| 应用动态复合震源模型模拟汶川Mw7.9地震强地面运动 |
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| 引用本文： | 孟令媛,史保平.应用动态复合震源模型模拟汶川Mw7.9地震强地面运动[J].地球物理学报,2011,54(4):1010-1027. |
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| 作者姓名： | 孟令媛 史保平 |
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| 作者单位： | 中国科学院研究生院地球科学院, 北京 100049 |
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| 基金项目： | 中国科学院知识创新工程，中国科学院百人计划资助 |
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| 摘 要： | 2008年5月12日中国汶川地区发生Mw7.9地震,震中位置103.4°E,31.0°N.主要发震断层空间展布长达300多公里,由南西方向到北东方向呈现明显的分段性,汶川一映秀段逆冲为主兼有少量的右旋走滑分量;安县一北川段为逆冲一右旋走滑的断层错动;青川段以右旋走滑为主兼有少量逆冲分量.采用改进后的复合震源强地面运动预...
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| 关 键 词： | 汶川地震 断层分段 复合震源模型 强地面运动 NGA 峰值加速度 Shaking Map |
| 收稿时间： | 2010-04-24 |
Near-fault strong ground motion simulation of the May 12, 2008, Mw7.9 Wenchuan Earthquake by dynamical composite source model |
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| MENG Ling-Yuan,SHI Bao-Ping.Near-fault strong ground motion simulation of the May 12, 2008, Mw7.9 Wenchuan Earthquake by dynamical composite source model[J].Chinese Journal of Geophysics,2011,54(4):1010-1027. |
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| Authors: | MENG Ling-Yuan SHI Bao-Ping |
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| Institution: | Earth Science College, Graduate University of Chinese Academy of Sciences, Beijing 100049, China |
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| Abstract: | The great Wenchuan Earthquake of May 12, 2008, Mw7.9 occurred in Sichuan province of western China with the epicenter at longitude 103.4°E and latitude 31.0°N. The main fault ruptured more than 300 km in length with a striking direction from southwest toward northeast along the Longmenshan Central Fault. The geological and geophysical investigations also revealed significant fault segmentation during the earthquake faulting. The Wenchuan-Yingxiu segment of the fault is dominated by pure thrusting with a dip angle about 40°, while the Beichuan-Anxian segment of the fault in the central part of the main fault underwent both thrusting and strike-slipping with a dip angle of 70°, and the remained segment of the fault, a part of the Qingchuan fault, underwent an almost pure strike slip motion with a dip angle of 80°. In this study, a modified composite source model, named as dynamical composite source model (DCSM), has been developed to simulate near-fault strong ground motion with associated fault rupture properties from a kinematic point of view. For the Wenchuan event, a specific finite fault model with a length of 320 km and a width of 20 km is constructed for simulation purpose. Moreover, the fault model consists of three major segments in which each segment could has a specific geometry related to the dip angle and strike direction. In addition, the rakes related to the slip direction on the fault plane of each segment could be assigned dynamically based on the focal mechanism solution. For comparing purpose, we conduct broadband ground motion predictions for three typical near-fault strong motion stations of Wolong, Pixian-Zoushishan and Mianzhu-Qingping. In general, the synthetic seismograms produced for these stations have good agreement with the observations in time histories, waveforms, peak values and frequency contents, which indicate that the numerical technique of current source model could reproduce the main characteristics of strong ground motion for the Wenchuan Earthquake. In addition, the near-fault peak ground acceleration (PGA) distributions resulted from current simulation show much higher PGA values in the areas of Wenchuan, Beichuan and Qingchuan than other places, which is consistent with recent field observation and reports. The map of PGA distribution also indicates that, compared with other two segments of earthquake faulting, the ground motion caused by Wenchuan-Yingxiu thrusting is much stronger on the hanging wall than on the footwall, for example, the PGA ratios of the hanging wall to footwall could reach 1.72∶1, 2.5∶1 and 1.77∶1 for N-S, E-W and UP components, respectively, at a given distance of 5 km from the fault trace on both sides of the fault. In fact, the numerical modeling developed in this study has the great potential application in the ground motion estimation/prediction for the earthquake engineering purpose. Furthermore, the numerical algorithm could also be used to generate the near-real-time shaking map in the implementation level if incorporated current finite fault inverse technique. |
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| Keywords: | Wenchuan earthquake Fault segmentation Composite source model Strong ground motion NGA Peak ground acceleration Shaking Map |
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