联合地震波和大地测量数据反演2015年皮山M_W6.4地震的同震破裂分布
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摘要
2015年7月3日在西昆仑推覆构造带前缘发生了M_W6. 4新疆皮山地震,是近40a以来该区域发生的最大的一次中强地震。文中利用近场大地测量数据,包括4个高精度GPS点和一景高空间分辨率ALOS-2 In SAR干涉数据,联合IRIS/USGS提供的25个远震台网P波数据,基于有限断层理论,采取多参数非线性模拟退火算法反演了此次地震的同震破裂模型。联合反演的断层滑移模型显示皮山地震的主破裂区深度集中于9～16km,最大滑移量为95cm,释放的矩能量相当于M_W6. 42,且沿断层走向N302°W单侧破裂,与余震分布吻合。通过与单一数据源反演结果进行对比分析,文中采用的多源数据可以同时约束地震矩能量和断层破裂分布,有效解决了远震台网波形数据模型空间分辨率低(尤其对中强地震而言)和近场大地测量数据在地震矩评估方面不够精确的问题。
On July 3 rd,2015,a M_W6. 4 earthquake occurred on Pishan County,Xinjiang,located in the front of western Kunlun thrust belt,which is the largest earthquake( M_W6. 0 ～ 7. 0) in the past 40 years in this region. In this study, we collected both the near-filed geodetic coseismic deformation observations including 4 GPS sites and one high-resolution ALOS-2 In SAR imagery,and far-field teleseismic P waveforms from 25 stations provided by IRIS/USGS,to invert the fault parameters( strike and dip) and coseismic rupture model of 2015 M_W6. 4 Pishan earthquake. Using the finite fault theory,a non-linear simulated annealing algorithm was employed to resolve our joint inversion problem. The strike( 120° ～ 130°) and dip angle( 35° ～ 40°) of optimal models are different from that of some previous studies,and the dip change is strongly constrained by combined data than that of strike. In fixing the geometric parameters of optimal fault model,we also considered data weight( 5)( geodetic data/teleseismic P waveforms) and constrained weight from moment and smooth factor( 2. 5). Clearly,our results indicate that the slip distribution mainly concentrates in the depth range from 9 to 16 km and a length range of 20 km along the strike direction,which is similar to the spatial distribution of the relocated aftershocks. The maximum slip is ～ 95 cm. The seismic moment release is5. 45×1018 N·m,corresponding to M_W6. 42. Compared with the single data set,geodetic data or teleseismic waveform,our joint inversion model could simultaneously constrain the seismic moment and slip distribution well,thus avoiding effectively a lower-resolution rupture distribution determined by teleseismic-only inversion and a bias released moment estimated by the geodetic-only inversion.Importantly,we should consider both the near-field geodetic data and far-field teleseismic data in retrieving the rupture model for accurately describing the seismogenic structure of active fault in western Kunlun region.
On July 3 rd,2015,a M_W6. 4 earthquake occurred on Pishan County,Xinjiang,located in the front of western Kunlun thrust belt,which is the largest earthquake( M_W6. 0 ～ 7. 0) in the past 40 years in this region. In this study, we collected both the near-filed geodetic coseismic deformation observations including 4 GPS sites and one high-resolution ALOS-2 In SAR imagery,and far-field teleseismic P waveforms from 25 stations provided by IRIS/USGS,to invert the fault parameters( strike and dip) and coseismic rupture model of 2015 M_W6. 4 Pishan earthquake. Using the finite fault theory,a non-linear simulated annealing algorithm was employed to resolve our joint inversion problem. The strike( 120° ～ 130°) and dip angle( 35° ～ 40°) of optimal models are different from that of some previous studies,and the dip change is strongly constrained by combined data than that of strike. In fixing the geometric parameters of optimal fault model,we also considered data weight( 5)( geodetic data/teleseismic P waveforms) and constrained weight from moment and smooth factor( 2. 5). Clearly,our results indicate that the slip distribution mainly concentrates in the depth range from 9 to 16 km and a length range of 20 km along the strike direction,which is similar to the spatial distribution of the relocated aftershocks. The maximum slip is ～ 95 cm. The seismic moment release is5. 45×1018 N·m,corresponding to M_W6. 42. Compared with the single data set,geodetic data or teleseismic waveform,our joint inversion model could simultaneously constrain the seismic moment and slip distribution well,thus avoiding effectively a lower-resolution rupture distribution determined by teleseismic-only inversion and a bias released moment estimated by the geodetic-only inversion.Importantly,we should consider both the near-field geodetic data and far-field teleseismic data in retrieving the rupture model for accurately describing the seismogenic structure of active fault in western Kunlun region.
