2008年汶川M_S8.0地震和2013年芦山M_S7.0地震震源特征比较分析
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摘要
2013年4月20日四川芦山发生了MS7.0地震,芦山地震震中距离2008年5月12日汶川MS8.0地震震中约85km,距离其余震密集分布区约60km。汶川地震和芦山地震均发生在龙门山断裂带上,震源机制均以逆冲为主,针对二者震源特征的比较分析,对解释龙门山地区强震特征意义显著。本文基于地震波辐射能及视应力与应力降的关系,对比讨论汶川地震和芦山地震的动态破裂过程,初步研究结果显示,汶川地震属于应力上调模式,而芦山地震则属于应力下调模式,通常应力上调模式的震后能量释放较为充分,应力下调模式则对应震后能量释放相对不够充分,余震空间分布相对集中。
The April 20,2013 MS7. 0 earthquake occurred in Lushan City,Sichuan Province,China,which was a result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on southern part of Longmenshan fault at a depth of 13 km. And the great Wenchuan MS8. 0 earthquake of the May 12,2008 also occurred in Sichuan Province of the western interior China with an epicenter located at the longitude 103. 4°E and latitude of 31. 0°N. Both the 2 important earthquakes located on the Longmenshan fault zone,and the distance between 2 epicneters is 85 km while the distance between aftershocks distribution of the 2 manshocks is 60 km. In this study,the dynamic source process with the focal mechanism and empirical relationships was calculated and the related energy and apparent stress were analyzed,respectively. The results indicated that there was frictional undershoot behavior in the dynamic source process of Lushan earthquake,which is actually different from the overshoot activity of the Wenchuan earthquake. Moreover,the characteristics of the source parameters,radiated energy from the fault and the aftershocks distribution from 2 mainshocks were discussed.It indicated that the rupture process was under the influence of apparent stress and frictional behavior on the fault plane.
The April 20,2013 MS7. 0 earthquake occurred in Lushan City,Sichuan Province,China,which was a result of east-west oriented reverse-type motion on a north-south striking fault. The source location suggests the event occurred on southern part of Longmenshan fault at a depth of 13 km. And the great Wenchuan MS8. 0 earthquake of the May 12,2008 also occurred in Sichuan Province of the western interior China with an epicenter located at the longitude 103. 4°E and latitude of 31. 0°N. Both the 2 important earthquakes located on the Longmenshan fault zone,and the distance between 2 epicneters is 85 km while the distance between aftershocks distribution of the 2 manshocks is 60 km. In this study,the dynamic source process with the focal mechanism and empirical relationships was calculated and the related energy and apparent stress were analyzed,respectively. The results indicated that there was frictional undershoot behavior in the dynamic source process of Lushan earthquake,which is actually different from the overshoot activity of the Wenchuan earthquake. Moreover,the characteristics of the source parameters,radiated energy from the fault and the aftershocks distribution from 2 mainshocks were discussed.It indicated that the rupture process was under the influence of apparent stress and frictional behavior on the fault plane.
引文
陈学忠、王小平、王琳瑛等,2003,地震视应力用于震后趋势快速判定的可能性,国际地震动态,(7),1~3。
陈运泰、许力生、张勇等,2009,2008年5月12日汶川特大地震震源特性分析报告,见:宋胜武,汶川大地震工程震害调查分析与研究,北京:科学出版社。
陈运泰、杨智娴、张勇等,2013,从汶川地震到芦山地震,中国科学:地球科学,43,1064~1072。
刘杰、易桂喜、张致伟等,2013,2013年4月20日四川芦山M7.0级地震介绍,地球物理学报,56,1404~1407。
孟令媛、周龙泉、刘杰,2013,2013年芦山MS7.0地震震源参数特征及近断层强地面运动初步估计,地震学报,35(4),632~641。
孟令媛、周龙泉、刘杰,2014,2013年四川芦山MS7.0地震近断层强地面运动模拟及烈度分布估计,地球物理学报,57(2),441~448。
徐锡伟、闻学泽、韩竹君等,2013,四川芦山7.0级强震:一次典型的盲断层型地震,科学通报,58,1887~1893。
徐锡伟、闻学泽、叶建青等,2008,汶川MS8.0地震地表破裂带及其发震构造,地震地质,30,597~629。
薛艳、刘杰、梅世荣等,2009,2008年汶川MS8.0地震前地震活动异常特征,地震学报,31,606~619。
张勇、许力生、陈运泰,2013,芦山4.20地震破裂过程及其至灾特征初步分析,地球物理学报,56,1408~1411。
Brune J N,1970,Tectonic stress and spectra of seismic shear waves from earthquakes,J Geophys Res,75,4997~5009.
