伽师强震群震源破裂特征的初步分析
|
摘要
为深入研究 1 997年新疆伽师地区连续发生的强震群的震源破裂特征 ,利用全球数字地震台网 (GDSN)宽频带数字资料及区域台网资料 ,较详细地研究了伽师强震群的震源机制及震源破裂特征 .结果表明 :伽师强震群的震源机制解主要有走滑和正倾两种破裂类型 ,其共同特点是主压应力轴方向沿北北东向 ,主张应力轴沿北西向 ,与区域构造应力场方向存在差异 ,具有明显局部特征 ;从震源破裂特征来看 ,伽师强震的滑动尺度、上升时间和持续时间均较小 ,震源破裂面积不大 ,是由一点向四周快速扩散的脆性破裂 ,无明显伸展方向 ;伽师强震群的破裂断层面为北东向 ,与震源深度梯度变化带、地壳接触变形梯度变化带、等烈度线以及地震扩展方向吻合 ;伽师强震群是在近南北向挤压环境下 ,在震源区附近剪切和张扭应力作用下发生的多次沿北东向的脆性快速破裂 ,从而造成了伽师强震群以张性破裂和左旋走滑为主的震源特征
A strong earthquake swarm, including 7 events with M s≥6.0, occurred in Jiashi, Xinjiang in 1997. It is exceptional for the intraplate seismicity. Using GDSN broadband P wave records and the adaptive hybrid global search algorithm, we have investigated the rupture process of the strong swarm. The results show that Jiashi strong swarm shows mainly strike slip and normal focal mechanisms. The common features of the earthquakes in the swarm are that the source stress field is characterized by a pressure stress in NNE, and a tension stress in NW. The directions of principal stresses are different from directions of the regional modern pressure stress field, showing out the local characteristics. The focus repture characteristics show that slip scales, risetimes and the rupture times of finite fault are smaller, similar with focal rupture area. The rupture growth trajectories are from one point to all sides without obvious extended direction. The rupture surface is to NNE, similar to gradient belt of focal depth, gradient belt of crustal deformation, isoseisms and extended direction of earthquakes. Jiashi strong earthquake swarm occurred several times with brittle failure to NNE under tension shear stress which is formed under nonhomogeneous deformation in the upper crust. The characteristics of focus mechanisms are formed with sinistral strike slip and normal rupture.
A strong earthquake swarm, including 7 events with M s≥6.0, occurred in Jiashi, Xinjiang in 1997. It is exceptional for the intraplate seismicity. Using GDSN broadband P wave records and the adaptive hybrid global search algorithm, we have investigated the rupture process of the strong swarm. The results show that Jiashi strong swarm shows mainly strike slip and normal focal mechanisms. The common features of the earthquakes in the swarm are that the source stress field is characterized by a pressure stress in NNE, and a tension stress in NW. The directions of principal stresses are different from directions of the regional modern pressure stress field, showing out the local characteristics. The focus repture characteristics show that slip scales, risetimes and the rupture times of finite fault are smaller, similar with focal rupture area. The rupture growth trajectories are from one point to all sides without obvious extended direction. The rupture surface is to NNE, similar to gradient belt of focal depth, gradient belt of crustal deformation, isoseisms and extended direction of earthquakes. Jiashi strong earthquake swarm occurred several times with brittle failure to NNE under tension shear stress which is formed under nonhomogeneous deformation in the upper crust. The characteristics of focus mechanisms are formed with sinistral strike slip and normal rupture.
引文
1)刘启元.新疆伽师强震群区三维地壳上地幔速度结构及其地震成因的探讨.中国地震局地质研究所课题研究报告.2000.论著号:2000J0026.[1] 王 琪,丁国瑜,乔学军等.用GPS研究南天山(伽师)地区现今地壳变形.地震学报,2000,22(2):263—270.WANGQi,DINGGuoYu,QIAOXueJun,etal.ResearchonpresentcrustaldeformationinthesouthernTianshan(Jiashi),Chinabygeodesy.ActaSeismologicaSinica(inChinese),2000,22(3):263—270.
