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Lahars move rapidly down valleys like rivers of concrete. If you are on the floor of a valley that leads from a volcano and become aware of an oncoming lahar, seek high ground. Lahar is an Indonesian term that describes a hot or cold mixture of water and rock fragments that flows down the slopes of a volcano and typically enters a river valley.
Making the world better, one answer at a time. A Lahar is a type of mudflow made of pyroclastic material and water that flows down from a volcano. the word Lahar originated from Indonesia. Lahars can be deadly because of their energy and speed.ahar is an outflow of mud, rock and other pyroclastic material from a volcano which mixes with water as it proceeds down a river valley. Essentially it is a mudflow or lands â¦ lide resulting from volcanic action, usually very fast moving and destructive.