| 华北盆地强震孕育的动力学机制研究 |
| |
| 引用本文： | 朱守彪,张培震,石耀霖.华北盆地强震孕育的动力学机制研究[J].地球物理学报,2010,53(6):1409-1417. |
| |
| 作者姓名： | 朱守彪 张培震 石耀霖 |
| |
| 作者单位： | 1.中国地震局地壳应力研究所，北京 100085;2.中国地震局地质研究所地震动力学国家重点实验室，北京 100029;3.中国科学院研究生院计算地球动力学实验室， 北京 100049 |
| |
| 基金项目： | 国家自然科学基金，北京市自然科学基金，中央级科研院所基本科研业务专项，地震动力学国家重点实验室基金项目 |
| |
| 摘 要： | 强震活跃区通常出现在地壳变形剧烈的地区.但是，华北盆地地壳变形速率小，而破坏性强震却十分频繁.文中利用有限元方法对华北盆地发震断层下方可能存在的速度异常体进行了力学分析，计算结果显示：无论这个异常区是低速异常还是高速异常，在水平构造力的作用下（无论是挤压还是引张力作用），应力及应变能密度都在空间某些区域积聚.根据本文的工作及前人的研究结果，认为华北盆地强震孕育的物理机制如下：华北克拉通在减薄、破坏过程中，浸入的岩浆或上涌的地幔物质经过漫长的地质时期演化，成为低速异常体.当断裂带下面存在这种低速异常体时，水平向构造力的作用，会使异常体上方应力集中、应变能积聚.当异常体上方的应力水平达到某种限度，介质发生破坏.在破坏过程中，异常体释放的能量，使断裂带上的应变能集聚速度加快；另一方面，异常体的破坏使断层的闭锁面积减小.随着外部构造应力的持续加载，当发震断层上的应力及能量积累达到一定极限，断层产生错动，发生强震.同时，文中结果还显示，断层在从闭锁、积累能量到解锁、发生强震的过程中，其下方的低速异常体起着重要的推进作用.
|
| 关 键 词： | 有限元 速度异常体 发震断层 应力积累 介质破坏 孕震机理 华北盆地 |
| 收稿时间： | 2010-01-23 |
A study on the mechanisms of strong earthquake occurrence in the North China Basin |
| |
| ZHU Shou-Biao,ZHANG Pei-Zhen,SHI Yao-Lin.A study on the mechanisms of strong earthquake occurrence in the North China Basin[J].Chinese Journal of Geophysics,2010,53(6):1409-1417. |
| |
| Authors: | ZHU Shou-Biao ZHANG Pei-Zhen SHI Yao-Lin |
| |
| Institution: | 1.Institute of Crustal Dynamics, China Earthquake Administration, Beijing 100085, China;2.Key Laboratory of Earthquake Dynamics, Institute of Geology, China Earthquake Administration, Beijing 100029, China;3.Key Lab of Calculation Geodynamics, Graduate University of Chinese Academy of Sciences, Beijing 100049, China |
| |
| Abstract: | Strong earthquakes often occur in the regions where the surface deformation is large. But destructive events took place frequently in the North China Basin in which the deformation is small. In the paper, we made a mechanical analysis of the possible region with seismic velocity anomaly in the North China Basin with finite element method. The calculated result shows that stresses and energy will accumulate both in the high and low-velocity anomaly bodies under the horizontal tectonic stresses. Based upon the results of this paper and previous workers, the physical mechanisms of strong earthquake occurrence in the North China Basin are as follows. In the process of break-up of the North China Craton through lithospheric thinning, the magmatic intrusions or the upwelling mantle material will evolve into low-velocity anomaly body (LVB) in the lower and middle crust. The stresses and strain energy will accumulate more quickly above the LVB underlain the seismogenic fault than in other regions under the horizontal tectonic stresses. The material above the LVB will rupture when stresses reach the failure limit, then the energy will be released. Some of the energy will be transferred to the seismogenic fault. At the same time, the locking area on the seismogenic fault will be reduced. With the loading of tectonic stresses, once the stresses in the seismogenic fault reach critical point, the fault slips, and a strong earthquake occurs. Also the result shows that the LVB plays an important role in stimulating strong earthquakes. Moreover, the analysis in the paper suggests that it is important to study the fine velocity structure in the crust in the North China Basin for earthquake prediction. |
| |
| Keywords: | Finite element Velocity anomaly body Seismogenic fault Stress accumulation Rock failure Mechanisms of strong earthquake preparation the North China Basin |
| 本文献已被 万方数据 等数据库收录！ |
| 点击此处可从《地球物理学报》浏览原始摘要信息 |
| 点击此处可从《地球物理学报》下载免费的PDF全文 |
