INTERNATIONAL ASSOCIATION OF SEISMOLOGY AND PHYSICS OF THE
EARTH’S INTERIOR 2006
Compiled by Pekka Heikkinen
Institute of Seismology, University of Helsinki (Pekka Heikkinen)
The research at the Institute of Seismology focuses on the structure of the lithosphere and
earthquakes in the Fennoscandian Shield.
STRUCTURE OF THE LITHOSPHERE
FIRE deep reflection profiling project
Deep seismic reflection profiles FIRE 1-4 (2165 km) study the structural architecture and
evolution of the Fennoscandian Shield. The profiles transect all major tectonic units and
boundaries of the Fennoscandian Shield in Finland. The project is carried out by the FIRE
consortium: the Geological Survey of Finland, the Institute of Seismology of the University
of Helsinki, the Institute of Geosciences of the University of Oulu and the Sodankylä
Geophysical Observatory of the University of Oulu. The data sets and preliminary
interpretations of the FIRE profiles were published in the Geological Society of Finland
Special Publication Series in 2006.
Stabilization processes of Precambrian continental crust
The correlation of the seismic reflection structures with surface geology has been continued
by studying the evolution of the Central Finland Granitoid Complex. The CFGC is cross-cut
by two deep seismic reflection lines FIRE 1&2 and 3, whose preliminary interpretation
indicates that the Granitoid Complex was formed on the top of a stack of continental slices
as a result of extension during gravitational collapse of the orogen. The field work
concentrated on the lithological and structural studies of the margin of the complex near the
village of Pihtipudas, where metamorphic block structures have previously been reported.
Receiver function studies
The aim of the study is to obtain crustal thickness and shear wave velocity model at the sites
of 15 permanent seismic broad-band stations in Finland as well as at 5 broad-band stations in
adjacent areas. The data collection has started in fall 2005.
Local seismic tomography
Results from SVEKALAPKO tomographic array 1998-1999 have been used to combine a
3D model of the P-wave, S-wave and Vp/Vs ratios in southern and central Finland. The
results suggests that local seismic tomography can be used to identify ancient block
boundaries and that closed basins can be detected as areas of lower velocity and lower
Vp/Vs ratio.
PASSEQ
The main aim of the PASSEQ 2006-2007 experiment is an investigation of the seismic
structure of the mantle in Central Europe in the Trans-European Suture Zone (TESZ).
During the project local, regional and teleseismic earthquakes are recorded continuously
from May 2006 to December 2007 by about 150 seismic stations in a corridor about 300 km
wide and about 1000 km long crossing the Teisseyre-Tornquist Zone (TTZ) from Germany
and Czech Republic, through Poland to Lithuania. During the field work 8 SP stations from
University of Helsinki are installed in Lithuania. The project is cooperation between 13
institutes from 10 countries.
ALPASS
ALPASS is a passive seismic monitoring project aiming to reveal upper mantle, lower
lithosphere, and asthenosphere beneath the wider Eastern Alpine region. Between May 2005
and summer 2006 about 50 field equipment were deployed on 4 lines crossing the Eastern
Alps, the Dinarides to Hungary, and a small area surrounding parts of the Vienna basin. The
project is cooperation between research groups from Austria, Croatia, Finland, Hungary,
Poland and USA. ALPASS is continuation of the active seismic experiment ALP 2002.
Interpretation of the ALP 2002 data continued during 2006.
Moho map of Europe
The study is a programme of ESC Subcommission-D and Working Group on “Crustal
Structure Maps of Europe“.The aim of the study is to compile a crustal map of Europe
including P- and S-wave velocities in the crust and just below the Moho boundary and the
depth of the Moho. The compilation work is a co-operative effort of the Institute of
Seismology, Physics Department of the University of Warsaw and British Geological
Survey.
FENNOSCANDIAN EARTHQUAKES
Earthquake source mechanisms in Anjalankoski and Kuusamo
In May 2003, the Finnish seismograph network recorded a swarm of 16 microearthquakes
(ML=0.6-2.1) at Anjalankoski, SE Finland. The relocated epicenters as well as the dip and
strike of the nodal plane coincided with an internal intrusion boundary of the Vyborg
rapakivi batholith. Relative location together with synthetic waveform modelling of the Rgwave confirmed that the events were unusually shallow, most likely occurring 1 to 2 km
below the surface.
A temporary network of five seismic stations was installed at Kuusamo, the seismically most
active area in Finland. Analysis of microearthquakes (with magnitude less than 2) recorded
by a dense local network can provide reliable data on the local stress field and slip pattern as
well as on active faults and their geometry. Earthquake activity in Kuusamo seems to cluster
at the intersections of the major shear zones. In addition to the research on local seismicity,
the recordings of the network will be used in local tomographic studies.
