2014年7月29日梓潼M_S4.9地震发震构造研究
|
摘要
2014年7月29日四川省绵阳市梓潼县发生M_S4.9地震,是梓潼县有地震记录以来发生的最大地震。梓潼M_S4.9地震没有形成地表破裂带,给研究发震构造带来了一定的困难。通过对余震序列的精确分析,显示余震序列呈NW-SE向展布,绝大部分余震分布在主震的北西侧。美国哈佛大学给出的震源机制解:节面Ⅰ走向322°,倾角83°,滑动角177°;节面Ⅱ走向52°,倾角87°,滑动角7°。根据余震序列和主震震源机制解,初步推断节面Ⅰ为梓潼M_S4.9地震的发震构造破裂面,由节面Ⅰ可知,此次地震的断错性质为右旋走滑逆断层。由于在实地考察中,没有发现显著的断层行迹或地表破裂带,所以认为该断裂带为一条隐伏性断裂带。通过布置土壤氡气测量剖面,对推断断裂带进行验证,测量结果与推断断裂带十分吻合,所以本文认为梓潼M_S4.9地震的发震构造为NW-SE向的一条隐伏性断裂带。
A MS4. 9 earthquake occurred in Zitong county,Mianyang city,Sichuan Province on July 29,2014,which is the largest earthquake in Zitong county since records began. Since the earthquake did not produce surface rupture zone,it is very difficult to study the seismogenic structure. Through the accurate analysis of aftershock sequence,it distributes in the NW-SE direction and the vast majority of aftershocks distributes in the north west of the main shock. The focal mechanism solution given by Harvard University includes 322°,83°,177°respectively for the strike,dip,and rake angles on the nodal planeⅠ and 52°,87°,7 °on the nodal planeⅡ. According to aftershock sequence and the focal mechanism of the main shock,it is preliminary deduced that the nodal plane Ⅰ is the seismogenic tectonic fracture surface of Zitong MS4. 9 earthquake. By the nodal plane Ⅰ,it is showed that the nature of earthquake dislocation is right-lateral strike-slip thrust faults. We did not find the significant fault trace or surface rupture zone in the field study,so we think the fault zone is a buried fault zone. Through the arrangement of the soil radon measurement section to verify that fault zone,and the results of the measurement are in good agreement with the results of the inference of fault zone. Therefore,this paper holds that the seismogenic structure of the Zitong MS4. 9 earthquake is an NW-SE striking buried fault zone.
A MS4. 9 earthquake occurred in Zitong county,Mianyang city,Sichuan Province on July 29,2014,which is the largest earthquake in Zitong county since records began. Since the earthquake did not produce surface rupture zone,it is very difficult to study the seismogenic structure. Through the accurate analysis of aftershock sequence,it distributes in the NW-SE direction and the vast majority of aftershocks distributes in the north west of the main shock. The focal mechanism solution given by Harvard University includes 322°,83°,177°respectively for the strike,dip,and rake angles on the nodal planeⅠ and 52°,87°,7 °on the nodal planeⅡ. According to aftershock sequence and the focal mechanism of the main shock,it is preliminary deduced that the nodal plane Ⅰ is the seismogenic tectonic fracture surface of Zitong MS4. 9 earthquake. By the nodal plane Ⅰ,it is showed that the nature of earthquake dislocation is right-lateral strike-slip thrust faults. We did not find the significant fault trace or surface rupture zone in the field study,so we think the fault zone is a buried fault zone. Through the arrangement of the soil radon measurement section to verify that fault zone,and the results of the measurement are in good agreement with the results of the inference of fault zone. Therefore,this paper holds that the seismogenic structure of the Zitong MS4. 9 earthquake is an NW-SE striking buried fault zone.
