鲜水河断裂带南东段的深部孕震环境与2014年康定M_S6.3地震
详细信息 本馆镜像全文    |  推荐本文 | | 获取馆网全文
摘要
2014年11月22日16时55分在四川省甘孜藏族自治州康定县发生的6.3级地震,结束了鲜水河断裂带近30多年以来没有较大地震发生的历史,其潜在的地震危险性再次引起国内外地学工作者的关注.为了研究鲜水河断裂带南东段深部孕震环境和探求康定MS6.3地震的成因,本文先利用四川区域数字地震台网和康定地区及周边所布设的流动地震台阵在2009年1月1日至2014年12月5日期间所记录到7397次区域地震事件的99287条P波到时资料,反演得到了鲜水河断裂带南东段上地壳范围内不同深度的三维P波速度结构特征;再对康定震区及周边的重力、航磁数据进行视密度、视磁化强度反演,得到了壳内不同深度密度的横向变化信息和视磁化强度的分布特征;在此基础上综合研究鲜水河断裂带南东段的深部孕震环境.研究结果表明,雅江—九龙一带的低速区与泸定—宝兴高速区的速度结构特征表明了鲜水河断裂带南东段两侧壳内物质存在显著的横向介质差异,康定MS6.3地震发生在该高低速异常区的分界线上;结合康定MS6.3地震的1028个余震序列的精确定位结果可以看出,重新定位后的余震沿着鲜水河断裂带南东段呈条带状分布,且震源深度优势分布层位深度为8~15km,该余震序列的空间分布特征与鲜水河断裂南东段的深部介质条件密切相关.鲜水河断裂带南东段特有的视密度和视磁化强度异常分布特征反映了康定地区东西两侧块体的基底性质存在明显差异,康定—石棉及其以东地区所表现出的磁异常高和重力高的位场特征,反映该区域由强磁性、高密度物质组成,而康定MS6.3地震就发生在康定—石棉重力梯度变化带上、雅安—泸定磁性穹窿区的西边界线上.随着川青块体向南东方向滑移,受到四川盆地西缘边界刚性基底对川青块体的强烈阻挡,加剧了康定—石棉及其以东地区基底岩层的褶皱变形并产生了强烈的应力积累,所积累的应力突然释放导致了康定MS6.3地震的发生,这正是此次鲜水河断裂带南东段康定地区强震孕育和发生的深部构造环境和介质特征.根据本文对鲜水河断裂带南东段深部孕震环境的综合研究成果可知,石棉段处于重磁异常梯级带上且其北东侧表现出的高密度、强磁性和高波速等物性特征有利于区域应力的相对集中,因此,鲜水河断裂带南东段石棉地区的地震活动趋势和地震危险性背景值得进一步关注和研究.
At 16∶55,November 22,2014,an MS6.3earthquake occurred in Kangding country,Garzê,a Tibetan autonomous prefecture in Sichuan Province.This event ended a 30-year interval without any large earthquake in the Xianshuihe fault zone and motivated scholars in China and elsewhere in the world to assess the seismic risk of this region.To study the deep seismogenic environment of the southeastern section of the Xianshuihe fault zone and the genesis of the Kangding MS6.3earthquake,we conducted a seismic tomography study.Using 99287P-wave travel time data of 7397 regional seismic events,recorded by a digital seismic network and by transportable seismic stations in Sichuan Province,the structure of the upper crustal threedimensional P-wave velocity was ascertained.Through field separation and inversion imaging of the gravity and aeromagnetic data of the Kangding seismic zone,the apparent density and apparent magnetization inversion results were obtained at different depths in the crust.The low velocity zone of the Yajiang-Jiulong area and the velocity structure characteristics of the LudingBaoxing high-speed zone indicate the existence of a transverse medium that is significantly different from the crustal material on either side of the southeastern section of the Xianshuihe fault zone.The Kangding MS6.3earthquake took place at the boundary of the high velocity anomaly zone and the low velocity anomaly zone.Accurate locating for the sequence of 1028 aftershocks of the Kangding MS6.3 earthquake reveals that these aftershocks show a zonal distribution along the southeastern Xianshuihe fault zone with focal depths 8~15km.Such spatial distribution characteristics of the aftershocks are closely related to the deep medium conditions of the southeastern segment of the Xianshuihe fault.The unique anomaly distribution of apparent density and apparent magnetization intensity reflect the existence of obvious differences in basal properties on both sides of the Kangding area.The high magnetic anomalies and high gravity potential field characteristics of the Kangding-Shimian′s eastern area indicate that this region is comprised of strong magnetism and high-density material.The Kangding earthquake occurred in the Kangding-Shimian gravity gradient belt,and its epicenter is located on the magnetic dome′s western boundary of the Ya′an-Luding area.When moving southeastward,the Sichuan-Qinghai block is strongly hampered by the rigid basement of the Sichuan basin on its western margin.Such a process has strengthened folding deformation and the accumulation of stress within the Kangding-Shimian area and its east.The sudden release of accumulated stress led to the occurrence of the Kangding MS6.3 earthquake.These are the deep seismogenic environment of the southeastern Xianshuihe fault zone.The Shimian segment of the southeastern Xianshuihe fault zone is also located in a gravitational and magnetic anomaly zone,with high density,strong magnetism,and high velocity media on its northeastern side.Therefore,this segment also deserves further risk assessment and investigation into its seismicity trend.
