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Photo glossary of volcano terms

Lahar rushes down a confined river channel, Guatamala

Photograph by J.N. Marso on 14 August 1989

A small lahar triggered by rainfall rushes down the Nima II River near the town of El Palmar in Guatemala. The lahar developed on the slopes of Santiaguito volcano.

Lahar
Lahar is an Indonesian word for a rapidly flowing mixture of rock debris and water that originates on the slopes of a volcano. Lahars are also referred to as volcanic mudflows or debris flows. They form in a variety of ways, chiefly by the rapid melting of snow and ice by pyroclastic flows, intense rainfall on loose volcanic rock deposits, breakout of a lake dammed by volcanic deposits, and as a consequence of debris avalanches.

More about lahars

 

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U.S. Department of the Interior, U.S. Geological Survey, Menlo Park, California, USA
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Last modification: Monday, 04-Sep-2000 22:40:24 EDT (SRB)