大凉山次级块体周边断层的闭锁特征
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摘要
利用1999—2007期和2009—2013期中国大陆GPS速度场数据,采用DEFNODE负位错反演程序估算了大凉山次级块体周边断层——大凉山断裂、马边-盐津断裂、会泽-彝良断裂在汶川地震前后的断层闭锁程度和滑动亏损空间分布动态变化特征,并结合地震空区和b值空间分布等结果分析了这几条断裂带的强震危险性。结果表明,汶川地震对这3条断裂带的影响可能较弱,它们在地震前后闭锁程度基本一致,两期结果均显示大凉山断裂南段、马边-盐津断裂、会泽-彝良断裂(西南端除外)基本为完全闭锁;汶川地震前后3条断裂带的滑动亏损速率均较小,大凉山断裂以左旋滑动亏损为主,马边-盐津断裂具有很弱的左旋和挤压滑动亏损分量并在震后均稍有增强,会泽-彝良断裂以挤压滑动亏损为主、兼有右旋滑动亏损,汶川地震后其右旋分量消失。结合其他方法的研究结果,认为目前这3条断裂带仍具有较大地震发生的危险性。
GPS campaign observations can monitor dynamic characteristic of crustal deformation near the fault zone effectively. Dynamic characteristic of crustal deformation is the manifestation of the dynamic action of the faults in deep and shallow structures. The locking and movement state of faults in deep and shallow structures can be an objective characterization of strain accumulation in seismogenic fault.So we can use dynamic GPS observations to invert fault locking and fault slip deficit rate by some models,and then judge the mid-to long-term seismic potential of the faults. Research about the faults around the Daliangshan sub-block is relatively poor,and the moderate-strong earthquakes increased significantly around the sub-block over the past decade,which makes fault locking and seismic potential around the sub-block be the problem to be urgently studied. Therefore,by using the GPS horizontal velocity field of 1999- 2007,2009- 2013 and the negative dislocation model of DEFNODE,we inverted for spatial fault locking and fault slip deficit rate in the Daliangshan subblock which contains three major fault zones,named Daliangshan,Mabian-Yanjin and Huize-Yiliang,before and after the Wenchuan earthquake. We analyzed the seismic potential characteristic of the three faults combining with the seismic gap and the spatial distribution of b value. The results show that the locking state of the three faults was basically same before and after the Wenchuan earthquake,which indicates that the earthquake probably has a very weak influence on the faults. The inversion results of two periods show that the southern segment of Daliangshan,Mabian-Yanjin and HuizeYiliang Faults are basically completely locked except the southwestern segment of Huize-Yiliang Fault. The slip deficit rates of the three faults are not huge before and after the earthquake.Daliangshan Fault is mainly of a sinistral strike-slip deficit,Mabian-Yanjin Fault has a little amount of sinistral strike-slip and compressional deficit which was slightly enhanced after the earthquake,and Huize-Yiliang Fault is characteristic of compressional deficit with a small amount of dextral strike-slip deficit,which reduced to about zero after the earthquake. Combining with some other results,we conclude that current seismic potential for strong or major earthquakes exists on the three faults.