引文
[1]宫悦,易桂喜,龙峰.梓潼地区地震活动异常调查[J].四川地震,2013,148(3):1-4.GONG Yue,YI Guixi,LONG Feng.Investigation on the seismicity in Zitong region[J].Earthquake Research in Sichuan,2013,148(3):1-4.(in Chinese)
[2]吕坚,郑勇,倪四道,等.2005年11月26日九江-瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究[J].地球物理学报,2008,51(1):158-164.LV Jian,ZHENG Yong,NI Sidao,et al.Focal mechanisms and seismogenic structures of the MS5.7 and MS4.8 Jiujiang-Ruichang earthquakes of Nov.26,2005[J].Chinese J.Geophys),2008,51(1):158-164.(in Chinese)
[3]李志海,郑勇,谢祖军,等.2012年6月30日新疆新源-和静MS6.6地震发震构造初步研究[J].地球物理学报,2014,57(2):449-458.LI Zhihai,ZHENG Yong,XIE Zujun,et al.A preliminary study of seismogenic structure for the Xinyuan-Hejing,Xinjiang MS6.6 earthquake of June 30,2012[J].Chinese J.Geophys,2014,57(2):449-458.(in Chinese)
[4]刘泽民,黄显良,倪红玉,等.2014年4月20日霍山MS4.3地震发震构造研究[J].地震学报,2015,37(3):402-410.LIU Zemin,HUANG Xianliang,NI Hongyu,et al.Seismogenic structure of the 20 April 2014 Huoshan MS4.3 earthquake in Auhui region[J].Acta Seismologica Sinica,2015,37(3):402-410.(in Chinese)
[5]赵小艳,韩立波,龙锋.2011年盈江MS>4.0地震序列震源机制解与发震构造研究[J].地震研究,2012,35(4):477-484.ZHAO Xiaoyan,HAN Libo,LONG Feng.Focal mechanism solutions and seismogenic structures of Yingjiang MS>4.0 earthquake sequences in2011[J].Journal of Seismological Research,2012,35(4):477-484.(in Chinese)
[6]薛良清,张光亚.中国中西部前陆盆地油气地质与勘探[M].北京:地质出版社,2005.XUE Liangqing,ZHANG Guangya.Petroleum geology and exploration of foreland basins in central and western China[M].Beijing:Geological Publishing House,2005.(in Chinese)
[7]李明欣.遥感技术在龙门山北段盆山耦合带的应用[D].绵阳:西南科技大学,2013.LI Mingxin.Application of remote sensing technology in basin-mountain coupling in the northern part of Longmen mountain[D].Mianyang:Southwest University of Science and Technology,2013.(in Chinese)
[8]杜龙,周本刚,王明明.2003年内蒙古巴林左旗MS5.9地震发震构造[J].中国地震,2009,25(2):123-131.DU Long,ZHOU Bengang,WANG Mingming.Seismogenic structure of 2003 Balinzuoqi MS5.9 earthquake in inner Mongolia,China[J].Earthquake Research in China,2009,25(2):123-131.(in Chinese)
[9]罗艳,赵里,曾祥方,等.芦山地震序列震源机制及其构造应力场空间变化[J].中国科学:地球科学,2015,45(4):538-550.LUO Yan,ZHAO Li,ZENG Xiangfang,et al.Focal mechanisms of the Lushan earthquake sequence and spatial variation of the stress field[J].Science China Earth Sciences,2015,45(2):538-550.(in Chinese)
[10]罗钧,赵翠萍,周连庆.2013年8月香格里拉德钦一得荣MS5.9地震序列震源机制与应力场特征[J].地球物理学报,2015,58(2):424-435.LUO Jun,GHAO Cuiping,ZHOU Lianqing.Focal mechanisms and stress field of the Shangri-La Deqen,Yunnan province-Derong,Sichuan province MS5.9 earthquake sequence in August,2013[J].Chinese J.Geophys,2015,58(2):424-435.(in Chinese)
[11]庞河清,王多义,蔡左花,等.川西什邡地区隐伏断层活动性及其对流体的控制作用[J].物探与化探,2010,34(1):14-18.PANG Heqing,WANG Duoyi,CAI Zuolun,et al.The activities of the concealed faults and their control over the fluids in Shifang area,western Sichuan[J].Geophysical and Geochemical Exploration,2010,34(1):14-18.(in Chinese)
[12]刘丰标,夏媛媛,沈阳,等.氡气测量法和地震勘探法在城市活断层调查中的应用[J].科技传播,2012,2(1):128-130.LIU Fengbiao,XIA Yuanyuan,SHEN Yang,et al.The application of radon measurement method and seismic exploration method in the investigation of active fault in city[J].Public Communication of Science and Technology,2012,2(1):128-130.(in Chinese)
