2008年于田M_W7.2地震滑动分布反演及三维同震形变场解算
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摘要
基于ENVISAT ASAR升降轨数据,利用InSAR获取2008年于田MW7.2地震同震形变场;采用SDM反演本次地震断层滑动分布;使用PSCMP正演获取于田MW7.2地震南北向模拟形变量,并结合升降轨同震形变场,解算三维同震形变场。同震形变场分析表明,2008年于田MW7.2地震以正断为主,且带有走滑运动特征,破裂带走向为NNE向。同震滑动分布反演结果显示,断层沿走向被分为4段F1、F2、F3、F4,其滑动分布集中在0~14km区间,以F2、F3段为主,最大滑动量约5.31m,位于F2段深部2.76km处;沿破裂带走向,左旋走滑位移与垂直位移比值有增大的趋势;反演获得的地震矩M0=5.58×1019 N·m,相当于矩震级MW7.1。三维同震形变场解算结果显示,断层上盘整体表现为沉降,断层下盘整体表现为隆升,且沉降量明显大于隆升量,表明地震以正断破裂为主;除靠近断裂带中上部表现为向东南运动外,上盘整体上表现为向西南运动;断层下盘则整体表现为向东北运动,证明破裂兼有左旋走滑运动。滑动分布反演、正演与三维同震形变场解算结果皆表明,于田MW7.2地震破裂以正断为主,且带有一定的左旋走滑。
We obtained the co-seismic deformation fields of the 2008 Yutian MW7.2 earthquake using InSAR based on ascending and descending orbits of ENVISAT ASAR data.SDM is used to invert the fault slip distribution.Using PSCMP to forward and obtain the simulated NS direction deformation,then combining with the co-seismic deformation fields of ascending and descending orbits to calculate the 3 Dco-seismic deformation field.The analysis of the co-seismic deformation fields shows that the 2008 Yutian MW7.2 earthquake is mainly rupturing along the NNE-trending normal fault with a slight strike-slip component.The inversion of the co-seismic slip distribution shows that the fault is divided into four segments along strike,and slip distribution mainly concentrates in 0 to 14 km depth and fault plane of F2 and F3,the largest slip is about 5.31 mlocated in depth of 2.76 km along the fault plane of F2,the ratio of left-lateral strike-slip deformation to vertical deformation along the rapture tends to increase,the inverted seismic moment is about M0=5.58×1019 N·m,which is equal to a moment magnitude of MW7.10.The result of threedimensional co-seismic deformation field calculation shows that the hanging wall of fault is subsidence deformation,the footwall of fault is uplift deformation,and the subsidence is obviously larger than the uplift,which proves that the earthquake is mainly normal fault.Except that the mid-upper part of the hanging wall near the fault zone moved to ES direction,the hanging wall moved to WS direction,however,the footwall moved EN direction on the whole,which demonstrates that the rupture has left-lateral strike-slip.Forward and inversion of the slip distribution and calculation of three-dimensional deformation field show that the 2008 Yutian MW7.2 earthquake is mainly normal fault with a significant leftlateral strike-slip.
We obtained the co-seismic deformation fields of the 2008 Yutian MW7.2 earthquake using InSAR based on ascending and descending orbits of ENVISAT ASAR data.SDM is used to invert the fault slip distribution.Using PSCMP to forward and obtain the simulated NS direction deformation,then combining with the co-seismic deformation fields of ascending and descending orbits to calculate the 3 Dco-seismic deformation field.The analysis of the co-seismic deformation fields shows that the 2008 Yutian MW7.2 earthquake is mainly rupturing along the NNE-trending normal fault with a slight strike-slip component.The inversion of the co-seismic slip distribution shows that the fault is divided into four segments along strike,and slip distribution mainly concentrates in 0 to 14 km depth and fault plane of F2 and F3,the largest slip is about 5.31 mlocated in depth of 2.76 km along the fault plane of F2,the ratio of left-lateral strike-slip deformation to vertical deformation along the rapture tends to increase,the inverted seismic moment is about M0=5.58×1019 N·m,which is equal to a moment magnitude of MW7.10.The result of threedimensional co-seismic deformation field calculation shows that the hanging wall of fault is subsidence deformation,the footwall of fault is uplift deformation,and the subsidence is obviously larger than the uplift,which proves that the earthquake is mainly normal fault.Except that the mid-upper part of the hanging wall near the fault zone moved to ES direction,the hanging wall moved to WS direction,however,the footwall moved EN direction on the whole,which demonstrates that the rupture has left-lateral strike-slip.Forward and inversion of the slip distribution and calculation of three-dimensional deformation field show that the 2008 Yutian MW7.2 earthquake is mainly normal fault with a significant leftlateral strike-slip.
引文
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[6]陈应涛,张国伟,鲁如魁,等.青藏高原西北缘郭扎错断裂~(40)Ar/~(39)Ar年代学研究:阿尔金断裂西延的新证据[J].地质通报,2010,29(8):1 129-1 137.
[7]徐锡伟,谭锡斌,吴国栋,等.2008年于田MS7.3地震地表破裂带特征及其构造属性讨论[J].地震地质,2011,33(2):462-471.
[8]沈军,宋和平,陈建波,等.2008年3月21日新疆于田7.1级地震近断层破坏作用[J].地学前缘,2013,20(6):85-93.
