th July
1998 Faial (Azores) Earthquake Detected by Radar Interferometry, Int. J. Rem. Sensing, in press.
Champollion, C., F. Masson, J. Van Baelen, A. Walpersdorf, J. Chéry, and E. Doerflinger (2004), GPS monitoring of the
tropospheric water vapor distribution and variation during the 9 September 2002 torrential precipitation episode in the
Cévennes (southern France), Journal of Geophysical Research (Atmospheres), 109, 24102. On 8-9 September 2002,
torrential rainfall and flooding hit the Gard region in southern France causing extensive damages and casualties. This is
an exceptional example of a so-called Cévenol episode with 24 hour cumulative rainfall up to about 600 mm at some
places and more than 200 mm over a large area (5500 km^2 ). In this work we have used GPS data to determine
integrated water vapor (IWV) as well as horizontal wet gradients and residuals. Using the IWV, we have monitored the
evolution of the convective system associated with the rainfall from the water vapor accumulation stage through the
stagnation of the convective cell and finally to the breakup of the system. Our interpretation of the GPS meteorological
parameters is supported by synoptic maps, numerical weather analyses, and rain images from meteorological radars. We
have evidenced from GPS data that this heavy precipitation is associated with ongoing accumulation of water vapor,
even through the raining period, but that rain stopped as soon as the weather circulation pattern changed. The evolution
of this event is typical in the context of the Cévenol meteorology. Furthermore, we have shown that the horizontal wet
gradients help describe the heterogeneity of the water vapor field and holds information concerning the passage of the
convective system. Finally, we have noticed that the residuals, which in theory should be proportional to water vapor
heterogeneity, were also highly perturbed by the precipitation itself. In our conclusions we discuss the interest of a
regional GPS network for monitoring and for future studies on water vapor tomography. http://adsabs.harvard.edu/cgibin/nph-bib_query?bibcode=2004JGRD.10924102C&db_key=PHY
Chlieh, M., J. B. de Chabalier, J. C. Ruegg, R. Armijo, R. Dmowska, J. Campos, and K. L. Feigl (2004), Crustal deformation
and fault slip during the seismic cycle in the North Chile subduction zone, from GPS and InSAR observations,
Geophysical Journal International, 158, 695-711. The different phases of the earthquake cycle can produce measurable
deformation of the Earth's surface. This work is aimed at describing the evolution of that deformation in space and time,
as well as the distribution of causal slip on the fault at depth. We have applied GPS and synthetic aperture radar (SAR)
interferometry (InSAR) techniques to northern Chile, where fast plate convergence rates are associated with large
subduction earthquakes and extensive crustal deformation. The region of northern Chile between 18°S and 23°S is one
of the most important seismic gaps in the world, with no rupture having occurred since 1877. In 1995, the Mw = 8.1
Antofagasta earthquake ruptured the subduction interface over a length of 180 km in the region immediately to the south
of this 450 km long gap. The coseismic deformation associated with this event has been documented previously. Here
we use GPS position time-series for 40 benchmarks (measured between 1996 and 2000) and ERS SAR interferograms
(for the interval between 1995 and 1999) to map both the post-seismic deformation following the 1995 event and the
ongoing interseismic deformation in the adjacent gap region. In the seismic gap, the interseismic velocities of 20-30 mm
yr^-1 to the east with respect to South America are mapped. Both the GPS and the InSAR measurements can be
modelled with 100 per cent coupling of the thrust interface of the subduction to a depth of 35 km, with a transition zone
extending down to 55 km depth. The slip rate in that zone increases linearly from zero to the plate convergence rate.
South of the gap, the interferometric map shows interseismic deformation superimposed with deformation following the
1995 earthquake and covering the same area as the coseismic deformation. Some 40 per cent of this deformation is
related to seismic activity in the 3.3 yr following the 1995 event, in particular slip during a Mw = 7.1 earthquake in
1998. However, most of the signal (60 per cent) corresponds to post-seismic deformation resulting from widespread
aseismic slip in the subduction interface. The afterslip appears to have occurred down-dip in the transition zone at 35-55
km depth and to have propagated laterally northwards at 25-45 km depth under the Mejillones Peninsula, which is a
prominent geomorphological feature at the boundary between the 1877 and 1995 rupture zones. We propose a simple
slip model for the seismic cycle associated with the Antofagasta earthquake, where the transition zone alternates between
aseismic shear and seismic slip.
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004GeoJI.158.695C&db_key=AST
Clifton, A. E., F. Sigmundsson, K. Feigl, G. Guðmundsson, and T. Árnadóttir (2001), Surface effects of faulting and
deformation resulting from magma accumulation at the Hengill triple junction, SW Iceland, 1994 - 1998, Journal of
Volcanology and Geothermal Research, 115, 233-255. The Hengill triple junction, SW Iceland, is subjected to both
tectonic extension and shear, causing seismicity related to strike-slip and normal faulting. Between 1994 and 1998, the
area experienced episodic swarms of enhanced seismicity culminating in a ML=5.1 earthquake on June 4, 1998 and a
ML=5 earthquake on November 13, 1998. Geodetic measurements, using Global Positioning System (GPS), leveling
and Synthetic Aperture Radar Interferometry (InSAR) detected maximum uplift of 2 cm/yr and expansion between the
Hrómundartindur and Grensdalur volcanic systems. A number of faults in the area generated meter-scale surface breaks.
Geographic Information System (GIS) software has been used to integrate structural, field and geophysical data to
determine how the crust failed, and to evaluate how much of the recent activity focused on zones of pre-existing
weaknesses in the crust. Field data show that most surface effects can be attributed to the June 4, 1998 earthquake and
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have occurred along or adjacent to old faults. Surface effects consist of open gashes in soil, shattering of lava flows,
rockfall along scarps and within old fractures, loosened push-up structures and landslides. Seismicity in 1994¯1998 was
distributed asymmetrically about the center of uplift, with larger events migrating toward the main fault of the June 4,
1998 earthquake. Surface effects are most extensive in the area of greatest structural complexity, where N- and Etrending structures related to the transform boundary intersect NE-trending structures related to the rift zone. InSAR,
GPS, and field observations have been used in an attempt to constrain slip along the trace of the fault that failed on June
4, 1998. Geophysical and field data are consistent with an interpretation of distributed slip along a segmented rightlateral strike-slip fault, with slip decreasing southward along the fault plane. We suggest a right step or right bend
between fault segments to explain local deformation near the fault.
Dalfsen, E. d. Z.-v., R. Pedersen, F. Sigmundsson, and C. Pagli (2004), Satellite radar interferometry 1993–1999 suggests
deep accumulation of magma near the crust-mantle boundary at the Krafla volcanic system, Iceland, Geophys. Res. Lett.,
31, 1-5. Deep magma accumulation near the crust-mantle boundary (21 km depth) at the Krafla volcanic system is
suggested from InSAR observations. A best fit model, derived from four interferograms covering 1993–1999,
comprises an opening dike, representing plate spreading and post-rifting deformation, and two Mogi sources. A Mogi
source deflating at a rate of 10^6 m^3 /yr coincides with the shallow Krafla magma chamber while a deeper inflating
Mogi source, further north, at 21 km depth, inflates at a rate of 26 x 10^6 m 3 /yr. The inflating source is at or near the
crust-mantle boundary as identified by seismic studies and is interpreted as accumulating magma. L13611
Delacourt, C., C. Squarzoni, and P. Allemand, One day slope motion in the Mercantour Massif (France) revealed by DINSAR, Geophys. Res. Lett., submitted, 2000.
Delacourt, C., P. Allemand, B. Casson, and H. Vadon (2004), Velocity field of the ``La Clapière'' landslide measured by the
correlation of aerial and QuickBird satellite images, Geophysical Research Letters, 31, 15619. Two displacement maps
of the ``La Clapière'' landslide (France) have been derived over two periods of 4 years (1995-1999 and 1999-2003) by
correlation of aerial photographs and a QuickBird satellite image. The movement of the landslide ranges from 2.5 m to
20 m per year. Those values have been validated over 13 points monitored by conventional tacheometric measurements.
Three areas with significant differences in velocity field have been mapped. Limits of those areas are in good agreement
with in situ observations. Velocity maps show the low long term temporal variability of the landslide movement and its
spatial variability. The optical correlation method using images derived from various sensors (airborne and spatial) is a
promising technique for improving the spatial resolution of velocity field observation of landslides over several years.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GeoRL.3115619D&db_key=AST&high=42fb8ddbb622015
Delouis, B., B. Giardini, P. Lundgren, and J. Salichon, Joint inversion of INSAR, teleseismic, and strong motion data for the
spatial and temporal distribution of earthquake slip: application to the Izmit mainshock, Bull. Seism. Soc. Amer.,
submitted, 2001.
Emardson, T. R., M. Simons, and F. H. Webb (2003), Neutral atmospheric delay in interferometric synthetic aperture radar
applications: Statistical description and mitigation, Journal of Geophysical Research (Solid Earth), 108e. Variations in
the refractive index of the atmosphere cause variations in satellite-based interferometric synthetic aperture radar (InSAR)
observations. We can mitigate tropospheric effects by averaging N-independent interferograms. Because the neutral
atmosphere is uncorrelated at timescales longer than 1 day, using this technique statistically reduces the variance, sigma
2, of the noise by a factor of N. Using zenith neutral atmospheric delays from Global Positioning System (GPS) data
from the Southern California Integrated GPS Network, we find that the average variance depends on the distance
between observations, L, and height difference, H, as sigma = c L alpha + kH with estimated values for c, alpha, and k
of about 2.5, 0.5, and 4.8, respectively, where sigma is in mm and L and H are in km. We expect that the value of alpha
is largely site-independent but the value of c will depend on the water vapor variability of the area of interest. This
model is valid over a range of L between approximately 10 and 800 km. Height differences between 0 and 3 km have
been used in this analysis. For distances of 100 and 10 km with negligible height differences, sigma is estimated to be
approximately 25 and 8 mm, respectively. For a given orbit revisit time and image archive duration, we calculate the
number and duration (assumed constant) of interferograms required to achieve a desired sensitivity to deformation rate
at a given length scale. Assuming neutral atmosphere is the dominant source of noise, a 30° look angle, and an image
revisit time of 7 days, detection of a deformation rate of 1 mm yr -1 over distances of 10 km requires about 2.2 years of
continuous observations. Given our results, we suggest a data covariance structure to use when using InSAR data to
constrain geophysical models.
http://adsabs.harvard.edu/cgibin/nphbib_query?bibcode=2003JGRB.108e.ETG4E&db_key=PHY&high=42760a9e8807230
Emardson, T. R., M. Simons, and F. H. Webb (2003), Neutral atmospheric delay in interferometric synthetic aperture radar
applications: Statistical description and mitigation, Journal of Geophysical Research (Solid Earth), 108e. Variations in
the refractive index of the atmosphere cause variations in satellite-based interferometric synthetic aperture radar (InSAR)
observations. We can mitigate tropospheric effects by averaging N-independent interferograms. Because the neutral
atmosphere is uncorrelated at timescales longer than 1 day, using this technique statistically reduces the variance,
sigma^2 , of the noise by a factor of N. Using zenith neutral atmospheric delays from Global Positioning System (GPS)
data from the Southern California Integrated GPS Network, we find that the average variance depends on the distance
between observations, L, and height difference, H, as sigma = c L^alpha + kH with estimated values for c, alpha, and k
of about 2.5, 0.5, and 4.8, respectively, where sigma is in mm and L and H are in km. We expect that the value of alpha
is largely site-independent but the value of c will depend on the water vapor variability of the area of interest. This
model is valid over a range of L between approximately 10 and 800 km. Height differences between 0 and 3 km have
been used in this analysis. For distances of 100 and 10 km with negligible height differences, sigma is estimated to be
approximately 25 and 8 mm, respectively. For a given orbit revisit time and image archive duration, we calculate the
number and duration (assumed constant) of interferograms required to achieve a desired sensitivity to deformation rate
at a given length scale. Assuming neutral atmosphere is the dominant source of noise, a 30° look angle, and an image
revisit time of 7 days, detection of a deformation rate of 1 mm yr^-1 over distances of 10 km requires about 2.2 years of
continuous observations. Given our results, we suggest a data covariance structure to use when using InSAR data to
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constrain geophysical models.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2003JGRB.108e.ETG4E&db_key=PHY&high=42fb8ddbb619944
Feigl, K. L., F. Sarti, H. Vadon, P. Durand, S. McClusky, S. Ergintav, R. Bürgmann, A. Rigo, D. Massonnet, and R.
