2010年玉树地震震前甘孜-玉树断裂形变场分析
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摘要
2010年4月14日青海玉树MW6.9地震发震断层为甘孜-玉树断裂NW段。断裂错动速率的准确估计能够为认识发震断裂的结构和地震的孕震过程提供帮助,甘孜-玉树断裂周边地区(89°～103°E,28°～39°N)1999—2007年的GPS观测使之成为可能。去除受到断裂锁定效应或其他断裂位错影响的数据后,将跨断裂剖面上的台站速率分解为平行断层和垂直断层2个分量,并进一步估算得到风火山断裂、甘孜-玉树断裂和鲜水河断裂NW段左旋走滑速率分别为(6.1±1.9)、(6.6±1.5)和(10.2±0.7)mm/a。结合该地区地质学研究结果,推测甘孜-玉树-鲜水河断裂自西向东逐段增强的走滑速率反映了不同区域地壳对印藏碰撞造成形变的转换、吸收方式之差异。甘孜-玉树断裂现今分段错动速率的定量估计为该断裂的深入研究和青藏高原变形发展过程的认识提供了宝贵数据。
The 14 April 2010 MW 6.9 Yushu earthquake ruptured the northwestern segment of the Ganzi-Yushu Fault in Qinghai,China.Accurate estimation of the secular slip rate across the fault would help understand tectonic structure of the fault and its seismogenic process.GPS data obtained from 1999 to 2007around the Ganzi-Yushu Fault spanning 89°～103°E,28°～39°N make such estimation possible.After removing GPS stations whose displacements were affected by fault locking effects and/or deformation of other faults,we decompose the remaining GPS station velocities into strike-parallel and strike-normal components and examine the data along profiles across corresponding fault segments.The slip rates of the Fenghuoshan,Ganzi-Yushu,and northwestern segment of the Xianshuihe Faults are estimated as 6.1±1.9,6.6±1.5,and 10.2±0.7mm/a,respectively.These results agree with geological estimates of the fault slip rates,which show progressive increase from northwest to southeast across segments of the Ganzi-Yushu-Xianshuihe Fault zone,implying variation in transferring and absorbing patterns of deformation in different regions in and around the Tibetan plateau.Estimation of present-day slip rates along segments of the Ganzi-Yushu Fault would provide valuable data for future research on seismo-tectonics of the fault and tectonic evolution of the Tibetan plateau.
The 14 April 2010 MW 6.9 Yushu earthquake ruptured the northwestern segment of the Ganzi-Yushu Fault in Qinghai,China.Accurate estimation of the secular slip rate across the fault would help understand tectonic structure of the fault and its seismogenic process.GPS data obtained from 1999 to 2007around the Ganzi-Yushu Fault spanning 89°～103°E,28°～39°N make such estimation possible.After removing GPS stations whose displacements were affected by fault locking effects and/or deformation of other faults,we decompose the remaining GPS station velocities into strike-parallel and strike-normal components and examine the data along profiles across corresponding fault segments.The slip rates of the Fenghuoshan,Ganzi-Yushu,and northwestern segment of the Xianshuihe Faults are estimated as 6.1±1.9,6.6±1.5,and 10.2±0.7mm/a,respectively.These results agree with geological estimates of the fault slip rates,which show progressive increase from northwest to southeast across segments of the Ganzi-Yushu-Xianshuihe Fault zone,implying variation in transferring and absorbing patterns of deformation in different regions in and around the Tibetan plateau.Estimation of present-day slip rates along segments of the Ganzi-Yushu Fault would provide valuable data for future research on seismo-tectonics of the fault and tectonic evolution of the Tibetan plateau.
引文
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国家地震局.1977.中国地震简目[M].北京:地震出版社.China Earthquake Administration.1977.The Brief Earthquake Catalog of China[M].Seismological Press,Beijing(in Chinese).
