基于新一代雷达卫星InSAR数据检测2015年尼泊尔M_W 7.8级地震的同震形变场  

Coseismic deformation field of 2015 Nepal earthquake(M_W 7.8)detected by new generation satellite radar interferometry data

作　　者：卢倩云[1] 郑茜[2] 孙建宝[2] 沈正康[1] 陈永顺[1] 陈兴国 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中国地震局地质研究所地震动力学国家重点实验室,北京100029 [3]北京地空软件技术有限公司,北京100083

出　　处：《地球物理学进展》2015年第6期2505-2510,共6页Progress in Geophysics

基　　金：中国地震局尼泊尔MS8.1级地震科学考察项目;国家自然科学基金项目(41374040)共同资助

摘　　要：2015年4月25日尼泊尔MW7.8级大震是自1934年尼泊尔~M 8.0＋级地震发生以来,又一次发生在喜马拉雅俯冲带上的逆冲型地震.尼泊尔大部分处于喜马拉雅山南麓强烈起伏的高山地区,首都加德满都虽位于一个小型的断陷盆地之上,但整体上仍然在喜马拉雅断裂带的上盘.其特殊地形和地质地貌条件造成雷达相干信号能量损失,非常不利于InSAR形变观测.本次地震的发生恰逢欧洲空间局（ESA）和日本宇航局（JAXA）新一代合成孔径雷达（SAR）卫星成功运行初期,其快速的重访周期,为成功获取该地震的同震形变场提供了良好的条件.本研究尝试使用JAXA ALOS-2L波段雷达数据,处理获得高精度同震形变场.结果表明,在较短重访周期条件下,InSAR技术在该地区发挥重要作用,为本次地震提供高信噪比的形变信息.InSAR结果揭示了加德满都地区在此次地震中强烈抬升,为形变极大值区,而其北侧则大幅沉降,形变场符合纯逆冲型地震的特点.InSAR观测结果与布设于加德满都地区的近场3分量GPS观测结果相一致.The 2015 Nepal earthquake（MW 7.8）is a megathrust event happened on the Himalaya subduction zone,where a ~ M 8.0＋ megathrust earthquake struck in 1934.Most of the Nepal territory is located in the ragged southern slope of the Himalayas.The capital city of Kathmandu is located in a sediment basin situated on the hanging wall of the Himalaya megathrust.The very unique topography as well as the geological and geomorphological environment gives rise to certain energy loss of the radar interferometry signals,making it difficult for conducting InSAR survey.Fortunately,the earthquake occurred at a time when new generations of SAR satellites of ESA and JAXA had been successfully launched and were in their testing mode,whose short revisit periods enabled acquisition of high quality data of this region.In this study,we processed JAXA ALOS-2Lband radar data and obtained high resolution result of coseismic displacement field.Our result indicates that the new generation of SAR satellite and technology with relative short revisit period can play a significant role in extracting high SNR deformation signals for this region.The InSAR results show that the Kathmandu region uplifted greatly and underwent maximum of deformation during this earthquake;while the northern region subsided significantly.Our results are well matched with the general pattern of a thrust earthquake and the near field threecomponent GPS measurements.

关 键 词：INSAR GPS 同震形变场 尼泊尔地震 逆冲型地震 

分 类 号：P315[天文地球—地震学]