由构造应力场研究汶川地震断层的分段性
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摘要
采用构造应力场均匀性对断层或板块边界进行分段的方法,利用"裁剪-粘贴"法给出的余震震源机制解资料,进一步从应力场角度确定汶川地震发震断层南、北段分界点位置及南、北段震后应力场.研究结果表明,发震断层南、北段分界点位于北川附近,与先前的研究结果较为一致.南、北段震后应力场反演结果显示,南、北段的最大主应力轴方位均呈北东东向,且近水平.南、北段应力场反演的平均拟合残差和置信区间均较大,主要原因可能是因为南、北段内应力场不均匀性造成的.因为本文仅由大余震给出了震源断层的一级分段,南、北段内应做进一步的细分.
This study determined the boundary between southern and northern segments of the Wenchuan earthquake fault based on the analysis of stress field after the main shock.The method of dividing fault or plate boundary into sections by means of stress field uniformity analysis is utilized.Aftershock focal mechanisms were obtained by using "cut and paste"(CAP) method,and used to infer the stress field.The results show that the boundary between the northern and southern segments of the seismogenic fault is located near Beichuan County,similar to those from previous studies.The inverted aftershock stress results show that the orientation of maximum principal stress axes for both northern and southern segments is ENE--WSW,and nearly horizontal.The average misfit and confidence level range of stress inversion result are relatively large,probably due to the stress heterogeneity in the northern and southern segments.Since this research only gives a gross segmentation of the seismogenic fault based on focal mechanism determination of large aftershocks,a further division of the northern and southern segments should be studied in detail in future.
This study determined the boundary between southern and northern segments of the Wenchuan earthquake fault based on the analysis of stress field after the main shock.The method of dividing fault or plate boundary into sections by means of stress field uniformity analysis is utilized.Aftershock focal mechanisms were obtained by using "cut and paste"(CAP) method,and used to infer the stress field.The results show that the boundary between the northern and southern segments of the seismogenic fault is located near Beichuan County,similar to those from previous studies.The inverted aftershock stress results show that the orientation of maximum principal stress axes for both northern and southern segments is ENE--WSW,and nearly horizontal.The average misfit and confidence level range of stress inversion result are relatively large,probably due to the stress heterogeneity in the northern and southern segments.Since this research only gives a gross segmentation of the seismogenic fault based on focal mechanism determination of large aftershocks,a further division of the northern and southern segments should be studied in detail in future.
引文
陈国光,计风桔,周荣军,徐杰,周本刚,黎小刚,叶友青.2007.龙门山断裂带晚第四纪活动性分段的初步研究[J].地震地质,29(3):657--673.
杜义,谢富仁,张效亮,荆振杰.2009.汶川MS8.0级地震断层滑动机制研究[J].地球物理学报,52(2):464--473.
胡幸平.2010.汶川地震序列震源机制及其动力学解释[D].北京:中国地震局地壳应力研究所:46--47.
胡幸平,俞春泉,陶开,崔效锋,宁杰远,王艳华.2008.利用P波初动资料求解汶川地震及其强余震震源机制解[J].地球物理学报,51(6):1711--1718.
华卫,陈章立,郑斯华.2009.2008年汶川8.0级地震序列震源参数分段特征的研究[J].地球物理学报,52(2):365-371.
李勇,周荣军,Densmore A L,Ellis M A.2006.青藏高原东缘龙门山晚新生代走滑-逆冲作用的地貌标志[J].第四纪研究,26(1):40--51.
李智武,刘树根,陈洪德,刘顺,郭兵,田小彬.2008.龙门山冲断带分段:分带性构造格局及其差异变形特征[J].成都理工大学学报(自然科学版),35(4):440--454.
李志雄,邵志刚,赵翠萍,李圣强,王慧敏,吕梅梅,和平,刘桂平,崔子键.2009.汶川8.0级地震序列活动的分段性研究[J].地震,29(1):26--32.
马寅生,龙长兴,谭成轩,王涛,张永双,雷伟志,李滨,龚明权,廖春庭,吴满路.2008.四川汶川MS8.0级地震同震变形特征和分段性[J].地质通报,27(12):2076--2085.
