阿拉善左旗M_S5.8地震前后地震活动性分析和重定位
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摘要
2015年4月15日15时39分,内蒙古自治区阿拉善左旗(39.78°N,106.34°E)发生M_S5.8级地震,震源深度为10km.本文通过收集中国地震科学台阵探测——喜马拉雅Ⅱ期布设在南北地震带北段的34个流动台站连续观测数据,首先以中国地震局台网中心目录给出的138个地震事件作为模板,采用匹配定位方法(Match&Locate)对阿拉善左旗M_S5.8地震前后(2015年1月1日至2015年7月31日)小震进行了检测和识别,检测后给出的地震事件高达1688个,相比于台网地震目录的地震事件数目增加了10倍多.然后利用双差层析成像方法(tomoDD)对研究区域内阿拉善M_S5.8地震前后(2015-01-01—2015-07-31)1级以上的地震序列进行重定位,重定位后的结果显示:主震震中为39.8023°N、106.4388°E,震源深度为20.597km,余震序列展布优势方向为NEE方向,且在深度方向呈近垂直分布,结合野外地质调查结果和震源机制解分析,认为该次地震事件为一次走滑型事件,其发震断裂可能是一条近E-W向的隐伏断层.
On April.15,2015,aM_S5.8 earthquake with a depth of～10 km shook the Alxa,Inner Mongolia Autonomous Region.In this paper,138 events from the China Earthquake Networks Center(CENC)standard catalog are used as templates for scanning through sevenmonth continuous waveform data(Jan.1,2015—July.31,2015)recorded at 34 stations by using the Match and Locate(M&L)technology.We totally detect 1688 events by using the CENC catalog templates which are ten times more events than listed in the CENC catalog.We then relocate the detected events by applying the double difference tomography(tomoDD)technique.Our relocation results show that the mainshock is located at 39.8023°N,106.4388°E with a focal depth of 20.597 km.The spatial distribution of aftershocks demonstrates a NEEstrike and the depth distribution shows a near-vertical plane.Combining with geological investigation and focal mechanism anlaysis,we suggest that the mainshock is a strike-slip event and the seismogenic fault is likely to be a nearly E-W striking blind fault.
On April.15,2015,aM_S5.8 earthquake with a depth of～10 km shook the Alxa,Inner Mongolia Autonomous Region.In this paper,138 events from the China Earthquake Networks Center(CENC)standard catalog are used as templates for scanning through sevenmonth continuous waveform data(Jan.1,2015—July.31,2015)recorded at 34 stations by using the Match and Locate(M&L)technology.We totally detect 1688 events by using the CENC catalog templates which are ten times more events than listed in the CENC catalog.We then relocate the detected events by applying the double difference tomography(tomoDD)technique.Our relocation results show that the mainshock is located at 39.8023°N,106.4388°E with a focal depth of 20.597 km.The spatial distribution of aftershocks demonstrates a NEEstrike and the depth distribution shows a near-vertical plane.Combining with geological investigation and focal mechanism anlaysis,we suggest that the mainshock is a strike-slip event and the seismogenic fault is likely to be a nearly E-W striking blind fault.
引文
Ben-Zion Y.2008.Collective behavior of earthquakes and faults:Continuum-discrete transitions,progressive evolutionary changes,and different dynamic regimes.Reviews of Geophysics,46(4):RG4006,doi:10.1029/2008RG000260.
State Seismological Bureau.1988.Active Fault System Around the Margins of Ordos Massif.Beijing:Seismological Press(in Chinese).
Crotwell H P,Owens T J,Ritsema J.1999.The TauP Toolkit:Flexible seismic travel-time and ray-path utilities.Seismological Research Letters,70(2):154-160.
Deng Q D,Cheng S P,Min W,et al.1999.discussion on Cenozoic tectonics and dynamics of Ordos block.Journal of Geomechanics(in Chinese),5(3):13-21.
Deng Q D,Zhang P Z,Ran Y K,et al.2003.Active tectonics and earthquake activities in China.Earth Science Frontiers(in Chinese),10(S1):66-73.
Fang L H,Wu J P,Wang W L,et al.2013.Relocation of the mainshock and aftershock sequences of MS7.0Sichuan Lushan earthquake.Chinese Science Bulletin,58(28-29):3451-3459,doi:10.1007/s11434-013-6000-2.