Reilinger (2002), Estimating slip distribution for the Izmit mainshock from coseismic GPS, ERS-1, RADARSAT and
SPOT measurements, Bull. Seism. Soc. Amer., 92, 138-160. We use four geodetic satellite systems (GPS, ERS,
RADARSAT, and SPOT) to measure the permanent deformation field produced by the Izmit earthquake of August 17,
1999. The emphasis is on measurements from interferometric analysis of synthetic aperture radar (INSAR) images
acquired by ERS and RADARSAT and their geodetic uncertainties. The primary seismological use of these data is to
determine earthquake source parameters, such as the distribution of slip and the fault geometry. After accounting for a
month's post-seismic deformation, tropospheric delay, and orbital gradients, we use these data to estimate the
distribution of slip at the time of the Izmit mainshock. The different data sets resolve different aspects of the distribution
of slip at depth. Although these estimates agree to first order with those derived from surface faulting, teleseismic
recordings, and strong motion, careful comparison reveals differences of 40% in seismic moment. We assume smooth
parameterization for the fault geometry and a standard elastic dislocation model. The RMS residual scatter is 25 mm and
11 mm for the ERS and RADARSAT range changes, respectively. Our estimate of the moment from a joint inversion of
the four geodetic data sets is M0 = 1.84E20 N.m, a moment magnitude of Mw = 7.50. These values are lower than other
estimates using more realistic layered earth models. Given the differences between the various models, we conclude that
the real errors in the estimated slip distributions are at the level of 1 meter. The prudent geophysical conclusion is that
co-seismic slip during the Izmit earthquake tapers gradually from approximately 2 m under the Hersek Delta to 1 m at a
point 10 km west of it. We infer that the Yalova segment west of the Hersek Delta may remain capable of significant slip
in a future earthquake.
http://www-gpsg.mit.edu/edocs/FEIGL_ET_AL_2001_BSSA D:\PapersToRead\Feigl_BSSA2002.pdf
Feigl, K. L., J. Gasperi, F. Sigmundsson, and A. Rigo (2000), Crustal deformation near Hengill volcano, Iceland 1993-1998:
coupling between volcanism and faulting inferred from elastic modeling of satellite radar interferograms, J. Geophys.
Res, 105, 26,555-525,670. We apply satellite radar interferometry to the Hengill Volcanic System, one of the most
active areas in Iceland. We analyze several ERS image pairs spanning up to four years under favorable orbital and
climatic conditions. To calculate the interferograms, we use the two-pass approach with the DIAPASON software
developed by CNES and licensed via GDR INSAR. Images acquired during the snow-free summer months remain
coherent on recent lava flows even after four years. We observe concentric fringes centered several km SW of
Hrómundartindur which we interpret as a mostly vertical uplift due to a pressure increase near this volcano. The number
of fringes is roughly proportional to the time interval spanned by the interferograms, suggesting that the volcanic uplift
rate is relatively constant. This result confirms that the increased volcanic and seismic activity observed since July 1994
continues through at least the summer of 1997. We model this signal as the deformation of a spherical (Mogi) source
buried in an elastic half-space. To the SW of this source, we observe a discontinuity in the fringe pattern. This
discontinuity appears in all interferograms spanning August 1995 (July 31 through September 3), and does not appear
in other interferograms outside this date. Furthermore, its magnitude (about a quarter of a 28-mm fringe) is the same in
interferograms analyzed with two independent digital elevation models. These measurements help define the interplay
between fluid pressure, seismicity, and faulting.
http://www-gpsg.mit.edu/edocs/FEIGL_REPRINTS/FeiglEtAlJGR2000.pdf
Fialko, Y., and M. Simons (2000), Deformation and seismicity in the Coso geothermal area, Inyo County, California:
Observations and modeling using satellite radar interferometry, Journal of Geophysical Research, 105, 21781-21794.
Interferometric synthetic aperture radar (InSAR) data collected in the Coso geothermal area, eastern California, during
1993-1999 indicate ground subsidence over a ~50 km 2 region that approximately coincides with the production area of
the Coso geothermal plant. The maximum subsidence rate in the peak of the anomaly is ~3.5 cmyr -1, and the average
volumetric rate of subsidence as of the order of 10^6 m 3 yr -1. The radar interferograms reveal a complex deformation
pattern, with at least two irregular subsidence peaks in the northern part of the anomaly and a region of relative uplift on
the south. We invert the InSAR displacement data for the positions, geometry, and relative strengths of the deformation
sources at depth using a nonlinear least squares minimization algorithm. We use elastic solutions for a prolate uniformly
pressurized spheroidal cavity in a semi-infinite body as basis functions for our inversions. Source depths inferred from
our simulations range from 1 to 3 km, which corresponds to the production depths of the Coso geothermal plant.
Underpressures in the geothermal reservoir inferred from the inversion are of the order of 0.1-1 MPa (except a few
abnormally high underpressures that are apparently biased toward the small source dimensions). Analysis of the InSAR
data covering consecutive time intervals indicates that the depths and/or horizontal extent of the deformation sources
may increase with time. This increase presumably reflects increasing volumes of the subsurface reservoir affected by the
geothermal exploitation. We show that clusters of microearthquakes associated with the geothermal power operation
may result from perturbations in the pore fluid pressure, as well as normal and shear stresses caused by the deflation of
the geothermal reservoir.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000JGR.10521781F&db_key=PHY&high=42fb8ddbb619944
Fialko, Y., and M. Simons (2000), Deformation and seismicity in the Coso geothermal area, Inyo County, California:
Observations and modeling using satellite radar interferometry, Journal of Geophysical Research, 105, 21781-21794.
Interferometric synthetic aperture radar (InSAR) data collected in the Coso geothermal area, eastern California, during
1993-1999 indicate ground subsidence over a ~50 km^2 region that approximately coincides with the production area
of the Coso geothermal plant. The maximum subsidence rate in the peak of the anomaly is ~3.5 cmyr^-1 , and the
average volumetric rate of subsidence as of the order of 10^6 m^3 yr^-1 . The radar interferograms reveal a complex
deformation pattern, with at least two irregular subsidence peaks in the northern part of the anomaly and a region of
relative uplift on the south. We invert the InSAR displacement data for the positions, geometry, and relative strengths of
the deformation sources at depth using a nonlinear least squares minimization algorithm. We use elastic solutions for a
prolate uniformly pressurized spheroidal cavity in a semi-infinite body as basis functions for our inversions. Source
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depths inferred from our simulations range from 1 to 3 km, which corresponds to the production depths of the Coso
geothermal plant. Underpressures in the geothermal reservoir inferred from the inversion are of the order of 0.1-1 MPa
(except a few abnormally high underpressures that are apparently biased toward the small source dimensions). Analysis
of the InSAR data covering consecutive time intervals indicates that the depths and/or horizontal extent of the
deformation sources may increase with time. This increase presumably reflects increasing volumes of the subsurface
reservoir affected by the geothermal exploitation. We show that clusters of microearthquakes associated with the
geothermal power operation may result from perturbations in the pore fluid pressure, as well as normal and shear
stresses caused by the deflation of the geothermal reservoir. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000JGR.10521781F&db_key=PHY&high=42fb8ddbb619944
Fialko, Y., and M. Simons (2001), Evidence for on-going inflation of the Socorro magma body, New Mexico, from
Interferometric Synthetic Aperture Radar imaging, Geophysical Research Letters, 28, 3549-3552. Interferometric
synthetic aperture radar (In-SAR) imaging of the central Rio Grande rift (New Mexico, USA) during 1992-1999 reveals
a crustal uplift of several centimeters that spatially coincides with the seismologically determined outline of the Socorro
magma body, one of the largest currently active magma intrusions in the Earth's continental crust. Modeling of
interferograms shows that the observed deformation may be due to elastic opening of a sill-like intrusion at a rate of a
few millimeters per year. Despite an apparent constancy of the geodetically determined uplift rate, thermodynamic
arguments suggest that it is unlikely that the Socorro magma body has formed via steady state elastic inflation.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.3549F&db_key=AST&high=41f192cbba08585
Fialko, Y., D. Sandwell, D. Agnew, M. Simons, P. Shearer, and B. Minster (2002), Deformation on nearby faults induced by
the 1999 Hector Mine earthquake, Science, 297, 1858-1862. Interferometric Synthetic Aperture Radar observations of
surface deformation due to the 1999 Hector Mine earthquake reveal motion on several nearby faults the eastern
California shear zone.We document both vertical and horizontal displacements of several millimeters to several
centimeters across kilometerwide zones centered on pre-existing faults. Portions of some faults experienced retrograde
(that is, opposite to their long-term geologic slip) motion during or shortly after the earthquake.The observed
deformation likely represents elastic response of compliant fault zones to the permanent co-seismic stress changes. The
induced fault displacements imply decreases in the effective shear modulus within the kilometer-wide fault zones,
indicating that the latter are mechanically distinct from the ambient crustal rocks. PDF
Fialko, Y., D. Sandwell, D. Agnew, M. Simons, P. Shearer, and B. Minster (2002), Deformation on nearby faults induced by
the 1999 Hector Mine earthquake, Science, 297, 1858-1862. Interferometric Synthetic Aperture Radar observations of
surface deformation due to the 1999 Hector Mine earthquake reveal motion on several nearby faults the eastern
California shear zone.We document both vertical and horizontal displacements of several millimeters to several
centimeters across kilometerwide zones centered on pre-existing faults. Portions of some faults experienced retrograde
(that is, opposite to their long-term geologic slip) motion during or shortly after the earthquake.The observed
deformation likely represents elastic response of compliant fault zones to the permanent co-seismic stress changes. The
induced fault displacements imply decreases in the effective shear modulus within the kilometer-wide fault zones,
indicating that the latter are mechanically distinct from the ambient crustal rocks. PDF
Fialko, Y., M. Simons, and D. Agnew (2001a), The complete (3-D) surface displacement field in the epicentral area of the
1999 Mw 7.1 Hector Mine earthquake, California, from space geodetic observations, Geophysical Research Letters, 28,
3063-3066. We use Interferometric Synthetic Aperture Radar (InSAR) data to derive continuous maps for three
orthogonal components of the co-seismic surface displacement field due to the 1999 Mw 7.1 Hector Mine earthquake in
southern California. Vertical and horizontal displacements are both predominantly antisymmetric with respect to the
fault plane, consistent with predictions of linear elastic models of deformation for a strike-slip fault. Some deviations
from symmetry apparent in the surface displacement data may result from complexity in the fault geometry.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.3063F&db_key=AST&high=42fb8ddbb619944
Fialko, Y., M. Simons, and D. Agnew (2001b), The complete (3-D) surface displacement field in the epicentral area of the
1999 Mw 7.1 Hector Mine earthquake, California, from space geodetic observations, Geophysical Research Letters, 28,
3063-3066. We use Interferometric Synthetic Aperture Radar (InSAR) data to derive continuous maps for three
orthogonal components of the co-seismic surface displacement field due to the 1999 Mw 7.1 Hector Mine earthquake in
southern California. Vertical and horizontal displacements are both predominantly antisymmetric with respect to the
fault plane, consistent with predictions of linear elastic models of deformation for a strike-slip fault. Some deviations
from symmetry apparent in the surface displacement data may result from complexity in the fault geometry.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.3063F&db_key=AST&high=42fb8ddbb619944
Fialko, Y., M. Simons, and D. Agnew (2001c), The complete (3-D) surface displacement field in the epicentral area of the
1999 Mw7.1 Hector Mine earthquake, California, from space geodetic observations, Geophys. Res. Lett., 28, 30633066.
Fialko, Y., M. Simons, and Y. Khazan (2001b), Finite source modelling of magmatic unrest in Socorro, New Mexico, and
Long Valley, California, Geophysical Journal International, 146, 191-200. We investigate surface deformation
associated with currently active crustal magma bodies in Socorro, New Mexico, and Long Valley, California, USA. We
invert available geodetic data from these locations to constrain the overall geometry and dynamics of the inferred
deformation sources at depth. Our best-fitting model for the Socorro magma body is a sill with a depth of 19km, an
effective diameter of 70km and a rate of increase in the excess magma pressure of 0.6kPayr^-1 . We show that the
corresponding volumetric inflation rate is ~6×10^-3 km^3 yr^-1 , which is considerably less than previously suggested.