Historical earthquakes in Northern Europe
The research initiative focuses on pre-instrumental earthquakes between 1750 and 1950 in
Northern Europe including the Baltic and Nordic countries. It is motivated by the current
situation in which macroseismic studies using original data, can mainly be found in printed
national publications, often in different languages and based on different intensity scales and
data analysis practices. One objective of the work is to create an online database of
historical earthquakes in Northern Europe. The improved database can be used to address
issues relevant to seismicity assessments such as the quantification of pre-instrumental
earthquakes, the long-term behaviour of areas of enhanced seismicity in Northern Europe
and return periods of different magnitudes.
The participating institutions are currently the Universities of Uppsala, Bergen and Helsinki;
Geological Survey of Denmark; Russian Academy of Sciences, Latvian Environment,
Geology and Meteorology Agency and Geological Survey of Lithuania.
The studies conducted so far have concentrated on reliable collections of intensity data
points for important earthquakes in the region. The time period covered includes the 1880s
and 1890s.
Modern earthquakes have been used for the calibration of intensity-magnitude scaling
relations. The earthquakes of magnitudes Mw5.0 and 5.2 in the Russian enclave of
Kaliningrad on 21 September 2004 were of the same order of size as some disputed
historical events in Northern Europe and thus provided an opportunity to compare
magnitudes with the respective areas of perceptibility. This work was carried out between
several scientists in the affected countries.
Sodankylä Geophysical Observatory of the University of Oulu (E. Kozlovskaya).
Sodankylä Geophysical Observatory of Oulu University (SGO) is located at 67° 22’ N, 26°
38’ E in the middle of Finnish Lapland. It was established in 1913 and since then has gained
a long experience in carrying out multidisciplinary geophysical observations in polar region.
The research activity is concentrated on structure of the Lithosphere in Finland and in
Central Europe.
LITHOSPHERE STUDIES IN FINLAND
a) FIRE (Finnish Reflection Experiment).
Sodankylä Geophysical Observatory is a member of FIRE Consortium and participated both
in the FIRE field experiment in 2001-2003 and in data processing and interpretation. In
2005-2006 modeling of wide-angle recordings along FIRE3 and FIRE4 profile was
performed. In addition, 3-D density model of the Kuhmo Greenstone Belt crossed by the
FIRE1 reflection profile and SVEKA wide-angle reflection and refraction profile.
b) Detailed analysis of S-waves registered during deep seismic sounding experiments in
Finland.
The purpose of the project is to make detailed analysis of high-quality recordings of S-waves
registered during previous wide-angle reflection and refraction experiments in Finland
(SVEKA, FENNIA, BALTIC ja POLAR) and compare them to the results of new FIRE
reflection survey, in order to evaluate variations of Vp/Vs ratio in the crust and upper mantle
and to define different types of crust-mantle transitions in the Precambrian Fennoscandian
Shield. New combined P- and S-wave velocity models of SVEKA, FENNIA and POLAR
profiles were obtained.
c) Deep structure of the upper mantle beneath Central Fennoscandian Shield from
seismic anisotropy studies.
The purpose of the project was to estimate anisotropy in the upper mantle beneath southern
and central Finland using analysis of teleseismic events registered during the
SVEKALAPKO experiment. The main method of anisotropy investigation is joint analysis
of S-wave splitting and P-wave residuals. The study revealed several domains with different
anisotropic pattern below the SVEKALAPKO seismic array and intercalating wedges of the
Proterozic and Archean lithospheres of different fabrics in south-central Finland.
d) Receiver function study of the crust and upper mantle of southeastern
Fennoscandian shield (central and southern Finland and Russian Karelia).
The main goal was to construct a 3-D P- and S-wave seismic velocity of the crust and
uppermost mantle of central and southern Finland and Russian Karelia by combining P-wave
receiver functions data and surface wave dispersion curves of the SVEKALAPKO temporary
seismic array. The project was finished in 2006.
e) POLENET/LAPNET
Polenet/Lapnet is a sub-project of the POLENET consortium related to seismic studies in the
Arctic regions during the International Polar Year 2007-2008. POLENET/LAPNET
activities will be carried out on the territory of northern Fennoscandia (Finland, Sweden,
Norway and northwestern Russia), coordinated by the Sodankylä Geophysical Observatory
of the University of Oulu (E. Kozlovskaya). The purpose of the project is to carry out a
passive seismic array experiment in Northern Fennoscandia during 2007-2009. Participating
organizations are: Institute of Seismology, University of Helsinki (FINLAND), University of
Grenoble Ecole et Observatorie des Sciences de la Terre (EOST-IPG) Strasbourg (FRANCE)
Geophysical Institute of CAS, Prague (CZECH REPUBLIC) Institute of Geodesy and
Geophysics of Vienna University of Technology (AUSTRIA), NORSAR (NORWAY),
Uppsala University (Sweden), Institute of Dynamics of Geospheres, RAS, Moscow (Russia),
ETZ Zuerich, Switzerland.
