2023’s Most Landslide-Vulnerable Counties

Debris from a mountain-edge landslide blocks a three-lane road in a forested area, trapping a semi-truck.

Which U.S. counties have the highest incidence and financial risk from landslides?

To mark the start of landslide season — November to March — Gutter Gnome ranked 2023’s Most Landslide-Vulnerable Counties.

We compared over 740 counties with moderate to very high landslide risk based on 3 categories. We also looked at landslide triggers — like earthquake risk, historical precipitation levels, and deforestation — as well as expected annual financial loss from landslides, among 10 total metrics.

See if your region is at risk in our ranking below. To learn how we ranked the counties, see our methodology.

Contents

Rankings

See how each county fared in our ranking:

Note: Several cities are located within counties bearing the same name but are not part of the county and operate independently. For example, Roanoke City, Virginia, is not considered part of Roanoke County, Virginia. Those cities are included among counties by the U.S. Census Bureau for data purposes and therefore were also included in our sample.

Top 5 Close Up

Check out the slideshow below for stats on each of our 5 most vulnerable counties.

No. 1: Douglas County, Oregon | Overall Score: 81

Landslide Risk Score: 99.97 | Rank: No. 2
Earthquake Risk Score: 97.9 | Rank: No. 55
20-Year Change in Tree Cover (kha): -61.5 | Rank: No. 9
20-Year Change in Tree Cover (%): -5.3% | Rank: No. 64
Expected Annual Loss from Landslides: $4.1 million | Rank: No. 2
No. 2: Lincoln County, Oregon | Overall Score: 80.69

Landslide Risk Score: 100 | Rank: No. 1
Earthquake Risk Score: 97.84 | Rank: No. 57
Historical Average Yearly Precipitation: 417.65 | Rank: No. 7
20-Year Change in Tree Cover (kha): -9.74 | Rank: No. 77
Expected Annual Loss from Landslides: $6.1 million | Rank: No. 1
No. 3: Lane County, Oregon | Overall Score: 75.67

Landslide Risk Score: 99.9 | Rank: No. 4
Earthquake Risk Score: 99.05 | Rank: No. 29
Historical Average Yearly Precipitation: 281.88 | Rank: No. 123
20-Year Change in Tree Cover (kha): -33.9 | Rank: No. 18
Expected Annual Loss from Landslides: -3.2% | Rank: No. 4
No. 4: Coos County, Oregon | Overall Score: 75.41

Landslide Risk Score: 99.94 | Rank: No. 3
Earthquake Risk Score: 98.54 | Rank: No. 41
Historical Average Yearly Precipitation: 288.56 | Rank: No. 109
20-Year Change in Tree Cover (kha): -15.2 | Rank: No. 52
Expected Annual Loss from Landslides: $2.9 million | Rank: No. 3
No. 5: Santa Cruz County, California | Overall Score: 72.45

Landslide Risk Score: 99.55 | Rank: No. 15
Earthquake Risk Score: 99.27 | Rank: No. 23
Drought Risk Score: 97.77 | Rank: No. 35
Wildfire Risk Score: 97.68 | Rank: No. 52
Expected Annual Loss from Landslides: $1.5 million | Rank: No. 11

The Upshot

Oregon, California, and Washington face the highest risk of landslides, with many counties expecting to lose millions of dollars annually to landslide damage. Some counties — like Clackamas County, Oregon (No. 10), Snohomish County, Washington (No. 8), and Mendocino County, California (No. 9) — also finished in the top 10 of Landslide Triggers, due to more frequent earthquakes and higher tree cover loss over the past 20 years.

The steep Appalachian Mountains and regional soil types make parts of Kentucky and West Virginia more susceptible to landslides, too. High landslide risk and annual precipitation sent Floyd County, Kentucky (No. 36), and two West Virginia counties — Kanawha County (No. 42) and Logan County (No. 48) — into the top 50 of our ranking. Experts have found that regions impacted by coal mining and mountaintop removal may also be more vulnerable to landslides.

Rainy regions along North Carolina’s Appalachian range, such as McDowell County (No. 30) and Caldwell County (No. 45), also experience high landslide risk and anticipated financial loss. 

Ask The Experts

We reached out to a some experts to learn more about the warning signs and aftermath of landslides, as well as how climate change and government regulations may be contributing factors. Read their insights below.

  1. What are the three most important signs that a landslide could be imminent?
  2. What are the top three ways to prepare for a landslide?
  3. What should victims do immediately after a landslide?
  4. How is climate change affecting landslide frequency and intensity?
  5. Is it possible for local governments to prevent residential structures from being built in landslide-prone areas? Why or why not?
Mohamed Aly
Associate Professor of Geoinformatics
Mohamed Aly
Associate Professor of Geoinformatics
University of Arkansas, Fayetteville / Department of Geosciences

What are the three most important signs that a landslide could be imminent?

1. Increased soil erosion — especially around the base of slopes — can be a precursor to landslides as the removal of soil weakens the stability of the slope.

2. Visible cracks on the ground — especially if they appear suddenly — may indicate stress and potential instability in the soil, signaling an increased risk of landslides.

3. Sudden changes such as slope cracks, ground movement, or tilting trees may indicate ground instability.

What are the top three ways to prepare for a landslide?

