A moving mass of rock, soil, and snow that occurs when the flank of a mountain
or volcano collapses and slides downslope.
As the moving debris rushes down a volcano and into river valleys, it incorporates
water, snow, trees, bridges, buildings, and anything else in the way. Debris
avalanches may travel several kilometers before coming to rest, or they
may transform into more water-rich lahars, which travel many tens of kilometers
|A debris avalanche rushes down the side of a volcano
to the valley floor. Many such debris avalanches transform into lahars
and travel tens of kilometers from the volcano. Note horseshoe shaped
crater on volcano's side, which is the scar created by the avalanche.
Credit: B. Myers / U.S. Geological Survey
AND PLANETARY SCIENCE