In 2006 the SGO started preparation to the POLENET/LAPNET experiment. The following
work has been completed:
 investigation of possible sites for deployment of temporary array (April-November,
2006)
 preliminary receiver function studies using data of permanent stations (in
collaboration with the Institute of Physics of the Earth, RAS, Russia).
 preliminary study of the upper mantle anisotropy using data of permanent stations (in
collaboration with the Institute of Geophysics of the Academy of Sciences of Czech
Republic).
LITHOSPHERE STUDIES IN CENTRAL EUROPE:
SEISMIC REFRATION/WIDE-ANGLE REFLECTION PROJECTS.
a) CELEBRATION 2000 and ALP2002:
The seismic group of the SGO participated in interpretation of data of CELEBRATION
2000 and ALP2002 wide-angle refraction and reflection survey.
b) SUDETES2003:
The main objective of the research was to develop methods of joint interpretation of seismic
and gravity data that can be used for interpretation of POLONAISE, CELEBRATION and
SUDETES projects. A 3-D velocity and density model of Sudetes Mountains and northern
part of the Bohemian Massif was developed using inversion of reflected and refracted waves
registered during SUDETES2003 experiment. The model was used to obtain a 3-D density
model of the area. The precise models of the crust and upper mantle from experiments
POLONAISE'97, CELEBRATION 2000 and SUDETES2003 as well as previous profiles LT
and TTZ were interpolated into a 3D P-wave velocity model for the whole Poland. The
crustal density model was used to calculate synthetic geoid elevation for the territory of
Poland and to estimate influence of separate layers (topography, sediments, crust and
mantle) on the gravity. For rapid calculation of effects of large-scale density models a code
based on mass point calculation scheme in ellipsoidal reference system was developed. The
synthetic geoid undulations caused by the crust were extracted from an existing gravimetric
quasi-geoid solution and the residual was inverted in order to evaluate density variations in
the upper mantle down to a depth of 250 km.
c) ALPASS (Alpine Lithosphere and Upper Mantle PASsive Seismic Monitoring):
The project is a passive seismic monitoring project aiming to reveal upper mantle, lower
lithosphere, and asthenosphere beneath the wider Eastern Alpine region, including the
Bohemian Massive, the Carpathians, the Pannonian Basin, and the Dinarides. In September,
2005 the seismic group of the SGO participated in the deployment of the ALPASS passive
seismic array. The data acquisition was finished in spring, 2006 and since then the group
performs routine processing and interpretation of the data.
d) PASSEQ (Passive Seismic Experiment in TESZ):
The purpose of the project is study of the investigation of the seismic structure of the mantle
and lithosphere-asthenosphere system in the transition between Proterozoic and Phanerozoic
Europe. The seismic group of the SGO participated in planning of the experiment and
deployment of the stations in 2006. The data acquisition will continue in 2007.
e) Studying of the deep lithosphere structure of the Polotsk -Kurzem zone of deep
faults from integration of seismic models of wide-angle reflection and refraction profile
with potential fields data, petrophysical information and results of magnetotelluric
soundings. (Partner: the Institute of Geochemistry and Geophysics of Academy of Sciences
of Belarus).
The main objective of the project was to summarize new and previously obtained geological,
geophysical and petrophysical data and seismic models of EB’96 and CEL05 wide-angle
reflection and refraction profiles in order to obtain an integrated geological and geophysical
model of the lithosphere of the Belarussian part of the Polotsk- Kurzem Shear Zone (PKZ).
Recent earthquakes in 2004 close to city of Kaliningrad caused by a strike-slip movement
along NW-SE trending near vertical fault suggest that the PKZ may represent an important
present-day intra-plate tectonic boundary capable to accumulate stresses. A 3-D combined
velocity and density model of the crust and upper mantle of the Belarussian part of the PKZ
was obtained.
f) Studies of the graphite-bearing rocks of the Outokumpu area in regard to its
comparison with the Palaeoproterozoic black shale complex in the Central Belarus
belt, Belarus (western part of the East European Craton). (Partners: the Institute of
Geochemistry and Geophysics of Academy of Sciences of Belarus, Geological Survey of
Finland).
The purpose is to investigate the Palaeoproterozoic black shale deposits in the Outokumpu
area (Fennoscandian Shield, Finland) and the Central Belarus belt (western part of the East
European Craton, Belarus). In 2006 the investigation focused on petrological, geochemical
and petrophysical studies aiming at providing the information on palaeotectonic position of
black shale formations and black shale ore (particularly Au-PGE) prospecting.