[2] 乔学军,王 琪,王晓强等.新疆伽师地区现今构造运动和地形变GPS监测的初步研究.地壳形变与地震,2000,20(3):49—57.QIAOXueJun,WANGQi,WANGXiaoQiang,etal.ResearchonpresenttectonicmovementandcrustaldeformationmonitorinJiashi,Xinjiangbygeodesy.CrustalDeformationandEarthquake(inChinese),2000,20(3):49—57.
[3] 朱令人,苏乃秦,杨马陵.1997年新疆伽师强震群及三次成功的临震预报.中国地震,1998,14(2):101—115.ZHULingRen,SUNaiQing,YANGMaLing.Activetyofthe1997JiashistrongswarminXinjiangandthreesuccessfulimpendingpredictionforit.EarthquakeResearchinChina(inChinese),1998,14(2):101—115.
[4] 刘启元,陈九辉,李顺成等.新疆伽师强震群三维地壳上地幔S波速度结构及其地震成因的探讨.地球物理学报,2000,43(3):356—365.LIUQiYuan,CHENJiuHui,LIShunCheng,etal.PassiveseismicexperimentinXinjianJiashistrongearthquakeregionanddiscussonitsseismicgenesis.ChineseJ.Geophys.,2000,43(3):356—365.
[5] 罗福忠,张云峰,吕桂林等.1997年4月6日、11日、16日新疆伽师4次6.3—6.6级地震烈度分布及震害特征.内陆地震,1997,11(4):399—404.LUOFuZhong,ZHANGYunFeng,LUGuiLin,etal.Intensitydistributionanddisastercharacteristicsof4earthquakeinthemagnituderangeof6.3to6.6inJiashi,XinjiangonApril6,11and16,1997.InlandEarthquake(inChinese),1997,11(4):399—404.
[6] 赵瑞斌,胡伟华,王 坚.1997年伽师地震震害与损失评估.内陆地震,1997,11(4):405—410.ZHAORuiBin,HUWeiHua,WANGJian.Hazardandassessmentofthe1997Jiashiearthquake.InlandEarthquake(inChinese),1997,11(4):405—410.
[7] 杨 欣,高国英.1997年伽师强震群序列特征和震源机制的初步研究.地震学报,1998,20(6):573—579.YANGXin,GAOGuoYing.ApreliminaryresearchonthecharacteristicsandthesourcemechanismoftheJiashistrongearthquakeswarm.ActaSeismologicaSinica(inChinese),1998,20(6):573—579.
[8] 李鸿吉,秦建业.缅甸弧及其周围地区的震源机制和现代应力场.地震学报,1994,16(4):463—471.LIHongJi,QINJianYe.EarthquakemechanismandmodernstressfieldinBurmaarcanditsadjacentarea.ActaSeismologicaSinica(inChinese),1994,16(4):463—471.
[9] 姚振兴,郑天愉,曹柏如等.用P波波形资料测定中强地震震源过程的方法.地球物理学进展,1991,6(4):1—26.YAOZhenXing,ZHENGTianYu,CAOBoRu,etal.Themethodofdeterminingmiddleandstrongearthquake’sprocessusingPwaveformdata.ProgressinGeophysics(inChinese),1991,6(4):1—26.
[10] 姚振兴.计算综合地震图的广义反射、透射系数矩阵和离散波数方法(三)———广义接收函数矩阵和半解析的波数积分方法.见:陈等主编,寸丹集.北京:科学出版社,1998.647—654.YAOZhenXing.Ageneralizedreflection transmissioncoefficientmatrixanddiscretewavenumbermethodforsyntheticseismograms(Ⅲ) generalizedreflection transmissioncoefficientmatrixandsemi analyticalwavenumberrepresentation.In:CHENYongetal,ed.CundanJi(inChinese).Beijing:SciencePress,1998.647—654.
[11] Zheng,TY ,Ai,YS ,andChen,QZ .The16September1994TaiwanStraitEarthquake:asimpleruptureeventstartingasabreakofaasperity.Phys.EarthPlanetInter.,1998,107:269—284.
