“Here in Sitka, we know the pain and the suffering of losing beloved community members so suddenly,” Busch said in an interview.
In fact, Busch, the director of the Sitka Sound Science Center, had just returned from an international landslide conference in Italy, where experts shared ideas on how to prevent exactly this kind of event.
Scientists say climate change is driving more landslides in Southeast Alaska, in part because of more intense rainstorms. That means communities are more at risk from devastating slides like the one that hit Wrangell, killing at least four people.
But there are things communities can do to prepare, Busch said.
“We’re going to be seeing these more intense rain events, and they’re going to cause natural hazards,” Busch said on Talk of Alaska Tuesday. “That’s what we’re seeing. This is what’s happening right now.”
Wrangell’s is the third deadly landslide in eight years to occur in Southeast Alaska. After the 2015 slides in Sitka, a 2020 landslide in Haines killed two.
All three communities experienced heavy precipitation leading up to the slides.
Southeast Alaska is no stranger to rain. What’s new, Busch said, is the increase in heavy rainstorms that release several inches of water in a 24-hour period. Climate change, driven primarily by burning fossil fuels, is warming the atmosphere. As the atmosphere warms, it can hold more moisture, leading to storms that can drop more precipitation in a shorter period of time.
“Just a lot of rain all at once,” Busch said. “Contributing to more flooding, more avalanches, more landslides.”
Wrangell experienced two inches of rain during the day of the slide and higher elevation wind gusts up to 60 miles per hour, Aaron Jacobs, a senior hydrologist for the National Weather Service in Juneau, told the Associated Press.
Those heavy rainstorms are also happening both earlier and later in the year, Jacobs said on Talk of Alaska.
“Later in the season is important, because there’s sometimes snow around, and that snowmelt can increase the water in the soils,” he said.
Saturated, wet soil and high winds can trigger landslides, Jacobs said. When the ground is no longer stable, gravity takes over and the muddy soil mass begins streaming downhill, taking down trees and anything else in its way.
State geologist Gabriel Wolken said the conditions in Wrangell last week were similar to the deadly landslides in Sitka and Haines.
And those wet conditions aren’t going away.
“Rain continues to fall on already saturated soils in Wrangell and across the region, so the potential for additional landslides continues, particularly following intense local rains and high winds in some of these areas,” Wolken said.
But there are ways for communities to prepare for landslides in the long term, Busch said. Sitka offers one example.
After the 2015 landslide, she said, there was a lot of anxiety that another one could strike at any moment.
“People were afraid. They were afraid of the rain and they were afraid of going out into the woods,” Busch said. “They were afraid to send their kids to school because maybe the schools were in landslide zones.”
As the director of a community science center, Busch’s instinct was to look for answers in science. So she and others reached out to researchers for help.
“We said to the scientists, what scientific questions can you answer that will make our community feel less anxious?” she said.
Scientists from the U.S. Geological Survey, the National Park Service, NASA and other agencies began modeling landslide conditions by gathering information like soil moisture content, precipitation levels and water volume in streams.
Sitka ended up partnering with researchers to develop a landslide warning system to identify areas of the community at risk when landslide conditions are present. The design process, which involved mapping the surrounding landscape and collecting extensive public input, took four years.
Today, 10 rain gauges around the community collect information about rain intensity to help model landslide risk. The warning system includes a simple online dashboard where residents can check current risk levels.
Busch and her team are now helping six other Southeast communities — Yakutat, Klawock, Skagway, Hoonah, Kasaan and Craig — build their own warning systems, with funding from the National Science Foundation.
Alaska’s landslide potential has received more attention in recent years. In 2020, responding to the Haines and Sitka landslides and the ongoing Barry Arm landslide in Prince William Sound, Congress directed the U.S. Geological Survey to establish the National Landslide Hazards Reduction Program, with a team of scientists based in Alaska.
Busch said there’s much more research to be done on landslide risk, and scientists are eager to work with communities to figure out how best to prepare.
“Communities have every reason to participate, to protect their property and their people,” Busch said. “I feel like we’re kind of ripe for it. (Alaska is) the perfect place for this kind of work.”