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lahar flowing from the crater of Mt. St. Helens
March 19, 1982


1. A mass of volcanic fragments, often mixed with water, moving rapidly down the side of a volcano.
2. The deposit produced by a lahar.

[Javanese, lava, lahar; akin to Hanunó'o (Malayo-Polynesian language of Mindoro) l´ʔad, dry streambed, arroyo, and Malay dialectal (Thailand and northern peninsular Malaysia) lahar, pool of water in the jungle.]


(Geological Science) a landslide of volcanic debris mixed with water down the sides of a volcano, usually precipitated by heavy rainfall
[C20: from Javanese: lava]
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.lahar - an avalanche of volcanic water and mud down the slopes of a volcano
avalanche - a slide of large masses of snow and ice and mud down a mountain
References in periodicals archive ?
These deposits can be remobilised by rainwater and generate lahars (mud flows) by themselves and or by incorporating existing erodible material on channel banks," Phivolcs warned in an advisory.
Remember that lahars and sediment-laden streams are both dangerous," Phivolcs director Renato Solidum told reporters after confirming that lahar was flowing from one lava channel on Mayon's slopes.
These deposits can be remobilized by rainwater and generate lahars by themselves and or by incorporating existing erodible material on channel banks," Phivolcs said.
The public is strongly advised to be vigilant and desist from entering the eight (8) kilometer-radius danger zone, and to be additionally vigilant against pyroclastic density currents, lahars and sediment-laden streamflows along channels draining the edifice,' it said.
Lahars act like concrete, flowing when carried by water but becoming solid when deposited on land.
They probably resulted from settling clouds of dry ash followed by denser lahars, deadly flows of water-saturated ash and rock, Sheridan adds.
Major volcanic hazards include lahars, landslides, and flank collapse.
Like concrete cascading down a cement truck chute, lahars could even entomb the streets of Orting.
Lahars can travel at more than 50 miles an hour, contain up to 90 per cent solid debris, and will entomb everything in their path.
Forests may be completely destroyed and buried by (1) lava flows, pyroclastic flows and ash falls (geological nomenclature follows Bates and Jackson, 1984 and Scarth, 1994) from active volcanoes or (2) lahars, mudflows, debris flows, earth flows and landslides from either active volcanoes or unstable terrain on the slopes of inactive volcanoes.
One of the worst causes of destruction after an eruption, lahars can be truly devastating.