مدل خطر لرزه ای برای برآورد کاهش و مدیریت ریسک در تایوان

We developed a seismic hazard model for Taiwan that integrates all available tectonic, seismicity, and seismic hazard information in the region to provide risk managers and engineers with a model they can use to estimate earthquake losses and manage seismic risk in Taiwan. The seismic hazard model is composed of two major components: a seismotectonic model and a ground-shaking model. The seismotectonic model incorporates earthquakes that are expected to occur on the Ryukyu and Manila subduction zones, on the intermediate-depth Wadati-Benioff seismicity zones, on the active crustal faults, and within seismotectonic provinces. The active crustal faults include the Chelungpu fault zone, the source of the damaging MW 7.6 Chi-Chi earthquake, and the Huangchi-Hsiaoyukeng fault zone that forms the western boundary of the Taipei Basin. The ground-shaking model uses both US, worldwide, and Taiwanese attenuation relations to provide robust estimates of peak ground acceleration and response spectral acceleration on a reference site condition for shallow crustal and subduction zone earthquakes. The ground shaking for other site conditions is obtained by applying a nonlinear soil-amplification factor defined in terms of the average shear-wave velocity in the top 30 m of the soil profile, consistent with the methodology used in the current US and proposed Taiwan building codes.

Risk managers are increasingly relying on computer models to help them identify and manage the risk from catastrophic perils such as earthquakes, hurricanes (typhoons), and flooding to portfolios that can be widely distributed geographically. This requires the use of hazard models that cover entire countries or in some cases even larger regions in a format that is consistent with the models used to quantify the resulting risk in terms of monetary and human losses. In this paper, we describe such an earthquake hazard model for the island of Taiwan. This model combines information on earthquake zonation, earthquake frequency, the attenuation characteristics of strong ground motion, and the dynamic response of the site profile beneath the site (site amplification) in a coherent and consistent representation of earthquake hazard throughout the country. Previous seismic hazard models [1], [2] and [3] have been based primarily on historic seismicity or on generalized faulting models in which faults have been randomly distributed within seismotectonic provinces [4]. Recurrence rates have been determined based exclusively on historic seismicity. The 1999 MW 7.6 Chi-Chi earthquake that ruptured 85 km of the Chelungpu fault zone, the largest earthquake to strike onshore Taiwan in several hundred years, demonstrated the importance of including individual fault sources in the assessment of seismic hazard. However, there is very little information on the slip rates of crustal faults in Taiwan. In this study, we have attempted to account for these faults using slip rates inferred from global positioning system (GPS) velocity vectors.