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The Top Three Places for Mudslides to Occur

Mudslides and landslides are types of mass movement of debris on a large scale. They can contain rocks, soil, trees and other plants, even cars and pieces of roadways. While landslides are movements of dry matter, mudslides are wet and either triggered or aggravated by heavy rain or flooding. The main cause for both of these phenomena is gravity; without the planet's pull, debris wouldn't go anywhere. But there is usually a trigger and some kind of slope for the debris to slide down.

Steep and Loose
- The most common and dangerous mudslides occur in areas that have steep slopes and loose soil over an impermeable substrate like bedrock or clay. Under heavy and prolonged rainfall, the water will seep into the loose soil until it hits the impermeable surface underneath, where it collects. The soil above it becomes saturated and heavy. When it gets too heavy it breaks apart and flows downhill. The best examples of these in America come from California, where mudslides have taken out houses, roads, and even giant redwood trees.
Wildfires or Human Modification
- Slopes can be more prone to mudslides in areas that have been subjected to recent wildfires or modification by people. Both of these make the soil more unstable that it would normally be. Plant roots hold soil together, and often the stability of a forest slope is dependent on the trees and shrubs that grow on it. Removal of the vegetation, either by fire, clear cutting or building or road development can destabilize a slope, even if it had no previous history of mudslides. Hillside homes in Malibu,California being taken away by mud and the Powari landslide in India are examples.
Seismically Active Areas
- Rain isn't the only thing that can create a mudslide. Volcanoes can too. Volcanic mudslides are called Lahars, and they can be as or more devastating than regular mudslides. Although heavy rainfall is usually a factor in the creation of a lahar, the volcano itself can create one all on its own by melting its snow cap or causing its crater lake to drain down the side, things that usually presage an eruption. Lahars are usually created by strata volcanoes, which are the very tall explosive ones that usually have a snow cap. Examples of lahars come from Nevado del Ruiz, Colombia, and the Ontake Volcano in Honshu, Japan.
Top Three Places for Mudslides
- The top three areas for mudslides to occur are where the top triggers of mudslides happen all together. When an area has steep slopes with loose soil, deforested and built up, in an area that is prone to sudden heavy rain and either earthquakes or volcanic eruptions, mudslides are inevitable. The top three in the United States are: first, the area around Los Angeles, California; second, West Virginia where the Appalachian mountains cut through; and third, a tie between Utah and Colorado on the edges of the Rocky mountains. All have steep slopes, loose soil, are heavily developed, and have to deal with lots of water, either rain or snow melt.

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