Risk analysis of coastal flooding due to distant tsunamis.

摘要

A more effective and feasible probabilistic methodology is developed for predicting the risk of coastal flooding due to distant tsunamis generated by earthquakes in the Pacific Ocean. This methodology predicts the occurrence frequency of coastal inundation indirectly by linking the probability of inundation with earthquake statistics. This indirect method is more feasible since there are more complete and reliable historical data on earthquakes in the Pacific Basin as compared with tsunami data. The link between earthquakes and tsunami inundation was established using advanced computer simulation models such as the Cornel COMCOT tsunami model. For validation purposes, the methodology is applied to predict the tsunami inundation risk in Hilo Bay, Hawai'i, where relatively more tsunami data are available. Despite the complex nature of the tsunami phenomenon and the many parameters involved in the modeling, the predicted return period of coastal inundation showed promising agreement with the return period calculated directly from the field data in Hilo Bay.; Besides developing and evaluating the probabilistic risk analysis methodology, other fundamental research was also carried out. By analyzing the earthquake data through different probability distributions, it was found that the commonly used Gumbel distribution in hydrology does not fit the earthquake data well and therefore may not be suitable for earthquake statistical analysis. Numerical simulations conducted also revealed that tsunami wrap-around phenomenon observed around smaller islands in Asia does not occur in the relatively larger Hawai'ian island chain. In addition, through thorough and careful numerical tests, the optimal domain size, time step and bathymetry resolution for numerical simulation of tsunamis in the Pacific Ocean were determined which can serve as helpful guidance for future simulation studies.; This study is among the first to develop and apply an indirect probabilistic methodology to study the risk of inundation caused by earthquake-generated distant tsunamis in the Pacific Basin and the results presented can be very useful to civil defense agencies and coastal engineers in their planning for coastal hazard mitigation and proper coastal development and management.