Himalayan mountain ranges separate the Tibetan plateau from the Indian subcontinent, where challenging topography, ongoing orogeny, and weather conditions are significant factors behind mass movements. The detachment of a composite rock-ice mass occurred on 7-Feb-2021 over the north-eastern slope of the Trisul mountain resulting in devastation along the Rishiganga-Dhauliganga valley, Uttarakhand. In this study, an attempt is made to understand the failure mechanism of the overhang wedge, where prolonged glacial mobility is seen as a possible factor behind the formation of such a structure. The temporal movement (2020–2021; annual & seasonal) of metamorphosed ice is assessed using sub-pixel offset tracking of Sentinel-1A-GRD data. Kinematic analysis checks failure susceptibility due to joint sets within the rockmass. Slope stability analysis is performed using probabilistic back analysis for three values of coefficient of variation (CoV), i.e., 10%, 15%, and 20% considering cohesion (c) and angle of internal friction (ϕ) as random variables. The detachment impact is quantified using rockfall simulation and parameters such as maximum bounce height, total kinetic energy, and translational velocity. Finally, probabilistic analysis of parameters is performed that may be useful in developing a mitigation system. © 2022 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.
