InSAR大气误差改正及其在活动断层形变监测中的应用

为了获取青藏高原东北缘老虎山断裂带精确的震间形变速率场，通过对短时间基线干涉图大气改正效果的评价，从3种外部大气数据(MERIS, ERA-Ⅰ, WRF)中确定出最优的大气改正方法，用于长时间基线干涉图中的大气信号改正；然后利用层叠法(stacking)累积平均经大气和轨道改正后的干涉图，获取了研究区的震间形变速率场.结果显示:海原断裂系统区域内，MERIS和ERA-Ⅰ的大气改正效果优于WRF；MERIS和ERA-Ⅰ的改正结果给出了相似的形变速率场，断层两盘相对形变速率为视线向2.5 mm/a，转换成平行于断层方向为6.5 mm/a，与GPS结果一致；在近断层5 km的范围内，出现了较大的形变梯度，揭示了浅层蠕滑的存在. 

Atmospheric correction for InSAR and its application in mapping ground motion due to interseismic strain accumulation

It is essential to correct the atmospheric error for measuring interseismic deformation in the order of mm/a. In this paper, Laohushan fault on the northeastern margin of the Tibetan Plateau is chosen as the study area. In order to derive the accurate interseismic deformation field, we evaluate three atmospheric correction methods (MERIS, ERA-Ⅰ, WRF) based on the corrected results on interferograms with small temporal-baselines. The optimal atmospheric correction methods and orbital correction methods are applied to correct errors in the large-temporal-baseline interferograms, then the average interseismic deformation fields are achieved by stacking the atmosphere and orbit-corrected interferograms. Our results show that the MERIS and ERA-Ⅰ are more suitable to be used to correct the atmospheric effect in ASAR interferograms than WRF in Haiyuan fault system area; on the other hand, the MERIS-corrected and ERA-Ⅰ-corrected deformation rate fields show a similar pattern of left-lateral displacement across the Laohushan fault, and the profiles across the fault show that the line-of-sight velocity across the fault is 2.5 mm/a, which is equal to 6.5 mm/a parallel to the fault and accords well with GPS observations. In addition, there is a large displacement gradient within 5 km near the fault, revealing shallow creep near the surface.