引文
李金,王琼,吴传勇,等.2016.2015年7月3日皮山6.5级地震发震构造初步研究[J].地球物理学报,59(8):2859-2870.LI Jin,WANG Qiong,WU Chuan-yong,et al.2016.Preliminary study for seismogenic structure of the Pishan MS6.5earthquake of July 3 2015[J].Chinese Journal of Geophysics,59(8):2859-2870(in Chinese).
李杰,王晓强,王琪,等.2012.2008年于田7.3级地震前西昆仑地形变的GPS初步研究[J].西北地震学报,34(3):256-263.LI Jie,WANG Xiao-qiang,WANG Qi,et al.2012.Crustal deformation in western Kunlun tectonic zone from GPSmeasurements before the Yutian MS7.3 earthquake in 2008[J].Northwestern Seismological Journal,34(3):256-263(in Chinese).
刘成利,郑勇,葛粲,等.2013.2013年MS7.0芦山地震同震破裂过程[J].中国科学(D辑),56(7):1187-1192.LIU Cheng-li,ZHENG Yong,GE Can,et al.2013.Rupture process of the MS7.0 Lushan earthquake,2013[J].Science in China(Ser D),56(7):1187-1192(in Chinese).
许才军,何平,温扬茂,等.2012.日本2011 Tohoku-Oki MW9.0地震的同震形变及其滑动分布反演:GPS和In SAR约束[J].武汉大学学报:信息科学版,37(12):1387-1391.XU Cai-jun,HE Ping,WEN Yang-mao,et al.2012.Coseismic deformation and slip distribution for 2011 Tohoku-Oki MW9.0 earthquake:Constrained by GPS and In SAR[J].Geomatics and Information Science of Wuhan University,37(12):1387-1391(in Chinese).
张广伟,张洪艳,孙长青.2016.2015年新疆皮山MS6.5地震震源机制及余震序列定位[J].地震地质,38(3):711-720.doi:10.3969/j.issn.0253-4967.2016.03016.ZHANG Guang-wei,ZHANG Hong-yan,SUN Chang-qing.2016.Mechanism of the 2015 Pishan,Xinjiang,MS6.5mainshock and relocation of its aftershock sequences[J].Seismology and Geology,38(3):711-720(in Chinese).
Avouac J P,Peltzer G.1993.Active tectonics in southern Xinjiang,China:Analysis of terrace riser and normal fault scarp degradation along the Hotan-Qira fault system[J].Journal of Geophysical Research:Solid Earth,98(B12):21773-21807.
Feng G,Li Z,Xu B,et al.2016.Coseismic deformation of the 2015 MW6.4 Pishan,China,earthquake estimated from Sentinel-1A and ALOS-2 data[J].Seismological Research Letters,87(4):800-806.
Hartzell S H,Liu P,Mendoza C.1996.The 1994 Northridge,California earthquake:Investigation of rupture velocity,risetime,and high-frequency radiation[J].Journal of Geophysical Research:Solid Earth,101(B9):20091-20108.
He P,Wang Q,Ding K,et al.2016.Source model of the 2015 MW6.4 Pishan earthquake constrained by In SAR and GPS:Insight into blind rupture in the western Kunlun Shan[J].Geophysical Research Letters,43(4):1511-1519.
Ji C,Helmberger D V,Wald D J,et al.2003.Slip history and dynamic implications of the 1999 Chi-Chi,Taiwan,earthquake[J].Journal of Geophysical Research,108(B9):2412,(5):1-20.
Ji C,Wald D J,Helmberger D V.2002a.Source description of the 1999 Hector Mine,California,earthquake,partⅠ:Wavelet domain inversion theory and resolution analysis[J].Bulletin of the Seismological Society of America,92:1192-1207.
Ji C,Wald D J,Helmberger D V.2002b.Source description of the 1999 Hector Mine,California,earthquake,partⅡ:Complexity of slip history[J].Bulletin of the Seismological Society of America,92(4):1192-1207.
Jiang X,Li Z,Li H.2013.Uplift of the West Kunlun Range,northern Tibetan plateau,dominated by brittle thickening of the upper crust[J].Geology,41(4):439-442.
Li T,Chen J,Fang L,et al.2016.The 2015 MW6.4 Pishan earthquake:Seismic hazards of an active blind wedge thrust system at the western Kunlun range front,northwest Tibetan plateau[J].Seismological Research Letters,87(3):601-608.