Gao X W,Wan Y G,Huang J C,et al.2015.Tectonic stress field analysis and static coulomb stress changes of the MS5.8Inner Mongolia′s Alxa left banner earthquake.North China Earthquake Sciences(in Chinese),33(2):48-54.
Han X M,Liu F,Zhang F,et al.2015.Source mechanism of the2015Alxa Zuoqi MS5.8earthquake and its relocation.Acta Seismologica Sinica(in Chinese),37(6):1059-1063,doi:10.11939/jass.2015.06.015.
Hou J X,Wang B.2017.Temporal evolution of seismicity before and after the 2014Ludian MS6.5earthquake.Chinese Journal of Geophysics(in Chinese),60(4):1446-1456,doi:10.6038/cjg20170418.
Huang W Q,Shi Z L,Cao X F.1989.Factors influencing the estimation of b value and the selection of b value in hazard analysis.Acta Seismologica Sinica(in Chinese),11(4):351-361.
Jones L M,Molnar P.1979.Some characteristics of foreshocks and their possible relationship to earthquake prediction and premonitory slip on faults.Journal of Geophysical Research:Solid Earth,84(B7):3596-3608.
Li M L.1979.Seismicity characteristics of in Bayinmuren MS6.2earthquake.Northwestern Seismological Journal(in Chinese),2(3):14-17.
Liang S S,Lei J S,Xu Z G,et al.2017.Relocation of the aftershock sequence and focal mechanism solutions of the 21January 2016 Menyuan,Qinghai.Chinese Journal of Geophysics(in Chinese),60(6):2091-2103,doi:10.6038/cjg20170606.
Omori F.1894.On aftershocks of earthquakes.J.Coll.Sci.Imp Univ.Tokyo,7:111-200.
Peng Z G,Zhao P.2009.Migration of early aftershocks following the 2004Parkfield earthquake.Nature Geoscience,2(12):877-881.
Ren X M.2011.Study on the estimation of b value on seismic zontion[Ph.D.thesis](in Chinese).Beijing:Geophysical Research Institute of China Seismological Bureau.
Song C,Ge Z X.2018.An iterative travel time inversion and waveform modeling method to determine the crust structure and the focal mechanism of 2015Alxa Left Banner MS5.8Earthquake.Chinese Journal of Geophysics(in Chinese),61(4):1225-1237,doi:10.6038/cjg2018L0655.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:Method and application to the northern Hayward fault,California.Bulletin of the Seismological Society of America,90(6):1353-1368.
Wan Y G,Shen Z G,Diao G L,et al.2008.An algorithm of fault parameter determination using distribution of small earthquakes and parameters of regional stress field and its application to Tangshan earthquake sequence.Chinese Journal of Geophysics(in Chinese),51(3):793-804.
Wang P,Wang Z G.1997.Division of the Alxa Block and its attribution.Earthquake(in Chinese),17(1):103-112.
Wang S Y,Gao A J,Xu Z H,et al.2000.Relocation of earthquakes in northeastern region of Qinghai-Xizang Plateau and characteristics of earthquake activity.Acta Seismologica Sinica(in Chinese),22(3):241-248.
Wang W L,Wu J P,Fang L H,et al.2014.Double difference location of the Ludian MS6.5earthquake sequences in Yunnan province in 2014.Chinese Journal of Geophysics(in Chinese),57(9):3042-3051,doi:10.6038/cjg20140929.
Wang X S,Lv J,Xie Z J,et al.2015.Focal mechanisms and tectonic stress field in the North-South Seismic Belt of China.Chinese Journal of Geophysics(in Chinese),58(11):4149-4162,doi:10.6038/cjg20151122.
Yao Z X,Wang C Y,Sandoval E,et al.2014.Lithospheric deformation of the Ordos block from Rayleigh wave phase velocities and azimuthal anisotropy.Chinese Journal of Geophysics(in Chinese),57(9):2777-2789,doi:10.6038/cjg20140905.
Zhang G W,Lei J S.2013.Relocations of Lushan,Sichuan strong earthquake(MS7.0)and its aftershocks.Chinese Journal of Geophysics(in Chinese),56(5):1764-1771,doi:10.6038/cjg20130534.
Zhang H J,Thurber C H.2003.Double-difference tomography:The method and its application to the Hayward Fault,California.Bulletin of the Seismological Society of America,93(5):1875-1889,doi:10.1785/0120020190.
