升降轨道ASAR雷达干涉揭示的巴姆地震(Mw6.5)3D同震形变场
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摘要
通过对覆盖同一地区的升降轨道ASAR雷达数据进行两路差分干涉(D-INSAR)处理,得到了2003年12月26日伊朗巴姆(Bam)地震(Mw6.5)在两种成像几何状态下的视线向(LOS)同震形变场。利用Okada弹性形变模型对形变场进行正演计算,得到地震断层的几何参数及形变的南北向分量。对得到的干涉条纹图进行相位解绕处理,综合分析两种不同的雷达成像几何关系,并利用模型估计得到的南北向分量,计算了该地震造成的3D同震形变场,结果显示了典型的单断层右旋走滑活动特征。研究表明,合并升降轨道雷达数据,能够为形变模型提供有效约束,用一条简化的断层模型就可以解释升降两条轨能的干涉形变场,更为复杂的双断层模型是不必要的。
We processed the ascending and descending pass ASAR radar data that covers the same area using 2-pass D-INSAR technology,and got the co-seismic deformation field in LOS direction of the Bam(Iran) earthquake(Mw6.5), which happened on Dec 26,2003,with two kinds of imaging geometry.After forward modeling of the co-seismic INSAR results using(Okada's) elastic model in half-space,we got the geometric parameters of the seismic fault and the north-south component of the deformation field.We unwrapped the interferometric phase and computed its 3D co-seismic deformation field by combining the two kinds of imaging geometry and the north-south component from(Okada's) model.The 3D deformation field shows typical characteristics of single right-lateral strike-slip fault.The research also shows that integration of ascending and descending pass radar data could provide effective constraints for deformation models.The Bam Co-seismic deformation field could be interpreted by the simplified 1-fault model,therefore the complex 2-fault model is unnecessary.
We processed the ascending and descending pass ASAR radar data that covers the same area using 2-pass D-INSAR technology,and got the co-seismic deformation field in LOS direction of the Bam(Iran) earthquake(Mw6.5), which happened on Dec 26,2003,with two kinds of imaging geometry.After forward modeling of the co-seismic INSAR results using(Okada's) elastic model in half-space,we got the geometric parameters of the seismic fault and the north-south component of the deformation field.We unwrapped the interferometric phase and computed its 3D co-seismic deformation field by combining the two kinds of imaging geometry and the north-south component from(Okada's) model.The 3D deformation field shows typical characteristics of single right-lateral strike-slip fault.The research also shows that integration of ascending and descending pass radar data could provide effective constraints for deformation models.The Bam Co-seismic deformation field could be interpreted by the simplified 1-fault model,therefore the complex 2-fault model is unnecessary.
引文
[1]Eshgh i S,ZaréM.Bam(SE Iran)Earthquake of 26 D ecember2003,Mw6.5:A Prelim inary Reconnaissance Report,W ebsite:http://www.iiees.ac.ir/English/bam_report_english_recc.htm l2003.
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[3]W ang C,L iu Z,Zhang H.Co-seism ic D eformation F ield ofZhangbei-Shangyi Earthquake from SAR Interferom etry[J].China Science Bulletin,2000,45(23):2550—2554.[王超,刘智,张红等.张北—尚义地震同震形变场雷达差分涉测量[J].科学通报,2000,45(23):2550—2554.]
[4]D iao G L,Zhang S C,Cai H C,et al.Cause of Formation ofD eformation F ield Near the Zhangbei Earthquake[J].ChinaScience Bulletin,2004,49(12):1214—1216.[刁桂苓,张四昌,蔡华昌等.张北震区附近形变的成因[J].科学通报,2004,49(12):1214—1216.]
[5]Okada Y.Surface D eformation due to Shear and Tensile Fau lts ina Half-space,Bu ll[J].Seism ological Society ofAm erica,1985,75:1135—1154.
[6]Taleb ian M.,F ield ing E J.Funn ing G J,et a.l The 2003 Bam(Iran)Earthquake-rupture of a b lind Strike-slip Fau lt[J].Geophysical Research Letters,2004,31:L11611,doi:10.1029/2004GL020058.
[7]Vernant P,N ilforoushan F,Hatzfeld,et a.l Present-day C rustD eformation and P late K inematics in theM idd le East Constrainedby GPS M easurem ents in Iran and Northern Oman[J].Geophy.J.In,t 2004,157:381—398.
[8]N ilforoushan F,Masson F,Vernant P,et a.l GPS NetworkMon itors the Arab ia-Eurasia Collision D eformation in Iran[J].J.ofGeodesy,2003,77:411—422.
[9]W alker R,Jackson J.O ffset and Evolution of the Gowk Fau lt,S.E.Iran:A Major Intra-continental Strike-slip System[J].J.ofStructural Geolog,y 2002,24:1677—1689.
[10]Lyons N S.Investigation of Fau lt C reep in Southern Californ iaUsing Interferom etric Synthetic Aperture Radar and GPS[D].PhD.Thesis,Un iversity of Californ ia,SAN D IEGO,2002.
[11]KanamoriH.The Energy Release in G reat Earthquakes[J].J.Geophysics Reasearch,1977,82:2981—2987.
[2]Peltzer G,Frederic C rampe,Geoffrey K ing.Evidence ofNon linear E lasticity of the C rust from the Mw7.6 Manyi(Tibet)Earthquake[J].Science,1999,286:272—276.
[3]W ang C,L iu Z,Zhang H.Co-seism ic D eformation F ield ofZhangbei-Shangyi Earthquake from SAR Interferom etry[J].China Science Bulletin,2000,45(23):2550—2554.[王超,刘智,张红等.张北—尚义地震同震形变场雷达差分涉测量[J].科学通报,2000,45(23):2550—2554.]
[4]D iao G L,Zhang S C,Cai H C,et al.Cause of Formation ofD eformation F ield Near the Zhangbei Earthquake[J].ChinaScience Bulletin,2004,49(12):1214—1216.[刁桂苓,张四昌,蔡华昌等.张北震区附近形变的成因[J].科学通报,2004,49(12):1214—1216.]
[5]Okada Y.Surface D eformation due to Shear and Tensile Fau lts ina Half-space,Bu ll[J].Seism ological Society ofAm erica,1985,75:1135—1154.
[6]Taleb ian M.,F ield ing E J.Funn ing G J,et a.l The 2003 Bam(Iran)Earthquake-rupture of a b lind Strike-slip Fau lt[J].Geophysical Research Letters,2004,31:L11611,doi:10.1029/2004GL020058.
[7]Vernant P,N ilforoushan F,Hatzfeld,et a.l Present-day C rustD eformation and P late K inematics in theM idd le East Constrainedby GPS M easurem ents in Iran and Northern Oman[J].Geophy.J.In,t 2004,157:381—398.
[8]N ilforoushan F,Masson F,Vernant P,et a.l GPS NetworkMon itors the Arab ia-Eurasia Collision D eformation in Iran[J].J.ofGeodesy,2003,77:411—422.
[9]W alker R,Jackson J.O ffset and Evolution of the Gowk Fau lt,S.E.Iran:A Major Intra-continental Strike-slip System[J].J.ofStructural Geolog,y 2002,24:1677—1689.
[10]Lyons N S.Investigation of Fau lt C reep in Southern Californ iaUsing Interferom etric Synthetic Aperture Radar and GPS[D].PhD.Thesis,Un iversity of Californ ia,SAN D IEGO,2002.
[11]KanamoriH.The Energy Release in G reat Earthquakes[J].J.Geophysics Reasearch,1977,82:2981—2987.
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