2013年芦山M_S7.0地震产生的静态库仑应力变化及其对余震空间分布的影响
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摘要
2013年4月20日芦山MS7.0地震发生在龙门山断裂带的西南段,距2008年汶川MS8.0地震仅约85km,时间上仅相隔5年.首先计算了汶川地震的静态库仑应力变化对本次芦山地震的影响,得出芦山地震是由汶川地震触发造成的(库仑应力上升了0.012 MPa);进一步计算了芦山地震与汶川地震这两次大地震共同产生的静态库仑应力变化.结果表明,芦山地震的余震受前面两次大地震的共同影响,而不仅仅是芦山地震单独作用的结果,超过85%的余震发生在两次地震共同产生的静态库仑应力变化增大的地方,而芦山地震本身触发不了本次的余震序列(仅48.7%的余震位于主震所产生的应力加载区).此外,计算结果表明芦山地震本身对周边断层影响较小,仅龙门山断裂带的东北段受到一定的加载作用;而由于汶川地震的作用,安宁河断裂、大凉山断裂、马尔康断裂、岷江断裂和虎牙断裂呈卸载趋势,仅鲜水河断裂东南段和龙门山断裂中段受到加载作用,这均会加速断层上新地震的发生.
On 20 April 2013,a MS7.0 earthquake struck Lushan County,Sichuan Province.The epicenter is on the southwest segment of the Longmenshan fault zone which is only about 85 km from the 2008 Wenchuan MS8.0 earthquake only after 5 years.This paper first calculated the impact of Coulombstress change induced by the Wenchuan earthquake on the Lushan earthquake,and found that the Lushan earthquake have been triggered by the Wenchuan earthquake(Coulomb stress increased by 0.012 MPa).Then the Coulomb stress change generated by the Lushan earthquake and the Wenchuan earthquake were calculated.The results show that the aftershocks have been promoted by the combined effect of the two strong earthquakes.More than 85% of the aftershocks occurred in the Coulomb stress increasing region.However,the Lushan earthquake alone cannot trigger the aftershock sequence(only 48.7% aftershocks fall into the increasing region).Furthermore,the calculation result also indicate that the Lushan earthquake has little influence on the surrounding faults.Only the northeast segment of the Longmenshan fault is brought closer to failure.Due to the Wenchuan earthquake,most of the surrounding faults,such as the Anninghe,Daliangshan,Barkam,Minjiang and Huya faults are being unloaded,while the southeast segment of the Xianshuihe fault and middle segment of the Longmenshan fault are enhanced,accelerating occurrence of new earthquakes.
On 20 April 2013,a MS7.0 earthquake struck Lushan County,Sichuan Province.The epicenter is on the southwest segment of the Longmenshan fault zone which is only about 85 km from the 2008 Wenchuan MS8.0 earthquake only after 5 years.This paper first calculated the impact of Coulombstress change induced by the Wenchuan earthquake on the Lushan earthquake,and found that the Lushan earthquake have been triggered by the Wenchuan earthquake(Coulomb stress increased by 0.012 MPa).Then the Coulomb stress change generated by the Lushan earthquake and the Wenchuan earthquake were calculated.The results show that the aftershocks have been promoted by the combined effect of the two strong earthquakes.More than 85% of the aftershocks occurred in the Coulomb stress increasing region.However,the Lushan earthquake alone cannot trigger the aftershock sequence(only 48.7% aftershocks fall into the increasing region).Furthermore,the calculation result also indicate that the Lushan earthquake has little influence on the surrounding faults.Only the northeast segment of the Longmenshan fault is brought closer to failure.Due to the Wenchuan earthquake,most of the surrounding faults,such as the Anninghe,Daliangshan,Barkam,Minjiang and Huya faults are being unloaded,while the southeast segment of the Xianshuihe fault and middle segment of the Longmenshan fault are enhanced,accelerating occurrence of new earthquakes.
引文
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沈正康,万永革,甘卫军,曾跃华,任群.2003.东昆仑活动断裂带大地震之间的黏弹性应力触发研究[J].地球物理学报,46(6):786--795.
万永革,沈正康,兰从欣.2005.兰德斯地震断层面及其附近余震产生的位移场研究[J].地震学报,27(2):139--146.
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张竹琪,陈永顺,林间.2008.1997年伽师震群中相邻正断层和走滑断层之间相互应力作用[J].中国科学:D辑,38(3):334--342.
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朱守彪,石耀霖.2005.青藏高原地形扩展力以及下地壳对上地壳的拖曳力的遗传有限单元法反演[J].北京大学学报:自然科学版,41(2):225--234.
朱守彪,张培震.2009.2008年汶川MS8.0地震发生过程的动力学机制研究[J].地球物理学报,52(2):418--427.
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Harrison T M,Copeland P,Kidd W,Yin A.1992.Raising Tibet[J].Science,255(5052):1663--1670.
