日本海沟S-net台网水平向海域板缘地震动模型研究

Horizontal ground-motion models for subduction interface earthquakes based on the offshore ground motion database of the S-net in the Japan Trench area

地震动反应谱预测模型是概率地震危险性分析的基础,该文基于日本海沟大型海底台网S-net的海域俯冲带板缘地震动数据库,建立了俯冲带地区的水平向海域板缘地震动预测模型,分析了板缘地震的海陆地震动模型差异。在地震动模型中考虑了与场地信息有关的台站水深和沉积层厚度。由于海底台站的埋设方式不同,在模型中将台站按埋设和未埋设进行区分,通过回归分析和参数平滑建立了考虑震源类型、矩震级、震源深度、断层距、水深、沉积层厚度和埋设方式的水平向海域板缘地震动预测模型。通过对事件内残差进行分离,给出了研究区域的海底板缘模型单台标准差,可用于特定场点的概率地震危险性分析。该文的水平向海域板缘地震动模型可为考虑震源类型的海域区划和海域概率地震危险性分析提供参考。

The prediction model for ground-motion response spectrum is the basis of probabilistic seismic hazard analysis(PSHA).Based on the offshore subduction interface ground-motion database of the large ocean-bottom network S-net in the subduction zone of the Japan Trench,the horizontal ground-motion model of the offshore interface earthquakes in the subduction zone was established.The difference between the offshore and onshore ground-motion models of interface earthquakes was analyzed.The prediction model took into account the water depth and the sedimentary thickness of the ocean-bottom stations,both of which were associated with the site condition.Due to the different buried methods of the ocean-bottom stations,these stations are classified according to buried and unburied conditions in the model.Based on the regression analysis and parameter smoothing,a prediction model of the horizontal offshore interface ground motion was established,taking into account earthquake types,moment magnitude,focal depth,rupture distance,water depth,sedimentary thickness and buried method.By separating the within-event residuals,the single-station standard deviation of the offshore interface prediction model in the offshore region was presented,which can be used for PSHA of specific sites.The offshore model can be utilized as a reference for the seismic zoning of offshore region considering the source type and also for the PSHA of offshore region.