| 鄂尔多斯东缘地震重定位及拉张盆地过渡区的地震分布特征 |
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| 引用本文： | 蔡妍,吴建平,房立华,王未来,黄静.鄂尔多斯东缘地震重定位及拉张盆地过渡区的地震分布特征[J].地球物理学报,2014,57(4):1079-1090. |
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| 作者姓名： | 蔡妍 吴建平 房立华 王未来 黄静 |
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| 作者单位： | 中国地震局地球物理研究所, 北京 100081 |
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| 基金项目： | 地震行业专项(201208009,201308013);基本科研业务费(DQJB13B08)资助 |
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| 摘 要： | 利用双差地震定位方法对鄂尔多斯东缘地区（34°N-41°N，110°E-115°E）2008年1月-2012年12月的中小地震进行了重新定位.重定位后，定位精度得到改善，震中分布更加集中.鄂尔多斯东缘拉张盆地内部震源深度较浅，大多小于13 km，向盆地两端震源深度有加深的趋势，特别是太原盆地北端，临汾盆地北端，以及运城与临汾盆地之间的峨眉台地，震源深度可达20~25 km左右.我们认为盆地内部地壳减薄，上地幔上隆，热作用导致地壳内部脆性层减薄，致使最大震源深度变浅；盆地之间的横向隆起区受区域应力场挤压剪切作用以及盆地内部上地幔上拱产生的水平向挤压力作用等，在横向隆起区与盆地接触带易产生应力集中，导致地震的发生，由于受脆性层厚度变化等的影响，在盆地向横向隆起区过渡部位出现震源深度加深的现象.鄂尔多斯东北缘地区地震分布弥散、震源深度相对较浅，可能与源自地幔的大范围深部热作用以及地壳脆性层厚度减薄有关.根据地震的空间分布特征，对部分盆地内部的断层特征进行了讨论.
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| 关 键 词： | 双差地震定位 鄂尔多斯东缘 山西断陷盆地 震源深度 |
| 收稿时间： | 2013-11-04 |
Relocation of the earthquakes in the eastern margin of Ordos block and their tectonic implication in the transition zones of extensional basin |
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| CAI Yan,WU Jian-Ping,FANG Li-Hua,WANG Wei-Lai,HUANG Jing.Relocation of the earthquakes in the eastern margin of Ordos block and their tectonic implication in the transition zones of extensional basin[J].Chinese Journal of Geophysics,2014,57(4):1079-1090. |
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| Authors: | CAI Yan WU Jian-Ping FANG Li-Hua WANG Wei-Lai HUANG Jing |
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| Institution: | Institute of Geophysics, China Earthquake Administration, Beijing 100081, China |
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| Abstract: | Using the double-difference earthquake location algorithm, we relocated the earthquakes in the eastern margin of Ordos block (34°N-41°N, 110°E-115°E) from 2008-2012. After relocation, the accuracy of the earthquakes is improved, and the epicenters are more concentrated. The focal depth within the basins in the eastern margin of Ordos block is shallow, mostly less than 13 km. It is shown that the focal depth deepens from inside to the ends of the basin, particularly in the northern end of Taiyuan and Linfen basin, and E'mei mesa between Yuncheng and Linfen basin, with the focal depth up to about 20~25 km. It is considered that with the circumstance of the thinned crust and upwelling mantle, the thermal effects reduce the thickness of the brittle layer in the crust, which shallows the maximum focal depth; the transverse uplifts between basins are subjected to some forces, such as shear-compression stress from the regional stress field and horizontal compression from upwelling mantle inside the basins. In this case, it is easy to produce stress concentration in the contact zones between the transverse uplifts and basins, which may induce earthquakes. Due to the change in thickness of the brittle layer, the focal depth deepens in the transition zone from basins to the transverse uplifts. The earthquakes in the northeastern margin of Ordos block are diffuse, and the focal depth is relatively shallow, which may be related to the large-scale thermal effect from mantle and the decreasing of the brittle layer thickness. According to the spatial distribution of the earthquakes, we discussed the characteristics of the faults in some basins. |
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| Keywords: | Double difference location Eastern margin of Ordos block Shanxi rifted basin Focal depth |
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