基于InSAR技术门源地震地表形变监测与分析

InSAR-based monitoring and analysis of Menyuan earthquake-induced surface deformations

地震引发的地表形变规模大、范围广,由地震引发的次生地质灾害对当地基础设施和工程建设影响明显。研究门源地震造成的地表形变,对理解地震形变运动过程、识别地质灾害隐患具有重要意义。利用合成孔径雷达差分干涉测量(differential interferometric synthetic aperture Radar,D-InSAR)技术获取门源地震同震形变场,根据升降轨几何关系,提取门源地震地表二维形变信息;利用覆盖研究区域的21景升轨Sentinel-1A影像,基于短基线集合成孔径雷达干涉测量(small baseline subset-interferometric synthetic aperture Radar,SBAS-InSAR)技术提取门源地震震后地表形变信息,得到视线向(line of sight,LOS)的时间序列和平均形变速率。结果表明,同震形变主要分布在冷龙岭断裂与托莱山断裂的交汇处,LOS向地表形变升轨隆升形变量为0.40 m,沉降量为-0.65 m,降轨隆升形变量为0.80 m,沉降量为-0.70 m;联合升降轨视线向结果分析二维形变,得到垂直方向最大形变量为-0.32 m,以沉降为主,水平方向最大形变量为0.87 m,以向东运动为主,说明此次地震水平方向形变显著,断层运动状态为左旋走滑作用。2022年1月17日—9月26日期间,整体形变较为稳定,部分区域形变明显,断裂带活动是影响地表形变的主要因素,平均形变速率最大值为53 mm/a,最大形变量达到77 mm。研究结果可为地震灾害防治、应急管理工作和社会经济可持续发展提供技术支持。

Earthquake-induced surface deformations are characterized by large scales and extensive coverage,and the resultant secondary geological disasters significantly impact local infrastructure and engineering construction.Investigating the surface deformations caused by the Menyuan earthquake is critical for understanding the seismic deformation movement and identifying potential geological disasters.This study obtained the coseismic deformation field of the Menyuan earthquake using the differential interferometric synthetic aperture Radar(D-InSAR)technique.Based on the geometric relationships between the ascending descending passes,this study extracted the two-dimensional information of surface deformations induced by the Menyuan earthquake.The results show that the coseismic deformations occurred primarily at the intersection of Lenglongling and Tuolaishan faults.The line-of-sight(LOS)surface deformations from ascending and descending passes exhibited uplift of 0.40 m and 0.80 m and subsidence of-0.65 m and-0.70 m,respectively.As indicated by the analysis of two-dimensional deformation based on the ascending and descending LOS surface deformation results,the maximum amplitude of vertical deformations dominated by subsidence was-0.32 m and the maximum amplitude of horizontal deformation dominated by eastward motion was 0.87 m,suggesting significant horizontal seismic deformations and fault activity dominated by left-lateral strike-slip process.Based on the 21 scenes of Sentinel-1A SAR images covering the study area taken from the ascending pass,this study extracted the information on the surface deformations after the Mengyuan earthquake using the small baseline subset-interferometric synthetic aperture Radar(SBAS-InSAR)technique,determining the LOS time series and average deformation rates.The results show that from January 17,2022 to September 26,2022,the study area experienced relatively stable overall deformations and significant local deformations.The fault activity was identified as the primary factor affecting the surface deformations,with a maximum average deformation rate of 53 mm/a and a maximum deformation amplitude of 77 mm.The results of this study will provide technical support for earthquake disaster mitigation,emergency management,and sustainable socio-economic development.