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Mapping Areas of Uplift and Subsidence Associated with the Great Sumatra-Nicobar-Andaman Earthquake of 2004, Using High-resolution Imagery

MELTZNER, A. J., AVOUAC, J.-P., and SIEH, K., Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125,,,; HUDNUT, K. W., U.S. Geological Survey, Pasadena, CA 91106,; JI, C., Seismological Laboratory, California Institute of Technology, Pasadena, CA 91125,; ABRAMS, M., Jet Propulsion Laboratory/California Institute of Technology, Pasadena, CA 91109,; SANCHEZ, R. D., U.S. Geological Survey, Reston, VA 20192; and NATAWIDJAJA, D. H., Puslit Geoteknologi LIPI, Bandung 40135, Indonesia

The Mw 9.0 Aceh earthquake of 26 December 2004 deformed a vast surface of the Earth's crust, uplifting the portion of the overriding plate nearest the trench and producing subsidence of the upper plate farther back from the trench. The boundary separating the region of uplift from that of subsidence marks the down-dip end of the ruptured area. Regions above the rupture, including the islands off the west coast of Sumatra, are expected to have risen during the earthquake, whereas regions behind the rupture, including the southwest coast of Aceh, should have subsided. Preliminary reports and observations suggest that this is indeed the case, particularly in northern Sumatra, where most of the coseismic slip occurred according to seismic body-wave inversions. There is also some indication that deformation extended northward to the Nicobar and Andaman Islands, with uplifted coral reefs and submerged forests along the islands' west and east coasts, respectively. This deformation occurred within the aftershock zone but well north of the ruptured fault patch as modeled from body waves, and north of the tsunamigenic source as well. This might suggest that slow slip occurred on the subduction interface below the Andaman Islands. Evidence for vertical ground displacements can be observed and mapped using satellite imagery; we intend to map areas of subsidence and uplift and to quantify uplift where possible, using SPOT, ASTER, IKONOS, QuickBird, and other available imagery.


Last Modified: 2011 Aug 10