Strong Motion and Seismic Risk of Large Urban Regions

为了准确发展大城市强地震动预报和地震微区划方法，利用唐山和上海地区的强地震动和长周期微震记录，开展了中日联合研究。为了检验这些方法，我们使用了地震震害数据。为了预测日本列岛至河北地区的地震活动，本文通过数值实验研究了构造应力的产生和传递机制。利用5级左右余震的加速度记录作为经验格林函数，对唐山地震近场5个临时观测站的强地面运动进行了估计。结果表明，地震地震动与震害数据相对应。例如，在震源强度为XI的震源区域内部，位于岩石场址且受到轻微破坏的水泥厂站，其估计的加速度峰值比中国烈度表建议的加速度峰值要少。结果表明，该方法能较好地模拟高频强地震动。根据上海及周边地区的地震活动性和长周期微震观测得到的地面振动特征，对上海地区的地震危险性进行了估计。本文还对上海中部地区空间框架结构的地震反应和城市生命线的地震风险进行了估计。大型数值实验表明，日本诸岛的火山和地震活动与中国大陆的火山和地震活动是通过构造应力转移而联系在一起的。

In order to develop precisely the methods of strong ground motion prediction and seismic microzonation in large urban regions, the joint researches between Japan and China were carried out by using the records of strong seismic ground motions and long-period microseisms in the Tangshan and Shanghai regions. To examine these methods, we used the data of seismic damage. To predict seismic activity from the Japan islands to the Heubei region, we investigated the mechanism of generation and transfer of tectonic stress by numerical experiments.Strong ground motions at 5 temporary observation stations in near-field of the Tangshan Earthquake were estimated by the method using acceleration records of after shocks with magnitude of about 5 as an empirical Green function. Resulted seismic ground motions were corresponding with damage data. For example, the estimated accelerograms has less peak values than those of proposed by Chinese Intensity Table at the station of Cement Plant, which is located at rock site and had slight damage, even though the plant is in the inside of epicentral region with intensity XI. It shows that this method can simulate strong ground motions of high frequency reasonably.We estimated seismic risk in the Shanghai region on the basis of seismic activity in and around Shanghai and vibratile characteristics of ground obtained from the observation of long-period microseisms. We also estimated seismic response for space frame structures and seismic risk of urban lifelines in the central Shanghai.From large numerical experiments, it was shown that volcanic and seismic activities in the Japan islands were connected with those in the China continent by the transfer of tectonic stress.