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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.]
American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.


(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]
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014
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
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
References in periodicals archive ?
Citing reports from the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA), the Philippine Institute of Volcanology and Seismology (Phivolcs) said the cyclone is estimated to bring moderate to heavy rainfall, which poses grave threat of extreme rainfall-induced landslides and lahars in volcanic edifices, particularly in Sorsogon.
It ordered the Lahars to pay a fine/compensation of Rs6.2 million to the other side after its members were found guilty of killing three Katohars, including two women, and injuring two other women in an attack on their Mukhtiar Khan Buledi village.
Stratovolcanoes are particularly dangerous because of pyroclastics flows and lahars caused by their eruptions.
"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.
'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.
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.
Rainwater could combine with the volcanic ash and rock to form deadly, fast-moving mudflows - called "lahars" - that could sweep away entire communities.