Is there a best source model of the Sumatra 2004 earthquake for simulating the consecutive tsunami?

Abstract

Many studies have attempted to invert the fault source of the Sumatra 2004 event. Whereas they mostly consider the same fault geometry, they lead to a wide range of potential slip distributions. Using tsunami modelling with GEOWAVE, a model based on fully non-linear Boussinesq equations, we investigate the influence of five distinct source models of various origins and the influence of rupture kinematics on the generated tsunami. The simulation results are considered both at ocean-scale and at country-scale. We then compare the results along the Jason-1 track to the corresponding sea surface height anomaly (SSHA) profile, and examine the patterns of maximum sea surface elevation around the Bay of Bengal and on the eastern and southern coastlines of Sri Lanka. In most cases, the synthetic SSHA profiles are not very consistent with the observed one, although they all display a prevailing first wave. The divergence in maximum sea surface elevation appears in particular along the Sri Lankan coast, where three of the models lead to a clearly underestimated tsunami impact. The best models derive from purely seismic and geodetic studies that did not consider any tsunami modelling, thus suggesting that the methods to invert a fault model from tsunami data still need some adjustment, especially concerning the handling of coastal data. In addition, it is important to consider the rupture kinematics along such a long fault, as the generated tsunami is more significant than when considering an instantaneous rupture. In the case of the Sumatra 2004 event, the tsunami impact on Sri Lanka is notably underestimated if modelled without the rupture kinematics. We conclude that for tsunami modelling, a complex description of the fault source model is not absolutely necessary, but some significant parameters such as rupture kinematics should be taken into account. © 2011 The Authors Geophysical Journal International © 2011 RAS.