2008年汶川M_S8.0地震在2013年芦山M_S7.0地震和2014年康定M_S6.3地震破裂区引起的库仑破裂应力
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摘要
2008年5月12日四川汶川发生M_S8.0地震发生之后,先后于2013年4月20日和2014年11月22日分别在汶川M_S8.0地震震中西南约80km的芦山县和约178km的康定县发生了M_S7.0和M_S6.3地震。芦山地震位于龙门山前主边界处,康定地震位于鲜水河断裂带上。芦山地震发生前有几位作者先后计算了汶川M_S8.0地震引起的库仑破裂应力,分析了其对周围断层的影响。本文对这些研究结果进行了简要回顾,并根据芦山地震和康定地震的实际发震断层面参数,计算了汶川M_S8.0地震在芦山地震和康定地震震源深度处的水平面上以及其发震断层面上产生的库仑破裂应力,还给出了其震中处库仑破裂应力随深度的变化。结果表明,汶川M_S8.0地震发生使芦山地震震源断层面上有利于其错动发震的应力大面积增加而使康定地震震源断层面上有利于其错动发震的应力大面积减小。在芦山地震初始破裂点处引起的库仑破裂应力达0.245MPa,在康定地震初始破裂点处引起的库仑破裂应力为-0.000 63 MPa。因此,汶川M_S8.0地震的发生对芦山地震具有明显的促进作用,而对康定地震的作用不明显。在目标断层面参数已知的情况下,根据库仑破裂应力在目标断层面上的分布,可能为未来地震发生的地点提供线索,进而对地震发生的危险性进行预测。若一次地震的发生使目标断层面上有利于其错动发震的应力大面积显著增加,这种情况下库仑破裂应力对未来地震具有预测意义。
On 12 May 2008 astrong M_S8.0earthquake struck Wenchuan,Sichuan province,China.After the M_S8.0 Wenchuan earthquake,two earthquakes of M_S7.0and M_S6.3occurred on 20 April 2013and 22 November 2014respectively.Their epicenters are located in Lushan,Sichuan and Kangding,Sichuan,southwest of the epicenter of the M_S8.0Wenchuan event with distances of about 80 km and 178 km.The Lushan earthquake was located at the frontier boundary of the Longmenshan mountain,and the Kangding earthquake was located on the Xainshuihe fault.Till the Lushan earthquake,several authors have calculated the Coulomb stress change imparted by the M_S8.0 Wenchuan earthquake and analyzed its effect on the surrounding faults.In this paper,after a brief review of their results,the Coulomb stress changes imparted by the M_S8.0 Wenchuan earthquake on the horizontal plane at the focal depth and the focal fault planes of the Lushan and the Kangding events were calculated.The Coulomb stress changes versus depth at their epicenters are obtained.The results show that the M_S8.0Wenchuan earthquake have made the stress on the focal fault plane of the Lushan event increased in a large area,and that on the focal fault plane of the Kangding event decreased in a large area.The Coulomb stress change at the initial rupture point for the Lushan event is 0.245 MPa,and for the Kangding event is-0.000 63 MPa.Therefore,the M_S8.0 Wenchuan earthquake would play apositive role in the occurrence of the Lushan event,but could has no significant effect on the occurrence of the Kangding event.Given parameters of the target fault plane,it could be possible that some clues for the epicenter of the future strong earthquake are provided according to the Coulomb stress changes on the horizontal plane at the focal depth and the focal fault plane,and then prediction for the future strong earthquake could be given.If a strong earthquake makes the stress on the target focal fault plane increased in a large area,the Coulomb stress change could be of important significance to the prediction of the future earthquakes.
On 12 May 2008 astrong M_S8.0earthquake struck Wenchuan,Sichuan province,China.After the M_S8.0 Wenchuan earthquake,two earthquakes of M_S7.0and M_S6.3occurred on 20 April 2013and 22 November 2014respectively.Their epicenters are located in Lushan,Sichuan and Kangding,Sichuan,southwest of the epicenter of the M_S8.0Wenchuan event with distances of about 80 km and 178 km.The Lushan earthquake was located at the frontier boundary of the Longmenshan mountain,and the Kangding earthquake was located on the Xainshuihe fault.Till the Lushan earthquake,several authors have calculated the Coulomb stress change imparted by the M_S8.0 Wenchuan earthquake and analyzed its effect on the surrounding faults.In this paper,after a brief review of their results,the Coulomb stress changes imparted by the M_S8.0 Wenchuan earthquake on the horizontal plane at the focal depth and the focal fault planes of the Lushan and the Kangding events were calculated.The Coulomb stress changes versus depth at their epicenters are obtained.The results show that the M_S8.0Wenchuan earthquake have made the stress on the focal fault plane of the Lushan event increased in a large area,and that on the focal fault plane of the Kangding event decreased in a large area.The Coulomb stress change at the initial rupture point for the Lushan event is 0.245 MPa,and for the Kangding event is-0.000 63 MPa.Therefore,the M_S8.0 Wenchuan earthquake would play apositive role in the occurrence of the Lushan event,but could has no significant effect on the occurrence of the Kangding event.Given parameters of the target fault plane,it could be possible that some clues for the epicenter of the future strong earthquake are provided according to the Coulomb stress changes on the horizontal plane at the focal depth and the focal fault plane,and then prediction for the future strong earthquake could be given.If a strong earthquake makes the stress on the target focal fault plane increased in a large area,the Coulomb stress change could be of important significance to the prediction of the future earthquakes.
