Landslides occur in all U.S. states and territories and can be caused by a variety of factors including earthquakes, storms, volcanic eruptions, fire and by human modification of land. Landslides can occur quickly, often with little notice and the best way to prepare is to stay informed about changes in and around your home that could signal that a landslide is likely to occur.
In a landslide, masses of rock, earth or debris move down a slope. Debris and mud flows are rivers of rock, earth and other debris saturated with water. They develop when water rapidly accumulates in the ground, during heavy rainfall or rapid snowmelt, changing the earth into a flowing river of mud or "slurry." They can flow rapidly, striking with little or no warning at avalanche speeds. They also can travel several miles from their source, growing in size as they pick up trees, boulders, cars and other materials.
Landslide problems can be caused by land mismanagement, particularly in mountain, canyon and coastal regions. In areas burned by forest and brush fires, a lower threshold of precipitation may initiate landslides. Land-use zoning, professional inspections and proper design can minimize many landslide, mudflow and debris flow problems.
Landslide Preparedness Checklist
- Be conscious of landslide and debris-flow risk when buying a home or property
- Make a disaster supply kit and have a family emergency plan
- Follow proper land-use procedures: avoid building near steep slopes, close to mountain edges, near drainage ways or along natural erosion valleys
- Become familiar with the land around you; learn whether debris flows have occurred in your area by contacting local officials — slopes where debris flows have occurred in the past are likely to experience them in the future
- Get a ground assessment of your property
- Consult a professional for advice on appropriate preventative measures for your home or business, such as flexible pipe fittings, which can better resist breakage
- Protect your property by planting ground cover on slopes and building retaining walls
- In mudflow areas, build channels or deflection walls to direct the flow around buildings, but be aware, if you build walls to divert debris flow and the flow lands on a neighbor's property, you may be liable for damages
- If you are at risk from a landslide talk to your insurance agent — debris flow may be covered by flood insurance policies from the National Flood Insurance Program (NFIP)
During Heavy Rainfall or a Landslide
- During heavy rain, stay alert and awake; many deaths from landslides occur while people are sleeping
- Listen to NOAA Weather Radio and local news stations on a battery-powered radio for warnings of heavy rainfall
- Listen for unusual sounds that might indicate moving debris, such as trees cracking or boulders knocking together
- Move away from the path of a landslide or debris flow as quickly as possible. The danger from a mudflow increases near stream channels and with prolonged heavy rains. Mudflows can move faster than you can walk or run. Look upstream before crossing a bridge and do not cross the bridge if a mudflow is approaching
- Avoid river valleys and low-lying areas
- If you are near a stream or channel, be alert for any sudden increase or decrease in water flow and notice whether the water changes from clear to muddy. Such changes may mean there is debris flow activity upstream so be prepared to move quickly
- Curl into a tight ball and protect your head if escape is not possible