引文
Allen C R,Luo Z L,Qian H,et al.1991.Field study of a highlyactive fault zone:The Xianshuihe fault of southwestern China.Geol.Soc.Am.Bull.,103(9):1178-1199.
    Boschetti F,Hornby P,Horowitz F G.2001.Wavelet basedinversion of gravity data.Exploration Geophysics,32(1):48-55.
    Burchfiel B C,Chen Z,Liu Y,et al.1995.Tectonics of theLongmen Shan and adjacent regions,central China.InternationalGeology Review,37(8):661-735.
    Chen Y T,Yang Z X,Zhang Y,et al.2013.A brief talk on the 20April 2013Lushan Mw6.7earthquake.ActaS eismologica Sinica(inChinese),35(3):285-295.
    Clark M K,Royden L H.2000.Topographic ooze:Building theeastern margin of Tibet by lower crustal flow.Geology,28(8):703-706.
    Cooper G.2004.The stable downward continuation of potentialfield data.Exploration Geophysics,35(4):260-265.
    Fedi M,Florio G.2002.A stable downward continuation by usingthe ISVD method.Geophys.J.Int.,151(1):146-156.
    Guan Z N,Yang M,An Y L.1990.An apparent magnetizationmapping method and its application.Geophysical and GeochemicalExploration(in Chinese),14(3):172-181.
    Guo B,Liu Q Y,Chen J H,et al.2009.Teleseismic P-wavetomography of the crust and upper mantle in Longmenshan area,west Sichuan.Chinese J.Geophys.(in Chinese),52(2):346-355.
    Hubbard J,Shaw J H.2009.Uplift of the Longmen Shan andTibetan plateau,and the 2008 Wenchuan(M=7.9)earthquake.Nature,458(7235):194-197.
    Li D H,Ding Z F,Liang M J,et al.2014.Field separation andanomaly feature extraction of mobile gravity data in Sichuanarea.Acta Seismologica Sinica(in Chinese),36(2):261-274
    Liu Q H,van der Hilst R D,Li Y,et al.2014.Eastward expansionof the Tibetan Plateau by crustal flow and strain partitioningacross faults.Nature Geoscience,7(5):361-365.
    Mooney W D,Ginzburg A.1986.Seismic measurements of theinternal properties of fault zone.Pure Appl.Geophys.,124(1-2):141-157.
    Paige C C,Saunders M A.1982.LSQR:An algorithm for sparselinear equations and sparse least squares.Assoc.Comput.Math.Trans.Math.Software,8(1):43-71.
    Parsons T,Ji C,Kirby E.2008.Stress changes from the 2008Wenchuan earthquake and increased hazard in the Sichuan basin.Nature,454(7203):509-510.
    Pilkington M.1989.Variable-depth magnetization mapping:Application to the Athabasca basin,northern Alberta andSaskatchewan,Canada.Geophysics,54(9):1164-1173.
    Qian H,Luo Z L,Wen X Z.1990.Preliminary study ofcharacteristic earthquakes in the Xianshuihe fault zone.ActaSeismologica Sinica(in Chinese),12(1):22-29.
    Royden L H,Burehfiel B C,King R W,et al.1997.Surfacedeformation and lower crustal flow in eastern Tibet.Science,276(5313):788-790.
    Song H B,Liu S G.1991.The relation of gravity and aeromagneticfield and deep structure in middle-northern LongmenshanMountains.Journal of Chengdu College of Geology(in Chinese),18(1):74-82.
