Sensitivity Analysis of Source Parameters for Earthquake-Generated Distant Tsunamis

Abstract

This paper presents a sensitivity analysis of the effects of different fault plane parameters on earthquake generated tsunamis in the far field. The parameters studied include the location of epicenter, rake angle, dip angle, strike angle, fault plane dimensions, slip displacement, and focal depth. The study was carried out by applying the verified Cornell COMCOT tsunami model to simulate distant tsunamis generated by earthquakes in three different seismic regions, namely, Japan, Aleutian Islands, and Chile in the Pacific Basin. In this study, each fault plane parameter was varied and its effect on the tsunami wave height at a distant location (Hawaii offshore waters as a case study) was examined. Our results showed that under the same earthquake magnitude, in general, variations within a reasonable range of uncertainty in rake and dip angles, epicenter location, and focal depth do not affect the resulting tsunamis significantly while a variation in the fault dimensions, strike angle, and slip displacement can cause a large change in the wave heights in the far field. The study revealed that the sensitivity of the far field wave height to certain earthquake parameters including the fault plane dimensions, slip displacement, and the strike angle does not always decrease as the distance between the earthquake and the far field increases. These results indicate the importance of accurate earthquake information for accurate tsunami predictions and that even for wave heights in a far field thousands of miles away, the earthquake may not be treated as a simple point source described by its epicenter location and magnitude alone.