地震研究

2016年11月25日新疆阿克陶MS6.7地震发生在帕米尔构造结的弧顶地区、木吉断陷盆地西端附近,此次地震主震破裂过程复杂,根据地震波反演确定的震源机制解也存在较大差异。利用InSAR技术处理Sentinel-1 SAR影像数据获取了此次地震的同震形变场,基于弹性半空间位错模型,确定了断层几何参数和滑动分布模型。结果表明,分布式滑动模型能较好地解释观测到的InSAR地表形变场。本次地震包括了至少2次破裂子事件,分别位于中国地震台网测定的震中以东约7 km处(74.11°E,39.25°N)、以东约33 km处(74.49°E,39.16°N)。地震引起的形变场呈上下对称性分布,最大LOS向形变量为20 cm。地震同震位错以右旋走滑为主,主要的滑动量集中在地下深度0～20 km处,最大滑动量为0.84 m。发震断层为木吉断裂,此次地震显示印度板块的北东向推挤作用在增强。

The Akto MS6.7 earthquake,Xinjiang occurred near the western end of the Muji fault basin in the top of the Pamir syntax.The main shock of this earthquake is complicated and the focal mechanism solutions show differences based on seismic wave inversions.Based on the Sentinel-1 SAR image data,the coseismic deformation field of the earthquake is obtained by InSAR technique.Based on the elastic half-space dislocation model,the geometrical parameters and the slip distribution model are determined by nonlinear and linear inversion algorithms.The results show that the distributed slip model can well explain the coseismic deformation field.The earthquake includes at least two rupture events,which are located at 7 km(74.11 ° E,39.25 ° N)and 33 km(74.49 ° E,39.16 ° N)east of the epicenter of the CENC.The deformation field caused by the earthquake shows symmetric distributions,with the maximum deformation(LOS)of 20 cm.The main seismic slip is concentrated in the 0～20 km depth,and the maximum slip is 0.84 m.The seismic fault is the Muji fault,and this earthquake shows that the N-E thrust of the Indian plate is enhanced.

引言
1 研究区概况
2 InSAR观测及结果
3 断层参数与滑动分布反演
4 讨论
5 结论

图1 2016年11月25日阿克陶地震震中区域及邻区地形、断层、GPS速度场及InSAR数据分布<br/>Fig.1 Topography,fault,GPS velocity field and InSAR data distribution of the epicenter and surrounding areas of the Akto earthquake

图1 2016年11月25日阿克陶地震震中区域及邻区地形、断层、GPS速度场及InSAR数据分布
Fig.1 Topography,fault,GPS velocity field and InSAR data distribution of the epicenter and surrounding areas of the Akto earthquake

表1 不同机构给出的2016年11月25日阿克陶地震震源参数<br/>Tab.1 Focal mechanisms of the Akto earthquake occurred on Nov.25,2016 from different institutions

表1 不同机构给出的2016年11月25日阿克陶地震震源参数
Tab.1 Focal mechanisms of the Akto earthquake occurred on Nov.25,2016 from different institutions

图2 不同机构给出的2016年阿克陶地震震源机制解<br/>Fig.2 Focal mechanism solutions of the 2016 Akto earthquake from different institutions

图2 不同机构给出的2016年阿克陶地震震源机制解
Fig.2 Focal mechanism solutions of the 2016 Akto earthquake from different institutions

图3 2016年阿克陶MS6.7地震InSAR同震形变场(LOS方向)<br/>Fig.3 InSAR coseismic deformation fields(in LOS direction)of the 2016 Akto MS6.7 earthquake

图3 2016年阿克陶MS6.7地震InSAR同震形变场(LOS方向)
Fig.3 InSAR coseismic deformation fields(in LOS direction)of the 2016 Akto MS6.7 earthquake

表2 SAR 数据基本信息<br/>Tab.2 Basic in formation of SAR data used in this study

表2 SAR 数据基本信息
Tab.2 Basic in formation of SAR data used in this study

表3 使用Okada位错模型反演获得的单一发震断层几何参数<br/>Tab.3 Geometric parameters of the single seismogenic fault inversed by the Okada dislocation model

表3 使用Okada位错模型反演获得的单一发震断层几何参数
Tab.3 Geometric parameters of the single seismogenic fault inversed by the Okada dislocation model

表4 使用Okada位错模型反演获得的2个发震断层几何参数<br/>Tab.4 Geometric parameters of two seismogenic faults inversed by the Okada dislocation model

表4 使用Okada位错模型反演获得的2个发震断层几何参数
Tab.4 Geometric parameters of two seismogenic faults inversed by the Okada dislocation model

图4 分布式滑动模型拟合结果<br/>Fig.4 Distributed sliding model fitting results

图4 分布式滑动模型拟合结果
Fig.4 Distributed sliding model fitting results

图5 阿克陶地震同震破裂滑动分布反演结果图<br/>Fig.5 Inversed coseismic slip distribution of the Akto earthquake

图5 阿克陶地震同震破裂滑动分布反演结果图
Fig.5 Inversed coseismic slip distribution of the Akto earthquake