石玉涛,高原,赵翠萍,姚志祥,太龄雪,张永久.2009.汶川地震余震序列的地震各向异性[J].地球物理学报,52(2):398--407.
唐荣昌,文德华,黄祖智,伍先国,林伟凡,陈国星,吴刚.1991.松潘—龙门山地区主要活动断裂带第四纪活动特征[J].中国地震,7(3):64--71.
万永革,吴忠良,周公威,黄静.2000.根据震源的两个节面的走向角和倾角求滑动角[J].地震地磁观测与研究,21(5):26--30.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
王敏.2009.基于GPS同震位移场约束反演2008年5·12汶川大地震破裂空间分布[J].地球物理学报,52(10):2519--2526.
王勤彩,陈章立,郑斯华.2009.汶川大地震余震序列震源机制的空间分段特征[J].科学通报,54(16):2348--2354.
徐锡伟,闻学泽,叶建青,马保起,陈杰,周荣军,何宏林,田勤俭,何玉林,王志才,孙昭民,冯希杰,于贵华,陈立春,陈桂华,于慎鄂,冉勇康,李细光,李陈侠,安艳芬.2008.汶川MS8.0地震地表破裂带及其发震构造[J].地震地质,30(3):597--629.
张勇,许力生,陈运泰.2009.2008年汶川大地震震源机制的时空变化[J].地球物理学报,52(2):379--389.
赵翠萍,陈章立,周连庆,李志雄,康英.2009.汶川MW8.0级地震震源破裂过程研究:分段特征[J].科学通报,54(22):3475--3482.
郑勇,马宏生,吕坚,倪四道,李迎春,韦生吉.2009.汶川地震强余震(MS≥5.6)的震源机制解及其与发震构造的关系[J].中国科学:D辑,39(4):413--426.
钟继茂,程万正.2006.由多个地震震源机制解求川滇地区平均应力场方向[J].地震学报,28(4):337--346.
周荣军,黄润秋,雷建成,何玉林,黎小刚,王世元,叶友清,刘玉法,亢川川,梁明剑,戈天勇,何强,黄伟.2008.四川汶川8.0级地震地表破裂与震害特点[J].岩石力学与工程学报,27(11):2173--2183.
朱艾斓,徐锡伟,刁桂苓,苏金蓉,冯向东,孙晴,王亚丽.2008.汶川MS8.0地震部分余震重新定位及地震构造初步分析[J].地震地质,30(3):759--767.
Bokelmann G H R,Beroza G C.2000.Depth-dependent earthquake focal mechanism orientation:Evidence for a weakzone in the lower crust[J].J Geophys Res,105(B9):21683--21695.
Gephart J W,Forsyth D W.1984.An improved method for determining the regional stress tensor using earthquake focalmechanism data:Application to the San Fernando earthquake sequence[J].J Geophys Res,89(B11):9305--9320.
Gillard D,Wyss M,Nakata J S.1992.A seismotectonic model for western Hawaii based on stress tensor inversion fromfault plane solutions[J].J Geophys Res,97(B5):6629--6641.
Gillard D,Wyss M.1995.Comparison of strain and stress tensor orientation:Application to Iran and California[J].J Geophys Res,100(B11):22197--22213.
Gillard D,Wyss M,Okubo P.1996.Type of faulting and orientation of stress and strain as a function of space and timein Kilauea’s south flank,Hawaii[J].J Geophys Res,101(B7):16025--16042.
Hardebeck J L,Nazareth J L,Hauksson E.1998.The static stress change triggering model:Constraints from twosouthern California aftershock sequences[J].J Geophys Res,103(B10):24427--24437.
Kao H,Angelier J.2001.Stress tensor inversion for the Chi-Chi earthquake sequence and its implications on regionalcollision[J].Bull Seism Soc Amer,91(5):1028--1040.
Lu Z,Wyss M.1996.Segmentation of the Aleutian plate boundary derived from stress direction estimates based on faultplane solutions[J].J Geophys Res,101(B1):803-816.
Lu Z,Wyss M,Pulpan H.1997.Details of stress directions in the Alaska subduction zone from fault plane solutions[J].J Geophys Res,102(B3):5385--5402.
