It is an old slide and initially triggered by the toe cutting by the Nagol Gad. Heavy rainfall in the area caused saturation and increase in pore water pressure resulting downslope movement of the material.

An Interim Report on Preliminary  Geological  Slope Stability Assessment of the Recent Disaster Affected Areas in Parts of Chamoli District, Uttarakhand by Bhupendra Singh, Bhupender Singh, Ajay Kumar and Arindam Roy, Senior Geologists, M-IV, NR GSI Dehr
UK_CHA_MDR_ 065
Removal of overhangs and loose debris, wiremesh with shotcrete, check bunds in the course of gullies, breast wall with weep holes, flexible retaining wall.
Heavfy rainfall caused increase in pore wate pressure of saturated overburden. This was accentuated by toe cutting by Nagol Gad and slope cutting at steep angle. Wedge failure also took place due to intersection of joint sets.