Identifying the most explainable fault ruptured of the 2018 Palu-Donggala earthquake in Indonesia using coulomb failure stress and geological field report

Abstract

This study investigates the relation between the Coulomb failure stress of the mainshock with the aftershocks sequence following the 2018 Palu-Donggala earthquake in Indonesia. We calculate the Coulomb failure stress using the available coseismic fault models, which had varied moment magnitudes between MW7.53 ∼ MW7.62. Different interpretations of the fault sources were suggested by previous studies. While two fault models suggested that one inland fault segment ruptured during the earthquake, another fault model proposed that two fault segments ruptured inland of Central Sulawesi and along the coast of Palu bay. We further overlay the positive and negative values of Coulomb failure stress with the reported relocated aftershock. We find that only by conducting Coulomb failure stress analysis, we can not favour the preference of the coseismic fault which explains aftershock distribution. This investigation demonstrates that additional observational data from geological field surveys are required to identify the surface rupture in comparison with the coseismic fault model.