The 1987 Río Colorado Rockslide and Debris Flow, Central Andes, Chile

A catastrophic rockslide of approximately 5.5 × 10 6 m 3 and subsequent debris flow occurred on November 29, 1987 on the Rio Colorado in the central Andes of Chile, 100 km east of Santiago. The debris flow killed 29 people, destroyed a large part of the installations and equipment of the El Alfalfal hydroelectric project under construction and damaged the Los Maitenes hydroelectric plant. Exceptionally high snow accumulation in 1987, together with a high snowmelt rate, helped to initiate the movement of unstable sedimentary rocks that subsequently slid 1,000 m on a 40 slope. The rock slide incorporated snow and water along its path, and transformed into a debris flow in the river channel below.