2013年7月22日岷县漳县6.6级地震震源机制解
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摘要
利用甘肃"十五"数字地震台网的波形资料,采用CAP方法反演了2013年7月22日岷县漳县6.6级地震的震源机制解。结果显示:本次地震的震源性质为逆冲兼走滑型,矩震级MW6.1,震源矩心深度为7km。最佳双力偶节面Ⅱ走向304°,倾角64°,滑动角44°,其走向与附近的临潭-宕昌断裂的走向一致;倾角和滑动角,表现为左旋走滑的特性与临潭-宕昌断裂的性质相符合,判定该节面代表了主震的发震断层面。分析认为岷县漳县6.6级地震的发生与该断裂的活动密切相关。
The Chinese seismological station net determined that an MS6.6 earthquake occurred on July 22,2013,at 7:45CST at the border of Minxian and Zhangxian counties in Gansu Province. By the end of August 26,1300aftershocks had occurred in the seismic region of the main earthquake,including one of 5.0～5.9level,one of 4.0～4.9level,and nine of 3.0～3.9level.The largest,with magnitude of 5.6,occurred at 9:12on July 22.This earthquake caused heavy casualties and economic losses. In this study,the cut-and-paste(CAP)method was used to determine that the earthquake was thrust and strike-slip,MW was 6.1,and the focal depth was 7km.The nodal plane Ⅱ parameters of the best double-couple are strike 304°,dip 64°,and rake 44°.The strike of the nodal plane had the same trend as that of the Lintan-Tanchang fault,and the characteristic of dip and slip represent left lateral slip,which also corresponds to the Lintan-Tanchang fault.The nodal plane is representative of the seismogenic fault plane.Therefore,the Minxian-Zhangxian Ms6. 6earthquake is in osculating correlation with activity of the Lintan-Tanchang fault.
The Chinese seismological station net determined that an MS6.6 earthquake occurred on July 22,2013,at 7:45CST at the border of Minxian and Zhangxian counties in Gansu Province. By the end of August 26,1300aftershocks had occurred in the seismic region of the main earthquake,including one of 5.0～5.9level,one of 4.0～4.9level,and nine of 3.0～3.9level.The largest,with magnitude of 5.6,occurred at 9:12on July 22.This earthquake caused heavy casualties and economic losses. In this study,the cut-and-paste(CAP)method was used to determine that the earthquake was thrust and strike-slip,MW was 6.1,and the focal depth was 7km.The nodal plane Ⅱ parameters of the best double-couple are strike 304°,dip 64°,and rake 44°.The strike of the nodal plane had the same trend as that of the Lintan-Tanchang fault,and the characteristic of dip and slip represent left lateral slip,which also corresponds to the Lintan-Tanchang fault.The nodal plane is representative of the seismogenic fault plane.Therefore,the Minxian-Zhangxian Ms6. 6earthquake is in osculating correlation with activity of the Lintan-Tanchang fault.
引文
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[2]Zhu L P,Helmberger D V.Advancement in Source Estimation Techniques Using Broadband Regional Seismograms[J].Bull.Seism.Soc.Am.,1996,86:1634-1641.
[3]Tan Ying,Zhu L P,Helmberger D V,et al.Locating and Modeling Regional Earthquakes with Two Stations[J].J.Geophys.Res.,2006,11(B01):306-314.
[4]Zhu L P,Rivera L A.A Note on the Dynamic and Static Displacements from A Point Source in Multilayered Media[J].Geophys.J.Int.,2002,148:619-627.
[5]吕坚,郑勇,倪四道,等.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[J].地球物理学报,2008,51(1):158-164.LV Jian,ZHENG Yong,NI Si-dao,et al.Focal Mechanisms and Seismogenic Structures of the MS5.7and MS4.8JiujiiangRuichang Earthquakes of Nov.26,2005[J].Chinese J.Geophys.,2008,51(1):158-164.(in Chinese)
[6]郑勇,马宏生,吕坚.汶川地震强余震(MS≥5.6)源机制解及其与发震构造的关系[J].中国科学:D辑,2009,39(4):23-36.ZHENG Yong,MA Hong-sheng,LV Jian,et al.Source Mechanism of Strong Aftershocks(MS≥5.6)of the 2008-05-12Wenchuan Earthquake and the Implication for Seismotectonics[J].Science in China:Series D,2009,39(4):23-36.(in Chinese)
[7]张辉,徐辉,姚军,等.祁连山中东段基于CAP方法的中小地震震源机制研究[J].山西地震,2010,141(1):25-29.ZHANG Hui,XU Hui,YAO Jun,et al.Study on Focal Mechanism by Using CAP Method for Small-moderate Earthquakes in Middle-east Segment of Qilian Mountain[J].Earthquake Research in Shanxi,2010,141(1):25-29.(in Chinese)
[8]龙锋,张永久,闻学泽,等.2008年8月30日攀枝花-会理6.1级地震序列ML≥4.0事件的震源机制解[J].地球物理学报,2010,53(12):2852-2860.LONG Feng,ZHANG Yong-jiu,WEN Xue-ze,et al.Focal Mechanism Solutions of ML≥4.0Events in the MS6.1Panzhihua-Huili Earthquake Sequence of Aug.30,2008[J].Chinese J.Geophys.,2010,53(12):2852-2860.(in Chinese)
[9]张辉,王熠煕.2012年5月3日金塔-阿拉善盟5.4级地震震源机制解[J].西北地震学报,2012,34(2):205-206.ZHANG Hui,WANG Yi-xi.Focal Mechanism of the 5.4Earthquake JinTan-Alashanmeng of May 3,2012[J].Northwestern Seismological Journal,2012,34(2):205-206.(in Chinese)
[10]张辉.2012年5月11日甘肃肃南MS4.9地震震源机制解[J].西北地震学报,2012,34(2):207-208.ZHANG Hui.Focal Mechanism of the Sunan MS4.9Earthquake in Gansu Province on May 11,2012[J].Northwestern Seismological Journal,2012,34(2):207-208.(in Chinese)
[11]李清河,郭建康,周民都,等.成县—西吉剖面地壳速度结构[J].西北地震学报,1991,13(增刊):37-43.LI Qing-he,GUO Jian-kang,ZHOU Min-du,et al.The Crustal Velocity Structure Inferred from Chengxian-Xiji Deep Seismic Sounding Profile[J].Northwestern Seismological Journal,1991,13(Suppl.):37-43.(in Chinese)
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