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A mudflow composed chiefly of volcaniclastic materials on the flank of a volcano. The debris carried in the flow includes pyroclasts, blocks from primary lava flows, and epiclastic material. Syn: mudflow (Neuendorf, K.K.E. and others, 2011)

Hot volcanic debris erupted onto the flanks of the volcano can melt snow, forming floods or fast-moving slurries of water, mud, rocks, and sand. Lahars may also occur when thick deposits of proximal ash are rapidly eroded by heavy rainfall following eruptions. (RI 2004-3)

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