A destructive flow of volcanic debris, ash and water that rushes down a volcano's slopes and valleys with the speed and consistency of wet concrete, triggered when an eruption rapidly melts snow and ice, or when heavy rain mobilizes loose volcanic ash. Lahars can travel far beyond the volcano itself and have caused some of the deadliest volcanic disasters in history, including the 1985 Armero tragedy in Colombia.
Facts
Process Type Timescaleflows several tens of metres per second and can exceed 200 kilometres per hour on steep slopes 1 First Proposed Year Connections
Sources
1. Lahar - Wikipedia
Description section, opening definition
a violent type of mudflow or debris flow composed of a slurry of pyroclastic material, rocky debris and water.
Description section, speed paragraph
Large lahars hundreds of metres wide and tens of metres deep can flow several tens of metres per second (22 mph or more), much too fast for people to outrun. On steep slopes, lahar speeds can exceed 200 kilometres per hour (120 mph).
Etymology section
Berend George Escher introduced it as a geological term in 1922.
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