利用GPS和海底基准点观测形变反演日本大地震(Mw 9.0)同震断层滑动分布
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摘要
收集了国际上发布的通过日本区域密集的地表观测数据获得的高精度同震形变位移,同时收集了靠近震中的5个海底基准点观测到的同震变形。基于以上结果采用分断层滑动模型,基于分层弹性半空间位错理论,采用二阶拉普拉斯平滑算子方法约束断层面上的滑动量,利用最速下降法求解模型的最优解,以期精化该地震断层的滑动分布,进而研究其地震活动机制。研究结果表明,日本地震断层的平均滑动为6.95m,最大滑动量为58.70m,位于东经143.17°,北纬38.25°,地震所释放的能量为4.48×1022 N.m(等效震级为Mw9.07),地震断裂主要集中于东经142°～143.8°,北纬37.2°～39.5°,海平面以下10～30km之间区域。
The Mar 11th 2011 Tohoku earthquake(Mw=9.0) is located in northeastern of Japan.The surface observation data were rapidly obtained using the dense continuously GPS stations covered the island after the earthquake broking.In this paper,the reliable co-seismic deformation field is derived from GPS measurements using the highly precise data processing method and sea-floor points set near the epicenter.The co-seismic fault slip distributions are further inverted to explore the seismic mechanism using the steepest descent method to get the optimal solution.The second-order Laplace smoothing operator method had been used to constrain the fault slip amplitude based on the layered elastic half-space homogeneous model.The inversion results show that the energy released by the earthquake is about 4.48 × 1022 N·m equivalent to moment magnitude Mw 9.07.The average fault slip is about 6.05m while the maximum slip is about 58.7 m at 143.17 degrees east longitude and 38.25 degrees north latitude according the GPS and sea-floor points observed co-seismic deformation.The seismic fault characteristic is mostly thrust slip slide at the epicenter while some strike slip slide at the edge of faults.
The Mar 11th 2011 Tohoku earthquake(Mw=9.0) is located in northeastern of Japan.The surface observation data were rapidly obtained using the dense continuously GPS stations covered the island after the earthquake broking.In this paper,the reliable co-seismic deformation field is derived from GPS measurements using the highly precise data processing method and sea-floor points set near the epicenter.The co-seismic fault slip distributions are further inverted to explore the seismic mechanism using the steepest descent method to get the optimal solution.The second-order Laplace smoothing operator method had been used to constrain the fault slip amplitude based on the layered elastic half-space homogeneous model.The inversion results show that the energy released by the earthquake is about 4.48 × 1022 N·m equivalent to moment magnitude Mw 9.07.The average fault slip is about 6.05m while the maximum slip is about 58.7 m at 143.17 degrees east longitude and 38.25 degrees north latitude according the GPS and sea-floor points observed co-seismic deformation.The seismic fault characteristic is mostly thrust slip slide at the epicenter while some strike slip slide at the edge of faults.
引文
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[13]李志才,张鹏,金双根,等,基于GPS观测数据的汶川地震断层形变反演分析[J].测绘学报,2009,38(2),108-113
[14]Okada Y.Internal Deformation Due to Shear andTensile Faults in a Half-space[J].Bull Seism SocAm,1992,82:1 018-1 040
[15]Jonsson S,Zebker H,Segall P,et al.Fault SlipDistribution of the 1999Mw7.1Hector Mine,Cali-fornia,Earthquake,Estimated from Satellite Radarand GPS Measurements[J].Bull Seismol Soc Am,2002,92:1 377-1 389
[2]张勇,许力生,陈运泰.2011年3月11日日本本州东海岸近海地震破裂过程快速反演结果[OL].ht-tp://ddsep.cea-igp.ac.cn/rp/2011/20115 e74367081165e565e5672c672c5dde4e1c6d775cb 88fd16d 7757309707783488c28fc77a0b5feb901f53cd 6f147ed 3679cv2,2012
[3]Shao Guangfu,Li Xiangyu,Ji Chen.PreliminaryResult of the Mar 11,2011Mw 9.1Honshu Earth-quake[OL].http://www.geol.ucsb.edu/faculty/ji/big_earthquakes/2011/03/0311_v3/Honshu.ht-ml,2012
[4]Charles J,Thorne L,Hiroo K.A Rupture Modelof the Great 2011 Tohoku Earthquake[J].EarthPlanets Space,2011,63:693-696
[5]Simons M,Minson S E,Sladen A,et al,The 2011Magnitude 9.0Tohoku-Oki Earthquake:Mosaick-ing the Megathrust from Seconds to Centuries[J].Science,2011,332(6 036):1421-1425
[6]Hayes G.Updated Result of the Mar 11,2011 Mw9.0Earthquake Offshore Honshu,Japan[OL].ht-tp://earthquake.usgs.gov/earthquakes/eqinthe-news/2011/usc0001xgp/finite_fault.php,2012
[7]Hayes G.Subduction Zone Geometry Analysis:Preliminary SZGC Results for M 8.9 Earthquakenear East Coast of Honshu,Japan[OL].http://earthquake.usgs.gov/earthquakes/eqarchives/sub-duction_zone/usc0001xgp/,2012
[8]Ozawa S,Nishimura T,Suito H,et al.Coseismicand Postseismic Slip of the 2011 magnitude-9 To-hoku-Oki Earthquake[J].Nature,2011,475(7356),doi:10.1038/nature10227
[9]Takeo I,Kazuhiro O,Tsuyoshi W,et al.Slip Dis-tribution of the 2011 Tohoku Earthquake Inferredfrom Geodetic Data[J].Earth Planets Space,2011,63:627-630
[10]刁法启,熊熊,倪四道,等.利用GPS位移反演日本Mw9.0仙台地震及Mw7.9强余震静态位错模型[J].科学通报,2011,56(24):1999-2005
[11]李志才,许才军,赵少荣,等.基于地壳分层的震后变形分析[J].武汉大学学报.信息科学版,2006,31(3):203-208
[12]李志才,许才军,张鹏,等.基于地壳分层的地震断层同震变形反演分析[J].武汉大学学报.信息科学版,2008,33(3):229-231
[13]李志才,张鹏,金双根,等,基于GPS观测数据的汶川地震断层形变反演分析[J].测绘学报,2009,38(2),108-113
[14]Okada Y.Internal Deformation Due to Shear andTensile Faults in a Half-space[J].Bull Seism SocAm,1992,82:1 018-1 040
[15]Jonsson S,Zebker H,Segall P,et al.Fault SlipDistribution of the 1999Mw7.1Hector Mine,Cali-fornia,Earthquake,Estimated from Satellite Radarand GPS Measurements[J].Bull Seismol Soc Am,2002,92:1 377-1 389
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