IRIS and UNAVCO Facility Proposals
Draft 20120221 – Distributed to IRIS and UNAVCO Boards
Coordinated Activities Text Boxes
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EarthScope in Cascadia and Synergy with GeoPRISMS
Twenty-five years ago, scientists were still debating whether the Cascadia subduction zone
was capable of generating great earthquakes. Today, Cascadia has rocketed to scientific
prominence not only because of the threat it poses, but also because of the GPS-based
discovery of aseismic slip transients, accompanied by tectonic tremor showing that
Cascadia is indeed active, despite its perplexing seismic quiescence. Now, EarthScope and
other NSF-funded installations of GPS stations, borehole strainmeters and seismometers,
and ocean-bottom seismometers yield massive data streams documenting Cascadia's interseismic activity. UNAVCO and IRIS play key roles in deploying and maintaining these
instruments, archiving the data, and making data products available to the Earth science
community worldwide.
Cascadia instrumentation was established in two waves: between 2004 and 2009, the PBO
installed 245 continuous GPS stations in Washington, Oregon, and northernmost California,
as well as 45 borehole strainmeters with co-located 3-component seismometers. With
funding from the American Reinvestment and Recovery Act (ARRA), NSF launched the
Cascadia Initiative, which upgraded all the PBO Cascadia GPS stations to real-time,
densified onshore seismic networks, and is deploying an array of ocean-bottom
seismometers for offshore community experiments.
Exciting new opportunities will exist for the region in the coming years. For instance, data
from the Cascadia Initiative ocean-bottom seismometer deployments will become available,
a unique new data source that will significantly enhance our ability to image the downgoing
oceanic slab, which despite USArray Transportable Array occupation continues to be a
challenging structure to image. In addition, the NSF-funded GeoPRISMS program has
selected Cascadia as one of three primary sites for the Subduction Cycles and Deformation
(SCD) Initiative. Collaboration between the EarthScope and GeoPRISMS communities will
ensure that continued studies of this region can be made with an explicitly interdisciplinary
effort.
Abers Geology 2009; Probably should include another figure in map view with a cool
geodetic result if available.
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EarthScope in Alaska and Synergy with GeoPRISMS
Alaska is an excellent target for EarthScope due to its diverse crustal structure and geologic
history. The Alaskan crust was built by successive subduction-to-arc systems and accreting
terranes combined with 1000s of kilometers of strike-slip motion on continental-scale fault
systems. In terms of active tectonics, all parts of Alaska currently have high surface
velocities relative to stable North America, and active seismicity spans most of the state
and surrounding areas. There are about five times more earthquakes annually within
Alaska than in the lower 48 states combined. This highly dynamic subduction system
therefore has significant potential for hazardous high-magnitude subduction and strike-slip
earthquakes, tsunamis, and volcanic eruptions. There is a high likelihood of recording a
magnitude 7 or larger event within the TA deployment.
In many ways, Alaska is a geoscience frontier with enormous area never having been
studied beyond reconnaissance level. There are large areas devoid of instrumentation of
any kind. First-order measurements, such as basic crust and mantle structure, and surface
velocities away from the plate boundary, remain to be determined. Further, zones of active
tectonics lack any precise earthquake locations.
Further new opportunities exist for the region in the coming years. For instance, the NSFfunded GeoPRISMS program has selected the Alaska-Aleutians margin as one of three
primary sites for the Subduction Cycles and Deformation (SCD) Initiative. Collaboration
between the EarthScope and GeoPRISMS communities will ensure that continued studies of
this region can be made with an explicitly interdisciplinary effort.
Freymueller AGU monograph, 2008.
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Seismicity fig from Roger Hansen; should include total counts in the size range?
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EarthScope and Real-Time GPS
Continental deformation operates on time scales that span seconds (earthquakes) to
millennia (tectonic deformation) and hence is best studied using seismic and geodetic
observations that both measure displacements over vastly different time scales. Merging
these data streams into rigorously integrated broadest-spectrum records will unify
observation of a very broad span of Earth processes, from fault rupture dynamics to
postseismic transients to long term plate motion.
Real time measurements are those that arrive with high rate and low latency. History
shows that when data arrive with very low latency, they fundamentally change how people
use and assimilate the information. While crucial for natural disaster research and warning,
RTGPS data also provides higher temporal resolution in observations of natural processes.