[13]石玉春,倪琦生,吴俊奇,等.用放射性方法研究隐伏断裂构造[J].地球物理学报,1996,39(1):134-140.SHI Yuchun,NI Qisheng,WU Junqi,et al.Radioactivity methods applied to detect hidden fault structures[J].Chinese J.Geophys,1996,39(1):134-140.(in Chinese)
[14]曾敏,董好刚,张宏鑫,等.土壤氡气测量在沙湾断裂带中段隐伏断裂探测中的应用研究[J].地震研究,2012,35(3):347-352.ZENG Min,DONG Haogang,ZHANG Hongxin,et al.Application research of soil radon measurement in concealed fault detection of middle segment of Shawan fault zone[J].Journal of Seismological Research,2012,35(3):347-352.(in Chinese)
[15]陈召文,马玉孝,阚泽忠,等.氡测量在成都平原隐伏断裂研究中的初步应用[J].甘肃地质,2007,16(4):88-92.CHEN Zhaowen,MA Yuxiao,KAN Zezhong,et al.The preliminary application of gas radon measuring in the research of the Chengdu plain buried faults[J].Gansu Geology,2007,16(4):88-92.(in Chinese)
[16]刘江平,周斌,李庆红.氡(Rn)射气测量在胜利油田隐伏断裂研究中的应用[J].华北地震科学,2004,22(1):42-45.LIU Jiangping,ZHOU Bin,LI Qinghong.The application of gas radon measuring in the research of buried faults in Shengli oil field[J].North China Earthquake Sciences,2004,22(1):42-45.(in Chinese)
[17]文龙,梁斌,王全伟,等.成都平原隐伏断层氡气特征及断层活动性判别[J].四川地质学报,2013,33(3):257-261.WEN Long,LIANG Bin,WANG Quanwei,et al.Radon survey and fault activity in buried faults on the Chengdu plain[J].Acta Geologica Sichuan,2013,33(3):257-261.(in Chinese)
[18]王志成.土氡测量在海口市活动断层探测中的初步应用[J].华南地震,2006,26(4):61-66.WANG Zhicheng.Preliminary application of soil radon measurement method in active fault survey in Haikou city[J].South China Journal of Seismology,2006,26(4):61-66.(in Chinese)
[19]李洪艺,张澄博,陈国能,等.土氡测量在广从断裂探测中的初步应用[J].华南地震,2011,31(2):61-70.LI Hongyi,ZHANG Chengbo,CHEN Guoneng,et al.Preliminary application of soil radon measurement in Guangzhou-Conghuafracture detection[J].South China Journal of Seismology,2011,31(2):61-70.(in Chinese)
[2]吕坚,郑勇,倪四道,等.2005年11月26日九江-瑞昌MS5.7、MS4.8地震的震源机制解与发震构造研究[J].地球物理学报,2008,51(1):158-164.LV Jian,ZHENG Yong,NI Sidao,et al.Focal mechanisms and seismogenic structures of the MS5.7 and MS4.8 Jiujiang-Ruichang earthquakes of Nov.26,2005[J].Chinese J.Geophys),2008,51(1):158-164.(in Chinese)
[3]李志海,郑勇,谢祖军,等.2012年6月30日新疆新源-和静MS6.6地震发震构造初步研究[J].地球物理学报,2014,57(2):449-458.LI Zhihai,ZHENG Yong,XIE Zujun,et al.A preliminary study of seismogenic structure for the Xinyuan-Hejing,Xinjiang MS6.6 earthquake of June 30,2012[J].Chinese J.Geophys,2014,57(2):449-458.(in Chinese)
[4]刘泽民,黄显良,倪红玉,等.2014年4月20日霍山MS4.3地震发震构造研究[J].地震学报,2015,37(3):402-410.LIU Zemin,HUANG Xianliang,NI Hongyu,et al.Seismogenic structure of the 20 April 2014 Huoshan MS4.3 earthquake in Auhui region[J].Acta Seismologica Sinica,2015,37(3):402-410.(in Chinese)
[5]赵小艳,韩立波,龙锋.2011年盈江MS>4.0地震序列震源机制解与发震构造研究[J].地震研究,2012,35(4):477-484.ZHAO Xiaoyan,HAN Libo,LONG Feng.Focal mechanism solutions and seismogenic structures of Yingjiang MS>4.0 earthquake sequences in2011[J].Journal of Seismological Research,2012,35(4):477-484.(in Chinese)
[6]薛良清,张光亚.中国中西部前陆盆地油气地质与勘探[M].北京:地质出版社,2005.XUE Liangqing,ZHANG Guangya.Petroleum geology and exploration of foreland basins in central and western China[M].Beijing:Geological Publishing House,2005.(in Chinese)
[7]李明欣.遥感技术在龙门山北段盆山耦合带的应用[D].绵阳:西南科技大学,2013.LI Mingxin.Application of remote sensing technology in basin-mountain coupling in the northern part of Longmen mountain[D].Mianyang:Southwest University of Science and Technology,2013.(in Chinese)
