2010年4月14日玉树Ms7.1地震加速度场预测

基于有限断层震源、且使用动力学拐角频率的地震动随机模拟方法预测玉树地震近断层的加速度场.首先,基于有限断层震源建模方法建立该次地震的震源模型;然后,基于上述地震动模拟方法预测玉树地震近断层191个节点的加速度时程.在此基础上,取每个结点的加速度峰值绘制该次地震的近断层加速度场.结果表明:(1)近断层加速度场主要受震源破裂过程和断层面上滑动分布的影响.断层面上凹凸体投影到地表的区域附近,加速度峰值最大,也是震害最严重的区域;(2)对于走滑地震,断层沿线附近的场地并非均会发生破裂方向性效应;发生破裂方向性效应的场地与凹凸体在断层面上的位置有关.

Prediction of acceleration field of the 14 April 2010 Yushu earthquake

Acceleration field of the Yushu earthquake was predicted by the stochastic method of ground motion simulation with the dynamic corner frequency based on the finite fault source. Firstly, the earthquake source model was established based on the method of modeling the finite fault source. Secondly, acceleration time histories of 191 near-fault nodes were predicted based on the above-mentioned ground motion simulation method. Finally, the acceleration field of the earthquake was drawn based on 191 nodes' PGAs (Peak Ground Accelerations). The results are as follows. (1) The near-fault acceleration field is significantly affected by both source rupture process and slip distribution on fault plane. The maximal PGA area on ground surface corresponds to the maximal asperity area, and this means that both buildings and other engineering structures on ground surface corresponding to the maximal asperity area on the earthquake fault may suffer severe damage. (2) For strike slip earthquake, not all sites in the vicinity of fault line are subjected to the forward directivity effect, and the occurrence of forward directivity effect is related to the location of asperities on the fault plane.