The availability of real time data can significantly enhance research outcomes, by rapidly
informing research teams and enabling immediate response and adaptation to changing
circumstances. Recent ARRA-funded upgrades of hundreds of GPS stations in the Pacific
Northwest have created new opportunities and incentives to develop RTGPS for
EarthScope science and applications.
While seismology has been a real-time business for decades, precise GPS geodesy is still in
a development phase where results are either very quick or very precise. The community is
working towards the availability of solutions that are both high rate, low latency, have the
required precision, and can be operationally applied to data from hundreds to thousands of
stations. The future development of RTGPS will require the combined attention and
resources of UNAVCO and IRIS facilities and communities, ideally through a focused
EarthScope-driven effort. This coordination will entail co-sponsorship of workshops,
working groups, development of data products,
formats and standards that ease use and
maximize the utility of these data.
Figure 1. Displacements associated with 2003
MW 8.3 Tokachi-oki, Japan earthquake and
estimated moment tensor solutions (figure from
Melgar et al., 2011). (Permission to use figure not
yet requested from author).
Melgar, D., Y. Bock, and B. Crowell (2011), Real-time
centroid moment tensor determination for large
earthquakes from local and regional displacement records,
Geophysical Journal International, 188, 703-718.
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EarthScope and Volcanic / Magmatic Systems
Volcanic and magmatic processes are a perennial source of fascination for scientists and
the public alike. The hazards posed by eruptions, including disruptions to air traffic,
property loss, and human health hazards, provide ample motivation to warrant sustained,
integrated research efforts. Geodesy and seismology continue to play leading roles in this
work. Advances in seismic imaging and GPS data analysis, coupled with new data from
USArray and PBO, also foreshadow new insights into dynamics of mantle-to-surface melt
transfer, separation and flux of volatile phases during magmatic intrusion events, and the
effects of magmatic intrusion episodes on local tectonics (and vice-versa). Imaging enabled
by USArray data suggests partial melt is widespread in the mantle beneath volcanic
provinces and rift zones of the western US Cordillera, and GPS data have shown unexpected
evidence of deep magmatic unrest episodes during the past decade in locations such as
Soccoro, NM and Lake Tahoe, NV. Comparisons of GPS time series and InSAR
interferograms at Yellowstone moreover exhibit patterns of simultaneous uplift and
subsidence that indicate the deformation associated with magmatic intrusion exerts
significant forcing on volatile flux.
PBO and USArray efforts have helped to improve instrument arrays for the Alaska
Volcanoes Observatory (AVO), Cascade Volcanoes Observatory (CVO), and Yellowstone
Volcano Observatory (YVO). The facilities have responded to crises and subsequent
eruptions at Okmok and Augustine volcanoes in Alaska, and Mt. St. Helens. Facility efforts
were also critical to monitoring of the unprecedented 2004-2010 uplift episode at
Yellowstone and associated earthquake swarm activity. The accrual of these data sets,
coupled with the impending arrival of the Transportable Array in Alaska, heralds additional
significant advances to come in our understanding of magmatic systems. Continued
coordination of data collection efforts in all of these regions is critical to long-term success
of improving our understanding of these systems.
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Figures from Chang et al. (Science, 2007) - full reference to be included
Don’t necessarily need both figures (or at least all panels); Should probably include a
USArray-type figure as well (Perhaps a figure from Schmandt and Humphreys 2010?)
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EarthScope in Eastern North America and Synergy with GeoPRISMS
With a complicated record of multiple Wilson cycles and significant along-strike geologic
variations, Eastern North America is an excellent place to study mountain building
processes, rift-initiation, and the evolution, structure, and deformation of a passive
continental margin. The transportable array of EarthScope arrives in the eastern United
States in 2012-13 providing the tools and observations necessary for studies at the whole
margin scale. GeoPRISMS has identified the Eastern North America Margin as a primary
site of the Rift Initiation and Evolution Initiative (RIE). Three high-priority focus areas have
been identified for study linking GeoPRISMS and EarthScope science: 1) a swath across the
Canadian Appalachians to oceanic crust offshore Nova Scotia crossing the transition from
magma-rich and magma-poor rupture and continental breakup, 2) a mid-Atlantic swath
that stretches along strike from Philadelphia, PA to Richmond, VA and across strike from
the Appalachian Plateau to the offshore Baltimore Canyon and Carolina troughs, and 3) a
NW-SE oriented swath from the Appalachian foreland in Kentucky to oceanic crust offshore
the Blake Plateau, through the city of Charleston, SC. Collectively these areas present clear
opportunities to address fundamental questions about terrane accretion, orogeny, rifting
and continental break-up including the importance of tectonic inheritance, post-rifting
passive margin development, and neotectonic deformation.
