西南天山—帕米尔2008年10月5日M_S6.7级地震震源机制研究
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摘要
利用Incorporated Research Institutions for Seismology(IRIS)提供的远场宽频带P波及SH波记录,基于点源模型及有限断层模型方法,反演研究了2008年10月5日发生在中国天山与塔吉克斯坦交界区域的一次MS6.7级地震震源机制.结果表明,本次地震为南倾高角度稍具小幅度走滑分量的逆冲破裂事件,断层走向为57.2°,倾角为42.7°,震源深度为7.4km.根据研究结果,我们认为这是一次逆断层加小幅度走滑分量的地震事件,推断该地震可能与帕米尔向北北西方向挤压西南天山,在帕米尔—西南天山边界引发的逆冲断层活动有关.
The rupture process of the MS6.7 earthquake occurring near the border between Xinjiang and Tajikistan on 5 October 2008 was investigated by pointsource and finite fault models using far field broadband P and SH waves provided by the IRIS.The results suggest that this shock resulted from rupturing on a southdipped thrust fault with lateral strike slip.The fault plane has a strike of 57.2°,a dip of 42.7° and focal depth of 7.4 km.Based on our inversion,we proposed that this earthquake was generated by thrust faulting due to NNW directed pushing of the Pamir toward the southwestern Tianshan Mountains.
The rupture process of the MS6.7 earthquake occurring near the border between Xinjiang and Tajikistan on 5 October 2008 was investigated by pointsource and finite fault models using far field broadband P and SH waves provided by the IRIS.The results suggest that this shock resulted from rupturing on a southdipped thrust fault with lateral strike slip.The fault plane has a strike of 57.2°,a dip of 42.7° and focal depth of 7.4 km.Based on our inversion,we proposed that this earthquake was generated by thrust faulting due to NNW directed pushing of the Pamir toward the southwestern Tianshan Mountains.
引文
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[21]张培震,邓启东,杨晓平等.天山的晚新生代构造变形及其地球动力学问题.中国地震,1996,12(2):127-140.Zhang P Z,Deng Q D,Yang X P,et al.Late Cenozoictectonic deformation and mechanism along the Tianshanmountain,Northwestern China.Earthquake Research in China(in Chinese),1996,12(2):127-140.
[22]张国民,马宏生,王辉等.中国大陆活动地块边界带与强震活动.地球物理学报,2005,48(3):602-610.Zhang G M,Ma H S,Wang H,et al.Boundaries betweenactive-tectonic blocks and strong earthquakes in the Chinamainland.Chinese J.Geophys.,(in Chinese),2005,48(3):602-610.
[23]胥颐,刘建华,刘福田等.天山—帕米尔结合带的地壳速度结构及地震活动研究.地球物理学报,2006,49(2):469-476.Xu Y,Liu J H,Liu F T,et al.Crustal velocity structure andseismic activity in the Tianshan-Pamir conjunctive zone.Chinese J.Geophys.,(in Chinese),2006,49(2):469-476.
[24]Dziewonski A M,Chow T A,Wookhouse J H.Determination ofearthquake source parameters from waveform data for studiesof global and regional seismicity.J.Geophys.Res.,1981,86(B4):2825-2852.
[25]Ekstrom G A.A broad band method of earthquake analysis[Ph.D.thesis].Cambridge:Harvard University,1987.
[26]Molnar P,Lyon-Caen H.Fault plane solutions of earthquakesand active tectonics of the Tibetan Plateau and its margins.Geophys.J.Int.,1989,99(1):123-154.
[2]Zubovich A V,Wang X Q,Scherba Y G,et al.GPS velocityfield from the Tien Shan and surrounding regions.Tectonics,2010,29:TC6014,doi:10.029/2010TC002772.
[3]王卫民,李丽,赵连锋等.2003年2月24日新疆伽师Ms6.5级地震震源破裂过程研究.地球物理学报,2003,48(2):343-351.Wang W M,Li L,Zhao L F,et al.Rupture process ofJiashi,Xinjiang earthquake(Ms6.5)of Feb.24,2003.Chinese J.Geophys.(in Chinese),2003,48(2):343-351.
[4]高星,段宗奇,王卫民等.2008年10月6日当雄Ms6.6级地震破裂过程.地球物理学报,2010,53(9):2083-2090,doi:10.3969/j.issn.0001-5733.210.09.008.Gao X,Duan Z Q,Wang W M,et al.Rupture process of theOct.6,2008 Ms6.6 Damxung earthquake,Tibet,China.Chinese J.Geophys(in Chinese),2010,53(9):2083-2090,doi:10.3969/j.issn.0001-5733.210.09.008.
[5]姚振兴,纪晨.时间域内有限地震断层的反演问题.地球物理学报,1997,40(5):691-701.Yao Z X,Ji C.The inverse problem of finite fault study intime domain.Chinese J.Geophys.(in Chinese),1997,40(5):691-701.
[6]姚振兴,郑天愉,曹柏如等.用P波波形资料测定中强地震震源过程的方法.地球物理学进展,1991,6(4):6-36.Yao Z X,Zheng T Y,Cao B R,et al.The method ofdetermining middle and strong earthquake′s process using Pwaveform data.Progress in Geophysics(in Chinese),1991,6(4):6-36.
