Heavy rainfall caused saturation of the debris material which resulted in loss of cohesion and inter friction angle of overburden mass and eventually started moving down.

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_NH_ 040
Along road right bank of Alagad before Pinder confluence
Slope dressing and road widening at steep angle, breast wall with weep holes, shotcrete with wiremesh in in situ rock, restoration of damaged retaining wall.
Heavy rainfall in the area for 3-4 days caused saturation and increase in pore water pressure in the rock as well as slope material, road cutting at steep angle daylighted vulnerable joint plane.