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What are lahars definition?

What are lahars definition?

Definition: A lahar is a hot or cold mixture of water and rock fragments that flow quickly down the slopes of a volcano.

How is a lahar formed?

Lahars can occur by rapid melting of snow and ice during eruptions, by liquefaction of large landslides (also known as debris avalanches), by breakout floods from crater lakes, and by erosion of fresh volcanic ash deposits during heavy rains.

What is lahar and floods?

‘Lahar’ is an Indonesian word for a flood, but by many volcanologists, it is taken to mean a primary debris flow, triggered by an eruption (Vallance, 2000). On volcanoes with perennial snow (or glaciers), pyroclastic flows sweeping downslope can rapidly transform into lahars that can be very far traveled.

What is a lahar zone?

Each lahar-hazard zone is based on the extents of the maximum known or envisioned flows that have occurred at each volcano and therefore represent the most distal flow hazard zones.

How do you pronounce lahar?

Phonetic spelling of Lahar

  1. la-har.
  2. la-har.
  3. lah-hahr.
  4. L-uh-h-uh-r.

What are the types of lahar?

The two types of lahar are:

  • PRIMARY: Primary lahars occur during a volcanic eruption.
  • SECONDARY: Secondary lahars occur after an eruption during periods of inactivity. For example, heavy rainfalls can trigger a secondary lahar with little warning.

What are the effects of lahars?

Lahars and excess sediment cause serious economic and environmental damage to river valleys and flood plains. Large lahars can crush, abrade, bury, or carry away almost anything in their paths. Buildings and valuable land may be partially or completely buried.

Are lahars landslides?

Some of the largest lahars begin as landslides of saturated and hydrothermally altered rock on the flank of a volcano or adjacent hillslopes. Landslides are triggered by eruptions, earthquakes, precipitation, or the unceasing pull of gravity on the volcano.

What is the difference between lahars and landslides?

The debris that is carried in a landslide destroys anything in its path, buries valleys in rock and debris and can dam waterways, leading to flooding. If the debris within the landslide mixes with enough water, the landslide can turn into a lahar, which is a flowing mass of volcanic debris and water.

What damage can lahars do?

How far can a lahar flow?

On steep slopes, lahar speeds can exceed 200 kilometres per hour (120 mph). With the potential to flow distances of more than 300 kilometres (190 mi), a lahar can cause catastrophic destruction in its path.