李闽峰,邢成起,蔡长星,等.1995.玉树断裂活动性研究[J].地震地质,17(3):218—224.LI Min-feng,XING Cheng-qi,CAI Chang-xing,et al.1995.Research on activity of Yushu Fault[J].Seismology and Geology,17(3):218—224(in Chinese).
彭华,马秀敏,白嘉启,等.2006.甘孜玉树断裂带第四纪活动特征[J].地质力学学报,12(3):295—304.PENG Hua,MA Xiu-min,BAI Jia-qi,et al.2006.Characteristics of Quaternary activities of the Garzê-Yushu Fault zone[J].Journal of Geomechanics,12(3):295—304(in Chinese).
沈正康,王敏,甘卫军,等.2003.中国大陆现今构造应变率场及其动力学成因研究[J].地学前缘,10(特刊):93—100.SHEN Zheng-kang,WANG Min,GAN Wei-jun,et al.2003.Contemporary tectonics strain rate field of Chinese continent and its geodynamic implications[J].Earth Science Frontiers,10(suppl):93—100(in Chinese).
四川地震资料汇编编辑组.1980.四川地震资料汇编(第一卷)[M].成都:四川人民出版社.Editorial Group of the Data Compilation of Earthquakes in Sichuan(ed).1980.The Data Compilation of Earthquakes in Sichuan(Book1)[M].People's Publishing House of Sichuan,Chengdu(in Chinese).
王敏,沈正康,甘卫军,等.2008.GPS连续监测鲜水河断裂形变场动态演化[J].中国科学(D辑),38(5):575—581.WANG Min,SHEN Zheng-kang,GAN Wei-jun,et al.2008.GPS monitoring of temporal deformation of the Xianshuihe Fault[J].Science in China(Ser D),51(9):1259—1266.
王敏.2008.GPS观测结果的精化分析与中国大陆现今地壳形变场研究[D]:[学位论文].北京:中国地震局地质研究所.WANG Min.2008.Analysis of GPS data with high precision and study on present-day crustal deformation in China[D].Ph D thesis.Institute of Geology,CEA,Beijing(in Chinese).
王阎昭,王恩宁,沈正康,等.2008.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学(D辑),38(5):582—597.WANG Yan-zhao,WANG En-ning,SHEN Zheng-kang,et al.2008.GPS-constrained inversion of present-day slip rates along major faults of the Sichuan-Yunnan region,China[J].Science in China(Ser D),51(9):1267—1283.
闻学泽,徐锡伟,郑荣章,等.2003.甘孜-玉树断裂的平均滑动速率与近代大地震破裂[J].中国科学(D辑),33(增刊):199—208.WEN Xue-ze,XU Xi-wei,ZHENG Rong-zhang,et al.2003.Average slip-rate and recent large earthquake ruptures along the Ganzi-Yushu Fault[J].Science in China(Ser D),33(suppl):199—208(in Chinese).
张裕明,李闵峰,孟勇琦,等.1996.巴颜喀拉山地区断层活动性研究及其地震地质意义[A].见:中国地震局地质研究所编.活动断裂研究(5).北京:地震出版社.154—171.ZHANG Yu-ming,LI Min-feng,MENG Yong-qi,et al.1996.Research on fault activity in the Bayan Har Mountain re-gion and the seismic and geologic implications[A].In:Institute of Geology,SSB(ed).Research on Active Faults(5).Seismological Press,Beijing.154—171(in Chinese).
中国地震局监测预报司预报管理处.1999.中国强地震目录(公元前23世纪—公元1999年)[Z].北京:地震出版社.Forecasting Administration,Monitoring and Forecasting Department of China Earthquake Administration.1999.The cat-alogue of strong earthquakes in China(from23Century B.C.to1999A.D.)(in Chinese)[Z].Seismological Press,Beijing.
周荣军,马长浩,蔡长星.1996.甘孜-玉树断裂带的晚第四纪活动特征[J].中国地震,12(3):250—260.ZHOU Rong-jun,MA Chang-hao,CAI Chang-xing.1996.Late Quatenery active feature of the Ganzi-Yushu fault zone[J].Earthequake Research in China,12(3):250—260(in Chinese).