Ji C.2008.Preliminary result of the May 12,2008 MW7.97Sichuan earthquake.[2008-12-08].http:∥www.geol.ucsb.edu/faculty/ji/big_earthquakes/2008/05/12/ShiChuan.html.
King G C P,Stein R S,Lin J.1994.Static stress changes and the triggering of earthquakes[J].Bull Seismol Soc Am,84(3):935--953.
Lin J,Stein R S.2004.Stress triggering in thrust and subduction earthquakes and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults[J].J Geophys Res,109(B2):B02303,doi:10.1029/2003JB002607.
Ma K,Chan C,Stein R S.2005.Response of seismicity to Coulomb stress triggers and shadows of the 1999 MW=7.6Chi-Chi,Taiwan,earthquake[J].J Geophys Res,110(B5):B05S19,doi:10.1029/2004JB003389.
Molnar P,Tapponnier P.1975.Cenozoic tectonics of Asia:Effects of a continental collision[J].Science,189(4201):419--426.
Nalbant S S,McCloskey J.2010.Stress evolution before and after the 2008 Wenchuan,China earthquake[J].Earth Planet Sci Lett,307(1/2):222--232.
Okada Y.1992.Internal deformation due to shear and tensile faults in a half-space[J].Bull Seismol Soc Am,82(2):1018--1040.
Parsons T,Ji C,Kirby E.2008.Stress changes from the 2008Wenchuan earthquake and increased hazard in the Sichuan basin[J].Nature,454(7203):509--510.
Robinson R,McGinty P J.2000.The enigma of the Arthur′s Pass,New Zealand,earthquake 2.The aftershock distribution and its relation to regional and induced stress fields[J].J Geophys Res,105(B7):16139--16150.
Royden L H,Burchfiel B C,van der Hilst R D.2008.The geological evolution of the Tibetan Plateau[J].Science,321(5892):1054--1058.
Stein R S,Barka A A,Dieterich J H.1997.Progressive failure on the North Anatolian fault since 1939by earthquake stress triggering[J].Geophys J Int,128(3):594--604.
Toda S,Lin J,Meghraoui M,Stein R S.2008.12 May 2008 M=7.9 Wenchuan,China,earthquake calculated to increase failure stress and seismicity rate on three major fault systems[J].Geophys Res Lett,35(17):L17305,doi:10.1029/2008GL034903.
Toda S,Stein R S,Richards-Dinger K,Bozkurt S B.2005.Forecasting the evolution of seismicity in southern California:Animations built on earthquake stress transfer[J].J Geophys Res,110(B5):B05S16,doi:10.1029/2004JB003415
Wan Y,Shen Z K.2010.Static Coulomb stress changes on faults caused by the 2008 MW7.9 Wenchuan,China earthquake[J].Tectonophysics,491(1/4):105--118.
Wang J,Shieh C,Chang T.2003.Static stress changes as a triggering mechanism of a shallow earthquake:case study of the 1999Chi-Chi(Taiwan)earthquake[J].Phys Earth Planet Inter,135(1):17--25.
Xu C,Wang J,Li Z,Drummond J.2010.Applying the Coulomb failure function with an optimally oriented plane to the2008 MW7.9Wenchuan earthquake triggering[J].Tectonophysics,491(1/4):119--126.
Zhu S,Shi Y.2011.Estimation of GPS strain rate and its error analysis in the Chinese continent[J].J Asian Earth Sci,40(1):351--362.
①http:∥www.globalcmt.org/.查询日期:2013-04-20
李玉江,陈连旺,陆远忠,詹自敏.2013.汶川地震的发生对周围断层稳定性影响的数值模拟[J].地球科学,38(2):398--410.
刘桂萍,傅征祥.2001.海原大地震对古浪大地震的静应力触发研究[J].地球物理学报,44(增刊):107--115.
邵志刚,傅容珊,薛霆婋,查显杰.2009.库仑应力变化与余震对应关系的初步探讨——以集集地震为例[J].地球物理学进展,24(2):367--374.
沈正康,万永革,甘卫军,曾跃华,任群.2003.东昆仑活动断裂带大地震之间的黏弹性应力触发研究[J].地球物理学报,46(6):786--795.
万永革,沈正康,兰从欣.2005.兰德斯地震断层面及其附近余震产生的位移场研究[J].地震学报,27(2):139--146.
王卫民,郝金来,姚振兴.2013.2013年4月20日四川芦山地震震源破裂过程反演初步结果[J].地球物理学报,56(4):1412--1417.
解朝娣,朱元清,Lei Xinglin,于海英,虎雄林.2010.MS8.0汶川地震产生的应力变化空间分布及其对地震活动性的影响[J].中国科学:D辑,40(6):688--698.
