2010年4月14日青海玉树M_S4.7、M_S7.1、M_S6.3地震震源机制解与发震构造研究
摘要
在整合CSN和青海、西藏、四川区域台网宽频带数字地震记录的基础上,采用"Cut and Paste"方法研究了2010年4月14日青海玉树地震序列中M_S4.7级前震、Ms7.1级主震、M_S6.3级强余震的震源机制解和可能的矩心深度,并结合震中附近活动断裂分布与地表破裂带调查资料讨论了发震构造.结果表明2010年4月14日青海玉树M_s 7.1级主震的破裂面为走向129°,倾角84°,滑动角17°,矩心深度6 km左右,矩震级6.8级;Ms4.7级前震的破裂面为走向114°,倾角67°,滑动角5°,矩心深度11 km左右,矩震级4.2级;M_S6.3级强余震的破裂面为走向123°、倾角89°、滑动角9°,矩心深度6 km左右,矩震级5.7级.本次地震序列的发震构造为甘孜一玉树风火山断裂,地震破裂时以左旋走滑为主,地表破裂的总体走向与主震的破裂面走向基本一致,前震-主震强余震的震源性质综合研究可推测发震构造在浅部的倾角陡立,到了深部有所变缓.
Based on digital broad-band seismic records of Qinghai,Xizang,Sichuan regional seismic network and CSN,we inversed the focal mechanisms and possible centroid depth of the M_S4.7 foreshock,M_S7.1 mainshock and M_S6.3 aftershock of the Apr 14,2010 Yushu earthquake sequences using the "Cut and Paste"(CAP) method,and analyzed the seismogenic structures combining with the distribution of active faults near the epicenter and filed investigation of surface rupture zone.The Results show that the earthquake surface rupture of the M_S7.1 mainshock is 129°,84°and 17°for strike,dip and rake angles,respectively,the centroid depth is about 6 km and the moment magnitude is 6.8;the earthquake surface rupture of the M_S4.7 foreshock is 114°,67°and-5°for strike,dip and rake angles,respectively,the centroid depth is about 11 km and the moment magnitude is 4.2;The earthquake rupture surface of the M_S6.3 strong aftershock is 123°,89°and 9°for strike,dip and rake angles,respectively,the centroid depth is about 6 km and the moment magnitude is 5.7.The seismogenic structure of the Yushu earthquake sequences is the Ganzi-Yushu-Fenghuoshan fault;the focal mechanism is mainly left lateral strike slip type.The strike of the source rupture plane is basically consistent with the general strike of surface rupture of the M7.1 mainshock.Comprehensive study on the source character of the foreshock-mainshock-strong aftershock indicates that the dip of the seismogenic structure in shallow is vertical and gradually becomes flat in the deep part
Based on digital broad-band seismic records of Qinghai,Xizang,Sichuan regional seismic network and CSN,we inversed the focal mechanisms and possible centroid depth of the M_S4.7 foreshock,M_S7.1 mainshock and M_S6.3 aftershock of the Apr 14,2010 Yushu earthquake sequences using the "Cut and Paste"(CAP) method,and analyzed the seismogenic structures combining with the distribution of active faults near the epicenter and filed investigation of surface rupture zone.The Results show that the earthquake surface rupture of the M_S7.1 mainshock is 129°,84°and 17°for strike,dip and rake angles,respectively,the centroid depth is about 6 km and the moment magnitude is 6.8;the earthquake surface rupture of the M_S4.7 foreshock is 114°,67°and-5°for strike,dip and rake angles,respectively,the centroid depth is about 11 km and the moment magnitude is 4.2;The earthquake rupture surface of the M_S6.3 strong aftershock is 123°,89°and 9°for strike,dip and rake angles,respectively,the centroid depth is about 6 km and the moment magnitude is 5.7.The seismogenic structure of the Yushu earthquake sequences is the Ganzi-Yushu-Fenghuoshan fault;the focal mechanism is mainly left lateral strike slip type.The strike of the source rupture plane is basically consistent with the general strike of surface rupture of the M7.1 mainshock.Comprehensive study on the source character of the foreshock-mainshock-strong aftershock indicates that the dip of the seismogenic structure in shallow is vertical and gradually becomes flat in the deep part
引文
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[12]周荣军,马声浩,蔡长星.甘孜—玉树断裂带的晚第四纪活动特征[J].中国地震,1996,12(3):250-260. Zhou L J,Ma S H,Cai C X.Late quaternary active features of the Ganzi-Yushu fault zone[J].Earthquake Research in China(in Chinese),1996,12(3),250-260.
