In the News

Landslides are considered among the most dangerous kinds of natural disasters, but they often catch communities off guard. Nearly half of the United States is at risk and not nearly enough people know it.

At least 31 people alone died from landslides after Helene triggered thousands of them in western North Carolina in September 2024. Autopsies identified victims found in mud and debris, many of them blindsided.

The landslides damaged or destroyed 350 homes, including the home that belonged to the Guinn family. Melissa Guinn, a wife and mother of four, died after multiple landslides struck the family's hillside home in Minneapolis, N.C. Her husband, Jamie, said the family had no clue the Avery County house they bought in 2018 was susceptible to a landslide. In fact, even as Helene brought heavy rain to their property, they felt safe.

"We never thought nothing about the mountain coming down on us," Jamie said. "Without knowing this, it literally upended my life and changed it forever."

Helene's landslides destroyed their home, sent Jamie and their son River 60 feet down the mountain into the river below and eventually killed his wife of nearly a decade as he stood helpless below. To this day, he can't bring himself back to the site where they once lived.

"The last thing I heard her scream was, 'Babe, watch out' and I grabbed River and got him up on the bank, but by the time I looked back, she was gone," Jamie said. "My second of relief turned into dread. I guess the worst pain you could imagine in a split second."

Scientists say past landslide activity on a property is a reliable predictor of future danger.

"If you put a school on an ancient landslide deposit, for example, you may be asking for trouble," North Carolina Geohazards Geologist David Korte said. "Could be 100 years, could be 10,000 years, could be 100,000 years, could be 10 years."

With that in mind, North Carolina lawmakers created a landslide mapping program in 2005. Geologists published maps online from the counties they finished, but then lawmakers froze the program for nearly a decade amid concerns from realtors and builders about liability, government regulation and property values.

At the time, budget woes and political changes within the North Carolina General Assembly also played a role in ultimately dooming the state's landslide mapping efforts. Although lawmakers restarted the program in 2019, by the time Helene hit North Carolina, most mountain counties were still unmapped.

"I think increased awareness could have made a difference," Korte said about the impact of the program sitting unfunded for so long leading up to Helene.

The landslides North Carolina suffered during Helene are just the latest to devastate the United States. According to the U.S. Geological Survey, nearly 44% of the country could experience a landslide at some point and people tend to underestimate the danger. The federal agency has documented close to a million landslides over the course of the country's history and estimates the number is actually much higher.

"Landslides have actually been observed and in our database in every single state, including D.C.," USGS Supervisory Research Geologist Ben Mirus said. "Now, how frequent they are varies considerably and how common they are, how big they are, how mobile they are, but every single state and most U.S. territories have observed landslides."

In 1969, the remnants of Hurricane Camille triggered thousands of landslides in Nelson County, VA. The damage caused by the sliding mountains coupled with the severe weather accounted for more than 120 deaths.

"There are reports of 27 to 31 inches of rainfall in an 8- to 12-hour period. That is almost a year's worth of rainfall for some areas in a matter of 12 hours," WUSA Chief Meteorologist Topper Shutt said. "There was so much rain in Nelson County over that short period of time that some of the mountains themselves lost hold. It took out 100 bridges and 900 buildings. It was just simply catastrophic. The county's population was roughly 12,000 and 124 passed, so like 1% of the of the county's population was wiped out."

More recently in 2014, a single landslide killed 43 people on the other side of the country in Oso, WA.

"It was on a sunny Saturday morning and so a lot of people were home and weren't expecting an event like this and so that was a real tragedy and really struck home the fact that there's so much we still have to learn about landslides," Mirus said. "Because of many weeks of prolonged rainfall that infiltrated down into the groundwater, it ultimately triggered that slope failure."

Geologists say everything from heavy or prolonged rainfall to snow melt, earthquakes to volcanic eruptions can trigger landslides on slopes that are predisposed to possible failure. In addition to the steepness of a slope, soil conditions, land cover and land use history (wildfires, deforestation, excavation) can impact the likelihood of a landslide.

Landslide "hot spots" include southeast Alaska, southern California, the Rocky Mountains, southern Appalachia and Puerto Rico, Mirus said. In addition, he said Cincinnati, Vermont, Minnesota, West Virginia and eastern Kentucky are notable for their landslide risk.

In the aftermath of the Oso landslide, Washington Congresswoman Suzan DelBene (D) helped create legislation to better protect the public. As a result of that effort, the National Landslide Preparedness Act was signed into law in 2021.

"We really didn't have any policy around landslides and I made that a priority to make sure that we were doing everything we could to prevent a natural disaster like this from becoming another national tragedy," DelBene said. "My team and I, working with other members of Congress and in the Senate, worked to put together legislation to create a program focused on landslides, so that we could actually do the work that needed to be done to prepare communities to do the mapping, so we could have early warning. All those things that are necessary to help communities be prepared."

The program expired in 2024, resulting in an ongoing funding lapse. While the Senate has passed legislation to reauthorize the program, the U.S. House has yet to take a vote.

"I'm definitely hopeful," DelBene said. "We've had strong bipartisan support. Communities across the country are vulnerable. This is about all of us coming together and making sure we're doing everything possible to prevent a national tragedy."