Zhang M,Tian D D,Wen L X.2014.A new method for earthquake depth determination:Stacking multiple-station autocorrelograms.Geophysical Journal International,197(2):1107-1116.
Zhang M.2015.Earthquake localization and detection[Ph.D.thesis](in Chinese).Hefei:China University of Science and Technology.
Zhang M,Wen L X.2015.An effective method for small event detection:Match and locate(M&L).Geophysical Journal International,200(3):1523-1537.
Zhu L P,Helmberger D V.1996.Advancement in source estimation techniques using broadband regional seismograms.Bulletin of the Seismological Society of America,86(5):1634-1641.
邓起东,程绍平,闵伟等.1999.鄂尔多斯块体新生代构造活动和动力学的讨论.地质力学学报,5(3):13-21.
邓起东,张培震,冉勇康等.2003.中国活动构造与地震活动.地学前缘,10(S1):66-73.
房立华,吴建平,王未来等.2013.四川芦山MS7.0级地震及其余震序列重定位.科学通报,58(20):1901-1909.
高熹微,万永革,黄骥超等.2015.内蒙古阿拉善左旗MS5.8地震的构造应力场和静态库伦应力变化分析.华北地震科学,33(2):48-54.
国家地震局.1988.鄂尔多斯周缘活动断裂系.北京:地震出版社.
韩晓明,刘芳,张帆等.2015.2015年阿拉善左旗MS5.8地震的震源机制和重新定位.地震学报,37(6):1059-1063,doi:10.11939/jass.2015.06.015.
侯金欣,王宝善.2017.2014年鲁甸MS6.5地震前后地震活动性.地球物理学报,60(4):1446-1456,doi:10.6038/cjg20170418.
黄玮琼,时振梁,曹学锋.1989.b值统计中的影响因素及危险性分析中b值的选取.地震学报,11(4):351-361.
李孟銮.1979.巴音木仁6.2级地震的活动特征.西北地震学报,2(3):14-17.
梁姗姗,雷建设,徐志国等.2017.2016年1月21日青海门源MS6.4余震序列重定位和主震震源机制解.地球物理学报,60(6):2091-2013,doi:10.6038/cjg20170606.
任雪梅.2011.地震区划中b值统计的若干问题研究[博士论文].北京:中国地震局地球物理研究所.
宋超,盖增喜.2018.利用走时和波形拟合迭代反演阿拉善地壳速度结构及2015年阿拉善左旗5.8级地震震源机制.地球物理学报,61(4):1225-1237,doi:10.6038/cjg2018L0655.
万永革,沈正康,刁桂苓等.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用.地球物理学报,51(3):793-804.
王萍,王增光.1997.阿拉善活动块体的划分及归宿.地震,17(1):103-112.
汪素云,高阿甲,许忠淮等.2000.青藏高原东北地区地震重新定位及活动特征.地震学报,22(3):241-248.
王未来,吴建平,房立华等.2014.2014年云南鲁甸MS6.5地震序列的双差定位.地球物理学报,57(9):3042-3051,doi:10.6038/cjg20140929.
王晓山,吕坚,谢祖军等.2015.南北地震带震源机制解与构造应力场特征.地球物理学报,58(11):4149-4162,doi:10.6038/cjg20151122.
姚志祥,王椿镛,Sandvol E等.2014.利用瑞利面波相速度和方位各向异性研究鄂尔多斯块体的岩石圈变形特征.地球物理学报,57(9):2777-2789,doi:10.6038/cjg20140905.
张广伟,雷建设.2013.四川芦山7.0级强震及其余震序列重定位.地球物理学报,56(5):1764-1771,doi:10.6038/cjg20130534.
张淼.2015.地震定位和检测[博士论文].合肥:中国科学技术大学.
State Seismological Bureau.1988.Active Fault System Around the Margins of Ordos Massif.Beijing:Seismological Press(in Chinese).
Crotwell H P,Owens T J,Ritsema J.1999.The TauP Toolkit:Flexible seismic travel-time and ray-path utilities.Seismological Research Letters,70(2):154-160.
Deng Q D,Cheng S P,Min W,et al.1999.discussion on Cenozoic tectonics and dynamics of Ordos block.Journal of Geomechanics(in Chinese),5(3):13-21.