The measured inflation rate of the Socorro magma body may result from a steady influx of magma from a deep source,
or a volume increase associated with melting of the magma chamber roof (i.e. crustal anatexis). In the latter case, the
most recent major injection of mantle-derived melts into the middle crust beneath Socorro may have occurred within the
last several tens to several hundreds of years. The Synthetic Interferometric Aperture Radar (InSAR) data collected in
the area of the Long Valley caldera, CA, between June 1996 and July 1998 reveal an intracaldera uplift with a maximum
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amplitude of ~11cm and a volume of 3.5×10^-2 km^3 . Modelling of the InSAR data suggests that the observed
deformation might be due to either a sill-like magma body at a depth of ~12km or a pluton-like magma body at a depth
of ~8km beneath the resurgent dome. Assuming that the caldera fill deforms as an isotropic linear elastic solid, a joint
inversion of the InSAR data and two-colour laser geodimeter data (which provide independent constraints on horizontal
displacements at the surface) suggests that the inferred magma chamber is a steeply dipping prolate spheroid with a
depth of 7-9km and an aspect ratio in excess of 2:1. Our results highlight the need for large radar look angles and
multiple look directions in future InSAR missions.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoJI.146.191F&db_key=AST&high=42fb8ddbb619944
Fialko, Y., M. Simons, and Y. Khazan (2001d), Finite source modelling of magmatic unrest in Socorro, New Mexico, and
Long Valley, California, Geophysical Journal International, 146, 191-200. We investigate surface deformation
associated with currently active crustal magma bodies in Socorro, New Mexico, and Long Valley, California, USA. We
invert available geodetic data from these locations to constrain the overall geometry and dynamics of the inferred
deformation sources at depth. Our best-fitting model for the Socorro magma body is a sill with a depth of 19km, an
effective diameter of 70km and a rate of increase in the excess magma pressure of 0.6kPayr -1. We show that the
corresponding volumetric inflation rate is ~6×10^-3 km 3 yr -1, which is considerably less than previously suggested.
The measured inflation rate of the Socorro magma body may result from a steady influx of magma from a deep source,
or a volume increase associated with melting of the magma chamber roof (i.e. crustal anatexis). In the latter case, the
most recent major injection of mantle-derived melts into the middle crust beneath Socorro may have occurred within the
last several tens to several hundreds of years. The Synthetic Interferometric Aperture Radar (InSAR) data collected in
the area of the Long Valley caldera, CA, between June 1996 and July 1998 reveal an intracaldera uplift with a maximum
amplitude of ~11cm and a volume of 3.5×10^-2 km 3. Modelling of the InSAR data suggests that the observed
deformation might be due to either a sill-like magma body at a depth of ~12km or a pluton-like magma body at a depth
of ~8km beneath the resurgent dome. Assuming that the caldera fill deforms as an isotropic linear elastic solid, a joint
inversion of the InSAR data and two-colour laser geodimeter data (which provide independent constraints on horizontal
displacements at the surface) suggests that the inferred magma chamber is a steeply dipping prolate spheroid with a
depth of 7-9km and an aspect ratio in excess of 2:1. Our results highlight the need for large radar look angles and
multiple look directions in future InSAR missions. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoJI.146.191F&db_key=AST&high=41f192cbba08585
Fialko, Y., Y. Khazan, and M. Simons (2001a), Deformation due to a pressurized horizontal circular crack in an elastic halfspace, with applications to volcano geodesy, Geophys J Int, 146, 181-190. SUMMARY We consider deformation due to
sill-like magma intrusions using a model of a horizontal circular crack in a semi-infinite elastic solid. We present exact
expressions for vertical and horizontal displacements of the free surface of a half-space, and calculate surface
displacements for a special case of a uniformly pressurized crack. We derive expressions for other observable
geophysical parameters, such as the volume of a surface uplift/subsidence, and the corresponding volume change due to
fluid injection/withdrawal at depth. We demonstrate that for essentially oblate (i.e. sill-like) source geometries the
volume change at the source always equals the volume of the displaced material at the surface of a half-space. Our
solutions compare favourably to a number of previously published approximate models. Surface deformation due to a
'point' crack (that is, a crack with a large depth-to-radius ratio) differs appreciably from that due to an isotropic point
source ('Mogi model'). Geodetic inversions that employ only one component of deformation (either vertical or
horizontal) are unlikely to resolve the overall geometry of subsurface deformation sources even in a simplest case of
axisymmetric deformation. Measurements of a complete vector displacement field at the Earth's surface may help to
constrain the depth and morphology of active magma reservoirs. However, our results indicate that differences in surface
displacements due to various axisymmetric sources may be subtle. In particular, the sill-like and pluton-like magma
chambers may give rise to differences in the ratio of maximum horizontal displacements to maximum vertical
displacements (a parameter that is most indicative of the source geometry) that are less than 30 per cent. Given
measurement errors in geodetic data, such differences may be hard to distinguish. http://www.blackwellsynergy.com/links/doi/10.1046/j.1365-246X.2001.00452.x/abs
Froger, J. L., O. Merle, and P. Briole (2001), Active spreading and regional extension at Mount Etna imaged by SAR
interferometry, Earth and Planetary Science Letters, 187, 245-258. Electronic Article Available from Elsevier Science.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001E%26PSL.187.245F&db_key=AST&high=42fb8ddbb608794
Froger, J. L., P. Briole, O. Merle, M. Coltelli, G. Puglisi, C. Deplus, and F. Obrizzo, Large flank collapse at Mount Etna
imaged by SAR interferometry, Earth Plan. Sci. Lett., submitted, 2000.
Froger, J. L., Y. Fukushima, P. Briole, T. Staudacher, T. Souriot, and N. Villeneuve (2004), The deformation field of the
August 2003 eruption at Piton de la Fournaise, Reunion Island, mapped by ASAR interferometry, Geophysical Research
Letters, 31, 14601. Three independent ASAR interferograms spanning the August 2003 Piton de la Fournaise eruption,
reveal a 3 by 3 km asymmetric pattern of range changes centred on the Dolomieu crater northern flank. It corresponds to
30 cm of displacement towards the satellite east of the eruptive fissures and 7 cm away from the satellite west of the
fissures. Displacements are caused by dyke emplacement below fissures. We model the deformation using a 3D mixed
boundary element method for elastic media. This consists of a dyke defined by six geometric parameters and an
overpressure gradient. A neighbourhood algorithm was applied to explore this 7 dimensional parameter space. The bestfit model is a 57° eastward dipping dyke with a base lying around 1520 m a.s.l. The model provides new evidence of the
dyke intrusion - related seaward displacements of the volcano eastern flank. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GeoRL.3114601F&db_key=AST&high=42fb8ddbb608794
Fruneau, B., and F. Sarti (2000), Detection of ground subsidence in the city of Paris using radar interferometry: isolation of
deformation from atmospheric artifacts using correlation, Geophysical Research Letters, 27, 3981-3984. This paper
presents a new method for the isolation of displacement from atmospheric fringes. This novel approach is based on
complex correlation of interferograms. Compared to other methods, this method has the advantage of requiring only a
few interferograms (two at least). Its main limitation is the hypothesis of temporally varying atmospheric conditions
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between acquisitions (not the same heterogeneities on different interferograms). In the city of Paris, this method reveals
2 subsiding zones. Both have the same location as an important underground working site, which took place from 1995
to 1997. The existence of subsidence in the area was known previously from ground truth data. Their spatial extent can
now be mapped by interferometry, and the temporal evolution of the subsidence is also examined here.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000GeoRL.27.3981F&db_key=AST&high=42fb8ddbb618880
Fruneau, B., E. Pathier, D. Raymond, B. Deffontaines, C. T. Lee, H. T. Wang, J. Angelier, J. P. Rudant, and C. P. Chang
(2001), Uplift of Tainan Tableland (SW Taiwan) revealed by SAR interferometry, Geophysical Research Letters, 28,
3071-3074. Interferometric processing of five SAR-ERS images reveals uplift of the Tainan Tableland (SW of Taiwan)
during the period 1996-1998. The maximum measured ground motion for these two years is 2.8 cm along the radar line
of sight towards the satellite, indicating for the displacement vector a vertical component of 3.2 cm, and a horizontal
component of 1.6 cm towards the WSW considering additional information from GPS data. The reconstructed
displacement field is consistent with the geological interpretation of the Tainan Tableland as an actively growing
anticline connected to the Taiwan fold-and-thrust belt. This implies that the deformation front is located farther west
than usually assumed in the Tainan area. The large Tainan city is thus located in an active deformation zone. Seismic
hazard assessment is however difficult because the mechanisms and kinematics are not known in detail.
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001GeoRL.28.3071F&db_key=AST
Gudmundsson, S., F. Sigmundsson, and J. M. Carstensen (2002), Three-dimensional surface motion maps estimated from
combined interferometric synthetic aperture radar and GPS data, Journal of Geophysical Research (Solid Earth), 107j.
We provide a technique to efficiently produce high-resolution three-dimensional surface motion maps by combining
information about the motion of the Earth's surface from interferometric observations of synthetic aperture radar images
and repeated Global Positioning System (GPS) geodetic measurements. Unwrapped interferograms, showing pixel-wise
change in range from ground to satellite, and sparse values of three-dimensional movements are required as input. The
problem of finding the full three-dimensional motion field is separated into two two-dimensional problems. Initially, the
vertical component of the deformation field and its horizontal component in the look direction of the satellite are found.
Later, the look direction component is resolved into north and east components. Initial values for the motion fields are
assigned to each pixel of interferograms from interpolation of available GPS observations. These values are then updated
and optimized by comparison with the interferograms and the GPS observations. An additional constraint is an
assumption of a smoothly varying motion field. Markov random field-based regularization and simulated annealing
algorithm are used for the optimization. The technique is applied to create surface motion maps for the Reykjanes
Peninsula, SW Iceland. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107jETG13G&db_key=PHY&high=42760a9e8807230
Hanssen, R., I. Weinreich, S. Lehner, and A. Stoffelen, Tropospheric wind and humidity derived from spaceborne radar
intensity and phase observations, Geophys. Res. Lett., 27, 1699-1702, 2000.
