江苏及周缘地区地震精定位与构造意义分析
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摘要
采用双差定位方法,对江苏地震台网记录到的江苏及邻区地震事件(1990—2009年)重新定位,共获取1020个定位结果,震中平均误差为:南北向0.42 km,东西向0.43 km,垂直向0.53 km。精定位后约94%的地震事件震源深度分布在5—20 km范围内,平均震源深度为12.3 km。震源深度自东向西,从海域向陆域呈现逐渐加深的变化特征。根据构造背景和断裂带分布的不同,分区讨论不同构造部位震源深度分布的特征与差异:沿郯庐断裂带(A)、中东部大陆边缘地区(B)以及苏南茅东断裂带地区(C),震源深度分布具有明显差异,其中C区的α、β、D值最高,分别为0.47、0.66、21 km。此外,精定位结果显示,发生在常熟一张家港地区的小震群,其震源深度自浅至深连续分布,深度区间为5—30 km。
Using double difference location method,we relocated the earthquakes of M_L≥1.0 recorded by the Jiangsu regional seismic network during period of 1990 to 2009,and obtained 1020 accurately located results.The average error of relocation is 0.42 km in the NS direction, 0.43 km in the EW direction and 0.53 km in the vertically direction.About 94% earthquakes distributed among the depth of 5—20 km range.The focal depth of the overall variation characteristics from the sea area to the land have gradually deepened.According to the different tectonic setting and fault distribution,we divided Jiangsu area into(A)along the Tancheng-Lujiang fault zone,(B)continental margin in the middle east region and(C)along the Mao-Dong fault zone.The three parts of the focal depth distribution and tectonic characteristics are studied in detail.The results show that the maximum of α、β、D were at the C region, about 0.47、0.66、21 km,respectively.Additionally,the relocation results displayed that the earthquake swarm occurred in Changshu-Zhangjiagang region as a whole with clear line-shape characteristics of vertical down continuously extended,about 30 km from 5 km extended.
Using double difference location method,we relocated the earthquakes of M_L≥1.0 recorded by the Jiangsu regional seismic network during period of 1990 to 2009,and obtained 1020 accurately located results.The average error of relocation is 0.42 km in the NS direction, 0.43 km in the EW direction and 0.53 km in the vertically direction.About 94% earthquakes distributed among the depth of 5—20 km range.The focal depth of the overall variation characteristics from the sea area to the land have gradually deepened.According to the different tectonic setting and fault distribution,we divided Jiangsu area into(A)along the Tancheng-Lujiang fault zone,(B)continental margin in the middle east region and(C)along the Mao-Dong fault zone.The three parts of the focal depth distribution and tectonic characteristics are studied in detail.The results show that the maximum of α、β、D were at the C region, about 0.47、0.66、21 km,respectively.Additionally,the relocation results displayed that the earthquake swarm occurred in Changshu-Zhangjiagang region as a whole with clear line-shape characteristics of vertical down continuously extended,about 30 km from 5 km extended.
引文
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刘昌锉,刘光夏,杜官恒.郯庐古裂谷中段地壳结构的初步研究--二维动力学射线追踪方法的解释结果[J].华北地震学,1987,5(2) :1-12．
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滕吉文,孙克忠,熊绍柏,等.中国东部马鞍山-常熟-启东地带地壳与上地幔结构和速度分布的爆炸地震研究[J].地球物理学报,1985,8(2) :156-169．
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杨智娴,陈运泰,郑月军,等.双差地震定位法在我国中西部地区地震精确定位中的应用[J].中国科学D辑,2003,33(增刊):129-134．
郑晔,滕吉文.随县-马鞍山地带地壳与上地幔结构及郯庐构造带南段的某些特征[J].地球物理学报,1989,32(6) :648-659．
张国民,张培震.近年来大陆强震机理与预测研究的主要进展[J].1999,2-4:47-58．
张国民,汪素云,李丽,等.中国大陆地震震源深度及其构造含义[J].科学通报,2002,47:663-668．
