Global Sensitivity Analysis Of Seismic Tsunami Hazard On Offshore Site To Potential Seismic Tsunami Source Parameters

In recent years,earthquake-triggered tsunami occurred frequently and brought mankind with tremendous casualties and immeasurable property losses with its horrendous destructive power,so the seismic tsunami hazard analysis have been put close attention in many coastal countries.Due to the lack and even missing of the tsunami historical data in some coastal areas,the seismic tsunami hazard analysis is mainly based on the seismic tsunami numerical simulation.Potential seismic tsunami source parameters are essential input parameters in the tsunami numerical simulation,the uncertainty of their values,however,is inevitable both on the base of earthquake monitoring as well as its data analysis and on the degree of geological exploration for the potential seismic tsunami source,so it's necessary to study the effect of this uncertainty on the seismic tsunami hazard at specific offshore sites,namely to study the sensitivity of the latter to former.In case study,sensitivity of seismic tsunami hazards,at six specific sites in mainland southeast offshore areas of China and in the south offshore areas of Taiwan Island,to the magnitude,focal depth and sliding angle among the seismic tsunami source parameters are analyzed.Firstly,the author choose the Manila trench subduction zone as a potentialsource,then establish its seismicity model based on the Generalized Pareto Distribution to estimate seismic hazard.The results show that the upper magnitude limit of the Manila Trench subduction zone is 9.0,the magnitude return level expectation of 10 years,50 years,100 years and 200 years is 7.1?7.6?7.7?7.9,respectively.These results can provide magnitude parameters for the seismic tsunami hazard analysis and sensitivity analysis.We estimate the distribution of focal depth and slip angle according to the historical earthquake data.We obtained multi-group parameter samples through Monte Carlo sampling for seismic tsunami numerical simulation,and extract the maximum wave height at specific offshore sites to analyze the qualitative and quantitative sensitivity of the seismic tsunami hazard at these sites to the potential seismic tsunami parameters.The results show that qualitative and quantitative sensitivity analysis are consistent,the seismic tsunami hazard is most sensitive to magnitude,the main effect is 0.703,0.499 and 0,511 respectively,followed by focal depth and slip angle for site-specific B2 near the Hong Kong?B3 near Zhan Jian and B4 near the San Ya.Site-specific B1 near the kaohsiung?B5 near the Zhongsha islands and B6 near the Nansha islands is most sensitive to focal depth and the main effect is 0.367,0.809,0.780 respectively,followed by magnitude and slip angle for and there are nonlinear effect,namely interaction,between these parameters,but the degree of interaction between potential seismic tsunami parameters is different for different sites.Combining with case study,this paper proposed the global sensitivity analysis methods of the seismic tsunami hazard at specific offshore site to the potential seismic tsunami source parameters.These methods and case study results can provide reference for the seismic tsunami hazard estimation,seismic tsunami early warning and offshore engineering protection and so on.