丽江地震区应力场研究
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摘要
通过现场调查工作,研究了丽江地区主要活动断裂的特征及现代活动性,分析了该地区构造应力场演化历史及现今构造应力场特征,探讨了丽江地震产生的机制,然后用离散元方法对该地区现今应力场进行了二维模拟,并进而深化了对丽江地震区应力场的认识。丽江地区处于川滇菱形断块的西南部,巨甸—九子海断块二级断块中的玉龙雪山—九子海三级断块上,该断块介于近南北向的楚波—白汉场断裂、北东走向丽江—小金河断裂和北西向中甸—永胜断裂之间,平面上成一顶角向东的三角形。在近南北向现今应力场的作用下,北东向的丽江—小金河断裂左旋走滑,北西向的中甸—永胜断裂右旋走滑,使两者所夹持的巨甸—九子海断块的主体部分发生向西的位移,在两者的复合部位,即断块的尖端附近,形成了局部的近东西向的拉张应力环境,从而使处于该部位的南北向玉龙雪山东麓断裂于1996年2月3日因发生了正断错动而导致了7.0级地震的发生。该地震后第三天,在其震中的正南方又发生了一次6.0级余震,其地震破裂是由北向南的一种撕裂,进而说明,本次地震的发生是由于玉龙雪山东麓断裂与中甸—永胜断裂复合部位拉张应力的强烈集中造成的。
This paper studies the activity and characteristics of main active faults in the Lijiang region, discusses the evolution of structural stress field and features of modern stress field, and probes into the mechanism of the Lijiang earthquake on February 3, 1996. By using the discrete element method, the stress field is simulated, which deepens the understanding of the stress field of the Lijiang earthquake. The Lijiang region is situated in a triangle tectonic block bordered by the NS-trending Chubo-Baihanchang fault, the NE-trending Lijiang- Xiaojinhe fault and the NW-trending Zhongdian-Yongsheng fault. Geological and seismological studies indicate that in the region the maximum principal stress is in the NNW-SSE direction. In such a stress field, the NE-trending Lijiang-Xiaojinhe fault is dislocated reversely with the left-lateral movement, and the NW-trending Zhongdian-Yongsheng fault is dislocated right-laterally. It is such a dislocation pattern of faults that causes the Judian-Jiuzihai block between the faults to move westward, thus producing local tensile stress of the east-west direction, leading to normal faulting of the fault at the east of Yulongxueshan Mountain, generating the M 7. 0 earthquake on February 3 of 1996. The mechanism of an after-shock on February 5 with a magnitude of 6. 0 south of the epicenter further indicates that the earthquake was induced by the strong concentration of tensile stress at the intersection of the fault at the east slope of Yulongxueshan Mountain with the Zhongdian-Yongsheng fault.
This paper studies the activity and characteristics of main active faults in the Lijiang region, discusses the evolution of structural stress field and features of modern stress field, and probes into the mechanism of the Lijiang earthquake on February 3, 1996. By using the discrete element method, the stress field is simulated, which deepens the understanding of the stress field of the Lijiang earthquake. The Lijiang region is situated in a triangle tectonic block bordered by the NS-trending Chubo-Baihanchang fault, the NE-trending Lijiang- Xiaojinhe fault and the NW-trending Zhongdian-Yongsheng fault. Geological and seismological studies indicate that in the region the maximum principal stress is in the NNW-SSE direction. In such a stress field, the NE-trending Lijiang-Xiaojinhe fault is dislocated reversely with the left-lateral movement, and the NW-trending Zhongdian-Yongsheng fault is dislocated right-laterally. It is such a dislocation pattern of faults that causes the Judian-Jiuzihai block between the faults to move westward, thus producing local tensile stress of the east-west direction, leading to normal faulting of the fault at the east of Yulongxueshan Mountain, generating the M 7. 0 earthquake on February 3 of 1996. The mechanism of an after-shock on February 5 with a magnitude of 6. 0 south of the epicenter further indicates that the earthquake was induced by the strong concentration of tensile stress at the intersection of the fault at the east slope of Yulongxueshan Mountain with the Zhongdian-Yongsheng fault.
引文
陈炳蔚.1987． 怒江-澜沧江-金沙江地区大地构造(中华人民共和国地质矿产部地质专报,构造地质).北京:地质出版社.
韩新民,周瑞崎.1997． 丽江7． 0级地震的烈度分布.地震研究,20(1) :35～46．
黄甫岗.1996年2月3日丽江7． 0级地震.地震研究,20(1) :1～8．
黄圣睽,董瑞英.1999． 川滇藏邻区巴塘-丽江地震块体强震活动特征的初步探讨.地震研究,22(1) :1～8．
苏有锦,刘祖荫.1997． 丽江7． 0级地震震源环境及其破裂过程讨论.地震研究,20(1) :66～71．
苏生瑞,黄润秋,王士天.2002． 断裂构造对地应力场的影响及其工程应用.北京:科学出版社.
王绍晋,龙晓帆.1998． 丽江地震前后震区环境应力场时空变化.地震地磁观测与研究,19(4) :17～24．
王绍晋,龙晓帆,罗淑进.1997． 丽江地震序列的震源机制、发震应力场和破裂特征.地震研究,20(1) :26～34．
王运生.1998． 虎跳峡水电枢纽区域构造稳定性工程地质研究.成都理工学院博士学位论文.
Chen Bingwei. 1987． Geotectonics of Nujiang-Lancangjiang-Jinshajiang Region(Geological Bulletin of the Ministry of Geology and Mineral Resources: Structural Geology). Beijing: Geological Publishing House (in Chinese with English abstract).