Geological Survey of Finland ( I.T. Kukkonen)
LITOSPHERE STUDIES
Finnish Reflection Experiment FIRE.
The aim of the project FIRE (Finnish Reflection Experiment) is to investigate the structure
of the crust in Finland on several transects using reflection seismics during 2001-2005. The
project is participated by the Geological Survey of Finland, and the universities of Helsinki
and Oulu. Field work was carried out in 2001-2003 and it resulted in 2100 km of highquality reflection lines. The transects crossed the major geotectonic units of the Precambrian
in Finland, including several areas of metallogenic significance. The field work was carried
out by the Russian government-owned company Spetgeofysika acting as a contractor. In
2006 the interpretation and reporting of the FIRE results was finalized and the major results
were published in a special volume by the Geological Survey of Finland (Kukkonen and
Lahtinen, 2006). Among the main results of the FIRE surveys are the strong reflectivity seen
often throughout the crust, distinctly three-dimensional structures and diffuse reflection
Moho, particularly under the anomalously thick crust area beneath the Central Finland
Granitoid Complex.
Outokumpu Deep Drilling Project
The Geological Survey of Finland is carrying out a deep drilling research project at
Outokumpu, eastern Finland. In January 2005, the Outokumpu deep drill hole reached
the final depth of 2516 m within a Palaeoproterozoic metasedimentary and ophioliterelated sequence. The basic drilling program included continuous coring and borehole
geophysics with 20 different methods, as well as fluid sampling and hydraulic
conductivity measurements in the hole.
The main criteria that motivated the Outokumpu Deep Drilling Project are as follows:
(1) Understanding the deep structure of a classical ore province in Precambrian terrain.
The Cu-Co-Zn deposits of the Outokumpu district, hosted by a distinct 1.96 Ga old
ophiolitic assemblage formed an important mining area for about 80 years. The ore
potential is still considered high; (2) Understanding the composition and origin of the
saline fluids and gases identified in earlier drill holes in the Outokumpu region, and
studying the deep biosphere;
(3) Investigating the vertical variation of different geological and geophysical
parameters and correlating geological, geophysical and petrophysical data sets;
(4) Using the Outokumpu hole as a deep geolaboratory for various in situ experiments,
fluid sampling and monitoring.
The Outokumpu Deep Drilling Project has already produced several important
observations regarding the nature of seismic reflectors, deep gas-bearing fluids, and
detection of a thick layer of pegmatitic granite at depths of 2.0-2.5 km and extending
probably much deeper.
Research projects in the framework of the Outokumpu Deep Drilling Project are
currently in preparation or already being carried out by several teams representing
Canada, Czech Republic, Finland, Germany, Netherlands, Norway, Russia and
Sweden. The Outokumpu project is receiving support from ICDP, and geophysical
logging, stress field studies, hydrogeological studies, a VSP seismic experiment, and a
fluid injection experiment are being planned for 2006-2008.
In 2006 an extensive VSP experiment and surface reflection seismic survey was
carried out in co-operation by Department of Geophysics of University of Alberta,
Institute of Seismology of University of Helsinki, and the Gelogical Survey of Finland.
Data is currently being processed. Borehole activities included temperature and fluid
salinity logs, sonic log and acoustic televiewer log carried out by the Operational
Suport Group of ICDP. Samples of the drill core were delivered to several teams in
Finland, Germany and Russia for various geological and geophysical investigations.
GEOTHERMAL RESEARCH
(related to the theme of the International Heat Flow Commission of the IASPEI)
Geothermal research at the Geological Survey of Finland includes temperature loggings of
boreholes, measurements of thermal parameters of rocks in laboratory, lithospheric thermal
modelling, studies of palaeoclimatic and hydrogeological effects on the subsurface thermal
field as well as studies of heat production of rocks.
In 2006 the activities were related to borehole temperature measurements for environmental
forestry studies in Lapland, repeated temperature loggings in a monitoring borehole for
permafrost studies at Ylläs, western Lapland and heat flow measurements in Lofoten Islands
in Norway. In the Outokumpu deep drill hole temperature logs were obtained with the help
of the ICDP-OSG logging team. Anthropogenic effects on subsurface temperatures were
investigated using empirical borehole data and 3D heat transfer models together with the
Geophysics Institute of the Czech Academy of Sciences.
I.T. Kukkonen acted as the past chairman of the International Heat Flow Commission of the
IASPEI for the period of 2003-2007.
Number of articles in peer-reviewed journals 24
Number of other reports and extended abstracts 23
Number of presentations 58