Landslides & Debris Flows
Landslides are prevalent throughout the United States. They are usually a result of human modification of land, , , , and . Landslides travel at rapid speeds, typically occur without notice. The most effective way to prepare for a landslide is to remain informed about local weather conditions that could lead to one.
During a landslide, rock, mud, and debris masses mixed with water descent down a slope. These masses form after water rapidly accumulates during rapid snowmelt or heavy rain storms, creating large pools of flowing mud often referred to as “slurry.” Mud often flows at rapid speeds and forms without warning. During a typical flood, slurry may travel miles from the source and grows in size as it accumulates boulders, trees, and other debris.
Poor land management in coastal, canyon, and mountainous regions often leads to landslides. Landslides typicaly occur in regions destroyed by burning after receiving minimal rainfall. Thorough inspections, effective land zoning, and proper design can limit landslide and debris flow problems.
What to Do Before a Landside Occurs
How to Recognize Landslide Warning Signs
- Develop a family communications plan and amass an emergency preparedness kit.
- Follow recommended land-use protocols by refraining from building structures near mountain edges, drainage ways, steep slopes, or natural erosion valleys.
- Familiarize yourself with your land surroundings. Learn about recent debris flows by speaking with local officials. Areas that have experienced previous debris flows are typically suspect for future flows.
- Obtain a property ground assessment.
- Discuss with a specialist steps you can take to protect your home and business from landslides. Many specialists recommend purchasing flexible pipe fittings designed to resist breakage.
- Construct retaining walls and place ground covers on sloped areas to safeguard your property.
- Within mudflow regions, construct defection walls or channels that manipulate flow around structures. However, ensure walls divert flow away from neighboring properties since you could be held liable for damages.
- Discuss with an insurance agent landslide damage risk. Many insurance companies pay for landslide damages listed in the National Flood Insurance Program (NFIP).
- Noticeable landscape changes, such as storm-water drainage flows on slopes, particularly in regions where water runoff converges. Watch for leaning trees, unusual flows, small slides, and unusual land movement.
- Window sticking and door jams.
- Foundation, brick, tile, or plaster cracks.
- Exterior stairs, walks, or walls begin moving away from your house.
- Formation or enlarging of sidewalk, driveway, or street cracks.
- Breakage of underground utility lines.
- Ground begins bulging at slope bases.
- The appearance of water at ground surface.
- Tilting trees, utility lines, and retaining walls.
- A rumbling noise gradually intensifies.
- Downward ground slopes in a single direction.
- Unusual noises, including knocking rocks and cracking trees.
- Fallen rocks, mud, and other debris flow is noticeable from a distance. Roadside embankments are often vulnerable to landslides.
What to Do During a Landslide
- Remain alert during a bad rainstorm, especially at night. Landslide deaths frequently occur while people sleep.
- Pay attention to local TV and radio broadcasts for heavy rainfall warnings.
- Listen for unusual noises that indicate landslides. Pay close attention to cracking trees and rocks knocking together.
- Move a safe distance from landslide paths as soon as possible. Mudflow dangers increase near stream channels during severe rainfalls. Mudflow moves at a quicker pace than people can run or walk. Never cross a bridge if you notice mudflow and always look upstream before crossing bridges.
- Stay away from low-lying regions and river valleys.
- Pay attention for sudden decreases or increases in water flow and dark water if you live by a channel or stream. These changes typically indicate debris flow activity.
- If you cannot escape a landslide, curl into the fetal position and protect your face.
What to Do After a Landslide
- Visit a public shelter if you receive evacuation orders and have nowhere to go. Text SHELTER + your ZIP code to 43362 (4FEMA) to locate the closest shelter in your region (example: shelter 84003).
- Avoid the slide area. Additional slides often occur.
- Pay attention to local TV and radio broadcasts for updates.
- Pay close attention for flooding that often occurs after landslides.
- Check areas hit by landslides for trapped or injured people, but do not enter the slide region. If you locate a trapped or injured person in a slide area, direct rescue personnel to their location.
- Report damaged utility lines and highways to local authorities. Alerted officials will more than likely switch the power off, decreasing fire hazards.
- Inspect chimneys, foundations, and surrounding property for damage. Doing this will help you determine the safety of your property.
- Replant trees and crops in damaged ground as quickly as possible because erosion created by ground cover loss often leads to future mudslides and flash floods.
- Seek guidance from a geotechnical specialist to assess landslide hazards or develop strategies to reduce future landslide risks.