2005年11月26日九江—瑞昌M_s5.7、M_s4.8地震的震源机制解与发震构造研究
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摘要
利用来源于江西区域台网和中国地震台网共6个台的宽频带数字地震记录,采用CAP方法反演了2005年11月26日九江—瑞昌5.7级地震和4.8级强余震的震源机制解,并结合地震序列的精确定位结果和区域地质背景讨论了发震构造.结果显示,5.7级主震的最佳双力偶解为节面Ⅰ走向223°,倾角75°,滑动角144°;节面Ⅱ走向324°,倾角55°,滑动角18°.4.8级强余震的最佳双力偶解为节面Ⅰ走向54°,倾角71°,滑动角-160°;节面Ⅱ走向317°,倾角71°,滑动角-20°,这两次地震的震源机制解不完全一致.地震序列在震中空间分布和震源深度分布上也具有复杂性.5.7级主震发生后,余震活动从SE向NW、从浅部往深部发展,在破裂过程中可能遇到障碍体,触发了4.8级强余震.5.7级主震的发震构造可能为隐伏在瑞昌盆地内的洋鸡山—武山—通江岭NW向断裂,4.8级强余震的发震构造可能为瑞昌盆地西北缘的丁家山—桂林桥—武宁NE向断裂北段.
Based on the records of 6 stations in Jiangxi regional seismic network and CSN, we obtained the focal mechanisms of the Ms?5.7 Jiujiang-Ruichang earthquake and its Ms?4.8 aftershock of Nov.26, 2005 with the "Cut and Paste"(CAP) method, and analyzed the seismogenic structure combining with relocation of the aftershock sequence and the geologic settings in the region. Our result shows that the best double couple solution of the Ms?5.7 event is 324°,55°and 18° for strike, dip and rake angles respectively, the other nodal plane is 223°,75° and 144°;for the Ms?4.8 aftershock the solution is 54°, 71°, -160° respectively with the other nodal plane of 317°, 71° and -20°. Complexities can be found from aftershock distribution and source depth of the sequence. After the occurrence of the M_s?5.7 main shock, aftershocks occurred and propagated from SE to NW and from shallower to deeper crust, then they probably encountered an asperity and triggered the Ms?4.8 strong aftershock. This complexity and the different focal mechanisms imply that the two earthquakes may not occur on the same fault, we infer that the Ms?5.7 main shock is caused by the NW striking Yangjishan-Wushan-Tongjiangling fault buried in Ruichang basin and the Ms?4.8 aftershock occurred on the NE striking Dingjiashan-Guilinqiao-Wuning fault in the northwest margin of the basin.
Based on the records of 6 stations in Jiangxi regional seismic network and CSN, we obtained the focal mechanisms of the Ms?5.7 Jiujiang-Ruichang earthquake and its Ms?4.8 aftershock of Nov.26, 2005 with the "Cut and Paste"(CAP) method, and analyzed the seismogenic structure combining with relocation of the aftershock sequence and the geologic settings in the region. Our result shows that the best double couple solution of the Ms?5.7 event is 324°,55°and 18° for strike, dip and rake angles respectively, the other nodal plane is 223°,75° and 144°;for the Ms?4.8 aftershock the solution is 54°, 71°, -160° respectively with the other nodal plane of 317°, 71° and -20°. Complexities can be found from aftershock distribution and source depth of the sequence. After the occurrence of the M_s?5.7 main shock, aftershocks occurred and propagated from SE to NW and from shallower to deeper crust, then they probably encountered an asperity and triggered the Ms?4.8 strong aftershock. This complexity and the different focal mechanisms imply that the two earthquakes may not occur on the same fault, we infer that the Ms?5.7 main shock is caused by the NW striking Yangjishan-Wushan-Tongjiangling fault buried in Ruichang basin and the Ms?4.8 aftershock occurred on the NE striking Dingjiashan-Guilinqiao-Wuning fault in the northwest margin of the basin.
