Before a Landslide •Avoid building near steep slopes, close to mountain edges, near drainage ways, or natural erosion valleys.•Get a ground assessment of your property.
The world's biggest historic landslide occurred during the 1980 eruption of Mount St. Helens, a volcano in the Cascade Mountain Range in the State of Washington, USA. The volume of material was 2.8 cubic kilometers (km). 
See the list of  worldwide catastrophic landslides of the 20th century. 
At this time there is no collective landslide inventory for the entire United States.
Landslides can and do occur in every state and territory of the U.S.; however, the type, severity and frequency of landslide activity varies from place to place, depending on the terrain, geology, and climate.
Detailed locations of areas susceptible to debris flows are given on "Preliminary Soil-Slip Susceptibility Maps, Southwestern California" published as U.S.
Several kinds of maps are used to depict danger from landslides.
USGS landslide researchers have ongoing field projects in several areas of the U.S., including parts of the Pacific coastal ranges, Rocky Mountains, and the Appalachians.
It’s not possible to exactly predict the number of days or weeks that landslides remain a danger after heavy rain. Residents near mountain slopes, canyons, and landslide prone areas should stay alert even after heavy rain subsides.   
Tsunamis are large, potentially deadly and destructive sea waves, most of which are formed as a result of submarine earthquakes.