Brune J N,1976,The physics of earthquake strong motion.In:Lomnitz C,Rosenblueth E eds,Seismic risk and engineering decisions,New York:Elsevier Sci Publ Co,141~177.
Choy Y T,Boatwright J L,1995,Global patterns of radiated seismic energy and apparent stress,J Geophys Res,100,18205~18228.
Orowan E,1960,Mechanism of seismic faulting in rock deformation:a symposium,Geol Soc Am Mem,79,323~345.
Savage J C,Wood M D,1971,The Relation between Apparent Stress and Stress Drop,Bull Seism Soc Am,61,1381~1388.
Smith K D,Brune J N,Priestly K F,1991,The seismic spectrum,radiated energy,and the Savage and Wood inequality for complex earthquake,Tectonophys,188,303~320.
Starr A T,1928,Slip in a crystal and rupture in a solid due to shear,Proc Cambridge Philos Soc,24,489~500.
Wyss M,Brune J N,1968,Seismic moment,stress,and source dimensions for earthquakes in the California-Nevada region,J Geophys Res,73,4681~4694.
Zúiga F R,1993,Fractional overshoot and partial stress drop,Which one?Bull Seism Soc Am,83,939~944.
1 http://www.csi.ac.cn/manage/sichuan/sichuan080512_72.htm
陈运泰、许力生、张勇等,2009,2008年5月12日汶川特大地震震源特性分析报告,见:宋胜武,汶川大地震工程震害调查分析与研究,北京:科学出版社。
陈运泰、杨智娴、张勇等,2013,从汶川地震到芦山地震,中国科学:地球科学,43,1064~1072。
刘杰、易桂喜、张致伟等,2013,2013年4月20日四川芦山M7.0级地震介绍,地球物理学报,56,1404~1407。
孟令媛、周龙泉、刘杰,2013,2013年芦山MS7.0地震震源参数特征及近断层强地面运动初步估计,地震学报,35(4),632~641。
孟令媛、周龙泉、刘杰,2014,2013年四川芦山MS7.0地震近断层强地面运动模拟及烈度分布估计,地球物理学报,57(2),441~448。
徐锡伟、闻学泽、韩竹君等,2013,四川芦山7.0级强震:一次典型的盲断层型地震,科学通报,58,1887~1893。
徐锡伟、闻学泽、叶建青等,2008,汶川MS8.0地震地表破裂带及其发震构造,地震地质,30,597~629。
薛艳、刘杰、梅世荣等,2009,2008年汶川MS8.0地震前地震活动异常特征,地震学报,31,606~619。
张勇、许力生、陈运泰,2013,芦山4.20地震破裂过程及其至灾特征初步分析,地球物理学报,56,1408~1411。
Brune J N,1970,Tectonic stress and spectra of seismic shear waves from earthquakes,J Geophys Res,75,4997~5009.
Brune J N,1976,The physics of earthquake strong motion.In:Lomnitz C,Rosenblueth E eds,Seismic risk and engineering decisions,New York:Elsevier Sci Publ Co,141~177.
Choy Y T,Boatwright J L,1995,Global patterns of radiated seismic energy and apparent stress,J Geophys Res,100,18205~18228.
Orowan E,1960,Mechanism of seismic faulting in rock deformation:a symposium,Geol Soc Am Mem,79,323~345.
Savage J C,Wood M D,1971,The Relation between Apparent Stress and Stress Drop,Bull Seism Soc Am,61,1381~1388.
Smith K D,Brune J N,Priestly K F,1991,The seismic spectrum,radiated energy,and the Savage and Wood inequality for complex earthquake,Tectonophys,188,303~320.
Starr A T,1928,Slip in a crystal and rupture in a solid due to shear,Proc Cambridge Philos Soc,24,489~500.
Wyss M,Brune J N,1968,Seismic moment,stress,and source dimensions for earthquakes in the California-Nevada region,J Geophys Res,73,4681~4694.
Zúiga F R,1993,Fractional overshoot and partial stress drop,Which one?Bull Seism Soc Am,83,939~944.
1 http://www.csi.ac.cn/manage/sichuan/sichuan080512_72.htm
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