GPS campaign observations can monitor dynamic characteristic of crustal deformation near the fault zone effectively. Dynamic characteristic of crustal deformation is the manifestation of the dynamic action of the faults in deep and shallow structures. The locking and movement state of faults in deep and shallow structures can be an objective characterization of strain accumulation in seismogenic fault.So we can use dynamic GPS observations to invert fault locking and fault slip deficit rate by some models,and then judge the mid-to long-term seismic potential of the faults. Research about the faults around the Daliangshan sub-block is relatively poor,and the moderate-strong earthquakes increased significantly around the sub-block over the past decade,which makes fault locking and seismic potential around the sub-block be the problem to be urgently studied. Therefore,by using the GPS horizontal velocity field of 1999- 2007,2009- 2013 and the negative dislocation model of DEFNODE,we inverted for spatial fault locking and fault slip deficit rate in the Daliangshan subblock which contains three major fault zones,named Daliangshan,Mabian-Yanjin and Huize-Yiliang,before and after the Wenchuan earthquake. We analyzed the seismic potential characteristic of the three faults combining with the seismic gap and the spatial distribution of b value. The results show that the locking state of the three faults was basically same before and after the Wenchuan earthquake,which indicates that the earthquake probably has a very weak influence on the faults. The inversion results of two periods show that the southern segment of Daliangshan,Mabian-Yanjin and HuizeYiliang Faults are basically completely locked except the southwestern segment of Huize-Yiliang Fault. The slip deficit rates of the three faults are not huge before and after the earthquake.Daliangshan Fault is mainly of a sinistral strike-slip deficit,Mabian-Yanjin Fault has a little amount of sinistral strike-slip and compressional deficit which was slightly enhanced after the earthquake,and Huize-Yiliang Fault is characteristic of compressional deficit with a small amount of dextral strike-slip deficit,which reduced to about zero after the earthquake. Combining with some other results,we conclude that current seismic potential for strong or major earthquakes exists on the three faults.
引文
川崎一郎.2013.何谓慢地震[M].陈会忠等译.北京:地震出版社.Ichiro Kawasaki.2013.What are Slow Earthquakes?[M].Translated into Chinese by CHEN Hui-zhong et al.Seismological Press,Beijing(in Chinese).
何宏林,池田安隆.2007.安宁河断裂带晚第四纪活动特征及模式的讨论[J].地震学报,29(5):537—548.HE Hong-lin,Yasutakyr Ikeda.2007.Faulting on the Anninghe fault zone,southwest China in late Quaternary and itsmovement model[J].Acta Seismologica Sinica,20(5):571—583.
何宏林,池田安隆,何玉林,等.2008.新生的大凉山断裂带:鲜水河-小江断裂系中段的截弯取直[J].中国科学(D辑),38(5):564—574.HE Hong-lin,Yasutakyr Ikeda,HE Yu-lin,et al.2008.Newly-generated Daliangshan Fault zone-Shortcutting on thecentral segment of Xianshuihe-Xiaojiang fault system[J].Science in China(Ser D),51(9):1248—1258.
M7专项工作组.2012.中国大陆大地震中-长期危险性研究[M].北京:地震出版社.Working Group on Research of Mid-to Long-term Potential of M≥7 Earthquakes on Chinese Continent,CEA.2012.Study on the Mid-to Long-term Potential of Large Earthquakes on the Chinese Continent[M].SeismologicalPress,Beijing(in Chinese).
任金卫.1994.则木河断裂晚第四纪位移及滑动速率[J].地震地质,16(2):146—155.REN Jin-wei.1994.Late Quaternary displacement and slip rate of Zemuhe Fault in Sichuan,China[J].Seismologyand Geology,16(2):146—155(in Chinese).
闻学泽,杜方,易桂喜,等.2013.川滇交界东段昭通、莲峰断裂带的地震危险背景[J].地球物理学报,56(10):3361—3372.doi:10.6038/cjg20131012.WEN Xue-ze,DU Fang,YI Gui-xi,et al.2013.Earthquake potential of the Zhaotong and Lianfeng Fault zones of theeastern Sichuan-Yunnan border region[J].Chinese Journal of Geophysics,56(10):3361—3372(in Chinese).
徐锡伟,江国焰,于桂华,等.2014.鲁甸6.5级地震发震断层判定及其构造属性讨论[J].地球物理学报,57(9):3060—3068.doi:10.6038/cjg20140931.XU Xi-wei,JIANG Guo-yan,YU Gui-hua,et al.2014.Discussion on seismogenic fault of the Ludian MS6.5earthquake and its tectonic attribution[J].Chinese Journal of Geophysics,57(9):3060—3068(in Chinese).
易桂喜,闻学泽,张致伟,等.2010.川南马边地区强震危险性分析[J].地震地质,32(2):282—293.doi:10.3969/j.issn.0253-4967.2010.02.011.YI Gui-xi,WEN Xue-ze,ZHANG Zhi-wei,et al.2010.Study on potential strong earthquake risk in Mabian area,southern Sichuan[J].Seismology and Geology,32(2):282—293(in Chinese).