Deng Q D,Zhang P Z,Ran Y K,et al.2003.Active tectonics and earthquake activities in China.Earth Science Frontiers(in Chinese),10(S1):66-73.
Fang L H,Wu J P,Wang W L,et al.2013.Relocation of the mainshock and aftershock sequences of MS7.0Sichuan Lushan earthquake.Chinese Science Bulletin,58(28-29):3451-3459,doi:10.1007/s11434-013-6000-2.
Gao X W,Wan Y G,Huang J C,et al.2015.Tectonic stress field analysis and static coulomb stress changes of the MS5.8Inner Mongolia′s Alxa left banner earthquake.North China Earthquake Sciences(in Chinese),33(2):48-54.
Han X M,Liu F,Zhang F,et al.2015.Source mechanism of the2015Alxa Zuoqi MS5.8earthquake and its relocation.Acta Seismologica Sinica(in Chinese),37(6):1059-1063,doi:10.11939/jass.2015.06.015.
Hou J X,Wang B.2017.Temporal evolution of seismicity before and after the 2014Ludian MS6.5earthquake.Chinese Journal of Geophysics(in Chinese),60(4):1446-1456,doi:10.6038/cjg20170418.
Huang W Q,Shi Z L,Cao X F.1989.Factors influencing the estimation of b value and the selection of b value in hazard analysis.Acta Seismologica Sinica(in Chinese),11(4):351-361.
Jones L M,Molnar P.1979.Some characteristics of foreshocks and their possible relationship to earthquake prediction and premonitory slip on faults.Journal of Geophysical Research:Solid Earth,84(B7):3596-3608.
Li M L.1979.Seismicity characteristics of in Bayinmuren MS6.2earthquake.Northwestern Seismological Journal(in Chinese),2(3):14-17.
Liang S S,Lei J S,Xu Z G,et al.2017.Relocation of the aftershock sequence and focal mechanism solutions of the 21January 2016 Menyuan,Qinghai.Chinese Journal of Geophysics(in Chinese),60(6):2091-2103,doi:10.6038/cjg20170606.
Omori F.1894.On aftershocks of earthquakes.J.Coll.Sci.Imp Univ.Tokyo,7:111-200.
Peng Z G,Zhao P.2009.Migration of early aftershocks following the 2004Parkfield earthquake.Nature Geoscience,2(12):877-881.
Ren X M.2011.Study on the estimation of b value on seismic zontion[Ph.D.thesis](in Chinese).Beijing:Geophysical Research Institute of China Seismological Bureau.
Song C,Ge Z X.2018.An iterative travel time inversion and waveform modeling method to determine the crust structure and the focal mechanism of 2015Alxa Left Banner MS5.8Earthquake.Chinese Journal of Geophysics(in Chinese),61(4):1225-1237,doi:10.6038/cjg2018L0655.
Waldhauser F,Ellsworth W L.2000.A double-difference earthquake location algorithm:Method and application to the northern Hayward fault,California.Bulletin of the Seismological Society of America,90(6):1353-1368.
Wan Y G,Shen Z G,Diao G L,et al.2008.An algorithm of fault parameter determination using distribution of small earthquakes and parameters of regional stress field and its application to Tangshan earthquake sequence.Chinese Journal of Geophysics(in Chinese),51(3):793-804.
Wang P,Wang Z G.1997.Division of the Alxa Block and its attribution.Earthquake(in Chinese),17(1):103-112.
Wang S Y,Gao A J,Xu Z H,et al.2000.Relocation of earthquakes in northeastern region of Qinghai-Xizang Plateau and characteristics of earthquake activity.Acta Seismologica Sinica(in Chinese),22(3):241-248.
Wang W L,Wu J P,Fang L H,et al.2014.Double difference location of the Ludian MS6.5earthquake sequences in Yunnan province in 2014.Chinese Journal of Geophysics(in Chinese),57(9):3042-3051,doi:10.6038/cjg20140929.
Wang X S,Lv J,Xie Z J,et al.2015.Focal mechanisms and tectonic stress field in the North-South Seismic Belt of China.Chinese Journal of Geophysics(in Chinese),58(11):4149-4162,doi:10.6038/cjg20151122.
Yao Z X,Wang C Y,Sandoval E,et al.2014.Lithospheric deformation of the Ordos block from Rayleigh wave phase velocities and azimuthal anisotropy.Chinese Journal of Geophysics(in Chinese),57(9):2777-2789,doi:10.6038/cjg20140905.
