| Earthquake epicentroids in the Beijing-Tianjin-Tangshan-Zhangjiakou region inversed by gravity variation data |
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| 作者姓名： | 郑金涵 宋胜合 刘克人 卢红艳 郭宗汾 |
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| 作者单位： | Institute of Geophysics，China Seismological Bureau，Beijing 100081，China，Institute of Geophysics，China Seismological Bureau，Beijing 100081，China，Institute of Geophysics，China Seismological Bureau，Beijing 100081，China，Institute of Geophysics，China Seismological Bureau，Beijing 100081，China，Columbia University，New York 10027，USA |
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| 基金项目： | State Natural Science Foundation of China (49774224)，Joint Seismological Science Foundation of China (102019). |
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| 摘 要： | Introduction Since the 1960s, gravity changes associated with seismogenesis and earthquake occurrences have been found by many researchers and various physical mechanisms have been proposed to explain these relationship (MEI, 1993; Chen, et al, 1979; Li, Fu, 1983). The US/China joint project beginning in 1981 presented a thorough study of the relationship between gravity variations and earthquake occurrences in the Beijing-Tianjin-Tangshan-Zhangjiakou (BTTZ) region, leading to a combined…
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| 关 键 词： | 重力变化 膨胀模型 地震 北京-天津-唐山-张家口区域 |
| 收稿时间： | 1 February 2002 |
| 修稿时间： | 12 March 2003 |
Earthquake epicentroids in the Beijing-Tianjin-Tangshan-Zhangjiakou region inversed by gravity variation data |
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| Zheng Jin-han , Song Sheng-he , Liu Ke-ren , Lu Hong-yan and J. T. Kuo.Earthquake epicentroids in the Beijing-Tianjin-Tangshan-Zhangjiakou region inversed by gravity variation data[J].Acta Seismologica Sinica(English Edition),2003,16(4):449-458. |
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| Authors: | Zheng Jin-han Song Sheng-he Liu Ke-ren Lu Hong-yan and J T Kuo |
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| Institution: | 1. Institute of Geophysics, China Seismological Bureau, Beijing 100081, China
2. Columbia University, New York 10027, USA |
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| Abstract: | Gravity variation data observed in the process of seismogenesis and occurrences of earthquakes show that the location with the greatest gravity changes does not necessarily coincide with the epicenter. To explain this we defined the center of effective mass of stress volume as hypocentroid, and the vertical projection of which on the earths surface as epicentroid. Here we adopt three rotating models, including spheroid, ellipsoid and cylinder, to represent the region of an impending earthquake. Based on the models of gravity variations induced by uniform dilatancy, epicentroids associated with sixteen earthquakes with M>4.0 occurred in 1981~2000 in the Beijing-Tianjin-Tangshan-Zhangjiakou region are determined by means of a proposed least squares iterative inversion method. The results indicate that cylinder model is preferable to the other two, and epicentroids obtained by the cylinder model separate from the epicenters by a range of 0~40 km. Epicentroids are inevitably located within intact tectonic blocks, and usually cluster in groups; while the epicenters are generally located at the terminations of faults or at the intersections of faults. It seems that there exist earthquake-hatching areas in the block among faults. Earthquakes hatch in these areas, but occur around these areas, meanwhile the existence of faults may play an important role in controlling the processes. |
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| Keywords: | gravity variation dilatancy model epicentroid inversion + |
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