[12] Hartzell,S,Liu,PC ,andMendoza,C .The1994Northridge,California,earthquake:investigationofrupturevelocity,risetime,andhigh frequencyradiation,J.Geophys.Res.,1996,101(B9):20091—20108.
[13] 艾印双,刘鹏程,郑天愉.自适应全局混合反演.中国科学(D辑),1998,28(2):105—110.AIYinShuang,LIUPenCheng,ZHENGTianYu.Adaptivehybridglobalsearchinversionalgorithm.ScienceinChina(D)(inChinese),1998,28(2):105—110.
[14] 许力生,陈运泰.1997年中国西藏玛尼Ms=7.9地震的时空破裂过程.地震学报,1999,21(5):1—8.XULiSheng,CHENYunTai.Tempo spatialruptureprocessofthe1997Mani,Tibet,ChinaearthquakeofMs7.9.ActaSeismologicaSinica(inChinese),1999,21(5):1—8.
[15] 高国英,戈澍谟,韩月鹏等.1996年3月19日新疆阿图什6.9级地震震源破裂特征的研究.地震,1997,17(2):290—295.GAOGuoYing,GEShuMuo,HANYuePeng,etal.ResearchonrupturecharacteristicsofMarch19,1996XinjiangAtushi6.9earthquake.Earthquake,1997,17(3):290—295.
[16] 何玉梅,郑天愉,单新建.1996年3月19日新疆阿图什6.9级地震:单侧破裂过程.地球物理学报,2001,44(4):510—519.HEYuMei,ZHENGTianYu,SHANXinJian.The1996Atush,Xinjiang,earthquake:aunilateral—ruptureevent.ChineseJ.Geophys,2001,44(4):510—519.
[17] 周仕勇.1997年伽师强震群研究及其生成机理的探素[博士论文].北京:中国地震局地球物理研究所,1999.ZHOUShiYong.ResearchonsourceparametersandseismogenesisoftheJiashistrongswarmin1997(inChinese)[Ph.D .Thesis].Beijing:GeophysicalInstitute,ChinaSeismologicalBureau1999.
[2] 乔学军,王 琪,王晓强等.新疆伽师地区现今构造运动和地形变GPS监测的初步研究.地壳形变与地震,2000,20(3):49—57.QIAOXueJun,WANGQi,WANGXiaoQiang,etal.ResearchonpresenttectonicmovementandcrustaldeformationmonitorinJiashi,Xinjiangbygeodesy.CrustalDeformationandEarthquake(inChinese),2000,20(3):49—57.
[3] 朱令人,苏乃秦,杨马陵.1997年新疆伽师强震群及三次成功的临震预报.中国地震,1998,14(2):101—115.ZHULingRen,SUNaiQing,YANGMaLing.Activetyofthe1997JiashistrongswarminXinjiangandthreesuccessfulimpendingpredictionforit.EarthquakeResearchinChina(inChinese),1998,14(2):101—115.
[4] 刘启元,陈九辉,李顺成等.新疆伽师强震群三维地壳上地幔S波速度结构及其地震成因的探讨.地球物理学报,2000,43(3):356—365.LIUQiYuan,CHENJiuHui,LIShunCheng,etal.PassiveseismicexperimentinXinjianJiashistrongearthquakeregionanddiscussonitsseismicgenesis.ChineseJ.Geophys.,2000,43(3):356—365.
[5] 罗福忠,张云峰,吕桂林等.1997年4月6日、11日、16日新疆伽师4次6.3—6.6级地震烈度分布及震害特征.内陆地震,1997,11(4):399—404.LUOFuZhong,ZHANGYunFeng,LUGuiLin,etal.Intensitydistributionanddisastercharacteristicsof4earthquakeinthemagnituderangeof6.3to6.6inJiashi,XinjiangonApril6,11and16,1997.InlandEarthquake(inChinese),1997,11(4):399—404.
[6] 赵瑞斌,胡伟华,王 坚.1997年伽师地震震害与损失评估.内陆地震,1997,11(4):405—410.ZHAORuiBin,HUWeiHua,WANGJian.Hazardandassessmentofthe1997Jiashiearthquake.InlandEarthquake(inChinese),1997,11(4):405—410.
