Seismically-induced soft sediment deformation structures in and around Chamoli, Garhwal Himalaya, India

Abstract

Soft-sediment deformation structures were identified along Nandakini River valley near Chamoli village of Garhwal Lesser Himalaya. The deformation, in each outcrop, is restricted to a single stratigraphic layer bounded by undeformed flat-lying layers, eliminating the influence of slope failure. The structures are multiple liquefaction features like sand dikes, flame structures, pear-drop disturbance and downward warping of beds. The preferred interpretation is that the deformations resulted from earthquake-induced liquefaction and their existence adjacent to the Nandaprayag Fault can be related to episodic seismicity that occurred along this fault. However, more data and dating technique is needed to constrain the timing and distance to the causative seismic source. It is possible that more than one earthquake has effected the deformations.