Despite the lapse in the program, some federal money remains available to help. In recent months, a dozen states have received grants to map landslides.

As a result of the National Landslide Preparedness Act, USGS created a national landslide inventory and susceptibility map. It gives the public a chance to see a snapshot of past landslide activity (where documented) and the likelihood of a potential landslide near them. However, the national map should not supersede local maps, if available, Mirus said.

"It's pretty common that people only become aware of landslide risk after they've been affected by it, and unfortunately, the best thing you can do to protect yourself and your property is be aware ahead of time," Mirus said. "What we hope is that people will use this to see, 'I'm in a landslide prone area. I need to understand more locally about the landslide conditions and maybe if I'm considering purchasing a property or building a home or planning a development or moving,' that they could then evaluate in a more site specific way whether the landslides are an issue or not. This is sort of a national scale broad brush approach and ultimately landslides are such a local phenomenon that it really is important that if you live in a landslide prone zone to learn about the landslides in your area and learn about how they might impact you and your property."

About half of the states in the country have landslide mapping programs and many of them have made those maps publicly available. Several of those states have used federal funding to enhance their maps.

"And not just the states with a lot of landslide problems," Mirus said. "You think of Washington, Oregon and California on the west coast and North Carolina on the east coast, but Indiana, North Dakota, Kentucky and Arkansas have all benefited from this grant program to identify landslides that happened in their state, map them and try to better characterize the risk."

While states have made great progress, many have mapped just a fraction of their historic landslides

"We're just scratching the surface, but if we focus on areas where people are, where infrastructure is, I think we can do a lot," Mirus said.

In Indiana, geologists have mapped nearly half of the 49 counties south of the Wisconsin Glacial Boundary. That area of the state has the greatest landslide hazard.

Kentucky, meanwhile, has four full counties and areas of four other counties mapped. Geologists have identified more than 6,000 landslide footprints in those counties alone and have proposed to map an additional five counties in the northeastern part of the state.

Arkansas, which began mapping landslides in 2016 after a major landslide in Crawford County, estimates half of its 75 counties contain landslides. While the goal is to eventually map all of the impacted counties, the state has mapped parts of a couple handful of counties so far. Those maps are not publicly available.

Washington began mapping landslides after Oso. Since then, geologists have mapped nearly a third of the state's counties, identifying almost 50,000 landslides in those areas alone. They hope to map the entire state, but that will take years or even decades. Washington is especially vulnerable to landslides due to the area's heavy rainfall and geology.

"We have the perfect recipe for landslides in the Northwest," KING 5 Senior Meteorologist Rich Marriott said. "We have a lot of steep terrain around here and a lot of rain, not to mention the occasional earthquake on top of that. We are moving into a time of more atmospheric rivers and higher snow levels. We're getting a whole lot of rain down into wider terrains more often, so the chances of a landslide occurring increase with that and we saw that back last December with that series of atmospheric rivers which produced hundreds of landslides around western Washington."

In nearby Oregon, geologists have mapped several areas, but much of the state remains unmapped.

"We still have a long way to go as Oregon is quite big," Oregon Department of Geology and Mineral Industries Engineering Geologist Bill Burns said.

In California, state law requires "basic landslide inventory mapping and investigations" throughout the state, specifically in every county with steeply sloping terrain that's susceptible to landslides. Geologists have worked proactively in roughly 20 counties with forests to avoid and mitigate landslide risk during timber harvesting operations, in about 19 counties in urban and suburban areas and about 18 counties along 460 miles of state highway corridors. The state has also 3-D mapped the geology in roughly 32 of the 58 counties in the state.

"California has always been exposed to landslides because of the steep terrain, the active geology like earthquakes and then also winter storms," ABC 10 Chief Meteorologist Monica Woods said. "Our communities are more exposed to those hazards, as well as wildfires really stripping the landscape."

Debris flow, a form of rapid landslide that combines rushing water, loose soil, rocks and trees, devastated Montecito in 2018. Intense rainfall a few weeks after a wildfire left the area vulnerable to debris flow and mudslides.

"There was no place for that rain to go, so instead, the hillside collapsed and sent debris into the lower community in the early morning hours," Woods said. "Twenty-three lives were lost, hundreds of homes damaged or destroyed, plus it closed Highway 101."

Woods said some parts of California need constant monitoring due to landslide risk. La Conchita in Ventura County has a long history of instability, for example. Most recently, in 2005, a prolonged period of heavy rain caused the hillside to collapse, killing 10 people. Big Sur, which is also along the California coast, remains prone to landslides too. Slides have closed Highway 1 twice in the past 10 years, Woods said.

"When emergency officials say, 'It's time to go,' don't wait," Woods recommended. "Time is of the essence. You want to make sure you're ahead of the event, not trying to escape it when it's actually happening."

In neighboring Arizona, geologists started basic mapping roughly a decade ago and in the time since, have mostly focused on major highway corridors, including a debris flow study in the metro Phoenix area. Like many other states, Arizona is also relying on Light Detection and Ranging (LiDAR), which allows geologists to see the earth's surface without tree cover to find landslides. The technology provides better models of ground elevation.