[7] 杨 欣,高国英.1997年伽师强震群序列特征和震源机制的初步研究.地震学报,1998,20(6):573—579.YANGXin,GAOGuoYing.ApreliminaryresearchonthecharacteristicsandthesourcemechanismoftheJiashistrongearthquakeswarm.ActaSeismologicaSinica(inChinese),1998,20(6):573—579.
[8] 李鸿吉,秦建业.缅甸弧及其周围地区的震源机制和现代应力场.地震学报,1994,16(4):463—471.LIHongJi,QINJianYe.EarthquakemechanismandmodernstressfieldinBurmaarcanditsadjacentarea.ActaSeismologicaSinica(inChinese),1994,16(4):463—471.
[9] 姚振兴,郑天愉,曹柏如等.用P波波形资料测定中强地震震源过程的方法.地球物理学进展,1991,6(4):1—26.YAOZhenXing,ZHENGTianYu,CAOBoRu,etal.Themethodofdeterminingmiddleandstrongearthquake’sprocessusingPwaveformdata.ProgressinGeophysics(inChinese),1991,6(4):1—26.
[10] 姚振兴.计算综合地震图的广义反射、透射系数矩阵和离散波数方法(三)———广义接收函数矩阵和半解析的波数积分方法.见:陈等主编,寸丹集.北京:科学出版社,1998.647—654.YAOZhenXing.Ageneralizedreflection transmissioncoefficientmatrixanddiscretewavenumbermethodforsyntheticseismograms(Ⅲ) generalizedreflection transmissioncoefficientmatrixandsemi analyticalwavenumberrepresentation.In:CHENYongetal,ed.CundanJi(inChinese).Beijing:SciencePress,1998.647—654.
[11] Zheng,TY ,Ai,YS ,andChen,QZ .The16September1994TaiwanStraitEarthquake:asimpleruptureeventstartingasabreakofaasperity.Phys.EarthPlanetInter.,1998,107:269—284.
[12] Hartzell,S,Liu,PC ,andMendoza,C .The1994Northridge,California,earthquake:investigationofrupturevelocity,risetime,andhigh frequencyradiation,J.Geophys.Res.,1996,101(B9):20091—20108.
[13] 艾印双,刘鹏程,郑天愉.自适应全局混合反演.中国科学(D辑),1998,28(2):105—110.AIYinShuang,LIUPenCheng,ZHENGTianYu.Adaptivehybridglobalsearchinversionalgorithm.ScienceinChina(D)(inChinese),1998,28(2):105—110.
[14] 许力生,陈运泰.1997年中国西藏玛尼Ms=7.9地震的时空破裂过程.地震学报,1999,21(5):1—8.XULiSheng,CHENYunTai.Tempo spatialruptureprocessofthe1997Mani,Tibet,ChinaearthquakeofMs7.9.ActaSeismologicaSinica(inChinese),1999,21(5):1—8.
[15] 高国英,戈澍谟,韩月鹏等.1996年3月19日新疆阿图什6.9级地震震源破裂特征的研究.地震,1997,17(2):290—295.GAOGuoYing,GEShuMuo,HANYuePeng,etal.ResearchonrupturecharacteristicsofMarch19,1996XinjiangAtushi6.9earthquake.Earthquake,1997,17(3):290—295.
[16] 何玉梅,郑天愉,单新建.1996年3月19日新疆阿图什6.9级地震:单侧破裂过程.地球物理学报,2001,44(4):510—519.HEYuMei,ZHENGTianYu,SHANXinJian.The1996Atush,Xinjiang,earthquake:aunilateral—ruptureevent.ChineseJ.Geophys,2001,44(4):510—519.
[17] 周仕勇.1997年伽师强震群研究及其生成机理的探素[博士论文].北京:中国地震局地球物理研究所,1999.ZHOUShiYong.ResearchonsourceparametersandseismogenesisoftheJiashistrongswarmin1997(inChinese)[Ph.D .Thesis].Beijing:GeophysicalInstitute,ChinaSeismologicalBureau1999.
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