引文
1)中国地震局地质研究所、中国地震局工程力学研究所、江西省防震减灾工程研究所.江西核电彭泽厂址可行性研究阶段地震安全性评价报告.2006年10月,166~182
1)地质部江西省地质局区域地质测量队.中华人民共和国地质图(1:200000瑞昌幅),1966
2)地矿部江西地质矿产勘查开发局赣西北大队区调分队.中华人民共和国地质图说明书(1:50000万,瑞昌县幅),1987
3)江西省地质矿产局.中华人民共和国地质图(1:50000瑞昌县幅),1987
[1]卢福水,曾新福,郑栋等.九江—瑞昌5.7级地震发震构造初探.防灾减灾工程学报,2006,26(增刊):75~82Lu F S,Zeng X F,Zheng D,et al.Study on the seismogenic structure of Jiujiang-RuichangM5.7earthquake.Journal of Disaster Prevention and Mitigation Engineering(in Chinese),2006,26(Suppl.):75~82
[2]吕坚,倪四道,沈小七等.九江-瑞昌地震的精确定位及其发震构造初探.中国地震,2007,23(2):166~174LJ,Ni S D,Shen X Q,et al.Discussion on precise relocation and seismo-tectonics of the Jiujiang-Ruichang earthquake.Earthquake Researchin China(in Chinese),2007,23(2):166~174
[3]Patton HJ.Reference point method for determining the source and path effects of surface waves.J.Geophys.Res.,1980,85:821~848
[4]Thio H K,H Kanamori.Moment-tensor inversions for local earthquakes using surface waves recorded at TERRAscope.Bull.Seis.Soc.Amer.,1995,85:1021~1038
[5]Fan G W,Wallace T C.The determination of source parameters for small earthquakes from a single very broadband seismic station.Geophys.Res.Lett.,1991,18:1385~1388
[6]Dreger DS,Helmberger D V.Determination of source parameters at regional distances with three component sparse network data.J.Geophys.Res.,1993,98:8107~8125
[7]Xu LS,Chen YT.Tempo-spatial rupture process of the1997,Mani,Xizang(Tibet),China earthquake ofMS=7.9.Acta Seismologica Sinica(in Chinese),1999,12(5):495~506
[8]许力生,陈运泰.从全球长周期波形资料反演2001年11月14日昆仑山地震时空破裂过程.中国科学(D辑),2004,34(3):256~264Xu L S,Chen Y T.Temporal and spatial rupture process of the November14,2001Kunlun Mountain great earthquake fromthe GDSN long period waveformdata.Sciencein China(Series D)(in Chinese),2004,34(3):256~264
[9]赵翠萍,陈章立,郑斯华等.2003年9月27日中、俄、蒙边界7.9地震震源机制及破裂过程研究.地震学报,2005,27(3):237~249Zhao C P,Chen Z L,Zheng S H,et al.Moment tensorinversion and source rupture process of the September27,2003MS=7.9earthquake occurred in the border area of China,Russia and Mongolia.Acta Seismologica Sinica(in Chinese),2005,27(3):237~249
[10]周云好,陈章立,缪发军.2001年11月14日昆仑山口西MS8.1地震震源破裂过程研究.地震学报,2004,26(增刊):9~20Zhou Y H,Chen Z L,Miao FJ.Source process of the14November2001western KunlunshanMS8.1earthquake.Acta Seismologica Sinica(in Chinese),2004,26(Suppl.):9~20
[11]Zhao L S,Helmberger D V.Source estimation from broadband regional seismograms.Bull Seis Soc Amer,1994,84(1):91~104
[12]Zhu L P,Helmberger D V.Advancement in source estimation techniques using broadband regional seismograms.Bull Seis Soc Amer,1996,86(5):1634~1641
[13]Tan Y,Zhu L P,Helmberger D V,et al.Locating and modeling regional earthquakes with two stations.J.Geophys.Res.,2006,111,B01306,doi:1029/2005JB003775
[14]王椿镛,张先康,丁志峰等.大别造山带上部地壳结构的有限差分层析成像.地球物理学报,1997,40(4):495~502Wang C Y,Zhang X K,Ding Z F,et al.Finite-differencetomographyof upper crustal structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(4):495~502
[15]王椿镛,张先康,陈步云等.大别造山带地壳结构研究.中国科学(D辑),1997,27(3):221~226Wang C Y,Zhang X K,Chen B Y,et al.Crustal structure in Dabieshan orogenic belt.Science in China(Series D)(in Chinese),1997,27(3):221~226
[16]王椿镛,丁志峰,宋建立等.大别造山带地壳S波速度结构.地球物理学报,1997,40(3):337~346Wang C Y,Ding Z F,Song J L,et al.Shear wave velocity structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(3):337~346
[17]吕新彪,姚书振,周宗桂.大冶—九瑞地区局部地质异常特征与成矿.地球科学-中国地质大学学报,1998,23(2):115~119LX B,Yao S Z,Zhou Z G.Character of the local geological anomaly and mineralization in Daye-Jiurui region.Earth Science-Journal ofChina UniversityofGeosciences(in Chinese),1998,23(2):115~119
[18]崔彬.江西九瑞地区铜金成矿系列模式.矿床地质,1995,14(1):44~50Cui B.Model of copper and gold metallogenic series in Jiujiang-Ruichang area.Mineral Deposits(in Chinese),1995,14(1):44~50