Armijo R,Tapponnier P,Mercier J L,et al.1986.Quaternary extension in southern Tibet:Field observations and tecton-ic implications[J].J Geophys Res,91(B14):13803—13872.
Gan Wei-jun,Zhang Pei-zhen,Shen Zheng-kang,et al.2007.Present-day crustal motion within the Tibetan Plateau in-ferred from GPS measurements[J].J Geophys Res,112.B08416.doi:10.1029/2005JB004120.
Meade B.2007.Present-day kinematics at the India-Asia collision zone[J].Geology,35(1):81—84.
Savage J C and Burford R O.1973.Geodetic determination of relative plate motion in central California[J].J Geophys Res,78(5):832—845.
Thatcher W.2007.Microplate model for the present-day deformation of Tibet[J].J Geophys Res,112,B01401.doi:10.1029/2005JB004244.
Wang S F,Fan C,Wang G,et al.2008.Late Cenozoic deformation along the northwestern continuation of the Xianshuihe Fault system,Eastern Tibetan Plateau[J].GSA Bull.120(3/4):312—327.doi:10.1130/B25833.1.
Yin An and Harrison T Mark.2000.Geological evolution of the Himalayan-Tibetan orogen[J].Annu Rev Earth Planet Sci,28:211—280.
Zhang Pei-zhen,Shen Zheng-kang,Wang Min,et al.2004.Continuous deformation of the Tibetan Plateau from global positioning system data[J].Geology,32(9):809—812.
国家地震局地球物理研究所.1990.中国历史地震图集(清朝(代)时期)[M].北京:中国地图出版社.24.Institute of Geophysics,SSB.1990.Atlas of Historical Earthquakes in China(the Qing Dynasty Period)[M].SinoMaps Press,Beijing.24(in Chinese).
国家地震局.1977.中国地震简目[M].北京:地震出版社.China Earthquake Administration.1977.The Brief Earthquake Catalog of China[M].Seismological Press,Beijing(in Chinese).
李闽峰,邢成起,蔡长星,等.1995.玉树断裂活动性研究[J].地震地质,17(3):218—224.LI Min-feng,XING Cheng-qi,CAI Chang-xing,et al.1995.Research on activity of Yushu Fault[J].Seismology and Geology,17(3):218—224(in Chinese).
彭华,马秀敏,白嘉启,等.2006.甘孜玉树断裂带第四纪活动特征[J].地质力学学报,12(3):295—304.PENG Hua,MA Xiu-min,BAI Jia-qi,et al.2006.Characteristics of Quaternary activities of the Garzê-Yushu Fault zone[J].Journal of Geomechanics,12(3):295—304(in Chinese).
沈正康,王敏,甘卫军,等.2003.中国大陆现今构造应变率场及其动力学成因研究[J].地学前缘,10(特刊):93—100.SHEN Zheng-kang,WANG Min,GAN Wei-jun,et al.2003.Contemporary tectonics strain rate field of Chinese continent and its geodynamic implications[J].Earth Science Frontiers,10(suppl):93—100(in Chinese).
四川地震资料汇编编辑组.1980.四川地震资料汇编(第一卷)[M].成都:四川人民出版社.Editorial Group of the Data Compilation of Earthquakes in Sichuan(ed).1980.The Data Compilation of Earthquakes in Sichuan(Book1)[M].People's Publishing House of Sichuan,Chengdu(in Chinese).
王敏,沈正康,甘卫军,等.2008.GPS连续监测鲜水河断裂形变场动态演化[J].中国科学(D辑),38(5):575—581.WANG Min,SHEN Zheng-kang,GAN Wei-jun,et al.2008.GPS monitoring of temporal deformation of the Xianshuihe Fault[J].Science in China(Ser D),51(9):1259—1266.
