2008年10月西藏当雄M_W6.3地震震后形变提取与余滑反演
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摘要
2008年10月6日西藏当雄发生M_W6.3地震.本文利用震后2008年10月26日至2010年8月22日的16期ENVISAT ASAR数据,通过小基线集干涉测量、误差校正与MInTS(Multiscale InSAR Time Series)技术提取高精度的震后形变场,利用SDM(Steepest Descent Method)方法反演断层震后余滑演化过程,并分析震后余滑与同震滑动的关系.结果表明:当雄M_W6.3地震的近场震后形变场主要位于断层西侧,在时间演化上具有明显的对数函数衰减规律;震后余滑主要集中于断层中南段深0～15km区间,最大的余滑量约0.07m,位于断层深约9.28km处,滑动角约-103°;震后余滑引起的地震矩能量M_0与矩震级MW在时间演化上具有指数函数递增规律;当剪切模量μ=32GPa,震后665天余滑释放的地震矩能量约为1.92×10~(17) N·m,约占同震滑动释放地震矩的4.8%,相当于矩震级M_W5.46;虽然震后余滑已经延伸到断层浅部0～5km区间,但由于余滑量相对较小,没有改变同震滑动在断层浅部区域的滑动亏损现象,这可能是2010年11月30日该区域又发生M_W5.3级余震的主要原因之一.
On October 6 th,2008,an M_W6.3 earthquake occurred in Damxung,Tibet.Based on 16 scenes of ENVISAT ASAR images acquired during October 26 th 2008 to August 22 th 2010,this paper employed the techniques of the small baseline interferometry,error correction,and MInTS(Multiscale InSAR Time Series)to extract the high-precision post-seismic deformation field.The fault after-slip evolution process was inverted using SDM(Steepest Descent Method).The relationship between the co-seismic slip and after-slip along the fault was analyzed.The results show that the post-seismic deformation field is mainly located at the west of fault with an obvious logarithmicfunction attenuation over time.The afterslip mainly concentrate at a depth of 0～15 km in the middle and south part of the fault,and the maximum after-slip is about 0.07 m,which is located at a depth about 9.28 km with a slip angle about-103°.The seismic moment energy(M_0)and seismic moment tensor(MW)caused by afterslip increased exponentially over time.When the shear modulusμ=32 GPa,the post-seismic moment energy in 665 days is about 1.92×10~(17) N·m,which is approximately 4.8% of the co-seismic moment energy,and is equivalent to M_W5.46.Although the after-slip extended to a shallow depth of 0～5 km along the fault,it didn′t change the sliding deficit caused by the coseismic slip because the afterslip is relatively small.It may be one of the major factors for the occurrence of the subsequent M_W5.3 aftershock at the same region on November 30 th 2010.
On October 6 th,2008,an M_W6.3 earthquake occurred in Damxung,Tibet.Based on 16 scenes of ENVISAT ASAR images acquired during October 26 th 2008 to August 22 th 2010,this paper employed the techniques of the small baseline interferometry,error correction,and MInTS(Multiscale InSAR Time Series)to extract the high-precision post-seismic deformation field.The fault after-slip evolution process was inverted using SDM(Steepest Descent Method).The relationship between the co-seismic slip and after-slip along the fault was analyzed.The results show that the post-seismic deformation field is mainly located at the west of fault with an obvious logarithmicfunction attenuation over time.The afterslip mainly concentrate at a depth of 0～15 km in the middle and south part of the fault,and the maximum after-slip is about 0.07 m,which is located at a depth about 9.28 km with a slip angle about-103°.The seismic moment energy(M_0)and seismic moment tensor(MW)caused by afterslip increased exponentially over time.When the shear modulusμ=32 GPa,the post-seismic moment energy in 665 days is about 1.92×10~(17) N·m,which is approximately 4.8% of the co-seismic moment energy,and is equivalent to M_W5.46.Although the after-slip extended to a shallow depth of 0～5 km along the fault,it didn′t change the sliding deficit caused by the coseismic slip because the afterslip is relatively small.It may be one of the major factors for the occurrence of the subsequent M_W5.3 aftershock at the same region on November 30 th 2010.
引文
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Chen C W,Zebker H A.2002.Phase unwrapping for large SARinterferograms:statistical segmentation and generalized network models.IEEE Transactions on Geoscience and Remote Sensing,40(8):1709-1719.
Doin M P,Lasserre C,Peltzer G,et al.2009.Corrections of stratified tropospheric delays in SAR interferometry:Validation with global atmospheric models.Journal of Applied Geophysics,69(1):35-50.
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Gray A L,Mattar K E,Sorko G.2000.Influence of ionospheric electron density fluctuations on satellite radar interferometry.Geophysical Research Letters,27(10):1451-1454.
Hetland E A,MuséP,Simons M,et al.2012.Multiscale InSARTime Series(MInTS)analysis of surface deformation.Journal of Geophysical Research,117:B02404,doi:10.1029/2011JB008731.
Hooper A.2008.A multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches.GeophysicalResearch Letters,35:L16302,doi:10.1029/2008GL034654.