1. Implement early detection systems — including ground sensors and monitoring equipment — to detect changes in slope stability. This allows for early warnings and timely evacuation if necessary.

2. Conduct educational programs to raise awareness about landslide risks and safety measures within the community. This can include workshops, drills, and dissemination of informational materials.

3. Prepare emergency kits with essential supplies and have an evacuation plan in place.

What should victims do immediately after a landslide?

  • Immediately evacuate to higher ground or a safe location.
  • Stay away from the affected area to prevent further harm.
  • Report the landslide to local authorities and seek assistance.

How is climate change affecting landslide frequency and intensity?

Climate change is usually associated with altered precipitation patterns, leading to more intense and frequent rainfall events. Heavy rainfall can saturate the soil, increasing the likelihood of landslides as the excess water reduces the strength of the ground.

In regions with permafrost, rising temperatures associated with climate change can lead to the thawing of frozen ground. This thawing destabilizes slopes and increases the risk of landslides, particularly in mountainous areas.

Changes in temperature affect the timing and patterns of snowmelt. Rapid snowmelt, especially when combined with heavy rainfall, can contribute to soil erosion and trigger landslides in snow-dominated regions.

Altered climate conditions may affect vegetation patterns. Changes in vegetation cover, such as deforestation or shifts in plant types, can impact slope stability. Vegetation plays a crucial role in stabilizing soil, and its loss can contribute to landslide risk.

Is it possible for local governments to prevent residential structures from being built in landslide-prone areas? Why or why not?

  • While it is technically possible for local governments to prevent residential structures in landslide-prone areas through regulatory and planning measures, the effectiveness of these measures depends on a combination of a variety of factors, including legal frameworks, land-use planning, economic considerations, and public policies.
  • Local governments can use land-use planning and zoning regulations to designate certain areas as unsuitable for residential development due to landslide risks. This involves assessing geological and environmental factors to determine safe building zones.
  • Before approving new developments, local governments may require environmental impact assessments that evaluate potential landslide risks. This process helps decision-makers understand the environmental implications of construction projects.
  • Economic considerations — such as the demand for housing and development — may create pressures to allow construction in areas with landslide risks. Balancing economic growth with safety concerns is a challenge for local governments.

Behind the Ranking

First, we determined the factors (metrics) that are most relevant to rank the Most Landslide-Vulnerable Counties. We then assigned a weight to each factor based on its importance and grouped those factors into 3 categories: Landslide Risk, Landslide Triggers, and Financial Risk. The categories, factors, and their weights are listed in the table below.

For each of the 743 U.S. counties with relatively moderate to very high landslide risk according to the Federal Emergency Management Agency (FEMA), we then gathered data on each factor from the sources listed below the table.

Finally, we calculated scores (out of 100 points) for each county to determine its rank in each factor, each category, and overall. A county’s Overall Score is the average of its scores across all factors and categories. The highest Overall Score ranked “Most Vulnerable” (No. 1) and the lowest “Least Vulnerable” (No. 743).

  • The “Least Vulnerable” among individual factors may not be No. 743 due to ties.
  • Alaska was not included in the ranking due to lack of FEMA data, but aspects of the state’s climate and landscape make Alaska very vulnerable to landslides.
  • Several cities are located within counties bearing the same name but are not part of the county and operate independently. For example, Roanoke City, Virginia, is not considered part of Roanoke County, Virginia. Those cities are included among counties by the U.S. Census Bureau for data purposes and therefore were also included in our sample.

Sources: Federal Emergency Management Agency, Global Forest Watch, and National Oceanic and Atmospheric Administration

Gut(ter) Check: Be Prepared

Landslides kill dozens of people, and millions of dollars are lost each year in the U.S. to the resulting damage.

Know the warning signs to look out for and reduce the impact of landslides on your property by following these tips:

  • Research the history of landslides in your area as they tend to recur in the same places.
  • Sign up for local emergency alerts, and create an evacuation plan for your household. 
  • Avoid building or clearing land along mountain edges or steep slopes.
  • Hire an expert to survey your property and provide building and rain dispersal recommendations. 
  • Update your home’s insurance — many policies do not cover damages caused by landslides or mudslides.
  • Plant trees and ground cover for increased erosion control, especially along steep or hilly areas.
  • Build retaining walls, channels, or deflection walls to enhance rainwater dispersal — but keep in mind that if you direct the flow to your neighbor’s property, you may be liable for any damages that occur. 
  • Make sure your roof, gutters, and downspouts are draining properly and away from your home.
  • Regrade your property with a slight downward slope going away from the foundation of your home.
  • Keep your gutters clean and damage-free

Optimize your gutter system by hiring a local pro through Gutter Gnome to clean out, repair, or replace your gutters before winter arrives.

What is Gutter Gnome?

Gutter Gnome — part of the Home Gnome family of home service sites — puts local gutter, gutter guard, and gutter cleaning experts at your fingertips. 

Media Resources

Main Photo Credit: Oregon Department of Transportation / Wikimedia Commons / CC BY 2.0

Sav Maive

Sav Maive is a writer and director based in San Antonio. Sav is a graduate from the University of Virginia and is a loving cat and plant mom.