陈杰,李涛,李文巧,等.2011.帕米尔构造结及邻区的晚新生代构造与现今变形[J].地震地质,33(2):241-259.
陈杰,李涛,孙建宝,等.2016.2016年11月25日新疆阿克陶MW6.6地震发震构造与地表破裂[J].地震地质,38(4):1160-1174.
房立华,陈运泰课题组,等.2016.2016年11月25日新疆阿克陶6.7级地震[EB/OL].(2016-11-25)[2017-10-24].http://www.cea-igp.ac.cn/tpxw/275080.html.
季灵运,刘传金,徐晶,等.2017.九寨沟MS7.0地震的InSAR观测及发震构造分析[J].地球物理学报,60(10):4069-4082.
季灵运,刘立炜,郝明.2015.利用InSAR技术研究滇西南镇康-永德地区现今地壳形变特征[J].地震研究,38(1):84-89.
孔祥艳,陈向军,钟世军,等.2017.2016年11月25日阿克陶MS6.7地震及其余震序列精定位[J].内陆地震,31(2):110-114.
潘家伟,李海兵,Van der Woerd J,等.2009.青藏高原西北部帕米尔东北缘构造地貌与活动构造研究[J].第四纪研究,29(3):586-598.
乔学军,王琪,杨少敏,等.2014.2008年新疆乌恰Mw6.7地震震源机制与形变特征的InSAR研究[J].地球物理学报,56(6):1805-1813.
王苏,李建有,徐晓雅,等.2018.2016年新疆阿克陶MS6.7地震和呼图壁MS6.2地震的余震触发研究[J].地震研究,41(1):98-103.
温扬茂,何平,许才军,等.2012.联合Envisat和ALOS卫星影像确定L'Aquila地震震源机制[J].地球物理学报,55(1):53-65.
杨少敏,李杰,王琪.2008.GPS研究天山现今变形与断层活动[J].中国科学:地球科学,38(7):872-880.
尹金辉,陈杰,郑勇刚,等.2001.卡兹克阿尔特断裂带活动特征[J].中国地震,17(2):221-230.
张旭,严川,许力生,等.2017.2016年阿克陶MS6.7地震震源复杂性与烈度[J].地球物理学报,60(4):1411-1422.
赵强,王双绪,蒋锋云,等.2017.利用InSAR技术研究2016年青海门源MW5.9地震同震形变场及断层滑动分布[J].地震,37(2):95-105.
Brunel M,Arnaud N,Tapponnier P,et al.1994.Kongur Shan normal fault:Type example of mountain building assisted by extension(Karakoram fault,eastern Pamir)[J].Geology,22(8):707-710.
Burtman V S,Molnar P.1993.Geological and Geophysical Evidence for Deep Subduction of Continental Crust Beneath the Pamir[J].Special Paper of the Geological Society of America,281(2):248-251.
Burtman V S.2000.Cenozoic crustal shortening between the Pamir and Tien Shan and a reconstruction of the Pamir-Tien Shan transition zone for the Cretaceous and Paleogene[J].Tectonophysics,319(2):69-92.
Fan G,Ni J F,Wallace T C.1994.Active tectonics of the Pamirs and Karakorum[J].Journal of Geophysical Research Solid Earth,99(B4):7131-7160.
Ge W,Molnar P,Shen Z,et al.2015.Present‐day crustal thinning in the southern and northern Tibetan Plateau revealed by GPS measurements[J].Geophysical Research Letters,42(13):5227-5235.
Metzger S,Schurr B,Schoene T,et al.2016.Rupture model of the 2015 M7.2 Sarez,Central Pamir,earthquake and the importance of strike-slip faulting in the Pamir interior[R].Abstract T11A-2579 presented at 2011 Fall Meeting,AGU,San Francisco,Calif,12-16 Dec.
Mohadjer S,Bendick R,Ischuk A,et al.2010.Partitioning of India‐Eurasia convergence in the Pamir‐Hindu Kush from GPS measurements[J].Geophysical Research Letters,37(4):90-98.
Robinson A C,Yin A,Manning C E,et al.2004.Tectonic evolution of the northeastern Pamir:Constraints from the northern portion of the Cenozoic Kongur Shan extensional system,western China[J].Geological Society of America Bulletin,116(7):953.
Robinson A C,Yin A,Manning C E,et al.2007.Cenozoic evolution of the eastern Pamir:Implications for strain-accommodation mechanisms at the western end of the Himalayan-Tibetan orogen[J].Geological Society of America Bulletin,119(7):882-896.
Schoenbohm L M,Chen J,Yuan Z,et al.2011.Spatial and Temporal Variation in Slip Rate along the Kongur Normal Fault,Chinese Pamir[J].Journal of Himalayan Earth Science.
Schurr B,Ratschbacher L,Sippl C,et al.2015.Seismotectonics of the Pamir[J].Tectonics,33(8):1501-1518.
Sippl C,Schurr B,Yuan X,et al.2013.Geometry of the Pamir‐Hindu Kush intermediate‐depth earthquake zone from local seismic data[J].Journal of Geophysical Research:Solid Earth,118(4):1438-1457.
Wang R J,Lorenzo-Martín F,Roth F.2006.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,32(4):527-541.
Wang R J,Parolai S,Ge M,et al.2013.The 2011 MW9.0 Tohoku Earthquake:Comparison of GPS and Strong-Motion Data[J].Bulletin of the Seismological Society of America,103(2B):1336-1347.
Wang R J,Schurr B,Milkereit C,et al.2011.An Improved Automatic Scheme for Empirical Baseline Correction of Digital Strong-Motion Records[J].Bulletin of the Seismological Society of America,101(5):2029-2044.
Werner C,Wegmller U,Strozzi T,et al.2001.GAMMA SAR and interferometric processing software[J].Proc.ERS-Envisat Symposium,Gothenburg.
Zhou Y,He J,Oimahmadov I,et al.2016.Present-day crustal motion around the Pamir Plateau from GPS measurements[J].Gondwana Research,35:144-154.

备注

引言

1 研究区概况

2 InSAR观测及结果

3 断层参数与滑动分布反演

4 讨论

5 结论

期刊信息