Debris Flow - John Seach


A debris flow is a water saturated mixture of boulders and particles which moved downhill under the force of gravity.

Well known debris flows occurred at Mount St Helens in 1980, Nevado del Ruiz in 1985, Redoubt in 1989–1990 and
Pinatubo in 1991.

The Chillos Valley Lahar was the largest debris flow in the past 10,000 years. It formed on Cotopaxi volcano’s north and northeast slopes and descended river systems 326 km NNW to the Pacific Ocean and 130 km east into the Amazon basin. The debris flow occurred 4500 years ago.