Henriot, O., T. Villemin, and F. Jouanne (2001), Long period interferograms reveal 1992-1998 steady rate of deformation at
Krafla volcano (North Iceland), Geophysical Research Letters, 28, 1067-1070. We formed interferograms of ERS-SAR
scenes covering the area of Krafla (N. Iceland) with time span values of up to six years (1992-1998). Our data reveals a
steady deformation rate at Krafla and within its fissure swarm, with values reaching +2.1 cm/y in the ground to satellite
direction, at the volcano. The area affected by deformation extends 20 km both north and south of the volcano. The best
fit dislocation model consists of sills, to the north and south of the volcano, and a magma chamber, located below the
volcano, all of them undergoing contraction. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.1067H&db_key=AST&high=41f192cbba08585
Jacobs, A., D. Sandwell, Y. Fialko, and L. Sichoix (2002), The 1999 (Mw 7.1) Hector Mine, California, Earthquake: NearField Postseismic Deformation from ERS Interferometry, Bull. Seism. Soc. Amer., 92, 1433–1442. Interferometric
synthetic aperture radar (InSAR) data over the area of the Hector Mine earthquake (Mw 7.1, 16 October 1999) reveal
postseismic deformation of several centimeters over a spatial scale of 0.5 to 50 km. We analyzed seven SAR acquisitions
to form interferograms over four time periods after the event. The main deformations seen in the line-of-sight (LOS)
displacement maps are a region of subsidence (60 mm LOS increase) on the northern end of the fault, a region of uplift
(45 mm LOS decrease) located to the northeast of the primary fault bend, and a linear trough running along the main
rupture having a depth of up to 15 mm and a width of about 2 km. We correlate these features with a double leftbending, rightlateral, strike-slip fault that exhibits contraction on the restraining side and extension along the releasing
side of the fault bends. The temporal variations in the near-fault postseismic deformation are consistent with a
characteristic time scale of 135 42 or 25 days, which is similar to the relaxation times following the 1992 Landers
earthquake. High gradients in the LOS displacements occur on the fault trace, consistent with afterslip on the earthquake
rupture. We derive an afterslip model by inverting the LOS data from both the ascending and descending orbits. Our
model indicates that much of the afterslip occurs at depths of less than 3 to 4 km.
Jonsson, S., H. Zebker, P. Segall, and F. Amelung (2002), Fault slip distribution of the Mw7.2 Hector Mine earthquake
estimated from Satellite Radar and GPS measurements, Bull. Seism. Soc. Amer., in press.
Jonsson, S., P. Segall, R. Pedersen, and G. Bjornsson (2003), Post-earthquake ground movements correlated to pore-pressure
transients, Nature, 424, 179 - 183. Large earthquakes alter the stress in the surrounding crust, leading to triggered
earthquakes and aftershocks. A number of time-dependent processes, including afterslip, pore-fluid flow and viscous
relaxation of the lower crust and upper mantle, further modify the stress and pore pressure near the fault, and hence the
tendency for triggered earthquakes. It has proved difficult, however, to distinguish between these processes on the basis
of direct field observations, despite considerable effort. Here we present a unique combination of measurements
consisting of satellite radar interferograms and water-level changes in geothermal wells following two magnitude-6.5
earthquakes in the south Iceland seismic zone. The deformation recorded in the interferograms cannot be explained by
either afterslip or visco-elastic relaxation, but is consistent with rebound of a porous elastic material in the first 1–2
months following the earthquakes. This interpretation is confirmed by direct measurements which show rapid (1–2month) recovery of the earthquake-induced water-level changes. In contrast, the duration of the aftershock sequence is
projected to be 3.5 years, suggesting that pore-fluid flow does not control aftershock duration. But because the surface
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strains are dominated by pore-pressure changes in the shallow crust, we cannot rule out a longer pore-pressure transient
at the depth of the aftershocks. The aftershock duration is consistent with models of seismicity rate variations based on
rate- and state-dependent friction laws. doi:10.1038/nature01776
Kontoes, C., P. Elias, O. Sykioti, P. Briole, D. Remy, M. Sachpazi, G. Veis, and I. Kotsis (2000), Displacement field and
fault model for the September 7, 1999 Athens earthquake inferred from ERS2 satellite radar interferometry, Geophysical
Research Letters, 27, 3989-3992. On September 7, 1999, a moderate (Mw =5.9) normal faulting earthquake occurred in
the northwest of Athens (Hellas) causing heavy damages and casualties. Using interferometric combinations of ERS2
SAR images, we analyzed the coseismic deformation field. Two fringes are observed south of the Fili mountain, up to
the coastline of the Elefsis gulf. They correspond to 56 mm increase in slant range. Modeling the earthquake as a
dislocation in an elastic half-space, we inverted the interferometric data to assess the fault location and geometry and the
amplitude of the coseismic slip. The model suggests ~300 mm slip on an 18 km long blind fault composed of two pieces.
The intersection of the fault plane with the Earth surface is located in the Fili mountain with a ~N120° orientation.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000GeoRL.27.3989K&db_key=AST&high=42fb8ddbb608794
Legresy, B., E. Rignot, and I. E. Tabacco (2000), Constraining ice dynamics at Dome C, Antarctica, using remotely sensed
measurements, Geophysical Research Letters, 27, 3493-3496. A first time description is given of the ice flow at Dome
C, Antarctica, around the EPICA drilling site. We used satellite radar altimetry to obtain the precise ice surface
topography, airborne radio echo sounding to obtain the ice thickness and satellite SAR interferometry to derive one
component of the surface velocity field. The balance flux around the Dome C area is then accurately mapped and
comparisons made between driving stress, surface and balance velocity to help us describe the ice flow in the region. As
a byproduct of the study, we also recover anomalies in the ice flow conditions in sub-glacial lake locations. These effects
result from localy invalid shallow-ice approximation. The results of this study form the basis for future investigations of
the ice flow conditions at Dome C in relation to ice core interpretation. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000GeoRL.27.3493L&db_key=AST&high=42fb8ddbb623888
Lohman, R. B., and M. Simons (2005), Some thoughts on the use of InSAR data to constrain models of surface deformation:
Noise structure and data downsampling, Geochemistry, Geophysics, Geosystems, 6, 01007. Repeat-pass Interferometric
Synthetic Aperture Radar (InSAR) provides spatially dense maps of surface deformation with potentially tens of millions
of data points. Here we estimate the actual covariance structure of noise in InSAR data. We compare the results for
several independent interferograms with a large ensemble of GPS observations of tropospheric delay and discuss how
the common approaches used during processing of InSAR data affects the inferred covariance structure. Motivated by
computational concerns associated with numerical modeling of deformation sources, we then combine the datacovariance information with the inherent resolution of an assumed source model to develop an efficient algorithm for
spatially variable data resampling (or averaging). We illustrate these technical developments with two earthquake
scenarios at different ends of the earthquake magnitude spectrum. For the larger events, our goal is to invert for the
coseismic fault slip distribution. For smaller events, we infer the hypocenter location and moment. We compare the
results of inversions using several different resampling algorithms, and we assess the importance of using the full noise
covariance matrix. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2005GGG.601007L&db_key=PHY&high=42fb8ddbb619944
Lohman, R. B., M. Simons, and B. Savage (2002), Location and mechanism of the Little Skull Mountain earthquake as
constrained by satellite radar interferometry and seismic waveform modeling, Journal of Geophysical Research (Solid
Earth), 107f. We use interferometric synthetic aperture radar (InSAR) and broadband seismic waveform data to estimate
source parameters of the 29 June 1992, Ms 5.4 Little Skull Mountain (LSM) earthquake. This event occurred within a
geodetic network designed to measure the strain rate across the region around Yucca Mountain. The LSM earthquake
complicates interpretation of the existing GPS and trilateration data, as the earthquake magnitude is sufficiently small
that seismic data do not tightly constrain the epicenter but large enough to potentially affect the geodetic observations.
We model the InSAR data using a finite dislocation in a layered elastic space. We also invert regional seismic
waveforms both alone and jointly with the InSAR data. Because of limitations in the existing data set, InSAR data alone
cannot determine the area of the fault plane independent of magnitude of slip nor the location of the fault plane
independent of the earthquake mechanism. Our seismic waveform data tightly constrain the mechanism of the
earthquake but not the location. Together, the two complementary data types can be used to determine the mechanism
and location but cannot distinguish between the two potential conjugate fault planes. Our preferred model has a moment
of ~3.2 × 10^17 N m (Mw 5.6) and predicts a line length change between the Wahomie and Mile geodetic benchmarks
of ~5 mm. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107f.ETG7L&db_key=PHY&high=42fb8ddbb619944
Lohman, R. B., M. Simons, and B. Savage (2002), Location and mechanism of the Little Skull Mountain earthquake as
constrained by satellite radar interferometry and seismic waveform modeling, Journal of Geophysical Research (Solid
Earth), 107f. We use interferometric synthetic aperture radar (InSAR) and broadband seismic waveform data to estimate
source parameters of the 29 June 1992, Ms 5.4 Little Skull Mountain (LSM) earthquake. This event occurred within a
geodetic network designed to measure the strain rate across the region around Yucca Mountain. The LSM earthquake
complicates interpretation of the existing GPS and trilateration data, as the earthquake magnitude is sufficiently small
that seismic data do not tightly constrain the epicenter but large enough to potentially affect the geodetic observations.
We model the InSAR data using a finite dislocation in a layered elastic space. We also invert regional seismic
waveforms both alone and jointly with the InSAR data. Because of limitations in the existing data set, InSAR data alone
cannot determine the area of the fault plane independent of magnitude of slip nor the location of the fault plane
independent of the earthquake mechanism. Our seismic waveform data tightly constrain the mechanism of the
earthquake but not the location. Together, the two complementary data types can be used to determine the mechanism
and location but cannot distinguish between the two potential conjugate fault planes. Our preferred model has a moment
of ~3.2 × 10^17 N m (Mw 5.6) and predicts a line length change between the Wahomie and Mile geodetic benchmarks
of ~5 mm. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107f.ETG7L&db_key=PHY&high=42fb8ddbb619944
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Lu, Z., and W. R. Danskin (2001), InSAR analysis of natural recharge to define structure of a ground-water basin, San
Bernardino, California, Geophysical Research Letters, 28, 2661-2664. Using interferometric synthetic aperture radar
(InSAR) analysis of ERS-1 and ERS-2 images, we detect several centimeters of uplift during the first half of 1993 in two
areas of the San Bernardino ground-water basin of southern California. This uplift correlates with unusually high runoff
from the surrounding mountains and increased ground-water levels in nearby wells. The deformation of the land surface
identifies the location of faults that restrict ground-water flow, maps the location of recharge, and suggests the areal
distribution of fine-grained aquifer materials. Our preliminary results demonstrate that naturally occurring runoff and
resultant recharge can be used with interferometric deformation mapping to help define the structure and important
hydrogeologic features of a ground-water basin. This approach may be particularly useful in investigations of remote
areas with scant ground-based hydrogeologic data. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.2661L&db_key=AST&high=42fb8ddbb620762
Lu, Z., C. Wicks, D. Dzurisin, J. A. Power, S. C. Moran, and W. Thatcher (2002c), Magmatic inflation at a dormant
stratovolcano: 1996-1998 activity at Mount Peulik volcano, Alaska, revealed by satellite radar interferometry, Journal of
Geophysical Research (Solid Earth), 107g. A series of ERS radar interferograms that collectively span the time interval
from July 1992 to August 2000 reveal that a presumed magma body located 6.6 +/- 0.5 km beneath the southwest flank
of the Mount Peulik volcano inflated 0.051 +/- 0.005 km^3 between October 1996 and September 1998. Peulik has
been active only twice during historical time, in 1814 and 1852, and the volcano was otherwise quiescent during the
1990s. The inflation episode spanned at least several months because separate interferograms show that the associated
ground deformation was progressive. The average inflation rate of the magma body was ~0.003 km^3 /month from
October 1996 to September 1997, peaked at 0.005 km^3 /month from 26 June to 9 October 1997, and dropped to ~0.001
km^3 /month from October 1997 to September 1998. An intense earthquake swarm, including three ML 4.8-5.2 events,
began on 8 May 1998 near Becharof Lake, ~30 km northwest of Peulik. More than 400 earthquakes with a cumulative
moment of 7.15 × 10^17 N m were recorded in the area through 19 October 1998. Although the inflation and
earthquake swarm occurred at about the same time, the static stress changes that we calculated in the epicentral area due
to inflation beneath Peulik appear too small to provide a causal link. The 1996-1998 inflation episode at Peulik confirms
that satellite radar interferometry can be used to detect magma accumulation beneath dormant volcanoes at least several
months before other signs of unrest are apparent. This application represents a first step toward understanding the
eruption cycle at Peulik and other stratovolcanoes with characteristically long repose periods.