    Sun J,Jin G W,Bai D H,et al.2003.The electrical structuredetection and its tectonic significance of the crust and uppermantle of the eastern margin of the Qinghai Tibet Plateau.Science in China(Series D)(in Chinese),33(S):173-181.
    Tang H J,Shi L B,Xu H J,et al.1995.The evidences for a strongpalaeoearthquake along the southeastern segment of the XianshuiheFault Zone.Journal of Seismological Research(in Chinese),18(1):86-89.
    Tao X F.1995.A discussion on the formation-mechanism of theShuangshi nappe structure in Longmen Mountains,Sichuan.Journal of Chengdu University of Technology(in Chinese),22(2):27-30.
    Thurber C H.1983.Earthquake locations and three-dimensionalcrustal structure in the Coyote Lake area,central California.J.Geophys.Res.,88(B10):8226-8236.
    Toda S,Lin J,Meghraoui M,et al.2008.12 May 2008 M=7.9Wenchuan,China,earthquake calculated to increase failurestress and seismicity rate on three major fault systems.Geophys.Res.Lett.,35(17):L17305,doi:10.1029/2008GL034903.
    Um J,Thurber C.1987.A fast algorithm for two-point seismic raytracing.Bull.Seismol.Soc.Am.,77(3):972-986.
    Unswonh M J,Jones A G,Wei W,et al.2005.Crustal rheology ofthe Himalaya and Southern Tibet inferred from magnetotelluricdata.Nature,438(7064):78-81.
    Wan Y G,Shen Z K,Sheng S Z,et al.2009.The influence of 2008Wenchuan earthquake on surrounding faults.Acta SeismologicaSinica(in Chinese),31(2):128-139.
    Wang C Y,Han W B,Wu J P,et al.2003a.Crustal structurebeneath Songpan-Ganze oroge belt.Acta Seismologica Sinica(in Chinese),25(3):229-241.
    Wang C Y,Wu J P,Lou H,et al.2003b.The P-wave crustalstructure of West Sichuan,China.Science in China(Series D)(in Chinese),33(S):181-189.
    Wang C Y,Lou H,LüZ Y,et al.2008.S wave velocity structureof the crust and upper mantle in the eastern Tibetan plateau-deepenvironment of lower crustal flow.Science in China(Series D)(in Chinese),38(1):22-32.
    Wang E,Kirby E,Furlong K P,et al.2012.Two-phase growth ofhigh topography in eastern Tibet during the Cenozoic.NatureGeoscience,5(9):640-645.
    Wang Q S,Teng J W,Zhang Y Q,et al.2009.The crustalstructure and gravity isostasy in the middle western Sichuanarea.Chinese J.Geophys.(in Chinese),52(2):579-583.
    Wen X Z,Allen C R,Luo Z L,et al.1989.Segmentation,geometric features,and the irseismotectonic implications for theholo-cene Xianshuihe Fault zone.Acta Seismologica Sinica(inChinese),11(4):362-372.
    Wen X Z.2000.Character of rupture segmentation of theXianshuihe-Anninghe-Zemuhe Fault zone,Western Sichuan.Seismology and Geology(in Chinese),22(3):239-249.
    Wen X Z,Zhang P Z,Du F,et al.2009.The background ofhistorical and modern seismic activities of the occurrence of the2008 MS8.0Wenchuan,Sichuan,earthquake.Chinese J.Geophys.(in Chinese),52(2):444-454.
    Wu P P,Li Z,Li D H,et al.2014.Numerical simulation of stressevolution on Xianshuihe Fault based on contact element model.Progress in Geophysics(in Chinese),29(5):2084-2091,doi:10.6038/pg20140514.
    Xu L L,Rondenay S,van der Hilst R D.2007.Structure of thecrust beneath the southeastern Tibetan Plateau from teleseismicreceiver functions.Phys.Earth Planet.Int.,165(3-4):176-193.
    Xu S Z,Yu H L,Li H X,et al.2009.The inversion of apparentdensity based on the separation and continuation of potentialfield.Chinese J.Geophys.(in Chinese),52(6):1592-1598,doi:10.3969/j.issn.0001-5733.2009.06.021.
    Xu Z Q,Hou L W,Wang Z X,et al.1992.Orogenic Process of theSongpan-Garze Orogenic Belt of China(in Chinese).Beijing:Geological Publishing House,1-188.
