Landslides risk in Wyoming

Landslides in Wyoming: Understanding the Hazard

Wyoming's landscape is dominated by the Rocky Mountains, vast high plains, and semi-arid basins. This varied terrain, combined with weather patterns that bring sudden thaws and intense rainstorms, creates conditions where landslides can occur. The state is rated Level 2 out of 5 for landslide risk, meaning it is moderate, but localized hazards can be significant.

Most landslides in Wyoming are triggered by one or more of the following:

• Rapid snowmelt in spring, which saturates soils and reduces stability.
• Heavy, sustained rainfall that can quickly overload slopes.
• Wildfires that burn vegetation, leaving slopes more vulnerable to erosion and debris flows.
• Natural erosion along rivers and streams, plus human activities like road construction or excavation that steepen slopes.

Areas most exposed include steep mountainsides in the Rockies (including the Absaroka, Wind River, and Bighorn ranges), slopes near canyons, and regions with weak or clay-rich soils. Even lower elevations can experience earth slumps or rockfalls, especially after heavy rain or seismic activity. Because landslides often occur without warning, it is important for homeowners to understand their property's specific risk.

Wyoming also faces the secondary hazard of debris flows—fast-moving mixtures of mud, rock, and water that can travel miles from the source. These are particularly common after wildfires in the state, when burned slopes lose their ability to absorb water.

How it affects homes

Landslides can damage homes in a variety of ways. A slow-moving slide can crack foundations, tilt walls, and break utility lines. A rapid debris flow can destroy anything in its path, including homes, septic systems, and access roads. Even if your home is not directly in a landslide path, the loss of nearby land or infrastructure can disrupt your property and safety.

Typical property damage includes:

• Foundation cracks or shifting, making the structure unsafe.
• Damage to driveways, decks, and detached garages.
• Blocked drainage, leading to water pooling and further soil movement.
• Broken gas, water, or electric lines.

Insurance is a critical consideration. Standard homeowners policies typically do not cover landslide damage. You may need to purchase a separate earth movement policy or an endorsement, and these are not widely available from all insurers. The Wyoming Office of Homeland Security advises residents to consult with their insurance provider about specific coverage for landslides and other geologic hazards. In some cases, federal disaster assistance may be available, but it is not a substitute for private insurance.

How to prepare your home

While you cannot stop all landslides, you can take steps to reduce your home's vulnerability. The following mitigation measures are recommended by Ready.gov and the USGS:

• Consult local geological experts or your county planning office to learn if your property is on or near a landslide-prone slope.
• Inspect your yard for early warning signs: small cracks in the ground, bulges at the base of a slope, tilted trees, or fences that lean.
• Maintain proper drainage: redirect downspouts and runoff away from steep slopes, and install French drains or culverts if needed.
• Avoid making major changes to slopes on your property, such as cutting into hillsides or adding heavy fill near the top of a slope.
• Reinforce retaining walls and foundation walls to help resist soil pressure.
• Plant deep-rooted vegetation on bare slopes to help stabilize soil, but avoid water-hungry plants that over-saturate the ground.
• Monitor your property after heavy rain, snowmelt, or earthquakes for new cracks or other movement.
• Create an emergency plan and kit, including a way to evacuate quickly if a landslide or debris flow threatens.

Taking these steps now can significantly reduce the likelihood of major damage and improve your safety.

Frequently asked questions

What are the warning signs that a landslide might occur?

Common signs include new cracks in plaster, tiles, or foundations; doors and windows that progressively stick; bulging ground or pavement at the base of a slope; and the sound of cracking trees or moving earth. If you notice any of these, contact your local emergency management office and consider temporary relocation.

Does my standard homeowners insurance cover landslide damage?

No. Standard homeowners policies in Wyoming generally exclude damage caused by earth movement, including landslides, mudslides, and debris flows. You should ask your insurance provider about adding a separate earth movement policy or endorsement. The Wyoming Office of Homeland Security also recommends staying aware of flood insurance, as debris flows often deposit mud and water that may be covered under flood insurance.

Can I build on a slope and still be safe?

Yes, but it requires careful planning. Hire a licensed geotechnical engineer to assess the slope's stability and design appropriate foundations, drainage, and retaining structures. Follow local building codes and obtain all necessary permits. Avoid cutting into the slope without professional guidance, as this can increase failure risk.

Official resources

• Wyoming Office of Homeland Security – State emergency management and hazard guidance.
• USGS Landslide Hazards Program – Scientific information, maps, and research on landslides.
• Ready.gov – Landslides & Debris Flow – Preparedness tips and safety recommendations.