[HDS08-P15] Influence of coastal structures on probabilistic tsunami inundation assessments
Keywords:probabilistic hazard assessments, Nankai Trough, G-R law
Procedures for making the probability map without coastal structures were the same as that of the previous report except for non-considering coastal structures. We used Hirata et al. (2017)’s 3967 faults models of the Nankai Trough earthquakes, and calculated tsunami propagations and inundations caused by the all fault models using the nonlinear shallow water equations. A nesting algorism was applied to improve the spatial resolution in the study area. Only the topographic data provided by the Cabinet Office was used. The coastal structure data was not involved in the calculations. We defined the relative weights among the earthquake fault models using the G-R law. The weights were used in superimposing all inundation maps to estimate the probabilities of tsunami inundation without the coastal structures.
Comparing the probability maps with and without the coastal structures showed the great importance of the coastal structures reducing the tsunami impacts in the wide area. In particular, the probability of inundation was decreased very much in areas near the sea or river. The coastal structures reduced the probability by 60 % at the maximum near the estuary. However, it is surprising to us that, in some areas near the upstream, the probability of inundation was increased by about 30% with considering the coastal structures.
We will evaluate target earthquakes with a magnitude of 8.0 or more, evaluate tsunami arrival time, and analyze another area.
Acknowledgments: This work was supported by JSPS KAKENHI Grant Number 19H02409.