http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107g.ETG4L&db_key=PHY&high=42fb8ddbb620762
Lu, Z., C. Wicks, D. Dzurisin, W. Thatcher, J. Freymueller, S. McNutt, and D. Mann, Aseismic inflation of Westdahl
volcano, Alaska revealed by satellite radar interferometry, Geophys. Res. Lett., 27, 1567-1570, 2000.
Lu, Z., D. Mann, J. T. Freymueller, and D. J. Meyer (2000a), Synthetic aperture radar interferometry of Okmok volcano,
Alaska: Radar observations, Journal of Geophysical Research, 105, 10791-10806. ERS-1/ERS-2 synthetic aperture
radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate
digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying
changes in interferometric coherence we found that the newly erupted lava lost radar coherence for 5-17 months after the
eruption. This suggests changes in the surface backscattering characteristics and was probably related to cooling and
compaction processes. Third, the atmospheric delay anomalies in the deformation interferograms were quantitatively
assessed. Atmospheric delay anomalies in some of the interferograms were significant and consistently smaller than one
to two fringes in magnitude. For this reason, repeat observations are important to confidently interpret small geophysical
signals related to volcanic activities. Finally, using two-pass differential interferometry, we analyzed the preeruptive
inflation, coeruptive deflation, and posteruptive inflation and confirmed the observations using independent image pairs.
We observed more than 140 cm of subsidence associated with the 1997 eruption. This subsidence occurred between 16
months before the eruption and 5 months after the eruption, was preceded by ~18 cm of uplift between 1992 and 1995
centered in the same location, and was followed by ~10 cm of uplift between September 1997 and 1998. The best fitting
model suggests the magma reservoir resided at 2.7 km depth beneath the center of the caldera, which was ~5 km from
the eruptive vent. We estimated the volume of the erupted material to be 0.055 km^3 and the average thickness of the
erupted lava to be ~7.4 m. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000JGR.10510791L&db_key=PHY&high=42fb8ddbb620762
Lu, Z., J. A. Power, and D. Dzurisin (2000b), Ground deformation associated with the March 1996 earthquake swarm at
Akutan volcano, Alaska, revealed by satellite radar interferometry, Journal of Geophysical Research, 105, 21483-21496.
In March 1996 an intense swarm of volcano-tectonic earthquakes (~3000 felt by local residents, Mmax =5.1, cumulative
moment of 2.7×10^18 Nm) beneath Akutan Island in the Aleutian volcanic arc, Alaska, produced extensive ground
cracks but no eruption of Akutan volcano. Synthetic aperture radar interferograms that span the time of the swarm reveal
complex island-wide deformation: the western part of the island including Akutan volcano moved upward, while the
eastern part moved downward. The axis of the deformation approximately aligns with new ground cracks on the western
part of the island and with Holocene normal faults that were reactivated during the swarm on the eastern part of the
island. The axis is also roughly parallel to the direction of greatest compressional stress in the region. No ground
movements greater than 2.83 cm were observed outside the volcano's summit caldera for periods of 4 years before or 2
years after the swarm. We modeled the deformation primarily as the emplacement of a shallow, east-west trending, north
dipping dike plus inflation of a deep, Mogi-type magma body beneath the volcano. The pattern of subsidence on the
eastern part of the island is poorly constrained. It might have been produced by extensional tectonic strain that both
reactivated preexisting faults on the eastern part of the island and facilitated magma movement beneath the western part.
Alternatively, magma intrusion beneath the volcano might have been the cause of extension and subsidence in the
eastern part of the island. We attribute localized subsidence in an area of active fumaroles within the Akutan caldera, by
as much as 10 cm during 1992-1993 and 1996-1998, to fluid withdrawal or depressurization of the shallow
hydrothermal system. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2000JGR.10521483L&db_key=PHY&high=42fb8ddbb620762
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Lu, Z., J. A. Power, V. S. McConnell, C. Wicks, and D. Dzurisin (2002b), Preeruptive inflation and surface interferometric
coherence characteristics revealed by satellite radar interferometry at Makushin Volcano, Alaska: 1993-2000, Journal of
Geophysical Research (Solid Earth), 107k. Pilot reports in January 1995 and geologic field observations from the
summer of 1996 indicate that a relatively small explosive eruption of Makushin, one of the more frequently active
volcanoes in the Aleutian arc of Alaska, occurred on 30 January 1995. Several independent radar interferograms that
each span the time period from October 1993 to September 1995 show evidence of ~7 cm of uplift centered on the
volcano's east flank, which we interpret as preeruptive inflation of a ~7-km-deep magma source (DeltaV = 0.022 km^3 ).
Subsequent interferograms for 1995-2000, a period that included no reported eruptive activity, show no evidence of
additional ground deformation. Interferometric coherence at C band is found to persist for 3 years or more on lava flow
and other rocky surfaces covered with short grass and sparsely distributed tall grass and for at least 1 year on most
pyroclastic deposits. On lava flow and rocky surfaces with dense tall grass and on alluvium, coherence lasts for a few
months. Snow and ice surfaces lose coherence within a few days. This extended timeframe of coherence over a variety of
surface materials makes C band radar interferometry an effective tool for studying volcano deformation in Alaska and
other similar high-latitude regions. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107k.ECV1L&db_key=PHY&high=42fb8ddbb620762
Lu, Z., T. Masterlark, D. Dzurisin, R. Rykhus, and C. Wicks (2003), Magma supply dynamics at Westdahl volcano, Alaska,
modeled from satellite radar interferometry, Journal of Geophysical Research (Solid Earth), 108g. A group of satellite
radar interferograms that span the time period from 1991 to 2000 shows that Westdahl volcano, Alaska, deflated during
its 1991-1992 eruption and is reinflating at a rate that could produce another eruption within the next several years. The
rates of inflation and deflation are approximated by exponential decay functions having time constants of about 6 years
and a few days, respectively. This behavior is consistent with a deep, constant-pressure magma source connected to a
shallow reservoir by a magma-filled conduit. An elastic deformation model indicates that the reservoir is located about 6
km below sea level and beneath Westdahl Peak. We propose that the magma flow rate through the conduit is governed
by the pressure gradient between the deep source and the reservoir. The pressure gradient, and hence the flow rate, are
greatest immediately after eruptions. Pressurization of the reservoir decreases both the pressure gradient and the flow
rate, but eventually the reservoir ruptures and an eruption or intrusion ensues. The eruption rate is controlled partly by
the pressure gradient between the reservoir and surface, and therefore it, too, decreases with time. When the supply of
eruptible magma is exhausted, the eruption stops, the reservoir begins to repressurize at a high rate, and the cycle
repeats. This model might also be appropriate for other frequently active volcanoes with stable magma sources and
relatively simple magma storage systems. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2003JGRB.108g.ETG9L&db_key=PHY&high=42fb8ddbb620762
Lu, Z., T. Masterlark, J. Power, D. Dzurisin, and C. Wicks (2002a), Subsidence at Kiska Volcano, Western Aleutians,
detected by satellite radar interferometry, Geophysical Research Letters, 29, 2-1. Sequential interferometric synthetic
aperture radar images of Kiska, the westernmost historically active volcano in the Aleutian arc, show that a circular area
about 3 km in diameter centered near the summit subsided by as much as 10 cm from 1995 to 2001, mostly during 1999
and 2000. An elastic Mogi-type deformation model suggests that the source is within 1 km of the surface. Based on the
shallow source depth, the copious amounts of steam during recent eruptions, and recent field reports of vigorous
steaming and persistent ground shaking near the summit area, we attribute the subsidence to decreased pore-fluid
pressure within a shallow hydrothermal system beneath the summit area. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002GeoRL.29r.2L&db_key=AST&high=42fb8ddbb620762
Lyuboshenko, I., and H. Maître, Unwrapping circular interferograms, Applied Optics, 39, 4817-4825, 2000.
Malassingne, C., F. Lemaître, P. Briole, and O. Pascal (2001), Potential of ground based radar for the monitoring of
deformation of volcanoes, Geophysical Research Letters, 28, 851-854. The ground based radar presented here is a new
tool for volcano deformation monitoring. With respect to other systems it has various advantages: operational by any
weather (rain, fog, aerosols), high frequency sampling capability (10 a few tens of seconds), possibility of monitoring
surfaces not equipped with reflectors. It can be used to monitor unstable and dangerous parts of volcanoes (craters, lava
domes.). The all weather capability and the high frequency sampling rate are crucial on volcanoes where activity can
change within a few hours or less. We present the system and show an application for range measurements on corner
reflectors. Then, we present the results obtained in the Pyrénées mountains (France) on a natural surface not equipped
with reflectors. We analyze the evolution of the coherence of the reflected signal as a function of the nature of the terrain
and elapsed time. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.851M&db_key=AST&high=42fb8ddbb608794
Mann, D., J. Freymueller, and Z. Lu (2002), Deformation associated with the 1997 eruption of Okmok volcano, Alaska,
Journal of Geophysical Research (Solid Earth), 107d. Okmok volcano, located on Umnak Island in the Aleutian chain,
Alaska, is the most eruptive caldera system in North America in historic time. Its most recent eruption occurred in 1997.
Synthetic aperture radar interferometry shows deflation of the caldera center of up to 140 cm during this time, preceded
and followed by inflation of smaller magnitude. The main part of the observed deformation can be modeled using a
pressure point source model. The inferred source is located between 2.5 and 5.0 km beneath the approximate center of
the caldera and ~5 km from the eruptive vent. We interpret it as a central magma reservoir. The preeruptive period
features inflation accompanied by shallow localized subsidence between the caldera center and the vent. We hypothesize
that this is caused by hydrothermal activity or that magma moved away from the central chamber and toward the later
vent. Since all historic eruptions at Okmok have originated from the same cone, this feature may be a precursor that
indicates an upcoming eruption. The erupted magma volume is ~9 times the volume that can be accounted for by the
observed preeruptive inflation. This indicates a much longer inflation interval than we were able to observe. The
observation that reinflation started shortly after the eruption suggests that inflation spans the whole time interval
between eruptions. Extrapolation of the average subsurface volume change rate is in good agreement with the long-term
eruption frequency and eruption volumes of Okmok. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002JGRB.107d.ETG7M&db_key=PHY&high=42fb8ddbb620762
Massonnet, D. (2001), Capabilities and limitations of the interferometric cartwheel, IEEE Trans. Geoscience Rem. Sens., 39,
506-520. Quasi-simultaneous radar images can be produced by a low cost system using a set of passive receivers
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onboard a constellation in a special orbial configuration. The combination of thes images can improve the final
resolution in range and azimuth and systematically produce across-track and along-track inteferometric data.
