Scientists Present Latest Findings On Chile Earthquake

The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. Photo: USGS The tsunami generated by the M 8.8 earthquake carried many boats onto land - in some cases hundreds of meters inland. Photo: USGS Scientists at Scripps Institution of Oceanography at UC San Diego will discuss preliminary findings from the Survey of the Earthquake and Rupture Offshore Chile (SIOSEARCH) "rapid response" research cruise and other studies using real-time satellite and GPS surveys of the major earthquake that struck off the coast of Chile earlier this year Scripps geophysicist David Chadwell and colleagues will present information on whether specific geomorphic features, such as slumps along submarine channel walls and floors, show any pre- or post-earthquake changes. The poster presentation is part of a series of scientific presentations related to the Feb. 27 earthquake and tsunami at the 2010 American Geophysical Union (AGU) Fall Meeting in San Francisco. (Wednesday, Dec. 15, 1:40 - 6:00 p.m. · Poster Hall, Moscone South) Less than three weeks after the momentous geological event and subsequent tsunami, the SIOSEARCH team collected multi-beam sonar images of the seafloor at the earthquake site off the coast of Chile. In order to determine what caused the 60-meter (197-feet) tsunami waves, the team used the information to produce detailed bathymetric maps to characterize structural changes in the seafloor that resulted from movement along faults and submarine landslides. The new digital data are being compared to similar "before" images taken by scientists at Germany's Leibniz Institute of Marine Sciences (IFM-GEOMAR). An illustration of the subduction zone off the west coast of South America. An illustration of the subduction zone off the west coast of South America. In a pair of poster presentations, Scripps graduate students Xiaopeng Tong and Karen Luttrell will discuss results from radar interferometry satellite and GPS data that captured the ground movement during the earthquake. Tong's study, which will be published in an upcoming issue of AGU's Geophysical Research Letters, revealed a 600-kilometer (372-mile) long and 160-kilometer (99-mile) wide fault rupture. The study also estimated the fault displacement, or slip, produced by the earthquake to reveal that most of the movement occurred above the continental moho, which is estimated to be at a depth of 40-kilometers over the region. (G33A-0840 · Wednesday, Dec. 15, 1:40 - 6:00 p.m. · Poster Hall Moscone South) Using these results, Luttrell and Tong collaborated on a second study to calculate the stress drop by comparing it to the region's topography. The analysis was used to better understand the fault's strength and how the stress associated with the 8.8-magintude earthquake was transmitted through Earth's mantle. (Wednesday, Dec. 15, 1:40 - 6:00 p.m. · Poster Hall Moscone South) The 2010 Chile earthquake that occurred off the coast of the Maule Region of Chile is a highly active tectonic plate subduction zone along the boundary between the Nazca and South American tectonic plates. # # # RELATED PRESENTATIONS: G33A-0851 · Wednesday, Dec 15, 1:40 - 6:00 p.m. · Poster Hall, Moscone South "AN EXAMINATION OF 'BEFORE' AND 'AFTER' BATHYMETRY FOR UPLIFT OF THE SEA FLOOR FOLLOWING THE FEB. 27, 2010 MAULE, CHILE EARTHQUAKE" G33A-0839 · Wednesday, Dec. 15, 1:40 - 6:00 p.m. · Poster Hall, Moscone South "THE MW8.8 2010 MAULE, CHILE EARTHQUAKE: SIGNIFICANT SLIP OCCURRED ONLY ABOVE THE CONTINENTAL MOHO" G33A-0840 · Wednesday, Dec. 15, 1:40 - 6:00 p.m. · Poster Hall Moscone South "ESTIMATES OF STRESS DROP FROM THE 27 FEBRUARY 2010 CHILE EARTHQUAKE AND TECTONIC STRESS IN THE CRUST: IMPLICATIONS FOR FAULT STRENGTH"