From: LARRY KLAES (ljk4_at_msn.com)
Date: Thu Feb 06 2003 - 06:04:26 PST
----- Original Message -----
From: NASA Jet Propulsion Laboratory
Sent: Wednesday, February 05, 2003 7:53 PM
To: ljk4_at_msn.com
Subject: Satellite Helps Scientists see Quake Effects in Remote Areas
MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIFORNIA 91109. TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov http://www.jpl.nasa.gov/
Alan Buis (818) 354-0474
Jet Propulsion Laboratory, Pasadena, Calif.
Krishna Ramanujan (301) 286-3026
Goddard Space Flight Center, Greenbelt, Md.
News Release: 2003-012
February 5, 2003
Satellite Helps Scientists see Quake Effects in Remote Areas
The unique capabilities of a NASA Jet Propulsion Laboratory-built and
managed instrument aboard an Earth-observing satellite have allowed
researchers to view effects of a major earthquake that occurred in
2001 in Northern India near the border of Pakistan.
Lead researcher Dr. Bernard Pinty of the Institute for Environment and
Sustainability in the Joint Research Centre of the European
Commission, Ispra, Italy, together with colleagues from the United
States, France and Germany, used the Multi-angle Imaging
SpectroRadiometer (Misr) instrument on NASA's Terra satellite to
observe the effects of a massive earthquake in the Gujarat province of
India. Results of their study appear in the current issue of the
American Geophysical Union's journal, Eos.
Considered one of the two most damaging seismic events in India's
recorded history, the Gujarat quake struck January 26, 2001, and had a
magnitude of 7.7 (Richter scale). About 20,000 people died and another
16 million people were affected. Local residents reported fountains of
water and sediments spouting from the ground following the earthquake.
The quake's intense ground shaking caused loosely-packed,
water-saturated sediments in the area to liquefy, behaving more like a
liquid than a solid. Ground water flowed up to the surface, carrying
sediments and flooding large areas, including ancient riverbeds.
"Although Misr's multiangle and multispectral capabilities weren't
specifically developed to detect surface water, this is an exciting
application that merits further investigation," said co-author Dr.
David J. Diner, Misr principal investigator at JPL. "Of significance
to the Gujarat event is Misr's acquisition of compelling evidence of
surface water far from the earthquake's epicenter, particularly over
remote locations inaccessible to teams on the ground."
Aside from collecting scientific data in hard-to-reach places, Misr
also provides a map overview of what happened and the area affected.
Such information could be used to detect places where survey teams
could concentrate their efforts. In this case, Misr data demonstrated
that specific areas of an ancient salt lakebed north of Bhuj, known as
the Rann of Kutch, were more affected than others by dewatering, or
release of water and sediment due to compression and liquefaction. In
addition, the data were instrumental in identifying distant sites of
liquefaction. Such information may help to validate earthquake models
and to further define relationships between earthquake magnitudes and
distances of impacts.
"Satellites provide the best way to have a global view of an entire
region," said Pinty. "Hundreds of square kilometers can be observed
in a few minutes, and this happens at any time they fly over a place.
In the case of Gujarat, scientists were able to conduct surveys near
the epicenter but could hardly access other regions also affected by
the quake, partly because of their proximity to the Pakistani border,
a high security and politically sensitive region."
The quake's epicenter was about 80 kilometers (50 miles) east of the
city of Bhuj, but the Misr instrument found dewatering as far as 200
kilometers (124 miles) from the epicenter. Additionally, there was
significant dewatering all along the 80 to 100-kilometer (50 to
62-mile) wide (south to north) Rann of Kutch.
In the days and weeks following the earthquake, along with ground
cracks and other types of deformation, water flowed to the surface and
progressively evaporated in various places. A year later, scientists
could still observe the consequences of the earthquake across the Rann
because the water that came up to the surface was very salty. After
evaporation, salt was left on the ground, and Misr was able to detect
it also.
Misr views the sunlit face of Earth simultaneously at nine widely
spaced angles, and provides ongoing global coverage with high spatial
detail. Its imagery is carefully calibrated to provide accurate
measurements of the brightness, contrast and color of reflected
sunlight.
One way Misr registers surface features is by picking up different
wavelengths of light as they are reflected off Earth's surface. As it
passes overhead, Misr collects information over a 400-kilometer
(248-mile) swath at a spatial resolution of 275 meters (300 yards),
instantaneously assessing surface features over large regions. Since
the bright soils of the Rann of Kutch reflect most of the Sun's
incoming near-infrared radiation, and water bodies absorb
near-infrared radiation, Misr can detect the contrast and thereby tell
where dewatering from the earthquake occurred. Changes in reflection
at different view angles also proved advantageous to identify the
presence of surface water in other regions.
For more information, see:
http://www.gsfc.nasa.gov/topstory/2003/0115gujarat.html . More
information on Misr is at: http://www-misr.jpl.nasa.gov/ . The
European Commission's press release is at:
http://www.jrc.cec.eu.int/pressroom/gujarat.htm .
The California Institute of Technology in Pasadena manages JPL for
NASA.
-end-
This archive was generated by hypermail 2.1.6 : Thu Feb 06 2003 - 06:21:38 PST