基于CAP方法的2013湖北巴东5.1级地震震源机制与发震构造研究
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摘要
利用湖北与重庆区域台网共9个台的宽频带数字地震记录,采用CAP法(Cut and Paste Method)反演了湖北巴东2013年12月16日MS5.1地震震源机制解,其最佳双力偶解为节面I:走向166°,倾角82°,滑动角41°;节面Ⅱ:走向69°,倾角49°,滑动角169°;最佳震源深度主要集中分布在5.5km附近。分析认为此次地震的发震断层为带有逆冲成分的走滑性质断层,主压应力P轴近EW向,主张应力轴近NS向。余震序列主要呈EW分布,少部分呈NS方向分布,较大余震的发震破裂滑动类型以正走滑型的居多,其次为逆倾滑型及逆走滑型。结合7次较大余震的机制解判断,近EW向节面为发震断层。
Using the records of nine stations in the Hubei and Chongqing Regional Seismic Network,we obtained the focal mechanisms of the Badong MS5.1earthquake in 2013 using the"Cut and Paste"(CAP)method.Our results show that the best double couple solution of the MS5.1event is 166°,79°,and-22°for strike,dip,and rake angles respectively;the strike,dip,and rake angles of the other nodal plane are 298°,68°,and-168°,respectively,and the optimum focus depth is 5.5km.The results show that the earthquakes mechanism was a thrust along strike-slip faults,with the principal stress P axis mainly in the EW direction and the lord tension T shaft mainly in the NS direction.The focal mechanisms of the biggest aftershocks are mostly normal dip-slips,and the aftershock sequence mainly propagated along the EW direction,with a few propagating along the NS direction.Therefore,we infer that the seismogenic structure of the MS5.1earthquake and aftershocks was the EW strike portion of the Daqiao fault.
Using the records of nine stations in the Hubei and Chongqing Regional Seismic Network,we obtained the focal mechanisms of the Badong MS5.1earthquake in 2013 using the"Cut and Paste"(CAP)method.Our results show that the best double couple solution of the MS5.1event is 166°,79°,and-22°for strike,dip,and rake angles respectively;the strike,dip,and rake angles of the other nodal plane are 298°,68°,and-168°,respectively,and the optimum focus depth is 5.5km.The results show that the earthquakes mechanism was a thrust along strike-slip faults,with the principal stress P axis mainly in the EW direction and the lord tension T shaft mainly in the NS direction.The focal mechanisms of the biggest aftershocks are mostly normal dip-slips,and the aftershock sequence mainly propagated along the EW direction,with a few propagating along the NS direction.Therefore,we infer that the seismogenic structure of the MS5.1earthquake and aftershocks was the EW strike portion of the Daqiao fault.
引文
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[16]许崇宝,钱进,孙立新.岩溶裂隙发育带地震解释方法研究[J].工程地球物理学报,2008,5(2):148-151.XU Chong-bao,Qian Jin,SUN Li-xin.Research on Seismic Lnterpretation Method of Karst-Fractured Zone[J].Chinese Journal of Engineering Geophysics,2008,5(2):148-151.(in Chinese)
[17]董兴朋,彭愿,吴阿丹.震源破裂过程反演方法研究现状及展望[J].华南地震,2012,32(2):72-77.DONG Xing-ping,PENG Yuan,WU A-dan.Status and Prospect of Inversion Study on Source Rupture Process[J].South China Journal of Seismology,2012,32(2):72-77.(in Chinese)
[2]陈俊华,陈正公,蒋玲霞,等.巴东5.1级地震事件初步研究[J].大地测量与动力学,2014,34(3):11-13.CHEN Jun-hua CHEN Zheng-song,JIANG Ling-xia,et al.Oncauses of Badong MS5.1Earthquake[J].Journal of Geodesy and Geodynamics,2014,34(3):11-13.(in Chinese)
[3]刘锁旺,甘家思,薛宏交.长江三峡地区的构造应力场与地震活动[J].地震地质,1983,.5(1):29-41.LIU Suo-wang,GAN Jia-si,XUE Hong-jiao.Tectonic Stress Field and Seismicity in the Three Gorge Region on the Changjiang River[J].Seismology and Geology,1983,5(1):29-41.(in Chinese)
[4]程万正.高烈度区的水库地震问题[J].国际地震动态,2013(4):10-18.CHENG Wan-zheng.The Reservoir Lnduced Earthquake Problem in the High Intensity Area[J].Recent Developments in World Seismology,2013(4):10-18.(in Chinese)
[5]Helmberger D V,Engen G R.Modeling the Long-period Body Waves From Shallow Earthquakes at Regional Ranges[J].Bul1Seism Soc Am,1980,70:1699-1714.