朱艾斓,徐锡伟,周永胜,等.川西地区小震重新定位及其活动构造意义[J].地球物理学报,2005,48(3) :629-636．
张国民,马宏生,王辉,等.中国大陆活动地块边界带与强震活动[J].地球物理学报,2005,48(3) :602-610．
赵旭,李强,刘瑞丰,等.三峡库区地震精定位中确定速度模型的方法[J].地震地磁观测与研究,2009,30(3) :27-35．
Got J L,Freche T J,Klein F W.Deep fault plane geometry inferred from multiplet relative relocation beneath the south flank of Ki-lauca[J].J Geophys Res,1994,99:15 375-15 386．
Prejean S G,Ellsworth W L,Zoback M D,et al.Fault structure and kinematics of the Long Valley Caldera region,Calfomia,revealedby high accuracy earthquake hypocenters and focal meehanismstress inversions[J].JGR,2002,107(4) :2 355-2 373．
Waldhauser F,Ellsworth W L.A double-difference earthquake location algorithm;method and application to the Northern Hayward Fault,CaIifornia[J].Bull Seismol Soc Amer,2000,90(6) :1 353-1 368．
Waldhauser F.Near-real-time double-difference event location using long-term seismic archives,with application to northernCalifornia[J].Bull Seismol Soc Amer,2009,99(5) :3 735-3 748．
Weng S J,Chen H S,Zhou X Q,et al.Deep seismic probing of continental crust in the Lower Yangtze region,eastern China[J].Tectonophysics,1990,173:297-305．
黄汲清,任纪舜,姜春发,等.中国大地构造及演化[M].北京:科学出版社,1980．
胡连英,徐学思,孙寿成,等.溧阳地震与茅东断裂带[M].北京:地震出版社,1997:144-150．
黄耘,李清河,孙业君,等.江苏及邻区地壳上地幔结构研究[J].西北地震学报,2006,28(4) :369-376．
黄媛,吴建平,张天中,等.汶川8． 0级大地震及其余震序列重定位研究[J].中国科学D辑,2008,38:1 242-1 249．
刘昌铨,祝治平,李捍东,等.连云港临沂-泗水测深剖面及临沂8． 5级地震深部构造背景[J].地震,1983,3:172-183．
刘昌锉,刘光夏,杜官恒.郯庐古裂谷中段地壳结构的初步研究--二维动力学射线追踪方法的解释结果[J].华北地震学,1987,5(2) :1-12．
李家灵,晁洪太,崔昭文,等.郯庐活断层的分段及其大震危险性分析[J].地震地质,1994,16(2) :121-126．
马宗晋,薛峰.中国大陆地震深度分布与“易震层”除探[J].地震科学研究,1983,3(3) :43-46．
梅卫萍,李清河,丁页岭,等.用双子地震相干函数法对常熟震群进行精确相对定位[J].西北地震学报,2007,29(2) :123-128．
滕吉文,孙克忠,熊绍柏,等.中国东部马鞍山-常熟-启东地带地壳与上地幔结构和速度分布的爆炸地震研究[J].地球物理学报,1985,8(2) :156-169．
徐纪人,赵志新.苏鲁造山带区域地壳山根结构特征[J].岩石学报,2004,20(1) :149-156．
杨文采,方慧,程振炎,等.苏鲁超高压变质带北部地球物理调查(2) --非地震方法[J].地球物理学报,1999,42(4) :508-519．
杨智娴,陈运泰,郑月军,等.双差地震定位法在我国中西部地区地震精确定位中的应用[J].中国科学D辑,2003,33(增刊):129-134．
郑晔,滕吉文.随县-马鞍山地带地壳与上地幔结构及郯庐构造带南段的某些特征[J].地球物理学报,1989,32(6) :648-659．
张国民,张培震.近年来大陆强震机理与预测研究的主要进展[J].1999,2-4:47-58．
张国民,汪素云,李丽,等.中国大陆地震震源深度及其构造含义[J].科学通报,2002,47:663-668．
朱艾斓,徐锡伟,周永胜,等.川西地区小震重新定位及其活动构造意义[J].地球物理学报,2005,48(3) :629-636．
张国民,马宏生,王辉,等.中国大陆活动地块边界带与强震活动[J].地球物理学报,2005,48(3) :602-610．
赵旭,李强,刘瑞丰,等.三峡库区地震精定位中确定速度模型的方法[J].地震地磁观测与研究,2009,30(3) :27-35．
Got J L,Freche T J,Klein F W.Deep fault plane geometry inferred from multiplet relative relocation beneath the south flank of Ki-lauca[J].J Geophys Res,1994,99:15 375-15 386．
Prejean S G,Ellsworth W L,Zoback M D,et al.Fault structure and kinematics of the Long Valley Caldera region,Calfomia,revealedby high accuracy earthquake hypocenters and focal meehanismstress inversions[J].JGR,2002,107(4) :2 355-2 373．
Waldhauser F,Ellsworth W L.A double-difference earthquake location algorithm;method and application to the Northern Hayward Fault,CaIifornia[J].Bull Seismol Soc Amer,2000,90(6) :1 353-1 368．
Waldhauser F.Near-real-time double-difference event location using long-term seismic archives,with application to northernCalifornia[J].Bull Seismol Soc Amer,2009,99(5) :3 735-3 748．
Weng S J,Chen H S,Zhou X Q,et al.Deep seismic probing of continental crust in the Lower Yangtze region,eastern China[J].Tectonophysics,1990,173:297-305．
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