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中国大陆地壳应力场与构造运动区域特征研究
引用本文:徐纪人,赵志新,石川有三.中国大陆地壳应力场与构造运动区域特征研究[J].地球物理学报,2008,51(3):770-781.
作者姓名:徐纪人  赵志新  石川有三
作者单位:1.中国地质科学院地质研究所,北京 100037;2.日本气象厅气象研究所,筑波市 3050052
基金项目:中国地质调查局区域地质调查项目,国家自然科学基金
摘    要:系统研究了1918~2006年间中国大陆及其周缘发生的3115个M4.6以上中、强地震的震源机制解,得到中国大陆地壳区域应力场的压应力轴和张应力轴空间分布的统计结果.探讨了大陆应力场的结构,以及周围板块运动对中国大陆应力场影响作用范围及其界线.结果表明,中国东部的华北地区受到太平洋板块向欧亚板块俯冲挤压的同时,又受到从贝加尔湖经过大华北直至琉球海沟的广阔范围内存在的方位为170°引张应力场的控制.华北地区大地震的震源机制解反映出,该区地震发生为NEE向挤压应力和NNW向张应力的共同作用结果.印度洋板块向欧亚板块的碰撞挤压运动所产生的强烈的挤压应力,控制了喜马拉雅、青藏高原、乃至延伸到天山及其以北的广大地区.在青藏高原周缘地区和中国西部的大范围内,压应力P轴水平分量位于20°~40°,形成了近北东方向的挤压应力场,大量逆断层型强震集中发生在青藏高原的南、北和西部周缘地区以及天山等地区. 本文结果表明,正断层型地震集中发生在青藏高原中部高海拔的地区.证明了青藏高原周缘区域发生南北向强烈挤压短缩的同时,中部高海拔地区存在着明显的近东西向的扩张运动.根据本文最新结果,得到了华北、华南块体之间地壳区域应力场的控制边界线,发现该分界线与大地构造、岩石圈板块构造图等有较大差异,特别是在大别及其以东地区, 该分界线向东南偏转,在沿海的温州附近转向东,最终穿过东海直至琉球海沟.台湾纵谷断层是菲律宾海板块与欧亚板块之间碰撞挤压边界,来自北西西向运动的菲律宾海板块构造应力控制了从台湾纵谷、华南块体,直到中国南北地震带南段东部地域的应力场. 地震震源机制结果还表明,南北地震带南段西侧其P轴大约为NNE方向,与青藏高原的P轴方位一致.南北地震带南段东侧其P轴大约为NWW方向,与华南块体的P轴方位一致.因此,将中〖JP2〗国大陆分成东、西两部分的南北地震带南段是印度洋板块与菲律宾海板块在中国大陆内部影响控制范围的分界线.

关 键 词:中国大陆  地壳应力场  震源机制解  构造运动  地震断层类型  
文章编号:0001-5733(2008)03-0770-12
收稿时间:2007-9-13
修稿时间:2007年9月13日

Regional characteristics of crustal stress field and tectonic motions in and around Chinese mainland
XU Ji-Ren,ZHAO Zhi-Xin,Ishikawa Yuzo.Regional characteristics of crustal stress field and tectonic motions in and around Chinese mainland[J].Chinese Journal of Geophysics,2008,51(3):770-781.
Authors:XU Ji-Ren  ZHAO Zhi-Xin  Ishikawa Yuzo
Institution:1.Institute of Geology,Chinese Academy of Geological Sciences, Beijing 100037, China;2.Meteorological Research Institute of Japan Meteorological Agency, Tsukuba, 3050052, Japan
Abstract:Focal mechanism solutions of 3115 middle and great crustal earthquakes (M≥4.6) have been analyzed in and around China between 1918 and 2006. The distribution of extensional and compressive axes was studied by statistic methods. The results suggest that crustal stress field and tectonic movement in and around China are attributable to motions relative to the Eurasian plate of the Indian, Pacific Ocean and Philippine Sea plates, and interactions along blocks of the mainland. The compressive stress due to the collision between the Eurasian and Indian plates dominates the movements from the Himalayas to Tianshan mountains in west China. Azimuths of the horizontal component of compressive stress P-axes likely lie between 20°and 40°, resulting in a stress field near about NE direction in the wide region west of the North-South Seismic Belt. Strong and great events with thrust faulting occurred frequently along the edges of the Tibetan plateau and in the Tianshan region. A lot of normal faulting type earthquakes concentrate in the central part of the Tibetan plateau with high elevations. It means that while north-south shortening occurs in the Tibet plateau and its surroundings, an extensional motion in near E-W direction, however, is revealed in the high elevation area of the plateau. Focal mechanism solutions in North China show that the events occurred under the compressive stress in near NE direction due to the subduction of the Pacific Ocean plate beneath Eurasian plate as well as an extensional stress of azimuth 170° from the Baikal extension. The boundary between North China and South China obtained from regional stress field is different from other tectonic results. The trend of boundary turns to southeast in and east of the Dabie region, passing through Wenzhou and the East China Sea, to the Ryukyu trench. The valley fault of Taiwan is the collision boundary between the Eurasian and Philippine Sea plates. The stress field due the northwestward motion of the Philippine Sea plate dominates the stress of lithosphere from the Taiwan region to the eastern part of the southern segment of the North-South Seismic Belt through South China.
Keywords:Chinese mainland  Crustal stress field  Focal mechanism solution  Tectonic motion  Earthquake faulting type
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