Landslides and Mudslides
Landslides and mudflows usually strike without warning. The force of rocks, soil, or other debris moving down a slope can devastate anything in its path.
What areas are at risk
Some areas are more likely to experience landslides or mudflows, including:
- Areas where wildfires or human modification of the land have destroyed vegetation;
- Areas where landslides have occurred before;
- Steep slopes and areas at the bottom of slopes or canyons;
- Slopes that have been altered for construction of buildings and roads;
- Channels along a stream or river; and
- Areas where surface runoff is directed.
Before a landslide
- Get a ground assessment of your property.
- Your county geologist or county planning department may have specific information on areas vulnerable to landslides. Consult a professional geotechnical expert for advice on corrective measures you can take.
Minimize home hazards
- Plant ground cover on slopes to stabilize the land, and build retaining walls.
- Build channels or deflection walls to direct the flow around buildings.
- Remember: If you build walls to divert debris flow and the flow lands on a neighbor’s property, you may be liable for damages.
Make evacuation plans
- Plan at least two evacuation routes since roads may become blocked or closed.
Learn to recognize the landslide warning signs
- Doors or windows stick or jam for the first time.
- New cracks appear in plaster, tile, brick or foundations.
- Outside walls, walks or stairs begin pulling away from the building.
- Slowly developing, widening cracks appear on the ground or on paved areas.
- Underground utility lines break.
- Bulging ground appears at the base of a slope.
- Water breaks through the ground surface.
- Fences, retaining walls, utility poles or trees tilt or move.
- You hear a faint rumbling sound that increases in volume as the landslide nears. The ground slopes downward in one specific direction and may begin shifting in that direction under your feet.
During a landslide:
If inside a building
- Stay inside.
- Take cover under a desk, table or other piece of sturdy furniture.
- Run to the nearest high ground in a direction away from the path.
- If rocks and other debris are approaching, run for the nearest shelter such as a group of trees or a building.
- If escape is not possible, curl into a tight ball and protect your head.
After a landslide
- Remember that flooding may occur after a mudflow or a landslide.
- Stay away from the slide area; there may be danger of additional slides.
- Check for injured and trapped persons near the slide area. Give first aid.
- Remember to help your neighbors who may require special assistance – infants, elderly people, and people with disabilities.
- Listen to a battery-operated radio or television for emergency information.
- Check for damaged utility lines. Report any damage to the utility company.
- Check the building foundation, chimney, and surrounding land for damage.
- Replant damaged ground as soon as possible. Erosion caused by loss of ground cover can lead to flash flooding.