Jolivet R,Grandin R,Lasserre C,et al.2011.Systematic InSARtropospheric phase delay corrections from global meteorological reanalysis data.Geophysical Research Letters,38:L17311,doi:10.1029/2011GL048757.
Jolivet R,Agram P S,Lin N Y,et al.2014.Improving InSARgeodesy using Global Atmospheric Models.Journal of Geophysical Research:Solid Earth,119(3):2324-2341,doi:10.1002/2013JB010588.
Jónsson S,Zebker H,Segall P,et al.2002.Fault slip distribution of the 1999 MW7.1 Hector Mine,California,earthquake,estimated from satellite radar and GPS measurements.Bulletin of the Seismological Society of America,92(4):1377-1389.
Laske G,Masters G,Ma Z T,et al.2013.Update on CRUST1.0-A1-degree global model of earth′s crust.∥EGU General Assembly2013.Vienna,Austria.
Li Z W,Xu W B,Feng G C,et al.2012.Correcting atmospheric effects on InSAR with MERIS water vapour data and elevationdependent interpolation model.Geophysical Journal International,189(2):898-910,doi:10.1111/j.1365-246X.2012.05432.x.
Liu Y,Xu C J,Wen Y M,et al.2012.Fault rupture model of the2008Dangxiong(Tibet,China)MW6.3earthquake from Envisat and ALOS data.Advances in Space Research,50(7):952-962.
Qiao X J,You X Z,Yang S M,et al.2009.Study on dislocation inversion of MS6.6 Damxung earthquake as constrained by InSAR measurement.Journal of Geodesy and Geodynamics(in Chinese),29(6):1-7.
Quenouille M H.1949.Problems in plane sampling.The Annals of Mathematical Statistics,20(3):355-375.
Quenouille M H.1956.Notes on bias in estimation.Biometrika,43(3-4):353-360.
Smith E K,Weintraub S.1953.The constants in the equation for atmospheric refractive index at radio frequencies.Proceedings of the Ire,41(8):1035-1037.
Wang R J,Martín F L,Roth F.2003.Computation of deformation induced by earthquakes in a multi-layered elestic crust-FORTRANprograms EDGRN/EDCMP.Computers&Geosciences,29(2):195-207.
Wang R,Parolai S,Ge M,et al.2013.The 2011 MW9.0Tohoku Earthquake:Comparison of GPS and strong-motion data.Bulletin of the Seismological Society of America,103(2B):1336-1347.
Wu Z H,Ye P S,Wu Z H.2009.The seismic intensity,seismogenic tectonics and mechanism of the MS6.6Damxung earthquake happened on October 6,2008in southern Tibet,China.Geological Bulletin of China(in Chinese),28(6):713-725.
Xu C J,Liu Y,Wen Y M,et al.2010.Coseismic slip distribution of the 2008 MW7.9Wenchuan Earthquake from joint inversion of GPS and InSAR data.Bulletin of the Seismological Society of America,100(5B):2736-2749,doi:10.1785/0120090253.
冯万鹏,许力生,李振洪.2010.2008年10月当雄MW6.3级地震断层参数的InSAR反演及其构造意义.地球物理学报,53(5):1134-1142,doi:10.3969/j.issn.0001-5733.2010.05.014.
高星,段宗奇,王卫民等.2010.2008年10月6日当雄MS6.6级地震破裂过程.地球物理学报,53(9):2083-2090,doi:10.3969/j.issn.0001-5733.2010.09.008.
乔学军,游新兆,杨少敏等.2009.当雄Ms6.6地震的InSAR观测及断层位错反演.大地测量与地球动力学,29(6):1-7.
吴中海,叶培盛,吴珍汉.2009.2008年10月6日西藏当雄MS6.6级强震的地震烈度控震构造和发震机理.地质通报,28(6):713-725.
Baby H B,GoléP,Lavergnat J.1988.A model for the tropospheric excess path length of radio waves from surface meteorological measurements.Radio Science,23(6):1023-1038.
Bie L D,Ryder I,Nippress S E J,et al.2014.Coseismic and postseismic activity associated with the 2008 MW6.3Damxung earthquake,Tibet,constrained by InSAR.Geophysical Journal International,196(2):788-803,doi:10.1093/gji/ggt444.
CavaliéO,Doin M P,Lasserre C,et al.2007.Ground motion measurement in the Lake Mead area,Nevada,by differential synthetic aperture radar interferometry time series analysis:Probing the lithosphere rheological structure.Journal of Geophysical Research,112:B03403,doi:10.1029/2006JB004344.
Chen C W,Zebker H A.2002.Phase unwrapping for large SARinterferograms:statistical segmentation and generalized network models.IEEE Transactions on Geoscience and Remote Sensing,40(8):1709-1719.
Doin M P,Lasserre C,Peltzer G,et al.2009.Corrections of stratified tropospheric delays in SAR interferometry:Validation with global atmospheric models.Journal of Applied Geophysics,69(1):35-50.
Efron B,Stein C.1981.The jackknife estimate of variance.The AnnalsofStatistics,9(3):586-596.