Han Xinmin, Zhou Ruiqi. 1997． Intensity distribution of the M7． 0 Lijiang earthquake. Journal of Seismological Research. 20(1) : 35～46 (in Chinese with English abstract).
Huang Fugang. 1997． The M7． 0 Lijiang Earthquake in Yunnan on February 3,1996． Journal of Seismological Research, 20 (1) : 1～8 (in Chinese with English abstract).
Huang Shengkui, Dong Ruiyin. 1999． Preliminary study on strong seismicity characteristics of the Baton-Lijiang seismic block in the neibouring area of Sichuan, Yunnan and Tibet. Journal of Seismological Research, 22 (1) : 1～8 (in Chinese with English abstract).
Su Youjin, Liu Zuyin. 1997． Discussion on the source environment and rupture process of the M7． 0 Lijiang earthquake. Journal of Seismological Research, 20(1) : 66～71 (in Chinese with English abstract).
Su Shengrui, Stephansson Ove. 1999． The effect of a fault on in situ stresses studied by the distinct element method. International Journal of Rock Mechanics and Mining Sciences, 36(8) : 1051～1056．
Su Shengrui, Huang Runqiu, Wang Shitian. 2002． The Effect of Fractures on Rock Stresses and Its Implication in the Geological Engineering. Beijing: Science Press.
Wang Shaojin, Long Xiaofan. 1998． Tempo-spatial variation of the ambient stress field in the seismic area before and after Lijiang earthquake. Seismological and Geomagnetic Observation and Research, 19(4) : 17～24 (in Chinese with English abstract).
Wang Shaojin, Long Xiaofan, Luo Shujin. 1997． The focal mechanism, seismogenic stress field and rupture characteristics of the Lijiang earthquake sequence. Journal of Seismological Research,20(1) : 26～34 (in Chinese with English abstract).
Wang Yunsheng. 1998． The engineering geological research on the earth's crustal stability of in the region of Hutiaoxia hydropower project. Thesis for Doctoral Degree of Chengdu University of Technology(in Chinese with English abstract).
韩新民,周瑞崎.1997． 丽江7． 0级地震的烈度分布.地震研究,20(1) :35～46．
黄甫岗.1996年2月3日丽江7． 0级地震.地震研究,20(1) :1～8．
黄圣睽,董瑞英.1999． 川滇藏邻区巴塘-丽江地震块体强震活动特征的初步探讨.地震研究,22(1) :1～8．
苏有锦,刘祖荫.1997． 丽江7． 0级地震震源环境及其破裂过程讨论.地震研究,20(1) :66～71．
苏生瑞,黄润秋,王士天.2002． 断裂构造对地应力场的影响及其工程应用.北京:科学出版社.
王绍晋,龙晓帆.1998． 丽江地震前后震区环境应力场时空变化.地震地磁观测与研究,19(4) :17～24．
王绍晋,龙晓帆,罗淑进.1997． 丽江地震序列的震源机制、发震应力场和破裂特征.地震研究,20(1) :26～34．
王运生.1998． 虎跳峡水电枢纽区域构造稳定性工程地质研究.成都理工学院博士学位论文.
Chen Bingwei. 1987． Geotectonics of Nujiang-Lancangjiang-Jinshajiang Region(Geological Bulletin of the Ministry of Geology and Mineral Resources: Structural Geology). Beijing: Geological Publishing House (in Chinese with English abstract).
Han Xinmin, Zhou Ruiqi. 1997． Intensity distribution of the M7． 0 Lijiang earthquake. Journal of Seismological Research. 20(1) : 35～46 (in Chinese with English abstract).
Huang Fugang. 1997． The M7． 0 Lijiang Earthquake in Yunnan on February 3,1996． Journal of Seismological Research, 20 (1) : 1～8 (in Chinese with English abstract).
Huang Shengkui, Dong Ruiyin. 1999． Preliminary study on strong seismicity characteristics of the Baton-Lijiang seismic block in the neibouring area of Sichuan, Yunnan and Tibet. Journal of Seismological Research, 22 (1) : 1～8 (in Chinese with English abstract).
Su Youjin, Liu Zuyin. 1997． Discussion on the source environment and rupture process of the M7． 0 Lijiang earthquake. Journal of Seismological Research, 20(1) : 66～71 (in Chinese with English abstract).
Su Shengrui, Stephansson Ove. 1999． The effect of a fault on in situ stresses studied by the distinct element method. International Journal of Rock Mechanics and Mining Sciences, 36(8) : 1051～1056．
Su Shengrui, Huang Runqiu, Wang Shitian. 2002． The Effect of Fractures on Rock Stresses and Its Implication in the Geological Engineering. Beijing: Science Press.
Wang Shaojin, Long Xiaofan. 1998． Tempo-spatial variation of the ambient stress field in the seismic area before and after Lijiang earthquake. Seismological and Geomagnetic Observation and Research, 19(4) : 17～24 (in Chinese with English abstract).
Wang Shaojin, Long Xiaofan, Luo Shujin. 1997． The focal mechanism, seismogenic stress field and rupture characteristics of the Lijiang earthquake sequence. Journal of Seismological Research,20(1) : 26～34 (in Chinese with English abstract).
Wang Yunsheng. 1998． The engineering geological research on the earth's crustal stability of in the region of Hutiaoxia hydropower project. Thesis for Doctoral Degree of Chengdu University of Technology(in Chinese with English abstract).
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