张广伟,雷建设,梁姗姗,等.2014.2014年8月3日云南鲁甸MS6.5地震序列重定位与震源机制研究[J].地球物理学报,57(9):3018—3027.doi:10.6038/cjg20140926.ZHANG Guang-wei,LEI Jian-she,LIANG Shan-shan,et al.2014.Relocations and focal mechanism solutions of the3 August 2014 Ludian,Yunnan MS6.5 earthquake sequence[J].Chinese Journal of Geophysics,57(9):3018—3027(in Chinese).
张世民,聂高众,刘旭东,等.2005.荥经-马边-盐津逆冲构造带断裂运动组合及地震分段特征[J].地震地质,27(2):221—233.ZHANG Shi-min,NIE Gao-zhong,LIU Xu-dong,et al.2005.Kinematical and structural patterns of Yingjing-MabianYanjin thrust fault zone,southeast of Tibetan Plateau,and its segmentation from earthquakes[J].Seismology andGeology,27(2):221—233(in Chinese).
赵静,江在森,牛安福,等.2014.川滇菱形块体东边界断层闭锁程度与滑动亏损动态特征研究[J].地球物理学报,(待刊).ZHAO Jing,JIANG Zai-sen,NIU An-fu,et al.2014.Study on dynamic characteristics of fault locking and fault slipdeficit in the eastern boundary of the Sichuan-Yunnan rhombic block[J].Chinese Journal of Geophysics,(inprint).
赵静,江在森,武艳强,等.2012.汶川地震前龙门山断裂带闭锁程度和滑动亏损分布研究[J].地球物理学报,55(9):2963—2972.doi:10.6038/j.issn.0001-5733.2012.09.015.ZHAO Jing,JIANG Zai-sen,WU Yan-qiang,et al.2012.Study on fault locking and fault slip deficit of theLongmenshan fault zone before the Wenchuan earthquake[J].Chinese Journal of Geophysics,55(9):2963—2972(in Chinese).
赵静,江在森,武艳强,等.2013a.Defnode负位错模型反演结果的可靠性和稳定性分析[J].大地测量与地球动力学,33(1):21—24.ZHAO Jing,JIANG Zai-sen,WU Yan-qiang,et al.2013a.Analysis of reliability and stability of inversion result withnegative dislocation model of Defnode[J].Journal of Geodesy and Geodynamics,33(1):21—24(in Chinese).
赵静,武艳强,江在森,等.2013b.芦山地震前龙门山断裂带闭锁程度与变形动态特征研究[J].地震学报,35(5):681—691.ZHAO Jing,WU Yan-qiang,JIANG Zai-sen,et al.2013b.Fault locking and dynamic deformation of the Longmenshan faultzone before the 2013 Lushan MS7.0 earthquake[J].Acta Seismologica Sinica,35(5):681—691(in Chinese).
中国地震局地质研究所.2014.云南鲁甸6.5级地震发震断层分析[EB/OL][Z].http://www.eq-igl.ac.cn/wwwroot/c_000000090001/d_1406.html.Institute of Geology,CEA.2014.Seismogenic fault analysis of Ludian 6.5 earthquake in Yunnan[EB/OL][Z].http://www.eq-igl.ac.cn/wwwroot/c_000000090001/d_1406.html(in Chinese).
Dong D,Hering T A,King R W.1998.Estimating regional deformation from a combination of space and terrestrialgeodetic data[J].J Geophys Res,72:200—214.
Herring T A,King R W,Mc Clusky S C.2010a.GAMIT Reference Manual.GPS Analysis at MIT.Release 10.4.Massachussetts Institute Technology[Z].http://www-gpsg.mit.edu/~simon/gtgk/index.htm.
Herring T A,King R W,Mc Clusky S C.2010b.GLOBK Reference Manual.Global Kalman filter VLBI and GPSanalysis program.Release 10.4.Massachussetts Institute Technology[Z].http://www-gpsg.mit.edu/~simon/gtgk/index.htm.