Elliott J R,Walters R J,England P C,et al.2010.Extension on the Tibetan plateau:recent normal faulting measured by InSARand body wave seismology.Geophysical Journal International,183(2):503-535.
Feng W P,Xu L S,Li Z H.2010.Fault parameters of the October2008Damxung MW6.3earthquake from InSAR inversion and its tectonic implication.Chinese J.Geophys.(in Chinese),53(5):1134-1142,doi:10.3969/j.issn.0001-5733.2010.05.014.
Gao X,Duan Z Q,Wang W M,et al.2010.Rupture process of the Oct.6,2008 MS6.6Damxung earthquake,Tibet,China.Chinese J.Geophys.(in Chinese),53(9):2083-2090,doi:10.3969/j.issn.0001-5733.2010.09.008.
Gray A L,Mattar K E,Sorko G.2000.Influence of ionospheric electron density fluctuations on satellite radar interferometry.Geophysical Research Letters,27(10):1451-1454.
Hetland E A,MuséP,Simons M,et al.2012.Multiscale InSARTime Series(MInTS)analysis of surface deformation.Journal of Geophysical Research,117:B02404,doi:10.1029/2011JB008731.
Hooper A.2008.A multi-temporal InSAR method incorporating both persistent scatterer and small baseline approaches.GeophysicalResearch Letters,35:L16302,doi:10.1029/2008GL034654.
Jolivet R,Grandin R,Lasserre C,et al.2011.Systematic InSARtropospheric phase delay corrections from global meteorological reanalysis data.Geophysical Research Letters,38:L17311,doi:10.1029/2011GL048757.
Jolivet R,Agram P S,Lin N Y,et al.2014.Improving InSARgeodesy using Global Atmospheric Models.Journal of Geophysical Research:Solid Earth,119(3):2324-2341,doi:10.1002/2013JB010588.
Jónsson S,Zebker H,Segall P,et al.2002.Fault slip distribution of the 1999 MW7.1 Hector Mine,California,earthquake,estimated from satellite radar and GPS measurements.Bulletin of the Seismological Society of America,92(4):1377-1389.
Laske G,Masters G,Ma Z T,et al.2013.Update on CRUST1.0-A1-degree global model of earth′s crust.∥EGU General Assembly2013.Vienna,Austria.
Li Z W,Xu W B,Feng G C,et al.2012.Correcting atmospheric effects on InSAR with MERIS water vapour data and elevationdependent interpolation model.Geophysical Journal International,189(2):898-910,doi:10.1111/j.1365-246X.2012.05432.x.
Liu Y,Xu C J,Wen Y M,et al.2012.Fault rupture model of the2008Dangxiong(Tibet,China)MW6.3earthquake from Envisat and ALOS data.Advances in Space Research,50(7):952-962.
Qiao X J,You X Z,Yang S M,et al.2009.Study on dislocation inversion of MS6.6 Damxung earthquake as constrained by InSAR measurement.Journal of Geodesy and Geodynamics(in Chinese),29(6):1-7.
Quenouille M H.1949.Problems in plane sampling.The Annals of Mathematical Statistics,20(3):355-375.
Quenouille M H.1956.Notes on bias in estimation.Biometrika,43(3-4):353-360.
Smith E K,Weintraub S.1953.The constants in the equation for atmospheric refractive index at radio frequencies.Proceedings of the Ire,41(8):1035-1037.
Wang R J,Martín F L,Roth F.2003.Computation of deformation induced by earthquakes in a multi-layered elestic crust-FORTRANprograms EDGRN/EDCMP.Computers&Geosciences,29(2):195-207.
Wang R,Parolai S,Ge M,et al.2013.The 2011 MW9.0Tohoku Earthquake:Comparison of GPS and strong-motion data.Bulletin of the Seismological Society of America,103(2B):1336-1347.
Wu Z H,Ye P S,Wu Z H.2009.The seismic intensity,seismogenic tectonics and mechanism of the MS6.6Damxung earthquake happened on October 6,2008in southern Tibet,China.Geological Bulletin of China(in Chinese),28(6):713-725.
Xu C J,Liu Y,Wen Y M,et al.2010.Coseismic slip distribution of the 2008 MW7.9Wenchuan Earthquake from joint inversion of GPS and InSAR data.Bulletin of the Seismological Society of America,100(5B):2736-2749,doi:10.1785/0120090253.
冯万鹏,许力生,李振洪.2010.2008年10月当雄MW6.3级地震断层参数的InSAR反演及其构造意义.地球物理学报,53(5):1134-1142,doi:10.3969/j.issn.0001-5733.2010.05.014.
高星,段宗奇,王卫民等.2010.2008年10月6日当雄MS6.6级地震破裂过程.地球物理学报,53(9):2083-2090,doi:10.3969/j.issn.0001-5733.2010.09.008.
乔学军,游新兆,杨少敏等.2009.当雄Ms6.6地震的InSAR观测及断层位错反演.大地测量与地球动力学,29(6):1-7.
吴中海,叶培盛,吴珍汉.2009.2008年10月6日西藏当雄MS6.6级强震的地震烈度控震构造和发震机理.地质通报,28(6):713-725.