Massonnet, D., and F. Sigmundsson, Remote sensing of volcano deformation by radar interferometry from various satellites,
in Remote sensing of active volcanism, edited by P. Mouginis-Mark, J. A. Crisp, and J. H. Fink, Geophys. Monogr. Ser.,
116, 207-221, AGU, Washington, D. C., 2000.
Masterlark, T., and Z. Lu (2004), Transient volcano deformation sources imaged with interferometric synthetic aperture
radar: Application to Seguam Island, Alaska, Journal of Geophysical Research (Solid Earth), 109, 01401. Thirty
interferometric synthetic aperture radar (InSAR) images, spanning various intervals during 1992-2000, document
coeruptive and posteruptive deformation of the 1992-1993 eruption on Seguam Island, Alaska. A procedure that
combines standard damped least squares inverse methods and collective surfaces, identifies three dominant amorphous
clusters of deformation point sources. Predictions generated from these three point source clusters account for both the
spatial and temporal complexity of the deformation patterns of the InSAR data. Regularized time series of source
strength attribute a distinctive transient behavior to each of the three source clusters. A model that combines magma
influx, thermoelastic relaxation, poroelastic effects, and petrologic data accounts for the transient, interrelated behavior
of the source clusters and the observed deformation. Basaltic magma pulses, which flow into a storage chamber residing
in the lower crust, drive this deformational system. A portion of a magma pulse is injected into the upper crust and
remains in storage during both coeruption and posteruption intervals. This injected magma degasses and the volatile
products accumulate in a shallow poroelastic storage chamber. During the eruption, another portion of the magma pulse
is transported directly to the surface via a conduit roughly centered beneath Pyre Peak on the west side of the island. A
small amount of this magma remains in storage during the eruption, and posteruption thermoelastic contraction ensues.
This model, made possible by the excellent spatial and temporal coverage of the InSAR data, reveals a relatively simple
system of interrelated predictable processes driven by magma dynamics. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004JGRB.10901401M&db_key=PHY&high=42fb8ddbb620762
Mellors, R. J., H. Magistrale, P. Earle, and A. Cogbill (2004), Comparison of moderate earthquake location in Southern
California using seismology and InSAR, Bull. Seism. Soc. Amer., 94, 2004 - 2014. Source parameters determined from
interferometric synthetic aperture radar (InSAR) measurements and from seismic data are compared from four moderatesize (less than M 6) earthquakes in southern California. The goal is to verify approximate detection capabilities of
InSAR, assess differences in the results, and test how the two results can be reconciled. First, we calculated the expected
surface deformation from all earthquakes greater than magnitude 4 in areas with available InSAR data (347 events). A
search for deformation from the events in the interferograms yielded four possible events with magnitudes less than 6.
The search for deformation was based on a visual inspection as well as cross-correlation in two dimensions between the
measured signal and the expected signal. A grid-search algorithm was then used to estimate focal mechanism and depth
from the InSAR data. The results were compared with locations and focal mechanisms from published catalogs. An
independent relocation using seismic data was also performed. The seismic locations fell within the area of the expected
rupture zone for the three events that show clear surface deformation. Therefore, the technique shows the capability to
resolve locations with high accuracy and is applicable worldwide. The depths determined by InSAR agree with wellconstrained seismic locations determined in a 3D velocity model. Depth control for well-imaged shallow events using
InSAR data is good, and better than the seismic constraints in some cases. A major difficulty for InSAR analysis is the
poor temporal coverage of InSAR data, which may make it impossible to distinguish deformation due to different
earthquakes at the same location. reviewed http://www.seismosoc.org/index.html
Michel, R., and J. P. Avouac (2002), Deformation due to the 17 August 1999 Izmit earthquake measured from SPOT images,
J. Geophys. Res., 107, ETG X-1 to X-4. The geometry of the ruptured areas and the coseismic slip distribution data are
key to highlighting the behavior of seismic faults. This information is generally retrieved from field investigations and
geodetic measurements or synthetic aperture radar (SAR) interferometry. Here we show that SPOT images can also be
used to accurately map the fault zone and to determine the slip distribution by subpixel correlation of images acquired
before and after an earthquake. The measured slip includes the contribution of possible distributed shear that might not
be clearly expressed in surface ruptures and smoothes out possible along-strike variability due to near-surface fault
complexities. We apply the technique to the Ms = 7.4, 1999, Izmit earthquake. Our results reveal a <100-m-wide and
very linear fault zone that can be traced for 70 km from Go¨lcu¨k to Akyazi, along which supershear rupture has been
inferred. The obtained slip distribution compares well with the field measurements and is consistent with ground
deformation measured at some distance from the fault zone using SAR images. Very little deformation was
accommodated off the main fault plane. Maximum slip is observed near Sapanca lake at a small fault jog that has
probably influenced rupture propagation. They no longer claim asymetric gradients across the fault.
10.1029/2000JB000102.
Niemi, N. A., B. P. Wernicke, A. M. Friedrich, M. Simons, R. A. Bennett, and J. L. Davis (2004), BARGEN continuous GPS
data across the eastern Basin and Range province, and implications for fault system dynamics, Geophysical Journal
International, 159, 842-862. We collected data from a transect of continuous Global Positioning System (GPS) sites
across the eastern Basin and Range province at latitude 39°N from 1997-2000. Intersite velocities define a region ~350
km wide of broadly distributed strain accumulation at ~10 nstr yr -1. On the western margin of the region, site EGAN,
~10 km north of Ely, Nevada, moved at a rate of 3.9 +/- 0.2 mm yr -1 to the west relative to site CAST, which is on the
Colorado Plateau. Velocities of most sites to the west of Ely moved at an average rate of ~3 mm yr -1 relative to CAST,
defining an area across central Nevada that does not appear to be extending significantly. The late Quaternary geological
velocity field, derived using seismic reflection and neotectonic data, indicates a maximum velocity of EGAN with
respect to the Colorado Plateau of ~4 mm yr -1, also distributed relatively evenly across the region. The geodetic and
late Quaternary geological velocity fields, therefore, are consistent, but strain release on the Sevier Desert detachment
and the Wasatch fault appears to have been anomalously high in the Holocene. Previous models suggesting horizontal
displacement rates in the eastern Basin and Range near 3 mm yr -1, which focused mainly along the Wasatch zone and
Intermountain seismic belt, may overestimate the Holocene Wasatch rate by at least 50 per cent and the Quaternary rate
by nearly an order of magnitude, while ignoring potentially major seismogenic faults further to the west.
http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004GeoJI.159.842N&db_key=AST
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Pagli, C., R. Pedersen, F. Sigmundsson, and K. L. Feigl (2003), Triggered fault slip on June 17, 2000 on the Reykjanes
Peninsula, SW-Iceland captured by radar interferometry, Geophysical Research Letters, 30, 6-1. Dynamically triggered
seismicity followed shortly after a Ms 6.6 earthquake in Iceland on June 17, 2000. Smaller earthquakes occurred on the
Reykjanes Peninsula up to 100 km from the mainshock rupture. Using interferometric analysis of Synthetic Aperture
Radar images (InSAR), we measure crustal deformation associated with three triggered deformation events. The largest
of these occurred at Lake Kleifarvatn, 85 km west of the mainshock epicenter. Modeling of the InSAR data reveals
strikeslip on a north-striking fault, with a geodetic moment of 6.2 × 10^17 Nm, equivalent to magnitude Mw 5.8
earthquake. A seismological estimate of the moment is not yet available, because the seismic signature of this event is
partly hidden by the mainshock waveform. The paucity of aftershocks on the triggered rupture plane suggests some
aseismic slip there, compatible with a thin seismogenic crust, high heat-flow, hydrothermal alteration and the presence
of fluids in the area. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003GeoRL.30f.6P&db_key=AST
Paillou, P., G. Grandjean, J. M. Malézieux, G. Ruffié, E. Heggy, D. Piponnier, P. Dubois, and J. Achache (2001),
Performances of Ground Penetrating Radars in arid volcanic regions: Consequences for Mars subsurface exploration,
Geophysical Research Letters, 28, 911-914. A GPR field experiment in the Republic of Djibouti provides evidence for
very low radar penetration in arid volcanic materials, in the range 100-500 MHz. This phenomenon is attributed to the
high iron oxide and evaporite concentration in soils, which significantly increases the conductivity, thus leading to poor
subsurface imaging performances. The geologic context in Djibouti is shown to provide a good terrestrial analogue to
Mars geology. Results of this study show that the future sounding radar missions to Mars may not reach the penetration
depths previously anticipated. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2001GeoRL.28.911P&db_key=AST&high=42fb8ddbb616940
Pedersen, R., and F. Sigmundsson (2004), InSAR based sill model links spatially offset areas of deformation and seismicity
for the 1994 unrest episode at Eyjafjallajokull volcano, Iceland, Geophysical Research Letters, 31, 14610. We present
InSAR observations of deformation due to an intrusion in the Eyjafjallajökull volcano, Southern Iceland, in 1994. More
than 15 cm of deformation in the line of sight (LOS) direction is detected in a series of interferograms spanning a microearthquake swarm occurring in June 1994. The location of the seismicity is more than 6 km offset compared to the area
of inferred maximum surface uplift. Through an inversion scheme we find that a horizontal sill intrusion experiencing
variable opening of up to 0.36 m agrees well with the deformation data. The total intrusion volume is 0.017 km^3 . The
northern periphery of the modeled intrusion fits well with the area of recorded seismicity, indicating a close connection.
Several processes may be responsible. Our preferred explanation is that the earthquakes are caused by opening of a
narrow magma channel from depth, feeding the sill. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GeoRL.3114610P&db_key=AST&high=41f192cbba08585
Pedersen, R., F. Sigmundsson, K. L. Feigl, and T. Árnadóttir (2001), Coseismic interferograms of two MS=6.6 earthquakes
in the South Iceland Seismic Zone, June 2000, Geophys. Res. Lett., 28, 3341-3344. We present InSAR observations of
deformation due to two MS=6.6 earthquakes in the South Iceland Seismic Zone in June 2000. Coseismic deformation
predominates a series of ERS interferograms. Range change, due to mainly right-lateral strike-slip on N-S striking faults,
amounting to more than 15 cm is observed, although displacement is mainly perpendicular to the satellite look direction.
Using elastic dislocation models in a trial-and-error scheme, we find a best-fitting model that agrees well with the
aftershock locations and moment magnitudes estimated from seismograms. The June 17 model has a fault patch 16 km
long, 10 km deep, striking N05°E, dipping 86°, with a slip maximum of 2.40 m. The June 21 model has a vertical patch
15 km long, 9 km deep, striking N01°W, with a slip maximum of 2.15 m.
