A Study of the Impact of Static Coulomb Stress Changes of Megathrust Earthquakes Along Subduction Zone on the Following Aftershocks

Abstract

AbstractResearch on static earthquake triggering has been carried out widely in the world, and achieved remarkable results. But it is still unclear whether this model is effective to all large earthquakes. In this paper, we investigated the Coulomb stress changes of 3 megathrust earthquakes along subduction zones (the 2011 Mw9.1 Tohoku earthquake, the 2010 Mw8.8 Chile earthquake, and the 2004 Mw9.0 Sumatra‐Andaman earthquake) to test the triggering effects by examining the correlation between Coulomb stress increases and spatial distribution of the following aftershocks. The calculated results suggest that there is no obvious evidence that the Coulomb stress changes caused by the 3 megathrust earthquakes promoted the occurrence of the aftershocks. There are only 47% of the encouraged aftershocks following the Tohoku earthquake. And there are 47.6% and 49.8% for the Sumatra‐Andaman and the Chile earthquake, respectively. We also calculated the Coulomb stress changes with different focal models and parameters. It is still less than 60% of the promoted aftershocks in the optimal case. However, the static triggering model is good for the Wenchuan earthquake and the Chi‐Chi earthquake which have enhanced more than 85% of the subsequent aftershocks. This model may be not reasonable for large subduction earthquakes. Therefore, other model should be introduced in studying earthquake triggering in subduction zone and further studies will be performed.