Mc Caffrey R.2002.Crustal block rotations and plate coupling[A].In:Stein S,Freymueller J(eds).Plate boundaryzones.AGU Geodynamics Series,30:101—122.
Mc Caffrey R.2007.DEFNODE User's Manual Version 2007.10.25[EB/OL][Z].http://web.pdx.edu/~mccaf/www/defnode/defnode_071025.html.
Savage J C,Gan W J,Svarc J L.2001.Strain accumulation and rotation in the eastern California shear zone[J].JGeophys Res,106(B10):21995—22007.
何宏林,池田安隆.2007.安宁河断裂带晚第四纪活动特征及模式的讨论[J].地震学报,29(5):537—548.HE Hong-lin,Yasutakyr Ikeda.2007.Faulting on the Anninghe fault zone,southwest China in late Quaternary and itsmovement model[J].Acta Seismologica Sinica,20(5):571—583.
何宏林,池田安隆,何玉林,等.2008.新生的大凉山断裂带:鲜水河-小江断裂系中段的截弯取直[J].中国科学(D辑),38(5):564—574.HE Hong-lin,Yasutakyr Ikeda,HE Yu-lin,et al.2008.Newly-generated Daliangshan Fault zone-Shortcutting on thecentral segment of Xianshuihe-Xiaojiang fault system[J].Science in China(Ser D),51(9):1248—1258.
M7专项工作组.2012.中国大陆大地震中-长期危险性研究[M].北京:地震出版社.Working Group on Research of Mid-to Long-term Potential of M≥7 Earthquakes on Chinese Continent,CEA.2012.Study on the Mid-to Long-term Potential of Large Earthquakes on the Chinese Continent[M].SeismologicalPress,Beijing(in Chinese).
任金卫.1994.则木河断裂晚第四纪位移及滑动速率[J].地震地质,16(2):146—155.REN Jin-wei.1994.Late Quaternary displacement and slip rate of Zemuhe Fault in Sichuan,China[J].Seismologyand Geology,16(2):146—155(in Chinese).
闻学泽,杜方,易桂喜,等.2013.川滇交界东段昭通、莲峰断裂带的地震危险背景[J].地球物理学报,56(10):3361—3372.doi:10.6038/cjg20131012.WEN Xue-ze,DU Fang,YI Gui-xi,et al.2013.Earthquake potential of the Zhaotong and Lianfeng Fault zones of theeastern Sichuan-Yunnan border region[J].Chinese Journal of Geophysics,56(10):3361—3372(in Chinese).
徐锡伟,江国焰,于桂华,等.2014.鲁甸6.5级地震发震断层判定及其构造属性讨论[J].地球物理学报,57(9):3060—3068.doi:10.6038/cjg20140931.XU Xi-wei,JIANG Guo-yan,YU Gui-hua,et al.2014.Discussion on seismogenic fault of the Ludian MS6.5earthquake and its tectonic attribution[J].Chinese Journal of Geophysics,57(9):3060—3068(in Chinese).
易桂喜,闻学泽,张致伟,等.2010.川南马边地区强震危险性分析[J].地震地质,32(2):282—293.doi:10.3969/j.issn.0253-4967.2010.02.011.YI Gui-xi,WEN Xue-ze,ZHANG Zhi-wei,et al.2010.Study on potential strong earthquake risk in Mabian area,southern Sichuan[J].Seismology and Geology,32(2):282—293(in Chinese).
张广伟,雷建设,梁姗姗,等.2014.2014年8月3日云南鲁甸MS6.5地震序列重定位与震源机制研究[J].地球物理学报,57(9):3018—3027.doi:10.6038/cjg20140926.ZHANG Guang-wei,LEI Jian-she,LIANG Shan-shan,et al.2014.Relocations and focal mechanism solutions of the3 August 2014 Ludian,Yunnan MS6.5 earthquake sequence[J].Chinese Journal of Geophysics,57(9):3018—3027(in Chinese).