The August 2011, the Mw 5.8 Mineral Virginia earthquake serves as a reminder that
passive margins are not tectonically quiescent and that seismic hazards on the east coast
are real and not well documented. Ground shaking associated with the event was felt over a
larger region of the U.S. than any previous instrumentally recorded earthquake due to
efficient energy propagation through crystalline bedrock that underlies much of the
eastern margin of the U.S. The arrival of EarthScope's Transportable Array on the east coast
combined with opportunities for flexible array deployments and the integration of GPS
data present new opportunities to better quantify deformation, raise awareness of
earthquake hazards, and motivate improved earthquake preparedness in eastern North
America.
Given the major population centers and critical infrastructure located in the northeast
corridor of the U.S., better understanding of deformation and stress release on both short
and long time scales has significant broader impacts. There is growing community interest
in a plate interior observatory extending from the east coast to central North America
integrating the synoptic geologic and geophysical data required to understand the
dynamics of plate interiors and nominally passive margin systems.
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Figure options from Donna Shillington and Anne Meltzer. Should get a single integrated
figure, depending on choices of which to use.
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EarthScope Education and Outreach
The UNAVCO and IRIS Education and Outreach (E&O) programs have collaborated
extensively since the initiation of the UNAVCO E&O program (7+ years) and that successful
partnership will continue. This is particularly true for EarthScope-related activities, where
UNAVCO and IRIS work closely with the EarthScope National Office (ESNO) to bring
EarthScope science to national, regional and local audiences within the EarthScope
footprint. Collaborations have ranged across each group’s products and services, including
workshops, short courses, media content, and internships.
In EarthScope-focused teacher workshops, UNAVCO and IRIS staff jointly develop the
teaching sequences, serve as instructors, and use course content drawn substantially from
UNAVCO- and IRIS-produced teaching materials. The UNAVCO-IRIS-ESNO team has
supported numerous workshops led by others, most often in regions with high hazard (e.g.
the Teachers on the Leading Edge, TOTLE, workshops in the Pacific northwest, the New
Madrid Seismic Zone) or in regions with enhanced opportunities for earth science
education (e.g. the Texas teachers series, responding to expanded requirements for science
education in that state). Both UNAVCO and IRIS also actively participate in the interpretive
workshops that have been organized by ESNO for informal educators (e.g. National and
regional park rangers, local and regional museums).
Both groups have led successful graduate/post-grad level short courses on the processing
and use of geodetic or seismic data, and with the increasing use of combined geodetic and
seismic data sets we propose the creation of a joint short course covering the use of PBO
and USArray data.
UNAVCO and IRIS also cooperate on EarthScope-related content in a variety of media
formats. For instance, the generation of EarthScope-centric content to the EarthScope
inSights quarterly newsletter (produced by ESNO), brochures on topics such as Episodic
Tremor and Slip, and Teachable Moments slide sets distributed by IRIS with contributions
from UNAVCO after major earthquakes. Technology-driven delivery is also a mainstay.
For instance, the development of the IRIS Active Earth Monitor, which includes real-time
and animated content for Cascadia, Basin and Range and New Madrid systems. Another
example is attractive and interactive content tailored for mobile devices, currently led by
UNAVCO to port EarthScope and PBO tools and topics, which can be extended to include
USArray information.
Student education and mentoring is also a mainstay. For instance, UNAVCO and IRIS
cooperate on the UNAVCO Research Experiences in Solid Earth Sciences for Students
(RESESS), through a subaward to IRIS. Under EarthScope, UNAVCO funds one of the
RESESS interns each summer, and some IRIS undergraduate interns (funded through a
separate REU award) engage in EarthScope sponsored research each summer. UNAVCO
and IRIS also collaborate on a student field trip at the annual SACNAS meeting, and share
booths at selected professional meetings.
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EarthScope Facility-Oriented Operations (Bob Woodward and Chuck Meertens)
Waiting for text
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