Lu R,Xu X,He D,et al.2016.Coseismic and blind fault of the 2015 Pishan MW6.5 earthquake:Implications for the sedimentary-tectonic framework of the western Kunlun Mountains,northern Tibetan plateau[J].Tectonics,35(4):956-964.
Pritchard M E,Ji C,Simons M.2006.Distribution of slip from 11 MW>6 earthquakes in the northern Chile subduction zone[J].Journal of Geophysical Research:Solid Earth,111(B10):B10302.
Pritchard M E,Norabuena E O,Jillings C,et al.2007.Geodetic,teleseismic,and strong motion constraints on slip from recent southern Peru subduction zone earthquakes[J].Journal of Geophysical Research:Solid Earth,112(B3):B03307.
Qiao X,Wang Q,Yang S,et al.2015.The 2008 Nura MW6.7 earthquake:A shallow rupture on the Main Pamir Thrust revealed by GPS and In SAR[J].Geodesy and Geodynamics,6(2):91-100.
Sun J,Shen Z K,Li T,et al.2016.Thrust faulting and 3-D ground deformation of the 3 July 2015 MW6.4 Pishan,China earthquake from Sentinel-1A radar interferometry[J].Tectonophysics,683:77-85.
Wang Q,Qiao X,Lan Q,et al.2011.Rupture of deep faults in the 2008 Wenchuan earthquake and uplift of the Longmen Shan[J].Nature Geoscience,4(9):634-640.
Wang Q,Zhang P Z,Freymueller J T,et al.2001.Present-day crustal deformation in China constrained by global positioning system measurements[J].Science,294(5542):574-577.
Wen Y,Xu C,Liu Y,et al.2016.Deformation and source parameters of the 2015 MW6.5 earthquake in Pishan,western China,from Sentinel-1A and ALOS-2 data[J].Remote Sensing,8(2):134-147.
Yue H,Lay T,Rivera L,et al.2014.Localized fault slip to the trench in the 2010 Maule,Chile MW8.8 earthquake from joint inversion of high-rate GPS,teleseismic body waves,In SAR,campaign GPS,and tsunami observations[J].Journal of Geophysical Research:Solid Earth,119(10):7786-7804.
Zhang G H,Shan X J,Zhang Y,et al.2016.Blind thrust rupture of the 2015 MW6.4 Pishan earthquake in the northwest Tibetan plateau by joint inversion of In SAR and seismic data[J].Journal of Asian Earth Sciences,132:118-128.
(1)http:∥www.iris.edu/hq/programs/gsn。
李杰,王晓强,王琪,等.2012.2008年于田7.3级地震前西昆仑地形变的GPS初步研究[J].西北地震学报,34(3):256-263.LI Jie,WANG Xiao-qiang,WANG Qi,et al.2012.Crustal deformation in western Kunlun tectonic zone from GPSmeasurements before the Yutian MS7.3 earthquake in 2008[J].Northwestern Seismological Journal,34(3):256-263(in Chinese).
刘成利,郑勇,葛粲,等.2013.2013年MS7.0芦山地震同震破裂过程[J].中国科学(D辑),56(7):1187-1192.LIU Cheng-li,ZHENG Yong,GE Can,et al.2013.Rupture process of the MS7.0 Lushan earthquake,2013[J].Science in China(Ser D),56(7):1187-1192(in Chinese).
许才军,何平,温扬茂,等.2012.日本2011 Tohoku-Oki MW9.0地震的同震形变及其滑动分布反演:GPS和In SAR约束[J].武汉大学学报:信息科学版,37(12):1387-1391.XU Cai-jun,HE Ping,WEN Yang-mao,et al.2012.Coseismic deformation and slip distribution for 2011 Tohoku-Oki MW9.0 earthquake:Constrained by GPS and In SAR[J].Geomatics and Information Science of Wuhan University,37(12):1387-1391(in Chinese).
张广伟,张洪艳,孙长青.2016.2015年新疆皮山MS6.5地震震源机制及余震序列定位[J].地震地质,38(3):711-720.doi:10.3969/j.issn.0253-4967.2016.03016.ZHANG Guang-wei,ZHANG Hong-yan,SUN Chang-qing.2016.Mechanism of the 2015 Pishan,Xinjiang,MS6.5mainshock and relocation of its aftershock sequences[J].Seismology and Geology,38(3):711-720(in Chinese).
Avouac J P,Peltzer G.1993.Active tectonics in southern Xinjiang,China:Analysis of terrace riser and normal fault scarp degradation along the Hotan-Qira fault system[J].Journal of Geophysical Research:Solid Earth,98(B12):21773-21807.