[7]郭志,高星,王卫民.2006年12月26日台湾南部滨海Ms7.2级地震破裂过程研究.地球物理学报,2008,51(4):1103-1113.Guo Z,Gao X,Wang W M.Rupture process of southernTaiwan offshore Ms7.2earthquake of Dec.12,2006.Chinese J.Geophys.(in Chinese),2008,51(4):1103-1113.
[8]Tian X,Zhao D,Zhang H,et al.Mantle transition zonetopography and structure beneath the central Tien Shanorogenic belt.J.Geophys.Res.,2010,115:B10308,doi:10.1029/2008JB006229.
[9]郭志,高星,王卫民等.采用地震背景噪音成像技术反演天山及周边区域地壳剪切波速度结构.科学通报,2010,55(26):2627-2634.Guo Z,Gao X,Wang W M,et al.S-wave velocity of thecrust around Tianshan Mountains inverted from seismicambient noise tomography.Chinese Sci.Bull.,2010,55(31):3590-3598.
[10]Brune J N.Tectonic stress and the spectra of seismic shearwaves from earthquakes.J.Geophys.Res.,1970,75(26):4997-5009.
[11]Oslon A H,Apsel R.Finite faults and inverse theory withapplications to the 1979Imperial Valley earthquake.Bull.Seism.Soc.Am.,1982,72(6A):1996-2001.
[12]Kirkpatrick S,Gelatt C D Jr,Vecchi M P.Optimization bysimulated annealing.Science,1983,220(4598):671-680.
[13]Mellman G R,Burdick L J,Helmberger D V.Determinationof source parameters from body wave seismograms.EarthquakeNote,1975,46-44.
[14]Wallace T C,Helmberger D V,Mellman G R.A techniquefor the inversion of regional data in source parameter studies.J.Geophys.Res.,1981,86(B3):1679-1685.
[15]Metropolis N,Ulam S.The monte carlo method.J.Amer.Stat.Assoc.,1949,44(247):335-341.
[16]赵翠萍,陈章立,郑斯华.1998～2003年伽师三次不同类型Ms6级地震震源破裂过程及短期内余震活动特征.地球物理学报,2008,51(4):1093-1102.Zhao C P,Chen Z L,Zheng S H.Source rupture process of 3Jiashi Ms6events(1998～2003)and its correlation with theaftershock activity.Chinese J.Geophys.(in Chinese),2008,51(4):1093-1102.
[17]楼小挺,刁桂苓,叶国扬等.帕米尔—兴都库什地区中源地震的空间分布和震源机制解特征.地球物理学报,2007,50(5):1448-1455.Lou X T,Diao G L,Ye G Y,et al.Spatial distribution ofintermediate earthquakes and focal mechanism solutions inthe Pamir-Hindu Kush region.Chinese J.Geophys.(inChinese),2007,50(5):1448-1455.
[18]宁杰远,臧绍先.帕米尔—兴都库什地区地震空间分布特征及应力场特征.地球物理学报,1990,33(6):657-669.Ning J Y,Zang S X.The distribution of earthquakes andstress state in Pamir-Hindu Kush regions.Chinese J.Geophys.,(in Chinese),1990,33(6):657-669.
[19]陈杰,丁国瑜,Burbank D W等.中国西南天山山前的晚新生代构造与地震活动.中国地震,2001,17(2):134-155.Chen J,Ding G Y,Burbank D W,et al.Late Cenozoictectonics and seismicity in the southwestern Tianshan,China.Earthquake Research in China(in Chinese),2001,17(2):134-155.
[20]沈军,汪一鹏,赵瑞斌等.帕米尔东北缘及塔里木盆地西北部弧形构造的扩展特征.地震地质,2001,23(3):381-389.Shen J,Wang Y P,Zhao R B,et al.Propagation of Cenozoicarcuate structures in northeast Pamir and northwest Tarimbasin.Seismology and Geology(in Chinese),2001,32(3):381-389.
[21]张培震,邓启东,杨晓平等.天山的晚新生代构造变形及其地球动力学问题.中国地震,1996,12(2):127-140.Zhang P Z,Deng Q D,Yang X P,et al.Late Cenozoictectonic deformation and mechanism along the Tianshanmountain,Northwestern China.Earthquake Research in China(in Chinese),1996,12(2):127-140.
[22]张国民,马宏生,王辉等.中国大陆活动地块边界带与强震活动.地球物理学报,2005,48(3):602-610.Zhang G M,Ma H S,Wang H,et al.Boundaries betweenactive-tectonic blocks and strong earthquakes in the Chinamainland.Chinese J.Geophys.,(in Chinese),2005,48(3):602-610.
[23]胥颐,刘建华,刘福田等.天山—帕米尔结合带的地壳速度结构及地震活动研究.地球物理学报,2006,49(2):469-476.Xu Y,Liu J H,Liu F T,et al.Crustal velocity structure andseismic activity in the Tianshan-Pamir conjunctive zone.Chinese J.Geophys.,(in Chinese),2006,49(2):469-476.
[24]Dziewonski A M,Chow T A,Wookhouse J H.Determination ofearthquake source parameters from waveform data for studiesof global and regional seismicity.J.Geophys.Res.,1981,86(B4):2825-2852.
[25]Ekstrom G A.A broad band method of earthquake analysis[Ph.D.thesis].Cambridge:Harvard University,1987.
[26]Molnar P,Lyon-Caen H.Fault plane solutions of earthquakesand active tectonics of the Tibetan Plateau and its margins.Geophys.J.Int.,1989,99(1):123-154.
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