1)地质部江西省地质局区域地质测量队.中华人民共和国地质图(1:200000瑞昌幅),1966
2)地矿部江西地质矿产勘查开发局赣西北大队区调分队.中华人民共和国地质图说明书(1:50000万,瑞昌县幅),1987
3)江西省地质矿产局.中华人民共和国地质图(1:50000瑞昌县幅),1987
[1]卢福水,曾新福,郑栋等.九江—瑞昌5.7级地震发震构造初探.防灾减灾工程学报,2006,26(增刊):75~82Lu F S,Zeng X F,Zheng D,et al.Study on the seismogenic structure of Jiujiang-RuichangM5.7earthquake.Journal of Disaster Prevention and Mitigation Engineering(in Chinese),2006,26(Suppl.):75~82
[2]吕坚,倪四道,沈小七等.九江-瑞昌地震的精确定位及其发震构造初探.中国地震,2007,23(2):166~174LJ,Ni S D,Shen X Q,et al.Discussion on precise relocation and seismo-tectonics of the Jiujiang-Ruichang earthquake.Earthquake Researchin China(in Chinese),2007,23(2):166~174
[3]Patton HJ.Reference point method for determining the source and path effects of surface waves.J.Geophys.Res.,1980,85:821~848
[4]Thio H K,H Kanamori.Moment-tensor inversions for local earthquakes using surface waves recorded at TERRAscope.Bull.Seis.Soc.Amer.,1995,85:1021~1038
[5]Fan G W,Wallace T C.The determination of source parameters for small earthquakes from a single very broadband seismic station.Geophys.Res.Lett.,1991,18:1385~1388
[6]Dreger DS,Helmberger D V.Determination of source parameters at regional distances with three component sparse network data.J.Geophys.Res.,1993,98:8107~8125
[7]Xu LS,Chen YT.Tempo-spatial rupture process of the1997,Mani,Xizang(Tibet),China earthquake ofMS=7.9.Acta Seismologica Sinica(in Chinese),1999,12(5):495~506
[8]许力生,陈运泰.从全球长周期波形资料反演2001年11月14日昆仑山地震时空破裂过程.中国科学(D辑),2004,34(3):256~264Xu L S,Chen Y T.Temporal and spatial rupture process of the November14,2001Kunlun Mountain great earthquake fromthe GDSN long period waveformdata.Sciencein China(Series D)(in Chinese),2004,34(3):256~264
[9]赵翠萍,陈章立,郑斯华等.2003年9月27日中、俄、蒙边界7.9地震震源机制及破裂过程研究.地震学报,2005,27(3):237~249Zhao C P,Chen Z L,Zheng S H,et al.Moment tensorinversion and source rupture process of the September27,2003MS=7.9earthquake occurred in the border area of China,Russia and Mongolia.Acta Seismologica Sinica(in Chinese),2005,27(3):237~249
[10]周云好,陈章立,缪发军.2001年11月14日昆仑山口西MS8.1地震震源破裂过程研究.地震学报,2004,26(增刊):9~20Zhou Y H,Chen Z L,Miao FJ.Source process of the14November2001western KunlunshanMS8.1earthquake.Acta Seismologica Sinica(in Chinese),2004,26(Suppl.):9~20
[11]Zhao L S,Helmberger D V.Source estimation from broadband regional seismograms.Bull Seis Soc Amer,1994,84(1):91~104
[12]Zhu L P,Helmberger D V.Advancement in source estimation techniques using broadband regional seismograms.Bull Seis Soc Amer,1996,86(5):1634~1641
[13]Tan Y,Zhu L P,Helmberger D V,et al.Locating and modeling regional earthquakes with two stations.J.Geophys.Res.,2006,111,B01306,doi:1029/2005JB003775
[14]王椿镛,张先康,丁志峰等.大别造山带上部地壳结构的有限差分层析成像.地球物理学报,1997,40(4):495~502Wang C Y,Zhang X K,Ding Z F,et al.Finite-differencetomographyof upper crustal structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(4):495~502
[15]王椿镛,张先康,陈步云等.大别造山带地壳结构研究.中国科学(D辑),1997,27(3):221~226Wang C Y,Zhang X K,Chen B Y,et al.Crustal structure in Dabieshan orogenic belt.Science in China(Series D)(in Chinese),1997,27(3):221~226
[16]王椿镛,丁志峰,宋建立等.大别造山带地壳S波速度结构.地球物理学报,1997,40(3):337~346Wang C Y,Ding Z F,Song J L,et al.Shear wave velocity structure in Dabieshan orogenic belt.Chinese J.Geophys.(in Chinese),1997,40(3):337~346
[17]吕新彪,姚书振,周宗桂.大冶—九瑞地区局部地质异常特征与成矿.地球科学-中国地质大学学报,1998,23(2):115~119LX B,Yao S Z,Zhou Z G.Character of the local geological anomaly and mineralization in Daye-Jiurui region.Earth Science-Journal ofChina UniversityofGeosciences(in Chinese),1998,23(2):115~119
[18]崔彬.江西九瑞地区铜金成矿系列模式.矿床地质,1995,14(1):44~50Cui B.Model of copper and gold metallogenic series in Jiujiang-Ruichang area.Mineral Deposits(in Chinese),1995,14(1):44~50
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