2013年洱源M_S5.5地震烈度分布及震区活动构造背景研究
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摘要
2013年洱源MS5.5地震震区地质构造复杂,发育有NW向和NE向2组活动断裂。据野外调查和探槽揭示,震中附近的维西-乔后断裂为晚第四纪活动断裂,其新近活动时代主要在晚更新世晚期,全新世仍有较明显的活动迹象,运动性质以右旋走滑为主兼有正断。此次地震等烈度线呈NNW向的椭圆形展布,极震区达Ⅶ度,长15km,宽10km,面积约279km2。震源机制解显示:该震源断层为正断兼走滑破裂型,与维西-乔后断裂的运动学特征基本吻合;节面Ⅱ为NW向,与维西-乔后断裂走向基本一致。结合地震烈度分布、滑坡崩塌体分布和微震分布特征等分析推断,此次地震的发震构造应为维西-乔后断裂。震区地处滇西北横断山脉腹地,巨大的地形高差,强烈的表层岩石风化,是造成此次地震破坏较重的自然地理条件,而居民房屋多为抗震性能差的土木结构和砖木结构等简易建筑,是造成地震灾害加重的构筑物背景。
The geological structure of the Eryuan MS5. 5 earthquake area is complex,with the two fault groups striking NW and NE. The filed investigation and exploratory trench showed that the Weixi-Qiaohou fault nearby the epicenter is one of the late Quaternary,with its new activities mainly in late Pleistocene. The signs of its activities can be found in Holocene,The movement is mainly of right lateral slipping with some normal faulting. The seismic intensity of this earthquake distribute as an ellipsoid with a NNW direction,and the intensity of meizoseismal area is up toⅦ,with a total area of around 279km2,15 km in length and 10 km in width. The focal mechanism result reveals that the earthquake source is in normal faulting and strike slipping,consistent with the kinematics characteristics of the Weixi-Qiaohou fault,and that the nodal section Ⅱ has a NW direction,basically consistent with the strike of the Weixi-Qiaohou fault. Combining with the distribution features of seismic intensity,the landslide and collapse,and micro earthquake,we believed that the earthquake was generated by the Weixi-Qiaohou fault. The earthquake area is located in the interior of the Hengduan Mountains,northwestern Yunnan. The great terrain relief and the intense weathering of the surface rock are the physical geography situation of the serious damage. The inhabitant is living in simple mud-wood structure or brick-wood structure building with poor seismic performance,and it is the social reason of the serious damage. In order to decrease earthquake losses,we need to increase the infrastructure in the remote rural areas,to improve the living environment in the countryside,and to enhance the seismic performance of the residential building.
The geological structure of the Eryuan MS5. 5 earthquake area is complex,with the two fault groups striking NW and NE. The filed investigation and exploratory trench showed that the Weixi-Qiaohou fault nearby the epicenter is one of the late Quaternary,with its new activities mainly in late Pleistocene. The signs of its activities can be found in Holocene,The movement is mainly of right lateral slipping with some normal faulting. The seismic intensity of this earthquake distribute as an ellipsoid with a NNW direction,and the intensity of meizoseismal area is up toⅦ,with a total area of around 279km2,15 km in length and 10 km in width. The focal mechanism result reveals that the earthquake source is in normal faulting and strike slipping,consistent with the kinematics characteristics of the Weixi-Qiaohou fault,and that the nodal section Ⅱ has a NW direction,basically consistent with the strike of the Weixi-Qiaohou fault. Combining with the distribution features of seismic intensity,the landslide and collapse,and micro earthquake,we believed that the earthquake was generated by the Weixi-Qiaohou fault. The earthquake area is located in the interior of the Hengduan Mountains,northwestern Yunnan. The great terrain relief and the intense weathering of the surface rock are the physical geography situation of the serious damage. The inhabitant is living in simple mud-wood structure or brick-wood structure building with poor seismic performance,and it is the social reason of the serious damage. In order to decrease earthquake losses,we need to increase the infrastructure in the remote rural areas,to improve the living environment in the countryside,and to enhance the seismic performance of the residential building.
