Thursday, March 13, 2008

LAHARS

A lahar is a deadly kind of volcanic mudflow. Here are specific details about what a lahar is, and about how dangerous, and deadly they can be. A lahar is composed of pyroclastic material and water. Lahars have the consistency of concrete: fluid when moving, then solid when stopped. Lahars can be extremely dangerous, because of their energy and speed. The force of a lahar is so big that buildings and valuable land may become partially or completely buried by one or more cement-like layers of rock debris. One of the greatest volcanic hazards is lahars. They can destroy by direct impact, lead to increased deposition of sediment, block tributary streams, and bury valleys and communities with debris. A lahar can be huge. The Osceola lahar produced 5,600 years ago by Mount Rainier in WA produced a wall of mud 140 meters (460ft.) deep in the White River Canyon and extends over on area of over 330sq. km. (130sq. mi.). Eruptions may trigger one lahars, by quickly melting snow and ice on a volcano or ejecting water from a crater lake. During subsequent rainy seasons, swollen rivers will erode the new deposits and sometimes generate lahars that are dangerous to people downstream. Even if no lahars occur, the erosion can lead to frequent floods because of the deposition of sediment along the river channels. People caught in the path of a lahar have a high risk of death from severe crush injuries, drowning or asphyxiation.

Mudflow (lahar) Deaths

Deaths

Volcano

When

25,000

Ruiz, Columbia

1985

5,110

Kelut, Indonesia

1919

4,011

Galunggung, Indonesia

1882

3,500

Vesuvius, Italy

1631

1,200

Mayon, Philippines

1814

1,000

Cotopaxi, Ecuador

1877

700

Ruiz, Columbia

1845

That is what a lahar is, and how it can be dangerous and deadly.

9 comments:

Anonymous said...

wow.sounds scary.
but pretty cool information
:)

Anonymous said...

Good idea for the chart, it explained a lot.

-SW1

Anonymous said...

interesting subject line

ek1

Anonymous said...

LOVE THE TITLE, good use of facts its well put toethger love the chart :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :) :)

Anonymous said...

yeah you could have more info on lahars instead of just using the chart

TO HR1

Anonymous said...

Lahars are very dangerous according to your info, but what instances need to be there to form a lahar?
ED3

Anonymous said...

very good information and very good idie of the chart and exlandined so much on it Em

Anonymous said...

Great job. I never knew lahar was that deadly. I enjoyed the chart. AH5

student08 said...

hehe, commenting on my own blog....