Comparisons of global coseismic displacements from several fault slip models for the 2004 Sumatra earthquake

After 2004 great Sumatra earthquake, some authors presented different fault slip models from seismic waves and/or GPS data. However, because half-space homogenous or layered medium was adopted, the inversion of the coseismic model from observed coseismic displacements can only use near-field GPS data as the constraint but not far-field data. This can result in great differences among fault slip models. Therefore, how to evaluate those modes is an important problem. ThiS paper uses the equivalent body force finite elements method, considering the earth curvature and layered structure, to compute global coseismic displacements using four fault slip models of the 2004 Sumatra earthquake provided by different authors. Comparisons of calculated coseismic displacements show that the vertical displacement is less sensitive to the fault slip model. Calculated coseismic displacements of all the four models agree well with near-field GPS observations, but significantly different in comparison with far-field GPS observations. In the whole four models, the Chlieh model is the best. The effects of data used in inversion, the fault geometry and the earth model are discussed in this paper. For great earthquakes, the consistency between calculated and observed global coseismic displacement is one important criterion for evaluating the fault slip model.