    Yang Z X,Waldhauser F,Chen Y T,et al.2005.Double-differencerelocation of earthquakes in central-western China,1992-1999.Journal of Seismology,9(2):241-264.
    Yi G X,Fan J,Wen X Z.2005.Study on faulting behavior andfault-segments for potential strong earthquake risk along thecentral-southern segment of Xianshuihe fault zone based oncurrent seismicity.Earthquake(in Chinese),25(1):58-66.
    Yi G X,Wen X Z,Xin H,et al.2011.Distributions of seismicityparameters and seismic apparent stresses on the LongmenshanMinshan tectonic zone before the 2008 MS8.0 Wenchuanearthquake.Chinese J.Geophys.(in Chinese),54(6):1490-1500,doi:10.3969/j.issn.0001-5733.2011.06.008.
    Yi G X,Long F,Wen X Z.2015.Seismogenic structure of the M6.3Kangding earthquake sequence on 22 Nov.2014,SouthwesternChina.Chinese J.Geophys.(in Chinese),58(4):1205-1219,doi:10.6038/cjg20150410.
    Zeng Y J,Yang X J,Li Y Q.2001.Petrostratigraphic sequence inDanba—Problem related to study on stratigraphy in an orogenicbelt.Acta Geologica Sichuan(in Chinese),21(1):6-11.
    Zhan Y,Zhao G Z,Unsworth M,et al.2013.Deep structurebeneath the southwestern section of the Longmenshan fault zoneand seismogeneac context of the 4.20Lushan MS7.0earthquake.Chin.Sci.Bull.(in Chinese),58(20):1917-1924.
    Zhang J S,Gao R,Zeng L S,et al.2009.Relationship betweencharacteristics of gravity and magnetic anomalies and theearthquakes in Longmenshan range and adjacent areas.ChineseJ.Geophys.(in Chinese),52(2):572-578.
    Zhang P Z,Wen X Z,Shen Z K,et al.2010a.Oblique,high-angle,listric-reverse faulting and associated development of strain:TheWenchuan earthquake of May 12,2008,Sichuan,China.Ann.Rev.Earth Planet.Sci.,38:353-382.
    Zhang X,Chen X W,Zhao L,et al.1998.Basement magneticinterface and earthquakes in seismic area of Sichuan Basin and itswestern margin.Earthquake Research in China(in Chinese),12(4):421-427.
    Zhang Y Q,Wang Q S,Teng J W.2010.Crustal isostatic state inwestern Sichuan and its dynamical mechanism.Quaternary Sciences(in Chinese),30(4):662-669.
    Zhang Z J,Wang Y H,Chen Y,et al.2009.Crustal structureacross Longmenshan fault belt from passive source seismicprofiling.Geophys.Res.Lett.,36(17):L17310.
    Zhao D P,Hasegawa A,Horiuchi S.1992.Tomographic imaging ofP and S wave velocity structure beneath northeastern Japan.J.Geophys.Res.,97(B13):19909-19928.
    Zhao D P,Hasegawa A,Kanamori H.1994.Deep structure ofJapan subduction zone as derived from local,regional,andteleseismic events.J.Geophys.Res.,99(B11):22313-22329.
    Zhao D P.2001.New advances of seismic tomography and itsapplications to subduction zones and earthquake fault zones:Areview.Island Arc,10(1):68-84.
    Zhao G,Unsworth M J,Zhan Y,et al.2012.Crustal structure andrheology of the Longmenshan and Wenchuan Mw7.9earthquakeepicentral area from magnetotelluric data.Geology,40(12):1139-1142.
    Zhao G Z,Chen X B,Wang L F,et al.2008.The electromagneticdetection evidence of east edge of Qinghai Tibet Plateau crust“channel flow”layer.Chin.Sci.Bull.(in Chinese),53(3):345-350.
    Zhong K,Xu M J,Wang L S,et al.2005.Study on characteristicsof gravity field and crustal deformation in Sichuan-Yunnanregion.Geological Journal of China Universities(in Chinese),11(1):111-117.
    陈运泰,杨智娴,张勇等.2013.浅谈芦山地震.地震学报,35(3):285-295.
    管志宁,阳明,安玉林.1990.视磁化强度填图方法及应用.物探与化探,14(3):172-181.
    郭飚,刘启元,陈九辉等.2009.川西龙门山及邻区地壳上地幔远震P波层析成像.地球物理学报,52(2):346-355.
