The Landslide Exposure Database (LED) maps building-by-building landslide risk in the United States

Landslides take a heavy toll in the United States each year, causing damage that runs into billions of dollars and resulting in multiple fatalities. Even so, until recently there was no consistent national picture showing exactly which people and properties sit most directly in the danger zone.

A new study changes that by providing the first building-by-building evaluation of landslide exposure across the country, highlighting clear regional differences in where the risk is concentrated.

A team at the University of Washington (UW) has created the Landslide Exposure Database (LED).

LED assigns a landslide susceptibility rating to 128 million buildings across the U.S. and combines that with socioeconomic indicators to gauge how exposed residents may be to the disruption and hazards that landslides can bring.

A long-overdue missing map

Across the United States, landslides are responsible for an estimated $3 billion to $6 billion in losses each year, and they also claim multiple lives annually.

These impacts may worsen as homebuilding expands into terrain known to be landslide-prone and as climate change increases the heavy rainfall that often sets landslides in motion.

Yet, despite the persistent threat, there had been no systematic, nationwide view of who is most at risk before this work.

“As a community of landslide researchers, we have spent almost all of our time studying the physical geography of landslides,” said co-author Joseph Wartman, a UW professor of civil and environmental engineering.

“But we never considered the human geography. Now we can answer some very important questions about who is exposed.”

Mapping landslide risk nationwide

To build the database, the researchers brought together several very large datasets. They started with a terrain and landslide susceptibility map produced by the U.S. Geological Survey.

They then paired that with building footprint and occupancy inventories from the Overture Maps Foundation and the Army Corps of Engineers, alongside detailed socioeconomic information from the Census Bureau.

Those socioeconomic measures included income, disability status, access to a vehicle, and housing conditions-factors that influence how effectively a community can prepare for, respond to, and recover from a disaster.

“This effort was much more than just merging massive datasets,” said lead author Daniel Acosta-Reyes, a UW doctoral student in civil and environmental engineering.

“The real work was the careful curation required to turn the incredibly rich data available in the U.S. into an accurate, usable tool for everyone from decision makers to the public.”

A surprisingly concentrated risk

The team’s analysis shows that almost 20 percent of U.S. land is susceptible to landslides, but that area contains only 2 percent of the population-about 6.5 million people.

Among those living with the highest exposure, 80 percent are on or near the West Coast or in Appalachia. West Virginia has the greatest proportion of residents in at-risk locations.

“Those concentrations were surprising,” Wartman said.

“In a sense, it’s good news because it shows landslide risk to be a localized hazard, which makes it more practical and affordable to address.”

Because the hazard is so geographically clustered, it becomes possible to focus attention and resources on a relatively defined set of regions rather than diluting efforts across the entire country.

A divide between city and countryside

One of the clearest results is an unexpected contrast between urban and rural patterns of landslide exposure.

Across rural areas nationwide, communities located in the most landslide-prone places more often face tighter economic circumstances, increasing their overall vulnerability.

People in these settings frequently have fewer means to prepare in advance or to bounce back after a landslide, and they are also more likely to be located at a greater distance from emergency services.

In urban areas, the relationship looks different. Landslide-prone zones can include sought-after hillside neighbourhoods valued for their views, so those exposed are often comparatively better off financially.

When landslides happen, city residents in these areas typically have a far stronger ability to recover than rural residents experiencing similar physical risk.

One-size-fits-all policy won’t work

Because the database reveals such varied regional and socioeconomic patterns, the researchers warn that landslide policy cannot rely on a single, uniform approach.

Instead, they argue for mitigation measures shaped to local circumstances. In Appalachia, that might involve early warning systems designed to reach a widely dispersed rural population.

In cities such as Seattle and San Francisco, it could involve tighter rules intended to deter new building on unstable slopes.

A tool for homeowners too

Wartman hopes the dataset will help researchers and regulators strengthen their understanding of landslide risk and create new ways to safeguard residents nationwide.

He also expects it to serve as a practical educational resource for homeowners who want clearer information about their own exposure.

“People email me because they want to know if their homes are at risk, and I haven’t had a resource to point them to,” Wartman said.

“That was a big part of the motivation for this work. Now I have something straightforward to offer them.”