[8]杜龙,周本刚,王明明.2003年内蒙古巴林左旗MS5.9地震发震构造[J].中国地震,2009,25(2):123-131.DU Long,ZHOU Bengang,WANG Mingming.Seismogenic structure of 2003 Balinzuoqi MS5.9 earthquake in inner Mongolia,China[J].Earthquake Research in China,2009,25(2):123-131.(in Chinese)
[9]罗艳,赵里,曾祥方,等.芦山地震序列震源机制及其构造应力场空间变化[J].中国科学:地球科学,2015,45(4):538-550.LUO Yan,ZHAO Li,ZENG Xiangfang,et al.Focal mechanisms of the Lushan earthquake sequence and spatial variation of the stress field[J].Science China Earth Sciences,2015,45(2):538-550.(in Chinese)
[10]罗钧,赵翠萍,周连庆.2013年8月香格里拉德钦一得荣MS5.9地震序列震源机制与应力场特征[J].地球物理学报,2015,58(2):424-435.LUO Jun,GHAO Cuiping,ZHOU Lianqing.Focal mechanisms and stress field of the Shangri-La Deqen,Yunnan province-Derong,Sichuan province MS5.9 earthquake sequence in August,2013[J].Chinese J.Geophys,2015,58(2):424-435.(in Chinese)
[11]庞河清,王多义,蔡左花,等.川西什邡地区隐伏断层活动性及其对流体的控制作用[J].物探与化探,2010,34(1):14-18.PANG Heqing,WANG Duoyi,CAI Zuolun,et al.The activities of the concealed faults and their control over the fluids in Shifang area,western Sichuan[J].Geophysical and Geochemical Exploration,2010,34(1):14-18.(in Chinese)
[12]刘丰标,夏媛媛,沈阳,等.氡气测量法和地震勘探法在城市活断层调查中的应用[J].科技传播,2012,2(1):128-130.LIU Fengbiao,XIA Yuanyuan,SHEN Yang,et al.The application of radon measurement method and seismic exploration method in the investigation of active fault in city[J].Public Communication of Science and Technology,2012,2(1):128-130.(in Chinese)
[13]石玉春,倪琦生,吴俊奇,等.用放射性方法研究隐伏断裂构造[J].地球物理学报,1996,39(1):134-140.SHI Yuchun,NI Qisheng,WU Junqi,et al.Radioactivity methods applied to detect hidden fault structures[J].Chinese J.Geophys,1996,39(1):134-140.(in Chinese)
[14]曾敏,董好刚,张宏鑫,等.土壤氡气测量在沙湾断裂带中段隐伏断裂探测中的应用研究[J].地震研究,2012,35(3):347-352.ZENG Min,DONG Haogang,ZHANG Hongxin,et al.Application research of soil radon measurement in concealed fault detection of middle segment of Shawan fault zone[J].Journal of Seismological Research,2012,35(3):347-352.(in Chinese)
[15]陈召文,马玉孝,阚泽忠,等.氡测量在成都平原隐伏断裂研究中的初步应用[J].甘肃地质,2007,16(4):88-92.CHEN Zhaowen,MA Yuxiao,KAN Zezhong,et al.The preliminary application of gas radon measuring in the research of the Chengdu plain buried faults[J].Gansu Geology,2007,16(4):88-92.(in Chinese)
[16]刘江平,周斌,李庆红.氡(Rn)射气测量在胜利油田隐伏断裂研究中的应用[J].华北地震科学,2004,22(1):42-45.LIU Jiangping,ZHOU Bin,LI Qinghong.The application of gas radon measuring in the research of buried faults in Shengli oil field[J].North China Earthquake Sciences,2004,22(1):42-45.(in Chinese)
[17]文龙,梁斌,王全伟,等.成都平原隐伏断层氡气特征及断层活动性判别[J].四川地质学报,2013,33(3):257-261.WEN Long,LIANG Bin,WANG Quanwei,et al.Radon survey and fault activity in buried faults on the Chengdu plain[J].Acta Geologica Sichuan,2013,33(3):257-261.(in Chinese)
[18]王志成.土氡测量在海口市活动断层探测中的初步应用[J].华南地震,2006,26(4):61-66.WANG Zhicheng.Preliminary application of soil radon measurement method in active fault survey in Haikou city[J].South China Journal of Seismology,2006,26(4):61-66.(in Chinese)
[19]李洪艺,张澄博,陈国能,等.土氡测量在广从断裂探测中的初步应用[J].华南地震,2011,31(2):61-70.LI Hongyi,ZHANG Chengbo,CHEN Guoneng,et al.Preliminary application of soil radon measurement in Guangzhou-Conghuafracture detection[J].South China Journal of Seismology,2011,31(2):61-70.(in Chinese)