引文
国家地震局地质所、云南省地震局,1990,滇西北地区活动断裂,北京:地震出版社。
虢顺民、计凤洁、向宏发等,2001,红河活动断裂带,北京:海洋出版社。
黄建平、倪四道、傅容珊等,2009,综合近震及远震波形反演2006文安地震(M5.1)的震源机制解,地球物理学报,52(1),120 ~130。
计凤桔、郑荣章、李建平等,2000,滇东、滇西地区主要河流低阶地地貌面的年代学研究,地震地质,22(3),265~276。
阚荣举、林忠洋,1986,云南地壳上地幔构造的初步研究,中国地震,2(4),50~61。
刘宁、陈棋福、韦生吉,2011,地震震源运动学参数获取方法研究进展,中国地震,27(1),29~38。
吕坚、郑勇、倪四道等,2008,2005年11月26日九江-瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究,地球物理学报,25(1),158~164。
任俊杰、张世民、侯治华等,2007,滇西北通甸-巍山断裂中段的晚第四纪滑动速率,地震地质,29(4),756~764。
韦生吉、倪四道、崇加军等,2009,2003年8月16日赤峰地震:一个可能发生在下地壳的地震?地球物理学报,52(1),111~119。
向宏发、韩竹军、虢顺民等,2004,红河断裂带大型右旋走滑运动与伴生构造地貌变形,地震地质,26(4),43~56。
张丽芬、姚运生、廖武林,2013,2011年MS4.6瑞昌-阳新地震的震源机制及发震构造探讨,地震地质,35(2),290~299。
钟大赉、Tapponnier P、吴海威等,1989,大型走滑断层-碰撞后陆内变形的重要形式,科学通报,(7),526~529。
周光全,2013,云南灾害评估与恢复重建规划主要技术指标,地震研究,36(2),207~214。
Darka A,1996,Slip distribution along the North Anatalian Fault associated with the large earthquakes of the period 1939~1967,Bull Seism Soc Am,86(5),1238~1254.
Leloup P H,Lacassin R,Tapponnier P,et al,1995,The Ailao Shan-Red River shear zone(Yunnan China),Tertiary transform boundary of Indochina,Tectonophysics,251,3~84.
Zhao L S,Helmberger D V,1994,Source estimation from broad-band regional seismograms,Bull Seism Soc Am,84(1),91~104.
Zhu L,Helmberger D V,1996,Advancement in source estimation techniques using broadband regional seismograms,Bull Seism Soc Am,86(5),1634~1641.
虢顺民、计凤洁、向宏发等,2001,红河活动断裂带,北京:海洋出版社。
黄建平、倪四道、傅容珊等,2009,综合近震及远震波形反演2006文安地震(M5.1)的震源机制解,地球物理学报,52(1),120 ~130。
计凤桔、郑荣章、李建平等,2000,滇东、滇西地区主要河流低阶地地貌面的年代学研究,地震地质,22(3),265~276。
阚荣举、林忠洋,1986,云南地壳上地幔构造的初步研究,中国地震,2(4),50~61。
刘宁、陈棋福、韦生吉,2011,地震震源运动学参数获取方法研究进展,中国地震,27(1),29~38。
吕坚、郑勇、倪四道等,2008,2005年11月26日九江-瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究,地球物理学报,25(1),158~164。
任俊杰、张世民、侯治华等,2007,滇西北通甸-巍山断裂中段的晚第四纪滑动速率,地震地质,29(4),756~764。
韦生吉、倪四道、崇加军等,2009,2003年8月16日赤峰地震:一个可能发生在下地壳的地震?地球物理学报,52(1),111~119。
向宏发、韩竹军、虢顺民等,2004,红河断裂带大型右旋走滑运动与伴生构造地貌变形,地震地质,26(4),43~56。
张丽芬、姚运生、廖武林,2013,2011年MS4.6瑞昌-阳新地震的震源机制及发震构造探讨,地震地质,35(2),290~299。
钟大赉、Tapponnier P、吴海威等,1989,大型走滑断层-碰撞后陆内变形的重要形式,科学通报,(7),526~529。
周光全,2013,云南灾害评估与恢复重建规划主要技术指标,地震研究,36(2),207~214。
Darka A,1996,Slip distribution along the North Anatalian Fault associated with the large earthquakes of the period 1939~1967,Bull Seism Soc Am,86(5),1238~1254.
Leloup P H,Lacassin R,Tapponnier P,et al,1995,The Ailao Shan-Red River shear zone(Yunnan China),Tertiary transform boundary of Indochina,Tectonophysics,251,3~84.
Zhao L S,Helmberger D V,1994,Source estimation from broad-band regional seismograms,Bull Seism Soc Am,84(1),91~104.
Zhu L,Helmberger D V,1996,Advancement in source estimation techniques using broadband regional seismograms,Bull Seism Soc Am,86(5),1634~1641.
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