From: LARRY KLAES (ljk4_at_msn.com)
Date: Fri Dec 05 2003 - 08:25:04 PST
----- Original Message -----
From: NASA Jet Propulsion Laboratory
Sent: Thursday, December 04, 2003 8:56 PM
To: ljk4_at_msn.com
Subject: Progress, Promise in Space-based Earthquake Research
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
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David E. Steitz (202) 358-1730
NASA Headquarters, Washington, D.C.
Alan Buis (818) 354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
NEWS RELEASE: 2003-162 December 4, 2003
Progress, Promise in Space-based Earthquake Research
Nearly 10 years after Los Angeles was shaken by the devastating,
magnitude 6.7 Northridge earthquake, scientists at NASA and other
institutions say maturing space-based technologies, new ground-based
techniques and more complex computer models are rapidly advancing our
understanding of earthquakes and earthquake processes.
Dr. Andrea Donnellan, a geophysicist at NASA's Jet Propulsion
Laboratory, Pasadena, Calif., says the past decade has seen
substantial progress in space-based earthquake research. "We've
confirmed through space observation the Earth's surface is constantly
moving, periodically resulting in earthquakes, and we can measure both
the seismically quiet motions before and after earthquakes, as well as
the earthquakes themselves. These technologies are allowing us to
pursue lines of data and research we didn't know existed only a few
years ago."
Two months before the Northridge earthquake, Donnellan and university
colleagues published a paper in the journal Nature on ground
deformation north of Los Angeles' San Fernando Valley. Six years of
Global Positioning System (GPS) data showed the area's faults were
active and building up strain, and indicated the size and style of a
potential earthquake there. Following the earthquake, the data made it
possible to rapidly determine where the fault ruptured and to measure
how the earthquake had deformed Earth's surface.
Space-based instruments can image Earth movements to within fractions
of an inch, measuring the slow buildup of deformation along faults,
and mapping ground deformation after an earthquake. Two primary tools
are the space-based GPS navigation system and Interferometric
Synthetic Aperture Radar (InSAR). The latter compares satellite radar
images of Earth taken at different times to detect ground movement.
InSAR complements surface measurements because it lets us look at
whole regions in a spatial context. An InSAR mission is also a key
component of EarthScope, a jointly led initiative by the National
Science Foundation, NASA and the U.S. Geological Survey.
EarthScope studies the North American continent's structure and
evolution, and the physical processes that control earthquakes and
volcanic eruptions, according to Dr. James Whitcomb, section head for
Special Projects, Earth Sciences Division, National Science
Foundation, Arlington, Va.
Precise Earth surface-movement data measure strain and provide a first
approximation of where earthquakes are likely to occur, notes Dr. Brad
Hager, a Massachusetts Institute of Technology professor and co-author
of the 1993 Nature paper. "In California, patterns of ground
deformation are complicated by the complex interactions between fault
systems. Interpreting this data requires computer models that can
estimate how much deformation has accumulated and identify regions
where strain should be released, but hasn't been."
University of California, Davis, researcher Dr. John Rundle says the
complexity of earthquakes requires we study them as part of the full
Earth system. "Most natural events result from interrelated Earth
processes over various lengths and times. "These processes have
variables that can't be readily observed, so understanding them
requires computers."
NASA's QuakeSim project is developing a similar forecasting
methodology. Its tools simulate earthquake processes, and manage and
model the increasing quantities of data available. "We're focusing on
observing and understanding earthquakes in space and time, and
developing methods that use patterns of small earthquakes to forecast
larger ones," Rundle explains. "New simulations of earthquakes on
California's active faults are providing considerable insight, showing
earthquakes tend to "cluster" in space and time due to their
interactions. That is, an earthquake on one fault section can turn on
or off earthquake activity on nearby fault sections, depending on the
relative orientation of the faults. Simulations have led researchers
to conclude that fault system geometry determines earthquake activity
patterns."
A NASA/Department of Energy-funded research team reports promising
results from an experiment to forecast earthquakes in southern and
central California from 2000 to 2010. It uses mathematical methods to
forecast likely locations of earthquakes above magnitude 5 by
processing data on earthquakes of about magnitude 3 from the past
decade. The high-risk regions identified in the forecast are refined
from those already identified by the government as susceptible to
large earthquakes. Five earthquakes greater than magnitude 5 have
occurred since the research was completed, all in those high-risk
regions.
Dr. Wayne Thatcher, a senior research geophysicist at the U.S.
Geological Survey, Menlo Park, Calif., says as these technologies are
validated they will be transferred to end users. "Such data and models
improve understanding of earthquake and volcanic processes,
substantially refining seismic hazard maps and resulting in more
appropriate, earthquake-resistant construction codes and more targeted
retrofitting strategies."
Points of contact for other organizations cited in this release are:
Andy Fell, University of California, Davis, 530/752-4533; Stephanie
Hannah, USGS, 206/220-4573; Deborah Halber, MIT, 617/258-9276; Cheryl
Dybas, NSF, 703/292-7734.
JPL is managed for NASA by the California Institute of Technology in
Pasadena.
-end-
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