'Lahar' is a natural disaster involving
eruption of large amount of material
Lahar is an Indonesian word, and it names a hazard associated with volcanoes rather than with wind or the sea.
A lahar is a flow of volcanic debris mixed with water that rushes down the slopes of a volcano and along the river valleys leading away from it. The solid material is what the volcano has erupted - ash, pumice and rock fragments - and the water may come from heavy rainfall on fresh ash deposits, from a crater lake breaking out, or from snow and ice on the summit melted by hot volcanic material. Mixed together they form a slurry with the consistency of wet concrete, which can travel tens of kilometres at high speed, carrying boulders and burying everything in its path.
Among the four options, the one that fits is eruption of large amount of material, since a lahar is made of erupted volcanic material and occurs as a consequence of eruption. Lahars can strike during an eruption or long afterwards, whenever rain remobilises ash left on the slopes, which makes them a persistent hazard around active volcanoes.
The most severe example on record is the destruction of Armero in Colombia in 1985, when a modest eruption of Nevado del Ruiz melted part of its ice cap and the resulting lahars killed more than twenty thousand people.
Strong winds describe cyclones, tornadoes and storms. Strong water waves describe tsunamis and storm surges. Strong winds together with water waves describe a cyclone making landfall. None of these involves volcanic material, and each is a distinct category of hazard.
Hence a lahar involves the eruption of a large amount of material.
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Important Questions from Natural Disasters
Which is not a natural disaster?
Who was the first geologist to devise an instrument used to detect an earthquake?
The mass movement of rock, debris or earth down a slope is referred to as:
What is the primary geological phenomenon responsible for generating the majority of destructive tsunamis?
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(A) Cold wave
(B) Seismic
(C) Collision of meteors with the earth
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Choose the correct answer from the options given below:
