Landslides & Debris Flows

Landslides move rock, soil and debris down slopes, sometimes slowly and sometimes in a fast, muddy rush called a debris flow that can destroy homes and kill people with little warning. They occur in every state and are triggered by heavy rain, rapid snowmelt, earthquakes, wildfire damage, erosion and human changes to slopes. Knowing the signs and leaving early is the best protection.

• Homeowners in Hilly Areas
• Renters
• Road & Utility Workers
• Hikers & Campers

What causes landslides

• Heavy or prolonged rain and rapid snowmelt that saturate soil, especially on steep slopes.
• Wildfires: burned slopes lose the plants that hold soil, and the ground can repel water. For several years after a fire, even moderate rain can cause debris flows. See Wildfires.
• Earthquakes and volcanic activity. See Earthquakes.
• Erosion from rivers, waves and runoff undercutting slopes.
• Human activity: cutting into slopes for roads or building pads, removing vegetation, adding water from leaking pipes, septic systems and irrigation, or piling fill on slopes.
• Places at higher risk: steep hillsides, canyon mouths, stream channels, areas below cliffs, previous slide areas, and bases of slopes. Check hazard maps from your state geological survey or the U.S. Geological Survey (USGS).

Warning signs

• New cracks or bulges in the ground, pavement, driveways, yards or foundations, and ground that has settled or tilted.
• Doors and windows that suddenly stick, new gaps around them, and cracks in walls or plaster.
• Leaning or tilting trees, fences, poles and retaining walls, and broken water or utility lines.
• New springs, seeps or muddy water appearing, or a sudden change in the color or flow of a stream, such as a drop in water level or increasing muddiness.
• Unusual sounds, such as a faint rumbling that grows louder, trees cracking, boulders knocking or a sound like a freight train.
• Heavy rain with small slides or rocks falling from slopes above.
• If you see warning signs, leave the area and report to local officials. Don't wait for a slide.

Prepare before the storm

• Know your risk: ask the local government, the state geological survey or the USGS about landslide hazard in your area, and whether your home is in a mapped zone or an area burned by wildfire.
• Make a plan and go-bag, with evacuation routes that avoid steep slopes and stream channels, and a meeting place. See Family Emergency Plan and Emergency Kit.
• Sign up for alerts from local emergency management and the National Weather Service. Watch for heavy rain forecasts, flash flood and debris flow warnings, and evacuate when told, since debris flows move too fast to outrun. See Hurricanes & Floods.
• Learn about insurance: standard homeowner's and renter's policies generally don't cover landslide damage. Ask your agent about separate coverage. Flood insurance has its own rules for mudflow.
• Talk to engineers or geologists before building, cutting or filling on slopes. Get permits. See Hiring Contractors.

Reduce risk around your property

• Control water: direct roof and surface runoff away from slopes, keep drains, culverts and gutters clear, and fix leaking pipes and irrigation. See Sump Pumps and Ice Dams.
• Plant ground cover with deep-rooted plants on slopes and keep trees healthy, and avoid removing vegetation that holds soil.
• Build properly: retaining walls designed by an engineer, with drainage, and avoid dumping fill or yard waste on slopes.
• Watch your property for the warning signs above, and keep records and photos.
• After a wildfire nearby, follow burn scar flood and debris flow guidance from your county and consider barriers and sandbags. See Sandbagging.

During a landslide or debris flow

• If you're inside and a slide is coming, move to the second floor if you can't get out, away from the downhill side, and take cover under a sturdy table. Better to evacuate early.
• If you're outside, run to the nearest high ground away from the slide path, at right angles to the flow, not downhill or along the channel. If you can't escape, curl into a tight ball and protect your head.
• If you're driving, watch for collapsed pavement, mud, fallen rocks and debris on roads, especially at night and in heavy rain. Don't cross flooded or debris-covered roads. See Flooded Roads.
• Listen for unusual sounds, and warn neighbors. Call 911 if people are trapped or in danger. See Calling 911 & Giving Your Location.

After a landslide

• Stay away from the slide area. More slides can follow, and flooding often comes next. Don't go in to look.
• Check for injured people near the slide, but don't enter the slide area; call for help. See First Aid Basics.
• Report broken utility lines and damaged roads and railways to the authorities. Stay away from downed power lines. See Gas Leaks and Shutting Off Utilities.
• Check your building for damage before going back inside, and get it inspected. Watch for foundation, chimney and gas line damage. Take photos for insurance. See Disaster Cleanup Safety.
• Seek help with stress and loss. See Post-Incident Stress.

Landslide checklist

• I know whether my home is in a landslide or burn-scar risk zone
• I have an evacuation plan, a go-bag and weather alerts for heavy rain
• I know the warning signs: cracks, tilting trees, sticking doors, new springs, unusual sounds
• I leave early when told, and move away from slide paths, not down them
• I checked whether my insurance covers landslides, and I stay away from slide areas afterward

Last updated: October 5, 2026