Landslides happen when a slope becomes unstable—because of denuding, from a fire or deforestation; over-steepening, from erosion or mining; overloading, from a reservoir or heavy snowpack; or oversaturation, with rain or melt water.

So many things can cause a landslide that they happen in every U.S. state and nearly every country.

When the slope gives way, soil can speed downhill at 50 to 100 miles an hour, carrying trees, boulders, cars, even houses.

Earthquakes trigger just five percent of landslides. Twenty percent are caused by human activities, while three-quarters come from precipitation.

Though some landslides happen suddenly, most give warning signs: cracks in pavement or soil, earth bulging at the base of a slope, water springs in new places.

Your chances of getting caught in a slide are remote. But if you live in a landslide-prone area, keep these things in mind:

Risk comes from uphill. You may want to move bedrooms or living areas to the downhill side of the house.

If you suspect a slide is coming, open downhill windows and doors to allow debris that could pass through the house to exit.

To escape a landslide, go up! Upstairs, and up on top of furniture, to have the best chance to stay on top of the debris.

In the very unlikely event you’re trapped, never give up. Make noise so rescue teams can find you.