"I'd say we have most of the major slides but every time we look at a new area in detail we find more," Arizona Geological Survey Research Geologist Joe Cook said. "With the availability of LiDAR we are able to find additional slides we missed in previous mapping efforts."

The geological conditions in Arizona, which include clay soils and rock, coupled with heavy rains and wildfires, leave parts of the state more vulnerable.

"We get what are called atmospheric rivers, and that's a narrow channel of focused energy in the atmosphere. It's like a fire hose pointing straight at the west coast," 12 News Meteorologist Chris Dunn explained. "Landslides in California are mainly a wintertime problem. Flooding and landslides and debris flow in Arizona, it's mainly a summertime deal where we get really strong storms with heavy rain at that time of the year."

The Rocky Mountains are also a notable part of the country susceptible to landslides. Idaho and Colorado are among the states with landslide mapping programs. Idaho, which started its inventory in 1991, published a digital version in 2020 and is relying on LiDAR to remap the entire state. The state has already mapped three counties "at a fine scale" using the technology and is in the process of mapping another 13 of its 44 counties using LiDAR.

Much like Arizona, Colorado is using LiDAR to update maps first created prior to 2015. The state has mapped 10 counties, but more than two dozen mountainous counties "still lack modern lidar-based landslide inventories," which are the primary focus of future mapping efforts "as funding becomes available."

"We've had a bunch of (landslides) here in Colorado," 9 News Meteorologist Chris Bianchi said. "The most notable recent one would be the Grizzly Creek one that led to a lot of devastation. In fact, it washed out part of I-70 near Glenwood Canyon. Our most common kind of landslide is going to be because of a wildfire burn scar. You get an average summertime thunderstorm, that might not mean much for an area that's got a lot of grass, that's got vegetation, but if you're in a burn scar area or you're down slope of one, you're in a more prone location. I would say the part of the state that's probably the most prone to it would be the San Juans, the southwestern mountains, because they tend to get the most rain from a monsoon."

On the east coast, Virginia and Pennsylvania are in the very early stages of landslide mapping. So far, Virginia has mapped just a handful of counties, but intends to continue detailed mapping in other counties in the future. In Pennsylvania, mapping is even newer. Lawmakers there are also considering landslide insurance, shifting the state to "a more proactive approach" to landslide mapping by building a statewide inventory and developing susceptibility maps.

"In northeastern and south Pennsylvania, along with the mid-Atlantic region and into the Northeast, we see landslides from time to time. Heavy rain and snowfall, that's the leading culprit to a lot of these landslides, mudslides and rock slides," WNEP Chief Meteorologist Kurt Aaron said. "The heavy rain can create erosion and erosion on our stream's banks, our river banks, that can be very problematic."

Vermont, meanwhile, expects to have mapped the entire state by the end of 2026.

"Vermont has just 14 counties, (three) of which had landslide inventories associated with them from prior years. Last year we proposed a project to the USGS to complete landslide map inventories for the remaining 11 counties and received funding to deliver on a comprehensive database by the end of the 2026 calendar year," Vermont Agency of Natural Resources State Geologist and Director Ben DeJong said. "This effort has been a priority and we are on schedule."

In North Carolina, lawmakers included $1 million in landslide mapping funding in their 2026 budget, which the governor signed into law in July. However, the money can only be used for roads and critical infrastructure, not neighborhoods and residential areas. The funding is half as much as David Korte previously requested.

"It's beautiful here. People want to live here, and there are a lot of places to build and there are a lot of places that you can build if you are careful, and there are probably a few that you don't want to build there," Korte said. "This works, it's simple and it's not meant to scare anybody. It's just meant to improve our decisions. I believe it's saved lives."

Perry Vaile Adams and her family are prime examples. They considered building a home on a piece of property in Chimney Rock, but after looking at the finished maps in that county, they learned of past landslide activity near the property. With the urging of a consultant, they walked away from the land purchase and bought land in another part of the state.

"I can't believe that we're so lucky," she said. "When I went back to see it, it was completely destroyed. Washed away. It wasn't something that would have been survivable. Being aware of how close you came to your children being one of the other news stories that we talk about is not something that any parent wants to think about."

North Carolina is in the process of migrating its landslide inventory to a new system, so some of the state's historical mapping data is temporarily unavailable.

WCNC Charlotte Meteorologist Brittany Van Voorhees said, along with telling people about landslide maps, raising generational awareness about landslide dangers is critical to ensuring history doesn't repeat itself.

"Most of North Carolina's historic landslides, back in 1916 and 1940 and then with Helene, were all caused by tropical systems that came after days of rain," she said. "If (people) don't know what landslides are, which a lot of people don't and they don't know that there's been a landslide on their property, how would they know they were at risk?"

The failure to alert the public about landslide dangers played a role in the death of Jamie Guinn's wife. Now that he knows the risks, he can only wonder "what if?" 

"If we had just knew or had an idea, we'd know what to watch for, what to look for," Guinn said. "If this is something that does get mapped out and people know, they won't have to go through what we did. I really wouldn't wish that on anybody."

Read the full article here.