Seismic structure along the South American subduction zone using satellite gravity data

Abstract

Great megathrust earthquakes occur regularly along convergent plate margins such as the Nazca-South American boundary. This is shown by historical and recent ruptures along this margin. Satellite missions designed for measuring Earth’s gravitational field and its temporal variations have improved our knowledge of the solid Earth structure and related dynamic processes. In this chapter, we analyze rupture zones and slip models for historical and recent earthquakes along the South American margin from satellite GOCE gravity-derived data, related to mass heterogeneities within the Earth. From mapping the vertical gravity gradient over different degrees of the harmonic expansion, we studied historical ruptures and coseismic slip models for recent events. From these analyses, we found that density structure through the forearc zone is associated with different features linked to the seismic rupture process, including seismic directivity, down-dip limit, asperities related to maximum slip, and barriers to seismic propagation.