    李大虎,丁志峰,梁明剑等.2014.四川地区流动重力资料的位场分离与异常特征提取.地震学报,36(2):261-274.
    钱洪,罗灼礼,闻学泽.1990.鲜水河断裂带上特征地震的初步研究.地震学报,12(1):22-29.
    宋鸿彪,刘树根.1991.龙门山中北段重磁场特征与深部构造的关系.成都地质学院学报,18(1):74-82.
    孙洁,晋光文,白登海等.2003.青藏高原东缘地壳、上地幔电性结构探测及其构造意义.中国科学D辑,33(增刊):173-181.
    唐汉军,史兰斌,胥怀济等.1995.鲜水河断裂带东南段一次强烈古地震的发现.地震研究,18(1):86-89.
    陶晓风.1995.龙门山双石推覆构造的形成机制探讨.成都理工学院学报,22(2):27-30.
    万永革,沈正康,盛书中等.2009.2008年汶川大地震对周围断层的影响.地震学报,31(2):128-139.
    王椿镛,韩渭宾,吴建平等.2003a.松潘—甘孜造山带地壳速度结构.地震学报,25(3):229-241.
    王椿镛,吴建平,楼海等.2003b.川西藏东地区的地壳P波速度结
    构.中国科学D辑,33(增刊):181-189.
    王椿镛,楼海,吕智勇等.2008.青藏高原东部地壳上地幔S波速度结构下地壳流的深部环境.中国科学D辑,38(1):22-32.
    王谦身,滕吉文,张永谦等.2009.四川中西部地区地壳结构与重力均衡.地球物理学报,52(2):579-583.
    闻学泽,Allen C R,罗灼礼等.1989.鲜水河全新世断裂带的分段性、几何特征及其地震构造意义.地震学报,11(4):362-372.
    闻学泽.2000.四川西部鲜水河—安宁河—则木河断裂带的地震破裂分段特征.地震地质,22(3):239-249.
    闻学泽,张培震,杜方等.2009.2008年汶川8.0级地震发生的历史与现今地震活动背景.地球物理学报,52(2):444-454.
    吴萍萍,李振,李大虎等.2014.基于ANSYS接触单元模型的鲜水河断裂带库仑应力演化数值模拟.地球物理学进展,29(5):2084-2091,doi:10.6038/pg20140514.
    徐世浙,余海龙,李海侠等.2009.基于位场分离与延拓的视密度反演.地球物理学报,52(6):1592-1598,doi:10.3969/j.issn.0001-5733.2009.06.021.
    许志琴,侯立玮,王宗秀等.1992.中国松潘—甘孜造山带的造山过程.北京:地质出版社,1-188.
    易桂喜,范军,闻学泽.2005.由现今地震活动分析鲜水河断裂带中—南段活动习性与强震危险地段.地震,25(1):58-66.
    易桂喜,闻学泽,辛华等.2011.2008年汶川MS8.0地震前龙门山—岷山构造带的地震活动性参数与地震视应力分布.地球物理学报,54(6):1490-1500,doi:10.3969/j.issn.0001-5733.2011.06.008.
    易桂喜,龙锋,闻学泽等.2015.2014年11月22日康定M6.3级地震序列发震构造分析.地球物理学报,58(4):1205-1219,doi:10.6038/cjg20150410.
    曾宜君,杨学俊,李云泉.2001.丹巴地区岩石地层层序———兼论造山带地层学研究的有关问题.四川地质学报,21(1):6-11.
    詹艳,赵国泽,Unsworth M等.2013.龙门山断裂带西南段4.20芦山7.0级地震区的深部结构和孕震环境.科学通报,58(20):1917-1924.
    张季生,高锐,曾令森等.2009.龙门山及邻区重、磁异常特征及与地震关系的研究.地球物理学报,52(2):572-578.
    张先,陈秀文,赵丽等.1998.四川盆地及其西部边缘震区基底磁性界面与地震的研究.中国地震,12(4):421-427.
    张永谦,王谦身,滕吉文.2010.川西地区的地壳均衡状态及其动力学机制.第四纪研究,30(4):662-669.
    赵国泽,陈小斌,王立风等.2008.青藏高原东边缘地壳“管流”层的电磁探测证据.科学通报,53(3):345-350.
    钟锴,徐鸣洁,王良书等.2005.川滇地区重力场特征与地壳变形研究.高校地质学报,11(1):111-117.

版权所有:© 2023 中国地质图书馆 中国地质调查局地学文献中心