王敏.2008.GPS观测结果的精化分析与中国大陆现今地壳形变场研究[D]:[学位论文].北京:中国地震局地质研究所.WANG Min.2008.Analysis of GPS data with high precision and study on present-day crustal deformation in China[D].Ph D thesis.Institute of Geology,CEA,Beijing(in Chinese).
王阎昭,王恩宁,沈正康,等.2008.基于GPS资料约束反演川滇地区主要断裂现今活动速率[J].中国科学(D辑),38(5):582—597.WANG Yan-zhao,WANG En-ning,SHEN Zheng-kang,et al.2008.GPS-constrained inversion of present-day slip rates along major faults of the Sichuan-Yunnan region,China[J].Science in China(Ser D),51(9):1267—1283.
闻学泽,徐锡伟,郑荣章,等.2003.甘孜-玉树断裂的平均滑动速率与近代大地震破裂[J].中国科学(D辑),33(增刊):199—208.WEN Xue-ze,XU Xi-wei,ZHENG Rong-zhang,et al.2003.Average slip-rate and recent large earthquake ruptures along the Ganzi-Yushu Fault[J].Science in China(Ser D),33(suppl):199—208(in Chinese).
张裕明,李闵峰,孟勇琦,等.1996.巴颜喀拉山地区断层活动性研究及其地震地质意义[A].见:中国地震局地质研究所编.活动断裂研究(5).北京:地震出版社.154—171.ZHANG Yu-ming,LI Min-feng,MENG Yong-qi,et al.1996.Research on fault activity in the Bayan Har Mountain re-gion and the seismic and geologic implications[A].In:Institute of Geology,SSB(ed).Research on Active Faults(5).Seismological Press,Beijing.154—171(in Chinese).
中国地震局监测预报司预报管理处.1999.中国强地震目录(公元前23世纪—公元1999年)[Z].北京:地震出版社.Forecasting Administration,Monitoring and Forecasting Department of China Earthquake Administration.1999.The cat-alogue of strong earthquakes in China(from23Century B.C.to1999A.D.)(in Chinese)[Z].Seismological Press,Beijing.
周荣军,马长浩,蔡长星.1996.甘孜-玉树断裂带的晚第四纪活动特征[J].中国地震,12(3):250—260.ZHOU Rong-jun,MA Chang-hao,CAI Chang-xing.1996.Late Quatenery active feature of the Ganzi-Yushu fault zone[J].Earthequake Research in China,12(3):250—260(in Chinese).
Armijo R,Tapponnier P,Mercier J L,et al.1986.Quaternary extension in southern Tibet:Field observations and tecton-ic implications[J].J Geophys Res,91(B14):13803—13872.
Gan Wei-jun,Zhang Pei-zhen,Shen Zheng-kang,et al.2007.Present-day crustal motion within the Tibetan Plateau in-ferred from GPS measurements[J].J Geophys Res,112.B08416.doi:10.1029/2005JB004120.
Meade B.2007.Present-day kinematics at the India-Asia collision zone[J].Geology,35(1):81—84.
Savage J C and Burford R O.1973.Geodetic determination of relative plate motion in central California[J].J Geophys Res,78(5):832—845.
Thatcher W.2007.Microplate model for the present-day deformation of Tibet[J].J Geophys Res,112,B01401.doi:10.1029/2005JB004244.
Wang S F,Fan C,Wang G,et al.2008.Late Cenozoic deformation along the northwestern continuation of the Xianshuihe Fault system,Eastern Tibetan Plateau[J].GSA Bull.120(3/4):312—327.doi:10.1130/B25833.1.
Yin An and Harrison T Mark.2000.Geological evolution of the Himalayan-Tibetan orogen[J].Annu Rev Earth Planet Sci,28:211—280.
Zhang Pei-zhen,Shen Zheng-kang,Wang Min,et al.2004.Continuous deformation of the Tibetan Plateau from global positioning system data[J].Geology,32(9):809—812.
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