Sea level changes from seismic dislocations: a self-consistent approach

San Fransisco, USA

Large earthquakes are a potentially important source of relative sea level variations, since they can drive global deformations and simultaneously perturb the gravity field of the Earth. We obtained a gravitationally self-consistent, integral sea level equation suitable for earthquakes, in which, for the first time, we are able to account for the first time both for direct effects by the seismic dislocation and for the feedback from water loading associated with sea level changes. The seismic sealevel equation can be solved numerically within the well-estabilisthed theoretical framework of glacio-isostatic adjustment modeling. Through a set of numerical benchmarks we demonstrate the effectiveness of the numerical implementation. As an application, we model sea level signals following the 2004 Sumatra-Andaman earthquake, showing that surface loading from ocean water redistribution (so far ignored in post-seismic deformation modeling) may account for a significant fraction of the total computed sea level variation.