Finite Element Modeling of the 2004 giant Sumatra Earthquake Postseismic Displacement Field

The 26 December 2004 Sumatra-Andaman earthquake is one of the largest earthquakes ever recorded since 1900. The earthquake resulted from complex slip on the fault where the oceanic portion of the Indian Plate slides under the Eurasian Plate, by the Indonesian Island of Sumatra. The particular features of the detected quasi-static displacement field has been previously attributed to the heterogeneous distribution of moment release on the fault plane. In the present work, we use a new computational FEM strategy to model the co- and postseismic displacement field associated with the Sumatra earthquake. For the first time we can study the joint effects of sphericity and 3D mechanical and rheological heterogeneities on the investigated observables. The comparison between our synthetic results and the available deformation data allows us to ascertain if also lateral heterogeneities in the physical properties of the medium could have played a role in assessing the deformation field.