Almost 44 percent of the United States could experience a landslide, according to new data from government scientists.
Some of those potential landslides could be catastrophic, according to researchers, but no one knows when they could happen.
“The best protection is knowledge,” said Benjamin Mirus, a research geologist with the United States Geological Survey, the federal agency that created the interactive risk map. “Knowing what a landslide is and how it might impact you is the best first step toward preparation.”
Last month, one person was killed and three were injured after a sudden slide in Ketchikan, Alaska. The map was part of a directive to develop a federal strategy to deal with the fatal hazard under the 2021 National Landslide Preparedness Act.
The map is based on newly compiled data that tracked nearly one million landslides observed through high-resolution maps, ancient landslide deposits and media reports showing roads or homes that had been affected by landslides.
Now, residents can input their address and figure out their own susceptibility. The risk at a given location is shown with a color gradient in which yellow means low susceptibility and red means high susceptibility.
Areas of the country particularly at risk include parts of Appalachia, like West Virginia and eastern Kentucky; the Rocky Mountains; the California coast; and southeast Alaska. Possibly the most at-risk region is Puerto Rico. More than 90 percent of the U.S. territory has high susceptibility for landslides, according to Dr. Mirus.
While homes can’t necessarily be moved, community members facing a potential landslide risk could still have options. For example, if they have the resources, developers or homeowners could hire an engineering geologist to assess their property or build site, Dr. Mirus said.
Those living in areas with greater landslide susceptibility could also learn more about the signs of an impending slide and what events trigger landslides — like heavy rain, tremors or development that can increase the risk a slope could give way. Those events will differ based on location.
“You need to understand the triggering conditions specific to eastern Kentucky or southeast Alaska,” Dr. Mirus said.
In general, studies show landslides are more likely to occur after land is affected by human development or slopes experience intense rain events, which is the No. 1 trigger for landslides. Heavy rain events are becoming more common under climate change, largely caused by the burning of fossil fuels.
The map focuses on the risk for the United States, but landslides are a problem around the globe.
In southern India this summer, a sudden burst of rainfall, which was made 10 percent heavier as a result of climate change, set off a landslide that left 560 people dead or missing. In Ethiopia, three rain-induced landslides occurring in close succession killed at least 257 people.
So far, 429 fatal landslides have caused more than 3,600 deaths in 2024, making the year “exceptional in terms of fatal landslides,” according to The Landslide Blog, a data set compiled by Dave Petley, vice chancellor of the University of Hull in England.
Noting the uncertainties around individual events, Dr. Petley wrote in August that “the most likely cause continues to be the exceptionally high global surface temperatures, and the resultant increase in high intensity rainfall events.”
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