Monday, December 13, 2010
Researchers Discuss Baja California's "Easter Earthquake"
Scripps researchers are using the recent event to study how faults move earthquake and their role in triggering movement on nearby faults
Scripps Institution of Oceanography / University of California, San DiegoAs a 7.2-magnitude earthquake rattled Baja California on April 4, 2010, scientists at Scripps Institution of Oceanography at UC San Diego were tracking the temblor along the U.S.-Mexico border using data from a network of seismic monitoring tools on the ground and in space.
Scripps research teams will present preliminary research findings from ongoing studies of the so-called "Easter Sunday" earthquake during several presentations at the 2010 American Geophysical Union (AGU) Fall Meeting in San Francisco.
During several talks, Scripps research geodesist and 2010 AGU Fellow Yehuda Bock and colleagues will discuss data collected from the California Real-Time Network, a prototype early warning system that uses GPS satellites to detect the surface deformation triggered by large earthquakes. (G11C-07 · Monday, Dec 13, 9:30 a.m. · 2003 Moscone West and T51E-05 · Friday, Dec. 17, 9:00 a.m. · 2011 Moscone West)
Scripps Research Geodesist Yehuda Bock and colleagues at a GPS station in California's Cleveland National Forest.
Within a day of the quake, Scripps geophysicists David Sandwell and Yuri Fialko headed to the U.S.-Mexico border city of Calexico on a rapid response research mission to deploy several GPS instruments near the rupture site to put together a picture of the ground movements.
"Most of the deformation occurs in the first day or two after the earthquake, so it was important to get out there soon after the event," said Sandwell, who used GPS and satellite image data to capture the post-seismic deformation at the rupture site.
Fialko, Sandwell and Scripps graduate student Meng Wei will discuss a slip model produced from surface deformation data to show how the fault moved at depth. Using satellite images, the team created a detailed map of surface motion that revealed more than 10 faults that moved during or soon after the quake, including the San Andreas Fault. The rupture produced both horizontal and vertical motion, which contributed to the complex pattern of seismic waves observed. (T53B-2125 · Friday, Dec. 17, 1:40 - 6:00 p.m. · Poster Hall Moscone South and T53B-2134 · Friday, Dec. 17, 1:40 - 6:00 p.m. · Poster Hall Moscone South)
A radar interferometry picture produced from satellite images by Sandwell's team also revealed the boundaries of a 20-kilometer-wide and 60-kilometer-long liquefaction zone. The agricultural area southwest of the ruptured fault produced sand volcanoes where the earthquake-induced stress liquefied the soil.
An interferogram derived from satellite data clearly shows the ground deformation and liquefaction cause by the "Easter" earthquake
"These findings have important implications to seismic hazard assessment in Southern California," said Wei.
Scripps scientists Catherine de Groot-Hedlin and Kris Walker will present an analysis of infrasound array data recorded in Southern California, which indicates that the surface shaking generated low-frequency sound waves that reached nearly 200 kilometers (124 miles) north and west of the epicenter. The research team used data recorded by an array near San Diego to model the surface shaking in the vicinity of the rupture and compared their results with U.S. Geological Survey ShakeMaps. (T53B-2119 · Friday, Dec. 17, 1:40 - 6:00 p.m. · Poster Hall Moscone South)
Prior to this temblor, the largest earthquake to shake Southern California was the 7.3-magnitude Landers earthquake, which occurred in the Mojave Desert in 1992. The 2010 Easter quake's epicenter was approximately 51 kilometers (32 miles) southeast of Mexicali in Baja California, Mexico and was felt as far away as Las Vegas.
# # #RELATED PRESENTATIONS:
G11C-07 · Monday, Dec 13, 9:30 a.m. · 2003 Moscone West
"RAPID MODELING OF AND RESPONSE TO LARGE EARTHQUAKES USING REAL-TIME GPS NETWORKS" (INVITED)
T51E-05 · Friday, Dec. 17, 9:00 a.m. · 2011 Moscone West
"OBSERVATIONS AND MODELING OF THE MW 7.2 2010 EL MAYOR-CUCAPAH EARTHQUAKE WITH REAL-TIME HIGH-RATE GPS AND ACCELEROMETER DATA: IMPLICATIONS FOR EARTHQUAKE EARLY WARNING AND RAPID RESPONSE" (INVITED)
S52A-03 · Fri, Dec 17, 10:50 a.m. · 2009 Moscone West
"COMBINING HIGH RATE GPS AND STRONG MOTION DATA: A KALMAN FILTER FORMULATION FOR REAL-TIME DISPLACEMENT WAVEFORMS"
T53B-2119 · Friday, Dec. 17, 1:40 - 6:00 p.m. · Poster Hall Moscone South
"INFRASONIC OBSERVATIONS OF GROUND SHAKING ALONG THE 2010 MW 7.2 EL MAYOR RUPTURE"
T53B-2125 · Friday, Dec. 17 1:40 - 6:00 p.m. · Poster Hall Moscone South
"STATIC RUPTURE MODEL OF THE 2010 M7.2 EL MAYOR-CUCAPAH EARTHQUAKE FROM ALOS, ENVISAT, SPOT AND GPS DATA"
T53B-2134 · Friday, Dec. 17, 1:40 - 6:00 p.m. · Poster Hall Moscone South
"SLIP ON FAULTS IN THE IMPERIAL VALLEY TRIGGERED BY THE 4 APRIL 2010 MW 7.2 EL MAJOR EARTHQUAKE AS REVEALED BY INSAR"
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Scripps Institution of Oceanography, at University of California, San Diego, is one of the oldest, largest and most important centers for global science research and education in the world. Now in its second century of discovery, the scientific scope of the institution has grown to include biological, physical, chemical, geological, geophysical and atmospheric studies of the earth as a system. Hundreds of research programs covering a wide range of scientific areas are under way today in 65 countries. The institution has a staff of about 1,300, and annual expenditures of approximately $155 million from federal, state and private sources. Scripps operates one of the largest U.S. academic fleets with four oceanographic research ships and one research platform for worldwide exploration.
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