张世民,聂高众,刘旭东,等.2005.荥经-马边-盐津逆冲构造带断裂运动组合及地震分段特征[J].地震地质,27(2):221—233.ZHANG Shi-min,NIE Gao-zhong,LIU Xu-dong,et al.2005.Kinematical and structural patterns of Yingjing-MabianYanjin thrust fault zone,southeast of Tibetan Plateau,and its segmentation from earthquakes[J].Seismology andGeology,27(2):221—233(in Chinese).
赵静,江在森,牛安福,等.2014.川滇菱形块体东边界断层闭锁程度与滑动亏损动态特征研究[J].地球物理学报,(待刊).ZHAO Jing,JIANG Zai-sen,NIU An-fu,et al.2014.Study on dynamic characteristics of fault locking and fault slipdeficit in the eastern boundary of the Sichuan-Yunnan rhombic block[J].Chinese Journal of Geophysics,(inprint).
赵静,江在森,武艳强,等.2012.汶川地震前龙门山断裂带闭锁程度和滑动亏损分布研究[J].地球物理学报,55(9):2963—2972.doi:10.6038/j.issn.0001-5733.2012.09.015.ZHAO Jing,JIANG Zai-sen,WU Yan-qiang,et al.2012.Study on fault locking and fault slip deficit of theLongmenshan fault zone before the Wenchuan earthquake[J].Chinese Journal of Geophysics,55(9):2963—2972(in Chinese).
赵静,江在森,武艳强,等.2013a.Defnode负位错模型反演结果的可靠性和稳定性分析[J].大地测量与地球动力学,33(1):21—24.ZHAO Jing,JIANG Zai-sen,WU Yan-qiang,et al.2013a.Analysis of reliability and stability of inversion result withnegative dislocation model of Defnode[J].Journal of Geodesy and Geodynamics,33(1):21—24(in Chinese).
赵静,武艳强,江在森,等.2013b.芦山地震前龙门山断裂带闭锁程度与变形动态特征研究[J].地震学报,35(5):681—691.ZHAO Jing,WU Yan-qiang,JIANG Zai-sen,et al.2013b.Fault locking and dynamic deformation of the Longmenshan faultzone before the 2013 Lushan MS7.0 earthquake[J].Acta Seismologica Sinica,35(5):681—691(in Chinese).
中国地震局地质研究所.2014.云南鲁甸6.5级地震发震断层分析[EB/OL][Z].http://www.eq-igl.ac.cn/wwwroot/c_000000090001/d_1406.html.Institute of Geology,CEA.2014.Seismogenic fault analysis of Ludian 6.5 earthquake in Yunnan[EB/OL][Z].http://www.eq-igl.ac.cn/wwwroot/c_000000090001/d_1406.html(in Chinese).
Dong D,Hering T A,King R W.1998.Estimating regional deformation from a combination of space and terrestrialgeodetic data[J].J Geophys Res,72:200—214.
Herring T A,King R W,Mc Clusky S C.2010a.GAMIT Reference Manual.GPS Analysis at MIT.Release 10.4.Massachussetts Institute Technology[Z].http://www-gpsg.mit.edu/~simon/gtgk/index.htm.
Herring T A,King R W,Mc Clusky S C.2010b.GLOBK Reference Manual.Global Kalman filter VLBI and GPSanalysis program.Release 10.4.Massachussetts Institute Technology[Z].http://www-gpsg.mit.edu/~simon/gtgk/index.htm.
Mc Caffrey R.2002.Crustal block rotations and plate coupling[A].In:Stein S,Freymueller J(eds).Plate boundaryzones.AGU Geodynamics Series,30:101—122.
Mc Caffrey R.2007.DEFNODE User's Manual Version 2007.10.25[EB/OL][Z].http://web.pdx.edu/~mccaf/www/defnode/defnode_071025.html.
Savage J C,Gan W J,Svarc J L.2001.Strain accumulation and rotation in the eastern California shear zone[J].JGeophys Res,106(B10):21995—22007.
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