引文
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[2] King G C P,Stein R S,Lin J.Static stress changes and the triggering of earthquakes[J].Bull Seism Soc Am,1994,84(3):935-953.
[3] Harris R A,Simpson R W,Reasenberg P A.Influence of static stress changes on earthquake locations in southern California[J].Nature,1995,375(6 528):221-224.
[4] Harris R A,Simpson R W.In the Shadow of 1857—the effect of the great Ft Tejon earthquake on subsequent earthquakes in Southern California[J].Geophys Res Lett,1996,23(3):229-232.
[5] Harris R A.Introduction to special section:Stress triggers,stress shadows,and implications for seismic hazard[J].J Geophys Res,1998,103(B1010):24 347-24 358.
[6] Stein R S,Barka A,Dieterich J H.Progressive failure on the North Anatolian fault since 1939by earthquake static stress triggering[J].Geophys J Int,1997,128(3):594-604.
[7] Toda S,Stein R S,Reasenberg F,et al.Stress transferred by the 1995 MW=6.9Kobe,Japan,shock:Effect on aftershocks and future earthquake probabilities[J].J Geophys Res,1998,103(B1010):24 543-24 565.
[8] Barka A.The 17august 1999Izmit earthquake[J].Science,1999,285(5 435):1 858-1 859.
[9] Stein R S.The role of stress transfer in earthquake occurrence[J].Nature,1999,402(6762):605-609.
[10] Mccloskey J,Nalbant S S,Steacy S.Indonesian earthquake:Earthquake risk from co-seismic stress[J].Nature,2005,434(7 031):291.
[11]沈正康,万永革,甘卫军,等.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,2003,46(6):786-795.
[12]万永革,沈正康,曾跃华,等.青藏高原东北部的库仑应力积累演化对大地震发生的影响[J].地震学报,2007,29(2):115-129.
[13]万永革,盛书中,李祥,等.2015年尼泊尔强震序列对中国大陆的应力影响[J].地球物理学报,2015,58(11):4 277-4 286.
[14]单斌,熊熊,郑勇,等.2013年芦山地震导致的周边断层应力变化及其与2008年汶川地震的关系[J].中国科学D辑:地球科学,2013,43(6):1 002-1 009.
[15] Parsons T,Chen J,Kirby E.Stress changes from the 2008Wenchuan earthquake and increase hazard in the Sichuan basin[J].Nature,2008,454(7 203):509-510.
[16]单斌,熊熊,郑勇,等.2008年5月12日MW7.9汶川地震导致的周边断层应力变化[J].中国科学D辑:地球科学,2009,39(5):537-545.
[17]万永革,沈正康,盛书中,等.2008年汶川大地震对周围断层的影响[J].地震学报,2009,31(2):128-139.
[18]解朝娣,朱元清,Lei X L,等.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:地球科学,2010,40(6):688-698.
[19]谢祖军,金笔凯,郑勇,等.近远震波形反演2013年芦山地震震源参数[J].中国科学:地球科学,2013,43(6):1 010-1 019.
[20]刘瑞丰,陈运泰,邹立晔,等.2013年4月20日四川芦山MW6.7(MS7.0)地震参数的测定[J].地震学报,2013,35(5):652-660.
[21]张勇,冯万鹏,许力生,等.2008年汶川大地震的时空破裂过程[J].中国科学D辑:地球科学,2008,38(10):1 186-1 194.
[22]许力生,严川,张旭,等.芦山MS7.0地震究竟发生在哪里[J].地球物理学报,2013,56(9):2 982-2 993.
[23]刘成利,郑勇,葛粲,等.2013年芦山7.0级地震的动态破裂过程[J].中国科学:地球科学,2013,43(6):1 020-1 026.
[24]赵翠萍,周连庆,陈章立.2013年四川芦山MS7.0级地震震源破裂过程及其构造意义[J].科学通报,2013,58(20):1 894-1 900.
[25]石耀霖,曹建玲.中国大陆岩石圈等效粘滞系数的计算和讨论[J].地学前缘,2008,15(3):82-95.