基于PSInSAR的2008年汶川MS8.0地震震后形变场特征

2008年5月12日汶川M_S8.0地震造成了巨大的同震形变, 地表破裂带分布广泛。 为了研究汶川地震震后形变的分布特征, 收集了震后2008年5月28日至2010年9月15日的多时相ENVISAT ASAR数据, 该数据包括两个相邻条带, 能够覆盖震后形变区域。 使用基于单一主图像的PSInSAR处理技术分别对两个条带进行处理并拼接, 获得了震后时序形变图和年平均形变速率图。 研究结果显示, 龙门山断裂带两侧的震后形变分布特征明显不同, 断裂带西北盘形变量表现为LOS向隆升, 最大累积形变约为26 mm, 最大形变速率约为17±7 mm/a; 断裂带东南盘形变表现为LOS向沉降, 形变量较小, 最大累积形变约为-10 mm, 最大形变速率约为-5 mm/a。 汶川地震后的形变特征反映了龙门山断裂在此段具有逆冲为主兼有走滑分量的活动性质, 本文研究结果与震后GPS观测结果在形变趋势和量级方面具有较好的一致性。

Post-seismic Surface Deformation of the 2008 Wenchuan MS8.0 Earthquake based on PSInSAR

The May 12, 2008 Wenchuan M_S8.0 earthquake caused severe disasters, and field observation revealed obvious coseismic surface displacement and widely distributed surface ruptures in the area. In order to study the post-seismic deformation, multi-temporal ENVISAT ASAR data were acquired during the period of May 28 2008 to 15 September 2010, including 2 adjacent tracks covering the post-seismic deformation regions. PSInSAR processing based on single-master image was implemented to the 2 tracks, respectively. Time-series deformation maps and mean deformation velocity maps for the 2 tracks were obtained and merged together in this study. The Results show that deformation pattern show differences along the two sides of the Longmenshan Fault. To the north-west of Longmenshan fault, the upward deformation accumulates to the maximum of 26 mm and the maximum deformation rate was about 17±7 mm/yr; however, to the south-east of the Longmenshan fault, the subsidence deformation accumulates to the maximum of -10 mm and the maximum deformation rate was about -5 mm/yr. Post-seismic deformation of this study reveals that the earthquake activity was dominated by thrust slip with minor right-lateral strike-slip at this segment of Longmenshan Fault, which is consistent with GPS observation results.