Thursday, March 13, 2008


Have you ever wondered just what a lahar really is? Or what causes them and what can come of them? Have you ever heard of a volcano to explode and include a lahar? Well I have done much research in order to answer these questions. The next few paragraphs will be explaining what I found out.

One of the greatest volcanic hazards in the world is called a lahar. But what are lahars really? A lahar is an Indonesian term that describes a hot or cold mixture of water fragments flowing down the slopes of a volcano. But I guess you could say a lahar is basically a deadly kind of volcanic mudflow. When moving, a lahar looks like a mass of wet concrete that carries rock debris ranging in size from clay to boulders more than 10 meters in diameter. Every time a lahar rushes down stream from a volcano, it’s size, speed, and amount of water and rock debris it carries constantly changes. Most large lahars are hundreds of meters wide, tens of meters deep and are usually to fast for people to outrun. Small lahars, on the other hand, are less than a few meters wide and several centimeters deep.

Do you know what causes a lahar? Well volcanic eruptions can be one cause. How may you ask? Well the heat of the eruption directly melts the snow and ice on the volcano or by ejecting water from a crater lake. Most lahars are caused by intense rainfall during or after an eruption. The largest lahars began as landslides of saturated and hydro thermally altered rock on the flank of a volcano or adjacent hill slopes. Serious economic and environmental damage can be a result of a lahar. Lahars are so powerful that they could crush you, but even if they don’t crush or carry you away, buildings and valuable land may become partially buried by a lahar.

One massive eruption that included a lahar was the 1991 eruption of Mount Pinatubo. This mountain was an active stratovolcano located on the island Luzon located in the Philippines. Before the eruption this mountain was inconspicuous ad heavily eroded. A dense forest that supported a population of several thousand indigenous people covered Mount Pinatubo. In June of 1991 Mount Pinatubo’s eruption produced the second largest terrestrial eruption or the 20th century. The surrounding areas were severely damaged by pyroclastic flows, ash deposits, and later, a massive lahar. This lahar was caused by rainwater remobilizing earlier volcanic deposits. Thousands of houses and other buildings were destroyed because of this lahar. It was a devastating time for many.

Lahars are one of the greatest volcanic hazards. They can be formed by a number of ways. And can destroy a lot of things. Lahars are very interesting things, but can leave many people devastated. These monstrous mudflows are very dangerous things.



student08 said...


Anonymous said...

Very well written. I now know more about lahars [RN1]

Anonymous said...

That was well written. I now know more about lahars than I did, just by reading the science book. It was also very informational. [CT3]

Anonymous said...

Your paper has a ton of good info. I hope that you enjoyed writing it.