浙江沿海潜在区域地震海啸风险分析

采用COMCOT海啸模型建立三重网格模型模拟了2011年3月11日日本东北部9.0级地震引发的海啸发生、发展以及在我国东南沿海传播过程。震源附近浮标站以及浙江沿海的潮位站实测资料验证结果显示,大部分监测站首波到达时间和海啸波的计算值相差在15%以内,表明模型可较好的模拟海啸在计算域内的传播过程。研究表明日本南海海槽、冲绳海槽以及琉球海沟南部是影响浙江沿海主要的区域潜在震源,通过情景计算分别模拟3个潜在震源9.1级、8.0级和8.7级地震引发的海啸对浙江沿海的海啸风险,计算结果表明,海啸波产生后可在3~8h内传至浙江省沿岸,海啸波达1~3m,最大可达4m,此时浙江沿岸面临Ⅲ~Ⅳ级海啸风险,达到淹没至严重淹没等级。

Risk analysis of potential regional earthquake tsunami on the coast of Zhejiang Province

A three-layer tsunami model was established utilizing COMCOT numerical model to simulate the generation and propagation of 2011 Tohoku-Oki earthquake tsunami event. The numerical results show that the errors between the computed arrive time and wave height and the observations at the DARTs near earthquake source and the tide gauge stations along Zhejiang coast are less than 15%. Studies show that Japan Nankai Trough,Okinawa Trough and South Ryukyu Trench would be the major potential regional tsunami sources which may threaten Zhejiang coast. Three hypothetical events of the above sources with M_w9.1,M_w8.0 and M_w8.7 earthquakes were studied by the model to assess their impacts on Zhejiang coast. The numerical results show that the tsunami waves generated by three hypothetical events would take 3 to 8 hours to reach the Zhejiang coast area,and the amplitude could vary between 1 and 3 m,with the maximum wave up to 4 m. The simulation indicates that the study area would face the tsunami hazards with level Ⅲ or level Ⅳ,which can cause inundation or serious inundation risk.