Asked in Global WarmingMudslides
How do mudslides happen?
In what countries do mudslides occur in?
Asked in History of the United States, Volcanoes
What are the problems caused by volcanoes erupting?
Asked in Meteorology and Weather, Mudslides
When and where in the US do mudslides happen?
Mudslides can occur almost anywhere, but mostly they seem to occur in parts of the US where there is a mountainous region that has been experiencing a prolonged drought; and then suddenly, the area experiences heavy rainstorms. These intense downpours can trigger mudslides, which is what occurred, for example, in Southern California's Antelope Valley in October of 2015.
What causes mudslides?
Mudslides often happen after a mountain slope has had its trees and vegetation removed. This can happen from deforestation, or even from forest fires. This means that the soil doesn't have the anchors from the strong root systems of plants and trees. It also loses the canopy coverage of the trees and so is very vulnerable to erosion and weathering from storms and rainfall. Strong cloudbursts and extreme rainfall can then wash the soil downhill as a mudslide, which then gathers strength as it gets bigger and bigger, bringing rocks and other debris with it. Mudslides can also be triggered by earthquakes, if there is enough water in the soil, and by volcanic eruption. Mudslides occur when the viscosity of saturated ground on a slope reaches a point where it is lowered by the force of gravity.
Where do mudslides happen?
Mudslides can happen anywhere in which there are soil slopes that are saturated with water. They tend to be more likely to occur in steeper slopes that have been deforested or where vegetation is sparse as this allows rainfall to enter the soil more rapidly and also reduces evapo-transpiration losses (so the soil is wetter than it would otherwise be which reduces it's effective strength due to increases in pore water pressure).