[13]周荣军,闻学泽,蔡长星,等.甘孜—玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,1997,19(2):115-124. Zhou L J,Wen X Z.Cai C X,et al.Recent earthquakes and assessment of seismic tendency on the Ganzi-Yushu fault zone [J].Seismology and GeologyGn Chinese),1997,19(2): 115-124
[14]李闽峰,邢成起,蔡长星,等.玉树断裂活动性研究[J].地震地质,1995,17(3):218-224. Li M F,Xing C Q,Cai C X,et al.Research on activity of Yushu fault[J].Seismology and Geology(in Chinese), 1995,17(3):218-224.
[15]张桂芳,屈春燕,单新建,等.2010年青海玉树M_s7.1级地震地表破裂带和形变特征分析[J].地球物理学报,2011,54 (1):121-127. Zhang G F,Qu C Y,Shan X J,et al.The surface rupture and coseismic deformation characteristics of the M_s7.1 earthquake at Qinghai Yushu in 2010[J],Chinese J. Geophys.(in Chinese),2011,54(1):121-127.
[16]张勇,许力生,陈运泰.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,2010,32(3):361-365. Zhang Y,Xu L S,Chen Y T.Fast inversion of rupture process for 14 April 2010 Yushu,Qinghai,earthquake[J].Acta Seismologica SinicaGn Chinese),2010,32(3):361-365.
[17]许力生,邸海滨,冯万鹏,等.2010年青海玉树M_s7.1地震近断层地面运动估计[J].地球物理学报,2010,53(6): 1366-1373. Xu L S,Di H B,Feng W P,et al.Estimation of the faultnear ground motion of the 2010 Yushu,Qinghai,M_s7.1 earthquake[J],Chinese J.Geophys.(in Chinese),2010,53 (6):1366-1373.
[18]王海云.2010年4月14日玉树M_s7.1地震加速度场预测[J].地球物理学报,2010,53(10):2345-2354. Wang H Y.Prediction of acceleration field of the 14 April 2010 Yushu earthquake[J].Chinese J.Geophys.(in Chinese),2010,53(10):2345-2354.
[19]徐彦,张俊伟,苏有锦.反投影全球子台网P波记录研究2010年4月14日玉树地震破裂过程[J].地球物理学报, 2011,54(5):1243-1250. Xu Y,Zhang J W,Su Y J.Imaging the rupture of 14 April, 2010 Yushu earthquake using back-projection of global subarray P-waves[J],Chinese J.Geophys.(in Chinese), 2011,54(5):1243-1250.
[2]Zhu L P,Helmberger D V.Advancement in source estimation techniques using broadband regional seismograms[J].Bull. Seis.Soc.Amer.,1996,86(5):1634-1641.
[3]Tan Y,Zhu L P,Helmberger D V,et al.Locating and modeling regional earthquakes with two stations[J].J. Geophys.Res.,2006,111,B01306,doi:1029/2005JB003775.
[4]吕坚,郑勇,倪四道,等.2005年11月26日九江一瑞昌M_s5.7、M_s4.8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. L(u|¨) J,Zheng Y,Ni S D,et al.Focal mechanisms and seismogenic structures of the M_s5.7 and M_s4.8 Jiujiang-Ruichang earthquakes of Nov.26,2005[J].Chinese J. Geophys.(in Chinese),2008,51(1):158-164.
[5]韦生吉,倪四道,崇加军,等.2003年8月16日赤峰地震:一个可能发生在下地壳的地震[J]?地球物理学报,2009,52 (1):111-119. Wei S J,Ni S D,Chong J J,et al.The 16 August 2003 Chifeng earthquake:Is it a lower crust earthquake[J]? Chinese J.Geophys.(in Chinese),2009,52(1):111-119.
[6]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 J P,Ni S D,Fu R S,et al.Source mechanism of the 2006 Mw5.1 Wenan Earthquake determined from a joint inversion of local and teleseismic broadband waveform data[J].Chinese J. Geophys.(in Chinese),2009,52(1):120-130.
[7]郑勇,马宏生,吕坚,等.汶川地震强余震(M_s≥5.6)的震源机制解及其与发震构造的关系[J].中国科学(D辑),2009,39 (4):413-426. Zheng Y,Ma H S,Lii J,et al.Source mechanism of strong aftershock of(M_s≥5.6) of Wenchuan earthquake and the implication for seismotectonic[J].Science in China(Series D) (in Chinese),2009,39(4):413-426.
