In a landslide, masses of rock, earth or trash move down a slope. Debris and mud flows are rivers of rock, earth and other debris soaked with water. Landslides develop quickly when water quickly gathers in the ground, during heavy rainfall or rapid snowmelt, changing the earth into a flowing river of mud or “slurry.” They can flow quickly, striking with little or no warning at avalanche speeds. They also can travel a number of miles from their source, growing in size as they pick up trees, boulders, cars and other things.
Landslide problems can be caused by land mismanagement, particularly in mountain regions. Landslides may begin in areas burned by forest and brush fires because of a lower starting point of precipitation. Land-use zoning, certified inspections, and proper design can lower the chances of landslide, mudflow and debris flow problems. The best way to get ready is to stay informed about changes in and around your home that could point to landslide occurring.
Before the Landslide
Use the list below to keep you, your family and your property safe from a landslide or debris flow.
- Build an emergency kit.
- Make a family communications plan.
- Get ready for landslides by following proper land-use measures. Do not build near steep slopes, close to mountain edges, near drainage ways or along natural erosion valleys.
- Know 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 have them in the future.
- Get a ground assessment of your property.
- Talk to a trained person for advice on the best ways to keep your home or business safe. These ways could be 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. Be aware, however, 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).
Know the landslide warning signs
- Changes occur in your landscape such as patterns of storm-water drainage on slopes (especially the places where runoff water meets) land movement, small slides, flows, or progressively leaning trees.
- Doors or windows stick or jam for the first time.
- New cracks show up in plaster, tile, brick or foundations.
- Outside walls, walks or stairs begin pulling away from the building.
- Slowly developing, widening cracks show up on the ground or on paved areas such as streets or driveways.
- Underground utility lines break.
- Bulging ground appears at the base of a slope.
- Water breaks through the ground surface in new locations.
- Fences, retaining walls, utility poles or trees tilt or move.
- You hear a faint rumbling sound that goes up in volume as the landslide nears.
- The ground slopes downward in one direction and may begin shifting in that direction under your feet.
- Unusual sounds, such as trees cracking or boulders knocking together, might mean moving debris.
- Collapsed pavement, mud, fallen rocks and other signs of possible debris flow can be seen when driving. Embankments along roadsides are particularly susceptible to landslides.
During a Landslide
- During a severe storm, stay alert and awake. Many deaths from landslides occur while people are sleeping.
- Listen to local news stations on a battery-powered radio for warnings of heavy rainfall.
- Listen for unusual sounds that might point to moving debris, such as trees cracking or boulders knocking together.
- Move away from the path of a landslide or debris flow as quickly as you can. The danger from a mudflow grows 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.
- Stay away from river valleys and low-lying areas.
- If you are near a stream or channel, be alert for any sudden rise or fall in water flow. Notice whether the water changes from clear to muddy. Such changes may mean there is debris flowing upstream, so be ready to move quickly.
- Curl into a tight ball and protect your head if escape is not possible.
After a Landslide
- Go to a public shelter that has been selected for your area if you have been told to leave or you feel it is unsafe to stay in your home.
- Stay away from the slide area. There may be danger of more slides.
- Listen to local radio or television stations for the latest emergency information.
- Watch for flooding, which may occur after a landslide or debris flow. Floods sometimes follow landslides and debris flows because they may both be started by the same event.
- Check for hurt and trapped people near the slide, without entering the direct slide area. Point rescuers to their locations.
- Look for and report broken utility lines, damaged roadways and railways to appropriate authorities. Reporting possible dangers will get the gas, water and power turned off as quickly as possible. This stops more dangers and injuries.
- Check the building foundation, chimney and surrounding land for damage. Damage to foundations, chimneys or surrounding land may help you judge the safety of the area.
- Replant damaged ground as soon as possible. Erosion caused by loss of ground cover can lead to flash flooding and additional landslides in the near future.
- Seek advice from a geotechnical expert for evaluating landslide dangers or designing ways to fix and lower your landslide risk. A trained person will be able to advise you of the best ways to prevent or lower landslide risk, without creating further danger.
More information on getting ready for and getting over from landslides is can be found at:
- U.S. Geological Survey Landslide Hazard Program
- Federal Emergency Management Agency
- American Red Cross
Listen to Local Officials
Learn about the emergency plans that have been made in your area by your state and local government. In any emergency, always listen to the orders given by local emergency management officials.