Probabilistic tsunami hazard assessment and its application to southeast coast of Hainan Island from Manila Trench

Abstract

Tsunami is one of the most destructive natural disasters and the probabilistic tsunami hazard assessment (PTHA) has become increasingly popular in both academic and engineering field. However, most methods to carry out PTHA cannot avoid large number of scenario simulations generated by comprehensive assessment of the uncertainties of all seismic parameters. In order to balance the accuracy and feasibility in PTHA, we propose a more efficient approach. Based on the linear assumption of tsunami waves in deep water, the computation of tsunami wave propagation is given by the linear superposition of waves caused by unit sources of water level disturbance, which transforms a large number of seismic tsunami scenarios simulations into a limited number of simulations on wave propagating from each unit source. By placing 5,438 unit sources in Gaussian-shaped waveform with the interval of 0.1° around Manila Trench to approximate the initial water level disturbance under any combination of seismic parameters, we have evaluated 1,380,000 potential seismic scenarios in the Manila trench area. The water level fluctuation process of each target point along 100 m isobaths in every scenario is calculated to estimate whether the maximum wave height of the leading wave exceeds a specific critical value. Combining the probability density of each seismic parameter, the exceedance probabilities of specific wave heights and hazard curves at all target points are given.