[8]丁志峰,何正勤,吴建平,等.青藏高原地震波三维速度结构的研究[J].中国地震,2001,17(2):202-209. Ding Z F,He Z Q,Wu J P,et al.Research on the 3-D seismic velocity structures in Qinghai-Xizang plateau[J].Earthquake Research in China(in Chinese),2001,17(2):202-209.
[9]庄真,傅竹武,吕梓龄,等.青藏高原及邻近地区地壳与上地幔剪切波三维速度结构[J].地球物理学报,1992,35(6): 694-709. Zhuang Z,Fu Z W,L(u|¨) Z L,et al.3-D shear velocity model of crust and upper mantle beneath the Tibetan plateau and its adjacent regions[J].Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1992,35(6):694-709.
[10]吴建平,明跃红,曾融生.遗传算法中的光滑约束反演及其在青藏高原面波研究中的应用[J].地震学报,2001,23(1): 45-53. Wu J P,Ming Y H,Zeng R S.Smooth constraint inversion technique in genetic algorithms and its application to surface wave study in the Tibetan plateau[J],Acta Seismologica Sinica(in Chinese),2001,23(1):45-53.
[11]闻学泽,徐锡伟,郑荣章,等.甘孜—玉树断裂的平均滑动速率与近代大地震破裂[J].中国科学(D辑),2003,33 (z1):199-208. Wen X Z,Xu X W,Zheng R Z,era/.Average slip rates and recent strong earthquakes rupture of the Ganzi-Yushu fault zone[J].Science in China(Series D)(in Chinese).2003,33 (zl):199-208.
[12]周荣军,马声浩,蔡长星.甘孜—玉树断裂带的晚第四纪活动特征[J].中国地震,1996,12(3):250-260. Zhou L J,Ma S H,Cai C X.Late quaternary active features of the Ganzi-Yushu fault zone[J].Earthquake Research in China(in Chinese),1996,12(3),250-260.
[13]周荣军,闻学泽,蔡长星,等.甘孜—玉树断裂带的近代地震与未来地震趋势估计[J].地震地质,1997,19(2):115-124. Zhou L J,Wen X Z.Cai C X,et al.Recent earthquakes and assessment of seismic tendency on the Ganzi-Yushu fault zone [J].Seismology and GeologyGn Chinese),1997,19(2): 115-124
[14]李闽峰,邢成起,蔡长星,等.玉树断裂活动性研究[J].地震地质,1995,17(3):218-224. Li M F,Xing C Q,Cai C X,et al.Research on activity of Yushu fault[J].Seismology and Geology(in Chinese), 1995,17(3):218-224.
[15]张桂芳,屈春燕,单新建,等.2010年青海玉树M_s7.1级地震地表破裂带和形变特征分析[J].地球物理学报,2011,54 (1):121-127. Zhang G F,Qu C Y,Shan X J,et al.The surface rupture and coseismic deformation characteristics of the M_s7.1 earthquake at Qinghai Yushu in 2010[J],Chinese J. Geophys.(in Chinese),2011,54(1):121-127.
[16]张勇,许力生,陈运泰.2010年4月14日青海玉树地震破裂过程快速反演[J].地震学报,2010,32(3):361-365. Zhang Y,Xu L S,Chen Y T.Fast inversion of rupture process for 14 April 2010 Yushu,Qinghai,earthquake[J].Acta Seismologica SinicaGn Chinese),2010,32(3):361-365.
[17]许力生,邸海滨,冯万鹏,等.2010年青海玉树M_s7.1地震近断层地面运动估计[J].地球物理学报,2010,53(6): 1366-1373. Xu L S,Di H B,Feng W P,et al.Estimation of the faultnear ground motion of the 2010 Yushu,Qinghai,M_s7.1 earthquake[J],Chinese J.Geophys.(in Chinese),2010,53 (6):1366-1373.
[18]王海云.2010年4月14日玉树M_s7.1地震加速度场预测[J].地球物理学报,2010,53(10):2345-2354. Wang H Y.Prediction of acceleration field of the 14 April 2010 Yushu earthquake[J].Chinese J.Geophys.(in Chinese),2010,53(10):2345-2354.
[19]徐彦,张俊伟,苏有锦.反投影全球子台网P波记录研究2010年4月14日玉树地震破裂过程[J].地球物理学报, 2011,54(5):1243-1250. Xu Y,Zhang J W,Su Y J.Imaging the rupture of 14 April, 2010 Yushu earthquake using back-projection of global subarray P-waves[J],Chinese J.Geophys.(in Chinese), 2011,54(5):1243-1250.
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