Large trench-parallel gravity variations predict seismogenic behavior in subduction zones.
We demonstrate that great earthquakes occur predominantly in regions with a strongly negative trench-parallel gravity anomaly (TPGA), whereas regions with strongly positive TPGA are relatively aseismic. These observations suggest that, over time scales up to at least 1 million years, spatial variations of seismogenic behavior within a given subduction zone are stationary and linked to the geological structure of the fore-arc. The correlations we observe are consistent with a model in which spatial variations in frictional properties on the plate interface control trench-parellel variations in fore-arc topography, gravity, and seismogenic behavior.
Song
Teh-Ru Alex
TR
Seismological Laboratory, Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA 91125, USA. alex@gps.caltech.edu
Simons
Mark
M