青海玉树Mw6.9级地震震源破裂过程
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摘要
针对2010年青海玉树藏族自治州发生的Mw6.9(Ms7.1)级地震,利用地震波形资料和InSAR获取的同震位移资料,根据同震形成的地表位移干涉图,构建三段式断层模型,反演重建地震的破裂过程。研究显示本次地震断层面走向为119°,倾角79°,滑动角-2.2°,最大滑动量达到200cm,震源深度12.5km,地震标量地震矩为2.18×1026dyn·cm。震源破裂特征表明,玉树地震主要是沿甘孜—玉树断裂发生的左旋走滑破裂事件,反映了印度板块向北的推挤作用下,青藏高原东部不同次级块体东向不均匀挤出的运动学特征。
On April 14, 2010, an Ms7.1 earthquake struck Yushu County in Qinghai Province. Based on the coseismic surface deformation interferogram, the authors created a three-part style finite-fault model, and reconstructed the source rupture process by utilizing the teleseismic waveform data and local coseismic displacement information obtained by InSAR. The inversion results show that the fault plane of the Yushu earthquake has a strike of 119° and a dip of 79°, with the focal depth being 12.5km, consistent with a moment release of 2.18×1026dyn·cm. It is characterized mainly by left-lateral strike slip motion along with Yushu-Ganzi fault, indicating the existence of inhomogeneous extrusion of different blocks in eastern Tibetan Plateau.
On April 14, 2010, an Ms7.1 earthquake struck Yushu County in Qinghai Province. Based on the coseismic surface deformation interferogram, the authors created a three-part style finite-fault model, and reconstructed the source rupture process by utilizing the teleseismic waveform data and local coseismic displacement information obtained by InSAR. The inversion results show that the fault plane of the Yushu earthquake has a strike of 119° and a dip of 79°, with the focal depth being 12.5km, consistent with a moment release of 2.18×1026dyn·cm. It is characterized mainly by left-lateral strike slip motion along with Yushu-Ganzi fault, indicating the existence of inhomogeneous extrusion of different blocks in eastern Tibetan Plateau.
引文
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[18]Okada Y.Surface deformation due to shear and tensile fault in a half-space[J].Bull.Seism.Soc.Am.,1985,75:1135-1154.
[2]王敏,沈正康,甘卫军,等.GPS连续监测鲜水河断裂形变场动态演化[J].中国科学(D辑),2008,38(5):575-581.
[3]邓起东,高翔,陈桂华,等.汶川地震系列与巴颜喀拉断块的最新活动[J].地学前缘,2010,17(5):163-178.
[4]周春景,吴中海,尼玛次仁,等.青海玉树Ms7.1级地震同震地表破裂构造[J].地质通报,2014,33(4):551-566.
[5]孙鑫喆,徐锡伟,陈立春,等.2010年玉树地震地表破裂带典型破裂样式及其构造意义[J].地球物理学报,2012,55(1):155-170.
[6]Massonnet D,Rossi M,Carmona C,et al.The displacement field of the Landers earthquake mapped by radar interferometry[J].Natrue,1993,364:138-142.
[7]Feil K L,Sarti F,Vadon H,et al.Estimating slip distribution for the Izmitmainshock from coseismic GPS,ERS-1,RADARSAT,and SPOT measurements[J].Bull.Seism.Soc.Am.,2002,92(1):138-160.
[8]Lasserre C,Peltzer G,Crampe F,et al.Coseismic deformation of the2001 Mw7.8 kokoxili Earthquake in Tibet,measured by synthetic aperture radar interferometry[J].J.Geophys.Res.,2005,110:B12408.doi:10.1029/2004JB003500.
[9]Funning G J,Parsons B,Wright T J.Fault slip in the 1997 Manyi,Tibet earthquake from linear elastic modeling of InSAR displacements[J].Geophys.J.Int.,2007,169(3):988-1008.
[10]Shen Z K,Sun J B,Zhang P Z,et al.Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake[J].Nature Geoscience,2009,2(10):718-724.
[11]姚振兴,纪晨.时间域有限地震断层的反演问题[J].地球物理学报,1997,40(5):691-701.
[12]王卫民,赵连锋,李娟,等.1999年台湾集集地震震源破裂过程[J].地球物理学报,2005,48(1):132-147.
[13]王卫民,赵连锋,李娟,等.四川汶川8.0级地震震源过程[J].地球物理学报,2008,51(5):1403-1410.
[14]Wang W M,He Y M,Yao Z X.Complexity of the coseismicrupture for 1999 Chi-Chi,Taiwan,Earthquake from inversion of GPS observations[J].Tectonophysics,2004,382:151-172.
[15]张国宏,屈春燕,单新建,等.2008年Ms7.1于田地震InSAR同震形变场及其震源滑动反演[J].地球物理学报,2011,54(11):2753-2760.
[16]Lohman R B,Simons M.Some thoughts on the use of InSAR data to constrain models of surface deformation:Noise structure and data downsampling[J].Geochem.Geophys.Geosyst.,2005,6(1)Q01007.doi:10.1029/2004GC000841.
[17]Lomax A,Michelini A,Piatanesi A.An energy-durationprocedure for rapid determination of earthquake magnitudeand tsunamigenic potential[J].Geophys.J.Int.,2007,170:1195-1209.
[18]Okada Y.Surface deformation due to shear and tensile fault in a half-space[J].Bull.Seism.Soc.Am.,1985,75:1135-1154.