短基线InSAR探测龙门山主断裂带两侧震后雨期的滑坡空间分布特征

Post-earthquake Landslides Distribution along Longmenshan Major Fault during Rainy Season with Short-baseline InSAR

为探测汶川震后龙门山主断裂带两侧滑坡灾害的空间分布特征,使用雨期前后的两幅超短基线PALSAR影像开展雷达干涉测量。提出三维空间因子SAR大气长波相位建模方法,利用雷达视线方向形变阈值扣除大气短波相位,联合地形坡度因子综合提取主断裂带两侧强降雨期的滑坡空间分布。计算结果表明,震后滑坡灾害基本沿映秀—北川主断裂带两侧呈条带状密集分布,其中90%滑坡分布于高程为1000~3000m区间,地形坡度因子则集中于15°~35°范围,多数滑坡距离发震断层约为3~15km,70%滑坡分布于断层上盘区,上下盘滑坡数量和面积存在明显差异,表明震后滑坡受发震断层上盘逆冲运动特性的滞后效应较为显著。

In order to investigate the spatial pattern of landslides along the major fault in Longmenshan area,the PALSAR interferometric pair with short baseline is utilized in the study.The atmospheric phase correction model with three dimensional geo-spatial factors is proposed to eliminate the long wavelength components.The LOS deformation threshold is set to reduce the short wavelength phase error.The terrain slope factor is introduced to analyze the spatial pattern of post-earthquake landslides triggered by the rainstorm.The results show that the active landslides presented clearly a linearly distribution along both sides of Yingxiu-Beichuan fault.Most of the landslides are about 3~15km away from the major fault.The statistical data suggested that almost 90%of the post-earthquake landslides locate in the elevation range of 1000~3000mand the terrain slope factor of 15°~35°.The spatial distribution characteristics with 70%landslides on the hanging wall indicated that the after effect of hanging wall upthrusting motion dominated the pattern of post-earthquake landslides.