[6]Zhao L S,Helmberger D V.Source Estimation From Broadband Regional Seismograms[J].Bull Seis Soc Amer,1994,84(1):91-104.
[7]Zhu L,Helmberger D V.Advancement in Source Estimation Techniques Using Broadband Regional Seismograms[J].Bull Seism Soc Am,1996,86:1634-1641.
[8]Zhu L,Tan Y,Helmberger D V,et al.Calibration of the Tibetan Plateau Using Regional Seismic Waveforms[J].Pageoph,2006,163:1193-1213.
[9]Tan Y,Zhu L,Helmberger D V,et a1.Locating and Modeling Regional Earthquakes with Two Stations[J].J Geophys Res,2006,111(B01):306-314.
[10]Zhu,Rivera.A Note on the Dynamic and Static Displacements From a Point Source in Multilayered Media[J].Geophys J Int,2002,148:619-627.
[11]洪德全,王行舟,韩立波,等.用CAP方法研究安庆4.8级地震震源机制[J].中国地震,2011,27(2):207-214.HONG De-quan,WANG Xing-zhou,HAN Li-bo.et al.Focal Mechanism Solution of the 2011 MS4.8Anqing Earthquake Determined from the CAP Method[J].Earthquake Research in China,2011,27(2):207-214.(in Chinese)
[12]张爱民,李强.双差定位法在三峡库区地震定位中的应用[J].大地测量与地球动力学,2006,26(3):73-77.ZHANG Ai-min,LI Qiang.Application of Double Difference Location Method to Earthquake in Three Gorges Reservoir area[J].Journal of Geodesy and Geodynamics,2006,26(3):73-77.(in Chinese)
[13]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 MS 5.7 and MS4.8Jiujiang-Ruichang Earthquakes of Nov.26,2005[J].Chinese Journal of Geophysics,2008,51(1):158-164.(in Chinese)
[14]张爱萍,倪四道,杨晓勇,等.2004年东乌珠穆沁旗地震震源参数研究[J].地震,2008,28(3):61-68.ZHANG Ai-ping,NI Si-dao,YANG Xiao-yong,et al.Source Parameters of 2004Xilin Gol League Earthquake[J].Earthquake,2008,28(3):61-68.(in Chinese)
[15]黄建平,倪四道,傅容珊,等.综合近震及远震波形反演2006文安地震(MW5.1)的震源机制解[J].地球物理学报,2009,52(1):120-130.HUANG Jian-ping,NI Si-dao,FU Rong-shan,et al.Source Mechanism of the 2006 M W5.1 Wenan Earthquake Determined from a Joint Inversion of Local and Teleseismic Broadband Waveform Data[J].Chinese Journal of Geophysics,2009,52(1):120-130.(in Chinese)
[16]许崇宝,钱进,孙立新.岩溶裂隙发育带地震解释方法研究[J].工程地球物理学报,2008,5(2):148-151.XU Chong-bao,Qian Jin,SUN Li-xin.Research on Seismic Lnterpretation Method of Karst-Fractured Zone[J].Chinese Journal of Engineering Geophysics,2008,5(2):148-151.(in Chinese)
[17]董兴朋,彭愿,吴阿丹.震源破裂过程反演方法研究现状及展望[J].华南地震,2012,32(2):72-77.DONG Xing-ping,PENG Yuan,WU A-dan.Status and Prospect of Inversion Study on Source Rupture Process[J].South China Journal of Seismology,2012,32(2):72-77.(in Chinese)
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