Deformation and slip along the Sunda megathrust in the great 2005 Nias-Simeulue earthquake.
Seismic rupture produced spectacular tectonic deformation above a 400-kilometer strip of the Sunda megathrust, offshore northern Sumatra, in March 2005. Measurements from coral microatolls and Global Positioning System stations reveal trench-parallel belts of uplift up to 3 meters high on the outer-arc islands above the rupture and a 1-meter-deep subsidence trough farther from the trench. Surface deformation reflects more than 11 meters of fault slip under the islands and a pronounced lessening of slip trenchward. A saddle in megathrust slip separates the northwestern edge of the 2005 rupture from the great 2004 Sumatra-Andaman rupture. The southeastern edge abuts a predominantly aseismic section of the megathrust near the equator.
Briggs
Richard W
RW
Tectonics Observatory, Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA. briggs@gps.caltech.edu
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