基于地震学资料探讨2013年岷县漳县6.6级地震发震构造
详细信息 本馆镜像全文    |  推荐本文 | | 获取馆网全文
摘要
应用速度和Q值成像方法以及小震精定位方法获得了2013年岷县漳县6.6级地震震源区的深部结构和余震序列的空间分布图像。结果表明:发震断层为一隐伏断裂,走向NW,倾向SW,逆冲兼左旋走滑,在地表距临潭-宕昌断裂岷县段约20km,在深部可能与临潭-宕昌断裂交汇在一起,向南组成一条NW向的断裂带。2003年11月13日岷县MS5.2、2004年9月7日岷县-卓尼MS5.0和本次MS6.6地震的发震断层可能属同一发震断层,位于漳县南部块体的西南边缘;该块体为次级块体(三角形),近几年来块体西南边界强震活跃,其它两边平静。
Velocity and Qvalue tomography,in addition to precise positioning methods of small earthquakes,were used to obtain the deep structure of seismic source area and spatial distribution images of aftershocks.The data of velocity and Qvalue imaging consist of two parts.The first includes the observation data from a high-density portable seismic array consisting of 150 stations with a reporting period of November 2009 to November 2011 in the area of 32.2-36°N,102.8-107.1°E.The second includes data from a fixed network during the period of 1970-2010.From these datasets,we selected 6 334seismic events recorded by at least 8stations and conducted velocity and Qvalue inversion calculation.We applied the three-dimensional grid search method to aftershock relocation,in which 746 seismic events met with S-P arrival time differences detected by at least three stations.Finally,we obtained the relocation results of 400 seismic events,and we applied the same method to relocation of the Minxian MS5.2earthquake occurring on November 13,2003,and the Minxian-Zhuoni MS5.0 earthquake occurring on September 7,2004.We set the P1profile perpendicular to the direction to research in the deep distribution of the seismogenic fault.The profile P1crosscut the Lintan-Tanchang fault and the Minxian-Zhangxian seismic source area.We obtained the velocity profile,Qvalue profile,and aftershock distribution,which were combined with the focal mechanism solutions of these three earthquakes and the distribution of smaller earthquakes recorded since instrumental record have been kept.The results show that the seismogenic fault of Minxian-Zhangxian MS6.6 earthquake is a buried fault with a NW strike direction,SW dip direction,and a dip angle steeper in the shallow region.In addition,the fault is thrust and sinistral strike-slip,and its exposure at the surface is 20km from Minxian section of the Lintan-Tanchang fault.The seismogenic fault and the Minxian section of the Lintan-Tanchang fault may have met at a deep level to form a fault zone to the south with a NW dip direction.The seismogenic faults of the Minxian MS5.2,Minxian-Zhuoni MS5.0,and Minxian-Zhangxian MS6.6 earthquakes may belong to the same fault.The seismogenic fault of the Minxian-Zhangxian MS6.6 earthquake is located in the suture parts of two secondary blocks.The east block is relatively stable,and the west block moves eastward and is blocked by the east block to form the extrusion area.The Qvalue of the extrusion area is lower and shows velocity uplift.In the Earth's crust of the west block,the Qvalue is lower,which provides eastward movement of west block with more favorable conditions.The occurrence region for earthquakes of MS≥5has included three events since 2003 with seismogenic faults at least 20km from the Lintan-Tanchang fault;the dip direction is contrary.The seismogenic fault is located in the southwestern edge of Zhangxian's southern block,which is a secondary block(triangle)with a stable internal region.Three strong earthquakes occurred in western boundary of this block,which is conducive to the strain energy accumulation of the eastern region and the northern edge,which is the north rim fracture of western Qinling.The eastern region and northern boundary will likely be main regions of seismic activity of the southeast area of Gansu for the next several years.
引文
[1]高见,张元生,郭飚,等.甘东南流动台阵微震监测结果[J].地震工程学报,2013,35(1):177-182.Gao J,Zhang Y S,Guo B.et al.Microearthquake Location Determined by Portable Seismic Array Data in southeast Gansu Province[J].China Earthquake Engineering Journal,2013,35(1):177-182.(in Chinese)
    [2]张元生,李清河,徐果明.联合利用走时与波形反演技术研究地壳三维速度结构(I)——理论与方法[J].西北地震学报,l998,20(2):8-15.Zhang Y S,Li Q H,Xu G M.Combined Inversion Technique to Study 3 Crustal Velocity Structure by Using Seismic Wave Travel Time and Wave Form(I)——Theorv and Method[J].Northwestern Seismological Journal,1998,20(2):8-15.(in Chinese)
    [3]张元生,李清河,刘耀炜,等.地震层析成像软件[J].西北地震学报,2003,25(2):170-174.Zhang Y S,Li Q H,Liu Y W,et a1.The Seismic Tomography Software[J].Northwestern Seismological Journal,2003,25(2):170-174.(in Chinese)
    [4]张元生,周民都,荣代潞,等.祁连山中东段地区三维速度结构研究[J].地震学报,2003,26(2):247-255.Zhang Y S,Zhou M D,Rong D L,et al.3DVelocity Structure in the Central Eastern Part of Qilinshan[J].Acta Seismologica Sinica,2003,26(2):247-255.(in Chinese)
    [5]李清河,张元生,So Gu Kim.朝鲜半岛南部三维地壳速度结构成像[J].地球物理学报,2007,50(4):1073-1081.Li Q H,Zhang Y S,So Gu Kim.3-D Crustal Velocity Tomography in the Southern Korean Peninsula[J].Chinese J.Geophys.,2007,50(4):1073-1081.(in Chinese)
    [6]惠少兴,张元生,李顺成.t-D地震定位方法研究[J].西北地震学报,2012,34(1):10-13.Hui S X,Zhang Y S,Li S C.Study on the t-D Earthquake Location Method[J].Northwestern Seismological Journal,2011,33(2):111-116.(in Chinese)
    [7]惠少兴.三维Q值层析成像[D].兰州:中国地震局兰州地震研究所,2012.Hui S X.Three-dimensional Q Tomography[D].Lanzhou:Lanzhou Institute of Seismology,CEA,2012.(in Chinese)
    [8]高见.甘东南地区三维Q值研究[D]〗.兰州:中国地震局兰州地震研究所,2013.Gao J.Study on Three-dimensional Q Value in the Southeast of Gansu Province[D].Lanzhou:Lanzhou Institute of Seismology,CEA,2013.(in Chinese)
    [9]郑文俊,刘小凤,赵广堃,等.2003年11月13日甘肃岷县MS5 .2地震基本特征[J].西北地震学报,2006,27(1):61-65.Zheng W J,Liu X F,Zhao G K,et al.Principal Features of Minxian MS5 .2Earthquake in Gansu Province,on Nov.13,2003[J].Northwestern Seismological Journal,2005,27(1):61 -65.(in Chinese)
    [10]何文贵,周志宇,马尔曼,等.岷县—卓尼5.0级地震的基本特征和地质背景研究[J].西北地震学报,2006,29(4):50-55 .He W G,Zhou Z Y,Ma E M,et al.Basic Features and Geological Background of the Minxian-Zhuoni M5.0Earthquake on Sep.7,2004[J].Northwestern Seismological Journal,2006,29(4):50-55.(in Chinese)
    [11]张辉,王熠熙,冯建刚.甘东南地区地壳介质各向异性特征[J].西北地震学报,2011,33(2):111-116.Zhang H,Wang Y X,Feng J G.Seismic Anisotropy in the Crust in Southeastern Area of Gansu Province[J].Northwestern Seismological Journal,2011,33(2):111-116.(in Chinese)

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