门源Mw5.9级地震形变InSAR观测及区域断裂带深部几何形态

InSAR Observation of Menyuan Mw5.9 Earthquake Deformation and Deep Geometry of Regional Fault Zone

利用Sentinel-1A卫星升轨、降轨合成孔径雷达影像数据,提取了2016年门源Mw5.9级地震的高精度合成孔径雷达干涉同震形变场,利用单纯形法和非负最小二乘法反演确定了地震断层几何和滑动分布,并构建了区域断裂带的深部几何形态模型。结果表明,门源Mw5.9级地震同震形变以地表抬升为主,沿升轨、降轨视线向的最大值分别为5.3 cm、7.1 cm;地震断层走向、倾角分别为133°、43°;地震滑动以逆冲为主,主要发生在地下6.14～12.28 km处,最大滑动量约0.5 m,平均滑动角为66.85°,地震矩为1.0×10^(18) N·m(Mw5.94);形变观测拟合残差均方根为0.36 cm;区域断裂带的深部几何形态以花状构造为特征,整体倾向南西,门源地震发震断裂为花状构造中未出露地表的盲断层。相关成果能够为研究区域地壳运动与变形、活动断裂与地震孕育发生等提供参考。

By using Sentinel-1 A ascending and descending synthetic aperture radar(SAR)data,this paper extracts the high-precision interferometric SAR(InSAR)coseismic deformation of the 2016 Menyuan Mw5.9 earthquake,inverts the fault geometry and slip distribution using simplex method and nonnegative least squares method,and constructs the deep geometry model of regional fault zone.The results show that coseismic deformation of the Menyuan Mw5.9 earthquake is dominated by surface uplift,and the maximums along the line-of-sight direction of ascending and descending tracks are 5.3 cm and 7.1 cm respectively.The fault strike and dip angles are 133°and 43°respectively.The seismic slip is dominated by thrust component,mainly occurring in 6.14-12.28 km underground.The maximum slip is about 0.5 m,the average slip angle is 66.85°,and the earthquake moment is 1.0×1018 N·m(Mw5.94).The fitting residual root mean square of deformation observations is 0.36 cm.The deep geometry of the regional fault zone is characterized by flower structure,which inclines to the south-west as a whole.The Menyuan earthquake rupture is a blind fault which does not appear on the surface in the flower structure.Relevant results can provide the reference for studying regional crustal movement and deformation,active fault and earthquake preparation and occurrence.