Polat O,Haessler H,Cisternas A,Philip H,Eyidogan H,Aktar M,Frogneux M,Comte D,Gürbüz C.2002.TheIzmit(Kocaeli),Turkey earthquake of17August1999:Previous seismicity,aftershock,and seismotectonics[J].Bull Seism Soc Amer,92(1):361--375.
Ratchkovski N A.2003.Change in stress directions along the central Denali fault,Alaska after the2002earthquakesequence[J].Geophys Res Lett,30(19):2017,doi:10.1029/2003GL017905.
Shen Z K,Sun J B,Zhang P Z,Wan Y G,Wang M,Bürgmann R,Zeng Y H,Gan W J,Liao H,Wang Q L.2009.Slipmaxima at fault junctions and rupturing of barriers during the2008Wenchuan earthquake[J].Nature Geoscience,2:718--724,doi:10.1038/NGEO636.
Wiemer S,Gerstenberger M,Hauksson E.2002.Properties of the aftershock sequence of the1999MW7.1Hector Mineearthquake:Implications for aftershock hazard[J].Bull Seism Soc Amer,92(4):1227--1240.
Wyss M,Lu Z.1995.Plate boundary segmentation by stress directions:Southern San Andreas Fault,California[J].Geophys Res Lett,22(5):547--550.
杜义,谢富仁,张效亮,荆振杰.2009.汶川MS8.0级地震断层滑动机制研究[J].地球物理学报,52(2):464--473.
胡幸平.2010.汶川地震序列震源机制及其动力学解释[D].北京:中国地震局地壳应力研究所:46--47.
胡幸平,俞春泉,陶开,崔效锋,宁杰远,王艳华.2008.利用P波初动资料求解汶川地震及其强余震震源机制解[J].地球物理学报,51(6):1711--1718.
华卫,陈章立,郑斯华.2009.2008年汶川8.0级地震序列震源参数分段特征的研究[J].地球物理学报,52(2):365-371.
李勇,周荣军,Densmore A L,Ellis M A.2006.青藏高原东缘龙门山晚新生代走滑-逆冲作用的地貌标志[J].第四纪研究,26(1):40--51.
李智武,刘树根,陈洪德,刘顺,郭兵,田小彬.2008.龙门山冲断带分段:分带性构造格局及其差异变形特征[J].成都理工大学学报(自然科学版),35(4):440--454.
李志雄,邵志刚,赵翠萍,李圣强,王慧敏,吕梅梅,和平,刘桂平,崔子键.2009.汶川8.0级地震序列活动的分段性研究[J].地震,29(1):26--32.
马寅生,龙长兴,谭成轩,王涛,张永双,雷伟志,李滨,龚明权,廖春庭,吴满路.2008.四川汶川MS8.0级地震同震变形特征和分段性[J].地质通报,27(12):2076--2085.
石玉涛,高原,赵翠萍,姚志祥,太龄雪,张永久.2009.汶川地震余震序列的地震各向异性[J].地球物理学报,52(2):398--407.
唐荣昌,文德华,黄祖智,伍先国,林伟凡,陈国星,吴刚.1991.松潘—龙门山地区主要活动断裂带第四纪活动特征[J].中国地震,7(3):64--71.
万永革,吴忠良,周公威,黄静.2000.根据震源的两个节面的走向角和倾角求滑动角[J].地震地磁观测与研究,21(5):26--30.
万永革,沈正康,刁桂苓,王福昌,胡新亮,盛书中.2008.利用小震分布和区域应力场确定大震断层面参数方法及其在唐山地震序列中的应用[J].地球物理学报,51(3):793--804.
王敏.2009.基于GPS同震位移场约束反演2008年5·12汶川大地震破裂空间分布[J].地球物理学报,52(10):2519--2526.
王勤彩,陈章立,郑斯华.2009.汶川大地震余震序列震源机制的空间分段特征[J].科学通报,54(16):2348--2354.
徐锡伟,闻学泽,叶建青,马保起,陈杰,周荣军,何宏林,田勤俭,何玉林,王志才,孙昭民,冯希杰,于贵华,陈立春,陈桂华,于慎鄂,冉勇康,李细光,李陈侠,安艳芬.2008.汶川MS8.0地震地表破裂带及其发震构造[J].地震地质,30(3):597--629.