Feng G,Li Z,Xu B,et al.2016.Coseismic deformation of the 2015 MW6.4 Pishan,China,earthquake estimated from Sentinel-1A and ALOS-2 data[J].Seismological Research Letters,87(4):800-806.
Hartzell S H,Liu P,Mendoza C.1996.The 1994 Northridge,California earthquake:Investigation of rupture velocity,risetime,and high-frequency radiation[J].Journal of Geophysical Research:Solid Earth,101(B9):20091-20108.
He P,Wang Q,Ding K,et al.2016.Source model of the 2015 MW6.4 Pishan earthquake constrained by In SAR and GPS:Insight into blind rupture in the western Kunlun Shan[J].Geophysical Research Letters,43(4):1511-1519.
Ji C,Helmberger D V,Wald D J,et al.2003.Slip history and dynamic implications of the 1999 Chi-Chi,Taiwan,earthquake[J].Journal of Geophysical Research,108(B9):2412,(5):1-20.
Ji C,Wald D J,Helmberger D V.2002a.Source description of the 1999 Hector Mine,California,earthquake,partⅠ:Wavelet domain inversion theory and resolution analysis[J].Bulletin of the Seismological Society of America,92:1192-1207.
Ji C,Wald D J,Helmberger D V.2002b.Source description of the 1999 Hector Mine,California,earthquake,partⅡ:Complexity of slip history[J].Bulletin of the Seismological Society of America,92(4):1192-1207.
Jiang X,Li Z,Li H.2013.Uplift of the West Kunlun Range,northern Tibetan plateau,dominated by brittle thickening of the upper crust[J].Geology,41(4):439-442.
Li T,Chen J,Fang L,et al.2016.The 2015 MW6.4 Pishan earthquake:Seismic hazards of an active blind wedge thrust system at the western Kunlun range front,northwest Tibetan plateau[J].Seismological Research Letters,87(3):601-608.
Lu R,Xu X,He D,et al.2016.Coseismic and blind fault of the 2015 Pishan MW6.5 earthquake:Implications for the sedimentary-tectonic framework of the western Kunlun Mountains,northern Tibetan plateau[J].Tectonics,35(4):956-964.
Pritchard M E,Ji C,Simons M.2006.Distribution of slip from 11 MW>6 earthquakes in the northern Chile subduction zone[J].Journal of Geophysical Research:Solid Earth,111(B10):B10302.
Pritchard M E,Norabuena E O,Jillings C,et al.2007.Geodetic,teleseismic,and strong motion constraints on slip from recent southern Peru subduction zone earthquakes[J].Journal of Geophysical Research:Solid Earth,112(B3):B03307.
Qiao X,Wang Q,Yang S,et al.2015.The 2008 Nura MW6.7 earthquake:A shallow rupture on the Main Pamir Thrust revealed by GPS and In SAR[J].Geodesy and Geodynamics,6(2):91-100.
Sun J,Shen Z K,Li T,et al.2016.Thrust faulting and 3-D ground deformation of the 3 July 2015 MW6.4 Pishan,China earthquake from Sentinel-1A radar interferometry[J].Tectonophysics,683:77-85.
Wang Q,Qiao X,Lan Q,et al.2011.Rupture of deep faults in the 2008 Wenchuan earthquake and uplift of the Longmen Shan[J].Nature Geoscience,4(9):634-640.
Wang Q,Zhang P Z,Freymueller J T,et al.2001.Present-day crustal deformation in China constrained by global positioning system measurements[J].Science,294(5542):574-577.
Wen Y,Xu C,Liu Y,et al.2016.Deformation and source parameters of the 2015 MW6.5 earthquake in Pishan,western China,from Sentinel-1A and ALOS-2 data[J].Remote Sensing,8(2):134-147.
Yue H,Lay T,Rivera L,et al.2014.Localized fault slip to the trench in the 2010 Maule,Chile MW8.8 earthquake from joint inversion of high-rate GPS,teleseismic body waves,In SAR,campaign GPS,and tsunami observations[J].Journal of Geophysical Research:Solid Earth,119(10):7786-7804.
Zhang G H,Shan X J,Zhang Y,et al.2016.Blind thrust rupture of the 2015 MW6.4 Pishan earthquake in the northwest Tibetan plateau by joint inversion of In SAR and seismic data[J].Journal of Asian Earth Sciences,132:118-128.
(1)http:∥www.iris.edu/hq/programs/gsn。
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