张竹琪,陈永顺,林间.2008.1997年伽师震群中相邻正断层和走滑断层之间相互应力作用[J].中国科学:D辑,38(3):334--342.
中国地震台网中心.2013.四川省雅安市芦山县发生7.0级地震[EB/OL].[2013-04-20].http:∥www.cenc.ac.cn/manage/html/402881891275f6df011275f971990001/__SUBAO/_content/13_04/20/13e24ca9cde00.html.
朱守彪,石耀霖.2005.青藏高原地形扩展力以及下地壳对上地壳的拖曳力的遗传有限单元法反演[J].北京大学学报:自然科学版,41(2):225--234.
朱守彪,张培震.2009.2008年汶川MS8.0地震发生过程的动力学机制研究[J].地球物理学报,52(2):418--427.
Harris R A.1998.Introduction to special section:Stress triggers,stress shadows,and implications for seismic hazard[J].J Geophys Res,103(B10):24347--24358.
Harris R A,Simpson R W.1996.In the shadow of 1857——the effect of the Great Ft.Tejon earthquake on subsequent earthquakes in southern California[J].Geophys Res Lett,23(3):229--232.
Harrison T M,Copeland P,Kidd W,Yin A.1992.Raising Tibet[J].Science,255(5052):1663--1670.
Ji C.2008.Preliminary result of the May 12,2008 MW7.97Sichuan earthquake.[2008-12-08].http:∥www.geol.ucsb.edu/faculty/ji/big_earthquakes/2008/05/12/ShiChuan.html.
King G C P,Stein R S,Lin J.1994.Static stress changes and the triggering of earthquakes[J].Bull Seismol Soc Am,84(3):935--953.
Lin J,Stein R S.2004.Stress triggering in thrust and subduction earthquakes and stress interaction between the southern San Andreas and nearby thrust and strike-slip faults[J].J Geophys Res,109(B2):B02303,doi:10.1029/2003JB002607.
Ma K,Chan C,Stein R S.2005.Response of seismicity to Coulomb stress triggers and shadows of the 1999 MW=7.6Chi-Chi,Taiwan,earthquake[J].J Geophys Res,110(B5):B05S19,doi:10.1029/2004JB003389.
Molnar P,Tapponnier P.1975.Cenozoic tectonics of Asia:Effects of a continental collision[J].Science,189(4201):419--426.
Nalbant S S,McCloskey J.2010.Stress evolution before and after the 2008 Wenchuan,China earthquake[J].Earth Planet Sci Lett,307(1/2):222--232.
Okada Y.1992.Internal deformation due to shear and tensile faults in a half-space[J].Bull Seismol Soc Am,82(2):1018--1040.
Parsons T,Ji C,Kirby E.2008.Stress changes from the 2008Wenchuan earthquake and increased hazard in the Sichuan basin[J].Nature,454(7203):509--510.
Robinson R,McGinty P J.2000.The enigma of the Arthur′s Pass,New Zealand,earthquake 2.The aftershock distribution and its relation to regional and induced stress fields[J].J Geophys Res,105(B7):16139--16150.
Royden L H,Burchfiel B C,van der Hilst R D.2008.The geological evolution of the Tibetan Plateau[J].Science,321(5892):1054--1058.
Stein R S,Barka A A,Dieterich J H.1997.Progressive failure on the North Anatolian fault since 1939by earthquake stress triggering[J].Geophys J Int,128(3):594--604.
Toda S,Lin J,Meghraoui M,Stein R S.2008.12 May 2008 M=7.9 Wenchuan,China,earthquake calculated to increase failure stress and seismicity rate on three major fault systems[J].Geophys Res Lett,35(17):L17305,doi:10.1029/2008GL034903.
Toda S,Stein R S,Richards-Dinger K,Bozkurt S B.2005.Forecasting the evolution of seismicity in southern California:Animations built on earthquake stress transfer[J].J Geophys Res,110(B5):B05S16,doi:10.1029/2004JB003415
Wan Y,Shen Z K.2010.Static Coulomb stress changes on faults caused by the 2008 MW7.9 Wenchuan,China earthquake[J].Tectonophysics,491(1/4):105--118.
Wang J,Shieh C,Chang T.2003.Static stress changes as a triggering mechanism of a shallow earthquake:case study of the 1999Chi-Chi(Taiwan)earthquake[J].Phys Earth Planet Inter,135(1):17--25.
Xu C,Wang J,Li Z,Drummond J.2010.Applying the Coulomb failure function with an optimally oriented plane to the2008 MW7.9Wenchuan earthquake triggering[J].Tectonophysics,491(1/4):119--126.
Zhu S,Shi Y.2011.Estimation of GPS strain rate and its error analysis in the Chinese continent[J].J Asian Earth Sci,40(1):351--362.
①http:∥www.globalcmt.org/.查询日期:2013-04-20
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