Zhang G W,Lei J S.2013.Relocations of Lushan,Sichuan strong earthquake(MS7.0)and its aftershocks.Chinese Journal of Geophysics(in Chinese),56(5):1764-1771,doi:10.6038/cjg20130534.
Zhang H J,Thurber C H.2003.Double-difference tomography:The method and its application to the Hayward Fault,California.Bulletin of the Seismological Society of America,93(5):1875-1889,doi:10.1785/0120020190.
Zhang M,Tian D D,Wen L X.2014.A new method for earthquake depth determination:Stacking multiple-station autocorrelograms.Geophysical Journal International,197(2):1107-1116.
Zhang M.2015.Earthquake localization and detection[Ph.D.thesis](in Chinese).Hefei:China University of Science and Technology.
Zhang M,Wen L X.2015.An effective method for small event detection:Match and locate(M&L).Geophysical Journal International,200(3):1523-1537.
Zhu L P,Helmberger D V.1996.Advancement in source estimation techniques using broadband regional seismograms.Bulletin of the Seismological Society of America,86(5):1634-1641.
邓起东,程绍平,闵伟等.1999.鄂尔多斯块体新生代构造活动和动力学的讨论.地质力学学报,5(3):13-21.
邓起东,张培震,冉勇康等.2003.中国活动构造与地震活动.地学前缘,10(S1):66-73.
房立华,吴建平,王未来等.2013.四川芦山MS7.0级地震及其余震序列重定位.科学通报,58(20):1901-1909.
高熹微,万永革,黄骥超等.2015.内蒙古阿拉善左旗MS5.8地震的构造应力场和静态库伦应力变化分析.华北地震科学,33(2):48-54.
国家地震局.1988.鄂尔多斯周缘活动断裂系.北京:地震出版社.
韩晓明,刘芳,张帆等.2015.2015年阿拉善左旗MS5.8地震的震源机制和重新定位.地震学报,37(6):1059-1063,doi:10.11939/jass.2015.06.015.
侯金欣,王宝善.2017.2014年鲁甸MS6.5地震前后地震活动性.地球物理学报,60(4):1446-1456,doi:10.6038/cjg20170418.
黄玮琼,时振梁,曹学锋.1989.b值统计中的影响因素及危险性分析中b值的选取.地震学报,11(4):351-361.
李孟銮.1979.巴音木仁6.2级地震的活动特征.西北地震学报,2(3):14-17.
梁姗姗,雷建设,徐志国等.2017.2016年1月21日青海门源MS6.4余震序列重定位和主震震源机制解.地球物理学报,60(6):2091-2013,doi:10.6038/cjg20170606.
任雪梅.2011.地震区划中b值统计的若干问题研究[博士论文].北京:中国地震局地球物理研究所.
宋超,盖增喜.2018.利用走时和波形拟合迭代反演阿拉善地壳速度结构及2015年阿拉善左旗5.8级地震震源机制.地球物理学报,61(4):1225-1237,doi:10.6038/cjg2018L0655.
万永革,沈正康,刁桂苓等.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用.地球物理学报,51(3):793-804.
王萍,王增光.1997.阿拉善活动块体的划分及归宿.地震,17(1):103-112.
汪素云,高阿甲,许忠淮等.2000.青藏高原东北地区地震重新定位及活动特征.地震学报,22(3):241-248.
王未来,吴建平,房立华等.2014.2014年云南鲁甸MS6.5地震序列的双差定位.地球物理学报,57(9):3042-3051,doi:10.6038/cjg20140929.
王晓山,吕坚,谢祖军等.2015.南北地震带震源机制解与构造应力场特征.地球物理学报,58(11):4149-4162,doi:10.6038/cjg20151122.
姚志祥,王椿镛,Sandvol E等.2014.利用瑞利面波相速度和方位各向异性研究鄂尔多斯块体的岩石圈变形特征.地球物理学报,57(9):2777-2789,doi:10.6038/cjg20140905.
张广伟,雷建设.2013.四川芦山7.0级强震及其余震序列重定位.地球物理学报,56(5):1764-1771,doi:10.6038/cjg20130534.
张淼.2015.地震定位和检测[博士论文].合肥:中国科学技术大学.