张勇,许力生,陈运泰.2009.2008年汶川大地震震源机制的时空变化[J].地球物理学报,52(2):379--389.
赵翠萍,陈章立,周连庆,李志雄,康英.2009.汶川MW8.0级地震震源破裂过程研究:分段特征[J].科学通报,54(22):3475--3482.
郑勇,马宏生,吕坚,倪四道,李迎春,韦生吉.2009.汶川地震强余震(MS≥5.6)的震源机制解及其与发震构造的关系[J].中国科学:D辑,39(4):413--426.
钟继茂,程万正.2006.由多个地震震源机制解求川滇地区平均应力场方向[J].地震学报,28(4):337--346.
周荣军,黄润秋,雷建成,何玉林,黎小刚,王世元,叶友清,刘玉法,亢川川,梁明剑,戈天勇,何强,黄伟.2008.四川汶川8.0级地震地表破裂与震害特点[J].岩石力学与工程学报,27(11):2173--2183.
朱艾斓,徐锡伟,刁桂苓,苏金蓉,冯向东,孙晴,王亚丽.2008.汶川MS8.0地震部分余震重新定位及地震构造初步分析[J].地震地质,30(3):759--767.
Bokelmann G H R,Beroza G C.2000.Depth-dependent earthquake focal mechanism orientation:Evidence for a weakzone in the lower crust[J].J Geophys Res,105(B9):21683--21695.
Gephart J W,Forsyth D W.1984.An improved method for determining the regional stress tensor using earthquake focalmechanism data:Application to the San Fernando earthquake sequence[J].J Geophys Res,89(B11):9305--9320.
Gillard D,Wyss M,Nakata J S.1992.A seismotectonic model for western Hawaii based on stress tensor inversion fromfault plane solutions[J].J Geophys Res,97(B5):6629--6641.
Gillard D,Wyss M.1995.Comparison of strain and stress tensor orientation:Application to Iran and California[J].J Geophys Res,100(B11):22197--22213.
Gillard D,Wyss M,Okubo P.1996.Type of faulting and orientation of stress and strain as a function of space and timein Kilauea’s south flank,Hawaii[J].J Geophys Res,101(B7):16025--16042.
Hardebeck J L,Nazareth J L,Hauksson E.1998.The static stress change triggering model:Constraints from twosouthern California aftershock sequences[J].J Geophys Res,103(B10):24427--24437.
Kao H,Angelier J.2001.Stress tensor inversion for the Chi-Chi earthquake sequence and its implications on regionalcollision[J].Bull Seism Soc Amer,91(5):1028--1040.
Lu Z,Wyss M.1996.Segmentation of the Aleutian plate boundary derived from stress direction estimates based on faultplane solutions[J].J Geophys Res,101(B1):803-816.
Lu Z,Wyss M,Pulpan H.1997.Details of stress directions in the Alaska subduction zone from fault plane solutions[J].J Geophys Res,102(B3):5385--5402.
Polat O,Haessler H,Cisternas A,Philip H,Eyidogan H,Aktar M,Frogneux M,Comte D,Gürbüz C.2002.TheIzmit(Kocaeli),Turkey earthquake of17August1999:Previous seismicity,aftershock,and seismotectonics[J].Bull Seism Soc Amer,92(1):361--375.
Ratchkovski N A.2003.Change in stress directions along the central Denali fault,Alaska after the2002earthquakesequence[J].Geophys Res Lett,30(19):2017,doi:10.1029/2003GL017905.
Shen Z K,Sun J B,Zhang P Z,Wan Y G,Wang M,Bürgmann R,Zeng Y H,Gan W J,Liao H,Wang Q L.2009.Slipmaxima at fault junctions and rupturing of barriers during the2008Wenchuan earthquake[J].Nature Geoscience,2:718--724,doi:10.1038/NGEO636.
Wiemer S,Gerstenberger M,Hauksson E.2002.Properties of the aftershock sequence of the1999MW7.1Hector Mineearthquake:Implications for aftershock hazard[J].Bull Seism Soc Amer,92(4):1227--1240.
Wyss M,Lu Z.1995.Plate boundary segmentation by stress directions:Southern San Andreas Fault,California[J].Geophys Res Lett,22(5):547--550.
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