Active surface deformation, displacement pattern, and erosional variability is estimated using the geomorphologically sensitive morphometry along with the Persistent Scatterer Interferometric Synthetic Aperture Radar (PSInSAR) technique using the Sentinel-1Adata (119 images) acquired between 07- 02-2017 and 10-02-2021. The average velocities for this dataset are estimated to be between ±11 mm/y. The Raunthi River catchment from where the flood was triggered is undergoing ~8 mm/y subsidence and ~10 mm/y uplift. Compared to this the basin wide deformation (Rishi Ganga basin) is estimated to be around ±10 mm/y with commulative ground displacement of around ±45 mm. The times series analysis suggests an increase in the ground displacement by around 5 mm/y and seems to be responsible for the expansion of pre-existing cracks in the vicinity of the Vaikrita Thrust (VT) and subsequent failure of the northern face of Nandi Peak on 7th February 2021. The Global Positioning System (GPS) derived strain distribution pattern indicate a relatively higher accumulation of strain (>0.35µ strain/y). The normalized steepness index (k_sn) variation along the longitudinal section of Rishi Ganga and Raunthi River sub-basin in Central Himalayan region shows anomalous increase at the glacio-fluvial transitional processes. Moreover, the χ profiles as well as planform plots shows anomalously lower values within the Raunthi River sub-basin when compared with the Rishi Ganga basin. Based on the lower values of χ it is observed that Raunthi River sub-basin is undergoing high erosion which can be caused by the presence of sheared lithology and incision of the relict glacial and paraglacial sediments. We negate the suggestion that abrupt rise in the temperature was the major triggering mechanism for the recent disaster, instead it is the sheared lithology and pre-existing fissure developed because of differential uplift and subsidence in Raunthi River that led to the wedge failure and subsequent flash flood. Had the climate was the major driver of the recent tragedy ?, it should have impacted multiple hanging glaciers in the Rishi Ganga valley. Therefore, the study calls for detailed geomorphological, structural and glaciological investigation in regions dominated by glacial and paraglacial processes in the strategic regions of the Himalaya. Towards this, the state of art PSInSAR technique seems to provide fast and reliable detection of terrain instability/stability along with identification of potential areas of slope failures in near future in the glacial and preglacial zones.

主动表面变形、位移模式和侵蚀变异性使用地貌敏感形态测量法以及使用 Sentinel-1Adata（119 幅图像）在 2017 年 7 月 2 日至 10 月 2 日之间采集的持续散射体干涉合成孔径雷达 (PSInSAR) 技术进行估计-2021 年。该数据集的平均速度估计在 ±11 mm/y 之间。引发洪水的 Raunthi 河流域正在经历约 8 毫米/年的沉降和约 10 毫米/年的隆起。与此相比，盆地范围内的变形（Rishi Ganga 盆地）估计约为±10 毫米/年，地面共同位移约为±45 毫米。时间序列分析表明，地面位移增加了约 5 毫米/年，这似乎是导致 Vaikrita 逆冲断层 (VT) 附近预先存在的裂缝扩大以及随后南迪峰北壁破坏的原因2021 年 2 月 7 日。全球定位系统 (GPS) 衍生的应变分布模式表明应变累积相对较高（>0.35µ 应变/年）。归一化陡度指数（k_锡) 沿喜马拉雅中部地区 Rishi Ganga 和 Raunthi 河次流域纵向剖面的变化在冰川-河流过渡过程中显示出异常增加。此外，与 Rishi Ganga 盆地相比，Raunthi 河流域内的 χ2 剖面和平面图显示异常低的值。基于较低的 χ 值，可以观察到 Raunthi 河次流域正在经历高度侵蚀，这可能是由剪切岩性的存在以及残存的冰川和冰旁沉积物的切割引起的。我们否定温度突然升高是最近灾难的主要触发机制的说法，相反，由于 Raunthi 河的差异隆起和沉降而形成的剪切岩性和预先存在的裂缝导致了楔形破坏和随后的山洪暴发。如果气候是最近悲剧的主要驱动因素？它应该影响到里希恒河谷的多个悬冰川。因此，该研究要求对喜马拉雅战略区域以冰川和副冰川过程为主的地区进行详细的地貌、结构和冰川学调查。为此，最先进的 PSInSAR 技术似乎提供了对地形不稳定性/稳定性的快速可靠的检测，以及在不久的将来在冰川和冰前区识别潜在的斜坡破坏区域。它应该影响了 Rishi Ganga 山谷的多个悬垂冰川。因此，该研究要求对喜马拉雅战略区域以冰川和副冰川过程为主的地区进行详细的地貌、结构和冰川学调查。为此，最先进的 PSInSAR 技术似乎提供了对地形不稳定性/稳定性的快速可靠的检测，以及在不久的将来在冰川和冰前区识别潜在的斜坡破坏区域。它应该影响了 Rishi Ganga 山谷的多个悬垂冰川。因此，该研究要求对喜马拉雅战略区域以冰川和副冰川过程为主的地区进行详细的地貌、结构和冰川学调查。为此，最先进的 PSInSAR 技术似乎提供了对地形不稳定性/稳定性的快速可靠的检测，以及在不久的将来在冰川和冰前区识别潜在的斜坡破坏区域。