Peltzer, G., F. Crampe, S. Hensley, and P. Rosen (2001), Transient strain accumulation and fault interaction in the Eastern
California shear zone, Geology, 29, 975-978. Satellite synthetic aperture radar interferometry reveals transient strain
accumulation along the Blackwater Little Lake fault system within the Eastern California shear zone. The surface strain
map obtained by averaging eight years (1992 2000) of Earth Re-source Satellite (ERS) radar data shows a 120-km-long,
20-km-wide zone of concentrated shear between the southern end of the 1872 Owens Valley earthquake surface break
and the northern end of the 1992 Landers earthquake surface break. The observed shear zone is continuous through the
Garlock fault, which does not show any evidence of left-lateral slip during the same time period. A dislocation model of
the observed shear indicates right-lateral slip at 7 +/- 3 mm/yr on a vertical fault below ~5 km depth, a rate that is two to
three times greater than the geologic rates estimated on northwest-trending faults in the eastern Mojave area. This transient slip rate and the absence of resolvable slip on the Garlock fault may be the manifestation of an oscillatory strain
pattern between interacting, conjugate fault systems.
Pritchard, M. E., and M. Simons (2004a), An InSAR-based survey of volcanic deformation in the central Andes, Geochem.
Geophys. Geosyst., 5, DOI 10.1029/2003GC000610.
Pritchard, M. E., and M. Simons (2004a), An InSAR-based survey of volcanic deformation in the central Andes,
Geochemistry, Geophysics, Geosystems, 5, 2002. We extend an earlier interferometric synthetic aperture radar (InSAR)
survey covering about 900 remote volcanos of the central Andes (14°-27°S) between the years 1992 and 2002. Our
survey reveals broad (10s of km), roughly axisymmetric deformation at 4 volcanic centers: two stratovolcanoes are
inflating (Uturuncu, Bolivia, and Hualca Hualca, Peru); another source of inflation on the border between Chile and
Argentina is not obviously associated with a volcanic edifice (here called Lazufre); and a caldera (Cerro Blanco, also
called Robledo) in northwest Argentina is subsiding. We explore the range of source depths and volumes allowed by our
observations, using spherical, ellipsoidal and crack-like source geometries. We further examine the effects of local
topography upon the deformation field and invert for a spherical point-source in both elastic half-space and layeredspace crustal models. We use a global search algorithm, with gradient search methods used to further constrain bestfitting models. Inferred source depths are model-dependent, with differences in the assumed source geometry generating
a larger range of accepted depths than variations in elastic structure. Source depths relative to sea level are: 8-18 km at
Hualca Hualca; 12-25 km for Uturuncu; 5-13 km for Lazufre, and 5-10 km at Cerro Blanco. Deformation at all four
volcanoes seems to be time-dependent, and only Uturuncu and Cerro Blanco were deforming during the entire time
period of observation. Inflation at Hualca Hualca stopped in 1997, perhaps related to a large eruption of nearby
Sabancaya volcano in May 1997, although there is no obvious relation between the rate of deformation and the eruptions
of Sabancaya. We do not observe any deformation associated with eruptions of Lascar, Chile, at 16 other volcanoes that
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had recent small eruptions or fumarolic activity, or associated with a short-lived thermal anomaly at Chiliques volcano.
We posit a hydrothermal system at Cerro Blanco to explain the rate of subsidence there. For the last decade, we calculate
the ratio of the volume of magma intruded to extruded is between 1-10, and that the combined rate of intrusion and
extrusion is within an order of magnitude of the inferred geologic rate. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GGG.5.2002P&db_key=PHY&high=42fb8ddbb619944
Pritchard, M. E., and M. Simons (2004b), An InSAR-based survey of volcanic deformation in the central Andes,
Geochemistry, Geophysics, Geosystems, 5, 2002. We extend an earlier interferometric synthetic aperture radar (InSAR)
survey covering about 900 remote volcanos of the central Andes (14°-27°S) between the years 1992 and 2002. Our
survey reveals broad (10s of km), roughly axisymmetric deformation at 4 volcanic centers: two stratovolcanoes are
inflating (Uturuncu, Bolivia, and Hualca Hualca, Peru); another source of inflation on the border between Chile and
Argentina is not obviously associated with a volcanic edifice (here called Lazufre); and a caldera (Cerro Blanco, also
called Robledo) in northwest Argentina is subsiding. We explore the range of source depths and volumes allowed by our
observations, using spherical, ellipsoidal and crack-like source geometries. We further examine the effects of local
topography upon the deformation field and invert for a spherical point-source in both elastic half-space and layeredspace crustal models. We use a global search algorithm, with gradient search methods used to further constrain bestfitting models. Inferred source depths are model-dependent, with differences in the assumed source geometry generating
a larger range of accepted depths than variations in elastic structure. Source depths relative to sea level are: 8-18 km at
Hualca Hualca; 12-25 km for Uturuncu; 5-13 km for Lazufre, and 5-10 km at Cerro Blanco. Deformation at all four
volcanoes seems to be time-dependent, and only Uturuncu and Cerro Blanco were deforming during the entire time
period of observation. Inflation at Hualca Hualca stopped in 1997, perhaps related to a large eruption of nearby
Sabancaya volcano in May 1997, although there is no obvious relation between the rate of deformation and the eruptions
of Sabancaya. We do not observe any deformation associated with eruptions of Lascar, Chile, at 16 other volcanoes that
had recent small eruptions or fumarolic activity, or associated with a short-lived thermal anomaly at Chiliques volcano.
We posit a hydrothermal system at Cerro Blanco to explain the rate of subsidence there. For the last decade, we calculate
the ratio of the volume of magma intruded to extruded is between 1-10, and that the combined rate of intrusion and
extrusion is within an order of magnitude of the inferred geologic rate. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GGG.5.2002P&db_key=PHY&high=42fb8ddbb619944
Pritchard, M. E., and M. Simons (2004b), An InSAR-based survey of volcanic deformation in the southern Andes,
Geophysical Research Letters, 31, 15610. We use Interferometric Synthetic Aperture Radar (InSAR) to search for
surface deformation in the southern Andes (40°S-46°S and 49°S-53°S) associated with magmatic processes. Although
the available data are not optimal, we can constrain the amount of volcanic deformation at about 27 Holocene volcanoes
between the years 1993-1999. We detect inflation of Cerro Hudson volcano following its 1991 eruption, and use
spherical and non-spherical models to constrain the source of deformation to be between 4 and 8 km below sea level.
We measure the rate of deformation to be about 5 cm/year in the radar line-of-sight, and infer that the maximum
deformation could exceed 10 cm/year in the center of the caldera. Within the errors of the measurements, the rate of
deformation is constant from 1993-1998 (10-30 × 10^6 m^3 /year). At this rate, 100-200 years is required to
accumulate the volume of material erupted in 1991. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GeoRL.3115610P&db_key=AST&high=42fb8ddbb619944
Pritchard, M. E., and M. Simons (2004c), An InSAR-based survey of volcanic deformation in the southern Andes,
Geophysical Research Letters, 31, 15610. We use Interferometric Synthetic Aperture Radar (InSAR) to search for
surface deformation in the southern Andes (40°S-46°S and 49°S-53°S) associated with magmatic processes. Although
the available data are not optimal, we can constrain the amount of volcanic deformation at about 27 Holocene volcanoes
between the years 1993-1999. We detect inflation of Cerro Hudson volcano following its 1991 eruption, and use
spherical and non-spherical models to constrain the source of deformation to be between 4 and 8 km below sea level.
We measure the rate of deformation to be about 5 cm/year in the radar line-of-sight, and infer that the maximum
deformation could exceed 10 cm/year in the center of the caldera. Within the errors of the measurements, the rate of
deformation is constant from 1993-1998 (10-30 × 10^6 m 3 /year). At this rate, 100-200 years is required to accumulate
the volume of material erupted in 1991. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2004GeoRL.3115610P&db_key=AST&high=41f192cbba08585
Pritchard, M. E., M. Simons, P. A. Rosen, S. Hensley, and F. H. Webb (2002a), Co-seismic slip from the 1995 July 30 Mw=
8.1 Antofagasta, Chile, earthquake as constrained by InSAR and GPS observations, Geophysical Journal International,
150, 362-376. Summary We analyse radar interferometric and GPS observations of the displacement field from the 1995
July 30 Mw= 8.1 Antofagasta, Chile, earthquake and invert for the distribution of slip along the co-seismic fault plane.
Using a fixed fault geometry, we compare the use of singular-value decomposition and constrained linear inversion to
invert for the slip distribution and find that the latter approach is better resolved and more physically reasonable.
Separate inversions using only GPS data, only InSAR data from descending orbits, and InSAR data from both ascending
and descending orbits without the GPS data illustrate the complimentary nature of GPS and the presently available
InSAR data. The GPS data resolve slip near GPS benchmarks well, while the InSAR provides greater spatial sampling.
The combination of ascending and descending InSAR data contributes greatly to the ability of InSAR to resolve the slip
model, thereby emphasizing the need to acquire this data for future earthquakes. The rake, distribution of slip and
seismic moment of our preferred model are generally consistent with previous seismic and geodetic inversions, although
significant differences do exist. GPS data projected in the radar line-of-sight (LOS) and corresponding InSAR pixels
have a root mean square (rms) difference of about 3 cm. Comparison of our predictions of vertical displacement and
observed uplift from corraline algae have an rms of 10 cm. Our inversion and previous results reveal that the location of
slip might be influenced by the 1987 Mw= 7.5 event. Our analysis further reveals that the 1995 slip distribution was
affected by a 1988 Mw= 7.2 event, and might have influenced a 1998 Mw= 7.0 earthquake that occurred downdip of the
1995 rupture. Our slip inversion reveals a potential change in mechanism in the southern portion of the rupture,
consistent with seismic results. Predictions of the satellite LOS displacement from a seismic inversion and a joint
seismic/GPS inversion do not compare favourably with the InSAR observations. http://www.blackwellsynergy.com/loi/gji
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Pritchard, M. E., M. Simons, P. A. Rosen, S. Hensley, and F. H. Webb (2002b), Co-seismic slip from the July 30, 1995 Mw
8.1 Antofagasta, Chile, earthquake as constrained by InSAR and GPS observations, Geophysical Journal International,
150, 362. We analyse radar interferometric and GPS observations of the displacement field from the 1995 July 30 Mw=
8.1 Antofagasta, Chile, earthquake and invert for the distribution of slip along the co-seismic fault plane. Using a fixed
fault geometry, we compare the use of singular-value decomposition and constrained linear inversion to invert for the
slip distribution and find that the latter approach is better resolved and more physically reasonable. Separate inversions
using only GPS data, only InSAR data from descending orbits, and InSAR data from both ascending and descending
orbits without the GPS data illustrate the complimentary nature of GPS and the presently available InSAR data. The
GPS data resolve slip near GPS benchmarks well, while the InSAR provides greater spatial sampling. The combination
of ascending and descending InSAR data contributes greatly to the ability of InSAR to resolve the slip model, thereby
emphasizing the need to acquire this data for future earthquakes. The rake, distribution of slip and seismic moment of
our preferred model are generally consistent with previous seismic and geodetic inversions, although significant
differences do exist. GPS data projected in the radar line-of-sight (LOS) and corresponding InSAR pixels have a root
mean square (rms) difference of about 3 cm. Comparison of our predictions of vertical displacement and observed uplift
from corraline algae have an rms of 10 cm. Our inversion and previous results reveal that the location of slip might be
influenced by the 1987 Mw= 7.5 event. Our analysis further reveals that the 1995 slip distribution was affected by a
1988 Mw= 7.2 event, and might have influenced a 1998 Mw= 7.0 earthquake that occurred downdip of the 1995
rupture. Our slip inversion reveals a potential change in mechanism in the southern portion of the rupture, consistent
with seismic results. Predictions of the satellite LOS displacement from a seismic inversion and a joint seismic/GPS
inversion do not compare favourably with the InSAR observations.
Reilinger, R. E. et al., Coseismic and postseismic fault slip for the 17 August 1999, M=7.4, Izmit, Turkey earthquake,
Science, 289, 1519-1524, 2000.