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[10]Elliott J R,Walters R J,England P C,et al.Extension on the Tibetan plateau:recent normal faulting measured by InSAR and body wave seismology[J].Geophys J Inter,2010,183(2):503-535.
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[12]许丹,姚鑫,陈奇,等.于田地震同震形变场ALOS干涉雷达观测及初步分析[J].地质力学学报,2011,17(4):373-380.
[13]蒋廷臣,李陶,刘经南.基于宽幅SAR干涉测量的新疆于田7.3级地震形变分析[J].大地测量与地球动力学,2012,32(6):13-16.
[14]刘智荣,黄静宜,白相东,等.基于梯度下降法反演于田MW7.1地震同震滑动分布[J].大地测量与地球动力学,2012,32(6):8-12.
[15]洪顺英,单新建,刘智荣,等.新疆于田MW7.2地震3D同震形变场解算与分析[J].大地测量与地球动力学,2013,33(1):6-12.
[16]Rodríguez E,Morris C S,Belz J E,et al.An assessment of the SRTM topographic products[J].2005.
[17]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].Geochemistry,Geophysics,Geosystems,2005,6(1):1-12.
[18]Jónsson S,Zebker H,Segall P,et al.Fault slip distribution of the 1999 MW7.1Hector Mine,California,earthquake,estimated from satellite radar and GPS measurements[J].Bull Seism Soc Am,2002,92(4):1 377-1 389.
[19]Okada Y.Surface deformation due to shear and tensile faults in a half-space[J].Bull Seism Soc Am,1985,75(4):1135-1154.
[20]Wang R,Diao F,Hoechner A.SDM-A geodetic inversion code incorporating with layered crust structure and curved fault geometry[C]//EGU General Assembly Conference.EGU General Assembly Conference Abstracts,2013.
[21]Wang R,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-a new code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geosciences,2006,32(4):527-541.
[2]陈学忠,蒋长胜,李燕娥.2008年3月21日新疆于田7.3级地震[J].国际地震动态,2008(4):18-28.
[3]尹光华,蒋靖祥,吴国栋.2008年3月21日于田7.4级地震的构造背景[J].干旱区地理(汉文版),2008,31(4):543-549.
[4]聂晓红,李莹甄.2008年3月21日新疆于田7.4级地震序列特征及震前部分地震学异常特征[J].内陆地震,2010,24(4):330-339.
[5]李志海,马宏生,曲延军.2008年3月21日新疆于田7.3级地震发震构造与震前地震活动特征研究[J].中国地震,2009,25(2):199-205.
[6]陈应涛,张国伟,鲁如魁,等.青藏高原西北缘郭扎错断裂~(40)Ar/~(39)Ar年代学研究:阿尔金断裂西延的新证据[J].地质通报,2010,29(8):1 129-1 137.
[7]徐锡伟,谭锡斌,吴国栋,等.2008年于田MS7.3地震地表破裂带特征及其构造属性讨论[J].地震地质,2011,33(2):462-471.
[8]沈军,宋和平,陈建波,等.2008年3月21日新疆于田7.1级地震近断层破坏作用[J].地学前缘,2013,20(6):85-93.
[9]Shan X,Zhang G,Wang C,et al.Source characteristics of the Yutian earthquake in 2008from inversion of the co-seismic deformation field mapped by InSAR[J].Journal of Asian Earth Sciences,2011,40(4):935-942.
[10]Elliott J R,Walters R J,England P C,et al.Extension on the Tibetan plateau:recent normal faulting measured by InSAR and body wave seismology[J].Geophys J Inter,2010,183(2):503-535.
[11]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):2 753-2 760.
[12]许丹,姚鑫,陈奇,等.于田地震同震形变场ALOS干涉雷达观测及初步分析[J].地质力学学报,2011,17(4):373-380.
[13]蒋廷臣,李陶,刘经南.基于宽幅SAR干涉测量的新疆于田7.3级地震形变分析[J].大地测量与地球动力学,2012,32(6):13-16.
[14]刘智荣,黄静宜,白相东,等.基于梯度下降法反演于田MW7.1地震同震滑动分布[J].大地测量与地球动力学,2012,32(6):8-12.
[15]洪顺英,单新建,刘智荣,等.新疆于田MW7.2地震3D同震形变场解算与分析[J].大地测量与地球动力学,2013,33(1):6-12.
[16]Rodríguez E,Morris C S,Belz J E,et al.An assessment of the SRTM topographic products[J].2005.
[17]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].Geochemistry,Geophysics,Geosystems,2005,6(1):1-12.
[18]Jónsson S,Zebker H,Segall P,et al.Fault slip distribution of the 1999 MW7.1Hector Mine,California,earthquake,estimated from satellite radar and GPS measurements[J].Bull Seism Soc Am,2002,92(4):1 377-1 389.
[19]Okada Y.Surface deformation due to shear and tensile faults in a half-space[J].Bull Seism Soc Am,1985,75(4):1135-1154.
[20]Wang R,Diao F,Hoechner A.SDM-A geodetic inversion code incorporating with layered crust structure and curved fault geometry[C]//EGU General Assembly Conference.EGU General Assembly Conference Abstracts,2013.
[21]Wang R,Lorenzo-Martín F,Roth F.PSGRN/PSCMP-a new code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geosciences,2006,32(4):527-541.
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