Remy, D., S. Bonvalot, P. Briole, and M. Murakami (2003), Accurate measurements of tropospheric effects in volcanic areas
from SAR interferometry data: application to Sakurajima volcano (Japan), Earth and Planetary Science Letters, 213,
299-310. Electronic Article Available from Elsevier Science. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2003E%26PSL.213.299R&db_key=AST&high=42fb8ddbb608794
Rigo, A., J.-B. d. Chabalier, B. Meyer, and R. Armijo (2004), The 1995 Kozani-Grevena (northern Greece) earthquake
revisited: an improved faulting model from synthetic aperture radar interferometry, Geophys J Int, 157, 727-736.
Salvi, S. Stramondo S. Cocco M. Sansosti E., Hunstad I., Anzidei M., Briole P., Baldi P., Tesauro M., Lanari R., Doumaz F.,
Pesci A., A. Galvani, Modeling Coseismic Displacements resulting from SAR interferometry and GPS measurements
during the 1997 Umbria-Marche seismic sequence, J. Seismology, in press, 2000.
Simons, F. J., and R. D. van der Hilst (2003), Seismic and mechanical anisotropy and the past and present deformation of the
Australian lithosphere, Earth and Planetary Science Letters, 211, 271-286. Electronic Article Available from Elsevier
Science. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2003E%26PSL.211.271S&db_key=AST
Simons, M., Y. Fialko, and L. Rivera (2002), Coseismic deformation from the 1999 Mw 7.1 Hector Mine, California
Earthquake as inferred from InSAR and GPS observations., Bull. Seismol. Soc. Am., 92, 1390–1402.
Stevens, N. F., G. Wadge, C. A. Williams, J. G. Morley, J.-P. Muller, J. B. Murray, and M. Upton (2001), Surface
movements of emplaced lava flows measured by synthetic aperture radar interferometry, J. Geophys. Res. Lava flows
continue to move after they have been emplaced by flow mechanisms. This movement is largely vertical and can be
detected using differential synthetic aperture radar (SAR) interferometry. There are three main components to this
motion: (1) movement of surface scatterers, resulting in radar phase decorrelation, (2) measurable subsidence of the flow
surface due to thermal contraction and clast repacking, and (3) time-dependent depression of the flow substrate. These
effects act in proportion to the thickness of the lava flow and decay with time, although there is a time lag before the
third component becomes significant. We explore these effects using SAR data from the ERS satellites over the Etna
volcano, Sicily. Phase decorrelation on young, thick a'a lava flows persists for a few years and probably results from
surface block rotations during flow contraction. Maximum measured subsidence rates of the 1991-1993 lava flow over a
period of 70 days are about 0.7 mm day-1, but are potentially greater in areas of data decorrelation. These rates fall to
<2.7 x 10-2 mm day-1 after about 20 years in flows about 50 m thick, sooner for thinner flows. Comparison with
measured subsidence rates on Kilauean lava lakes suggests that thermal contraction only accounts for about one third of
the observed subsidence. The remaining motion is thought to come from surface clast repacking during cooling and from
creep mechanisms in the flow substrate. Measurements of postemplacement surface movement provide new constraints
on the thermomechanical properties of lava flows and have cautionary implications for the interpretation of
interferometric SAR data of volcanoes.
Talebian, M., E. J. Fielding, G. J. Funning, M. Ghorashi, J. Jackson, H. Nazari, B. Parsons, K. Priestley, P. A. Rosen, R.
Walker, and T. J. Wright (2004), The 2003 Bam (Iran) earthquake: Rupture of a blind strike-slip fault, Geophysical
Research Letters, 31, 11611. An Mw 6.5 earthquake devastated the town of Bam in southeast Iran on 26 December
2003. Surface displacements and decorrelation effects, mapped using Envisat radar data, reveal that over 2 m of slip
occurred at depth on a fault that had not previously been identified. It is common for earthquakes to occur on blind
faults which, despite their name, usually produce long-term surface effects by which their existence may be recognised.
However, in this case there is a complete absence of morphological features associated with the seismogenic fault that
destroyed Bam. http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2004GeoRL.3111611T&db_key=AST
Van Puymbroeck, N., R. Michel, R. Binet, J. P. Avouac, and J. Taboury, Measuring earthquakes from optical satellite
images, Applied Optics, 39, 2000. [Cover]
Wicks, C. W., D. Dzurisin, S. Ingebritsen, W. Thatcher, Z. Lu, and J. Iverson (2002), Magmatic activity beneath the
quiescent Three Sisters volcanic center, central Oregon Cascade Range, USA, Geophysical Research Letters, 29, 26-21.
Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in
the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The last
eruption in the volcanic center occurred ~1500 years ago. Multiple satellite images from 1992 through 2000 indicate
that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. Geochemical
(water chemistry) anomalies, first noted during 1990, coincide with the area of uplift and suggest the existence of a
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crustal magma reservoir prior to the uplift. We interpret the uplift as inflation caused by an ongoing episode of magma
intrusion at a depth of ~6.5 km. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002GeoRL.29g.26W&db_key=AST&high=42fb8ddbb620762
Wicks, C. W., D. Dzurisin, S. Ingebritsen, W. Thatcher, Z. Lu, and J. Iverson (2002), Magmatic activity beneath the
quiescent Three Sisters volcanic center, central Oregon Cascade Range, USA, Geophysical Research Letters, 29, 26-21.
Images from satellite interferometric synthetic aperture radar (InSAR) reveal uplift of a broad ~10 km by 20 km area in
the Three Sisters volcanic center of the central Oregon Cascade Range, ~130 km south of Mt. St. Helens. The last
eruption in the volcanic center occurred ~1500 years ago. Multiple satellite images from 1992 through 2000 indicate
that most if not all of ~100 mm of observed uplift occurred between September 1998 and October 2000. Geochemical
(water chemistry) anomalies, first noted during 1990, coincide with the area of uplift and suggest the existence of a
crustal magma reservoir prior to the uplift. We interpret the uplift as inflation caused by an ongoing episode of magma
intrusion at a depth of ~6.5 km. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2002GeoRL.29g.26W&db_key=AST&high=41f192cbba08585
Wright, T. J. (2002), Remote monitoring of the earthquake cycle using satellite radar interferometry, Phil. Trans. R. Soc.
Lond. A, 360, 2873-2888.
Wright, T. J., B. E. Parsons, and Z. Lu (2004b), Toward mapping surface deformation in three dimensions using InSAR,
Geophysical Research Letters, 31, 01607. One of the limitations of deformation measurements made with
interferometric synthetic aperture radar (InSAR) is that an interferogram only measures one component of the surface
deformation - in the satellite's line of sight. We investigate strategies for mapping surface deformation in three
dimensions by using multiple interferograms, with different imaging geometries. Geometries for both current and future
missions are evaluated, and their abilities to resolve the displacement vector are compared. The north component is
always the most difficult to determine using data from near-polar orbiting satellites. However, a satellite with an
inclination of about 60°/120° would enable all three components to be well resolved. We attempt to resolve the 3D
displacements for the 23 October 2002 Nenana Mountain (Alaska) Earthquake. The north component's error is much
larger than the signal, but proxies for eastward and vertical motion can be determined if the north component is assumed
negligible. Inversions of hypothetical coseismic interferograms demonstrate that earthquake model parameters can be
well recovered from two interferograms, acquired on ascending and descending tracks. http://adsabs.harvard.edu/cgibin/nph-bib_query?bibcode=2004GeoRL.3101607W&db_key=AST
Wright, T. J., B. Parsons, P. C. England, and E. J. Fielding (2004), InSAR Observations of Low Slip Rates on the Major
Faults of Western Tibet, Science, 305, 236-239. Two contrasting views of the active deformation of Asia dominate the
debate about how continents deform: (i) The deformation is primarily localized on major faults separating crustal blocks
or (ii) deformation is distributed throughout the continental lithosphere. In the first model, western Tibet is being
extruded eastward between the major faults bounding the region. Surface displacement measurements across the western
Tibetan plateau using satellite radar interferometry (InSAR) indicate that slip rates on the Karakoram and Altyn Tagh
faults are lower than would be expected for the extrusion model and suggest a significant amount of internal deformation
in Tibet.
Wright, T. J., E. J. Fielding, B. E. Parsons, and P. C. England, Triggered slip: observations of the 17 August 1999 Izmit
(Turkey) earthquake using radar interferometry, Geophys. Res. Lett., in press, 2000.
Wright, T. J., Z. Lu, and C. Wicks (2003), Source model for the Mw 6.7, 23 October 2002, Nenana Mountain Earthquake
(Alaska) from InSAR, Geophysical Research Letters, 30. The 23 October 2002 Nenana Mountain Earthquake (Mw ~
6.7) occurred on the Denali Fault (Alaska), to the west of the Mw ~ 7.9 Denali Earthquake that ruptured the same fault
11 days later. We used 6 interferograms, constructed using radar images from the Canadian Radarsat-1 and European
ERS-2 satellites, to determine the coseismic surface deformation and a source model. Data were acquired on ascending
and descending satellite passes, with incidence angles between 23 and 45 degrees, and time intervals of 72 days or less.
Modeling the event as dislocations in an elastic half space suggests that there was nearly 0.9 m of right-lateral strike-slip
motion at depth, on a near-vertical fault, and that the maximum slip in the top 4 km of crust was less than 0.2 m. The
Nenana Mountain Earthquake increased the Coulomb stress at the future hypocenter of the 3 November 2002, Denali
Earthquake by 30-60 kPa. http://adsabs.harvard.edu/cgi-bin/nphbib_query?bibcode=2003GeoRL.30SDE12W&db_key=AST&high=41f192cbba08585
Wright, T., B. Parsons, and E. Fielding (2001a), Measurement of interseismic strain accumulation across the North Anatolian
Fault by satellite radar interferometry, Geophys. Res. Lett., 28, 2117-2120.
Zebker, H. A., F. Amelung, and S. Jonsson, Remote sensing of volcano surface and internal processes using radar
interferometry, in Remote Sensing of Active Volcanos, edited by P. Mouginis-Mark, 116, pp. 179-205, Amer. Geophys.
Union, Washington, D.C., 179-205, 2000.
Theses
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National Toulouse, 1997.
Berthier, E. (2005), Universite Paul Sabatier, Toulouse.
Catita,(2005), Faculty of Sciences, Lisbon.
Carnec, C., Interférométrie SAR Différentielle : Application à la détection et au suivi de mouvements de terrain, Doctorat de
l'Université, U. Paris 7, 1996.
Chlieh, M., Etude du cycle sismique en zone de subduction par Interferometrie Radar, these doctorale, IPG Paris, prevu
2002.
Delacourt, C., Détection et analyse de mouvements de surface par interférométrie différentielle, Ph.D., Institut de Physique
du Globe de Paris, 1997.
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Dupont, S., Génération de modèles numériques de terrain par interférométrie ROS, Doctoral, U. Nice-Sophia Antipolis,
1997.
Funinng, G. (2005), D. Phil. thesis, University of Oxford.
Gasperi, J., Etude de la déformation lithosphérique active par interférométrie radar. Application à la region de Hengill,
Islande, Ph.D., Univ. P. Sabatier, 1999.
Henriot, O., Fonctionnement d'une zone transformante et de son raccord avec un rift : L'exemple de la zone transformante de
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Deffontaines, B., J. P. Rudant, S. Wade, S. Gobert, A. Bedidi, F. B., D.-F. P., and Bailly A, Geomorphological and
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Fielding, E., T. J. Wright, B. Parsons, P. England, P. Rosen, S. Hensley, and R. Bilham, Topography of Northwest Turkey
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