A catastrophe resembling the disaster that struck Nepal could also unfold in parts of the United States, where unstable mountainsides have the potential to collapse, hurl massive waves across waterways and send fast-moving walls of mud into nearby communities.
The deadly flash flood that hit Nepal on Wednesday was probably set off when a huge section of glacier broke loose and crashed thousands of feet into the valley beneath it, according to an early scientific analysis.
Scientists have been closely watching two areas of the US for years, warning that a sudden slope failure could either generate a tsunami or unleash a destructive mudflow with little time for residents to react.
‘Alaska has much of the same ingredients for hazard cascades that occur in Nepal and surrounding countries,’ Marten Geertsema, an adjunct professor of earth sciences at Canada’s Simon Fraser University, told Our News Outlet. He said warming conditions can thaw frozen ground and destabilize steep terrain, while shrinking glaciers can strip away the icy support that once helped hold mountain slopes in place.
In 2020, Geertsema and 13 other scientists raised alarms about Barry Arm in Alaska’s Prince William Sound, where an unstable slope could give way and plunge into the water, potentially producing a devastating landslide-triggered tsunami. At the time, the researchers described such an event as ‘likely within 20 years.’
Another major concern lies in Washington state, where Mount Rainier — an active, heavily glaciated stratovolcano towering near the Seattle-Tacoma metro area and more than 3.3 million people — has ice-capped slopes capable of releasing deadly surges of mud, rock and debris with minimal warning.
More than 90,000 people are believed to live inside mapped hazard zones for lahars, the volcanic mudflows that can roar downstream like wet concrete. Made up of water, rock, mud and debris, these powerful flows do not always require a volcanic eruption to begin.
Computer models indicate that a large Mount Rainier lahar could reach neighborhoods beyond the boundaries of Mount Rainier National Park in as little as 15 minutes, or within about an hour, depending on where it starts.
Nepal’s devastation (pictured) offers a warning for some American communities, where unstable mountainsides could give way to towering waves and deadly torrents of mud
Wednesday’s deadly flash flood in Nepal was likely triggered when an enormous chunk of glacier broke away and plunged thousands of feet into the valley below
More than 360 people have died and more than 1,400 remain missing across Nepal and Tibet following Wednesday’s disaster.
The US Geological Survey (USGS) identified a glacier collapse and debris flow that produced a seismic signal initially mistaken for an earthquake.
The disaster illustrates a ‘hazard cascade,’ where one collapse sets off destruction far downstream.
In Alaska, retreating glaciers bring deep seawater closer to unstable mountainsides, allowing falling rock to unleash powerful waves, Geertsema explained.
‘As we have seen at Taan, Lituya and Tracy Arm, rock slides into deep waterbodies can cause very high localized tsunamis,’ he said.
At Taan Fiord in October 2015, a landslide sent water surging 633 feet up nearby slopes, stripping forest from eight square miles. No one was injured.
At Lituya Bay in July 1958, an earthquake triggered a rockslide that forced water 1,720 feet up a ridge. The tsunami destroyed a cabin and lighthouse and killed two people aboard a fishing boat.
At Tracy Arm on August 10, 2025, another collapse sent water nearly 1,600 feet up the opposite mountainside, stripping vegetation from the inlet’s walls. No fatalities were reported.
More than 360 people have died, and more than 1,400 remain missing across Nepal and Tibet following Wednesday’s disaster.
An aerial view of a town along the confluence of the Trishuli and Tadi rivers in Nepal’s Nuwakot district which was overwhelmed by muddy flood waters
Scientists also monitor Barry Arm, about 30 miles northeast of Whittier, where a mountainside could collapse into the water and generate a tsunami.
Alaska’s latest monitoring update reports no signs of large-scale active movement, although smaller failures could still trigger localized tsunamis.
Despite improvements in monitoring technology, Geertsema said events such as the Tracy Arm landslide-tsunami remain ‘frustratingly difficult to predict.’
At Washington’s Mount Rainier, the danger takes another form: torrents of water, mud and rock that can race toward communities below.
Rainier, located roughly 60 miles from Seattle, is heavily covered in glaciers and unstable volcanic rock, conditions experts say create the perfect setup for catastrophic mudflows.
USGS has previously said: ‘The volcano is not ‘due’ for an eruption and we do not see any signs of a potential eruption at this time.’
The disaster illustrates a ‘hazard cascade,’ where one collapse sets off destruction far downstream
Scientists warned in 2020 that an unstable slope at Barry Arm (pictured), in Alaska’s Prince William Sound, could collapse into the water and trigger a catastrophic tsunami
However, the agency also noted that a devastating lahar could come without warning, citing the Electron Mudflow of 1500AD that was caused by a landslide on the volcano’s west flank.
Scientists have found no signs of a volcanic eruption taking place.
USGS set up a lahar detection and warning system on Mount Rainier in 1998, which uses sensors buried in the ground and tripwires along key river valleys that sense the vibrations of an approaching lahar and automatically alert emergency centers.
The system was later upgraded between 2015 and 2021 with 14 new modern stations to transmit data in real time, cover additional river drainage areas and use better technology such as seismometers and cameras to spot lahars earlier.
Still, the resulting devastation from a lahar down Mount Rainier could come too fast for residents to react in time.
Studies of the west flank have warned that this area is still vulnerable to a ‘future large-scale collapse’ which would send mudslides down multiple river paths.
Scientists are warning that three Washington towns could be devastated within minutes if a massive volcanic mudflow suddenly roars down Mount Rainier during an eruption
This mudflow could hit communities such as Orting, then continue toward Sumner and Puyallup. It could also travel south toward the town of Ashford and areas near Alder Lake.
The deadliest modern US lahar struck during the 1980 eruption of Mount St Helens, when the volcano’s collapsing north flank and scorching pyroclastic flows rapidly melted glacial ice.
The resulting torrents of mud and debris surged more than 60 miles through the Toutle and Cowlitz river valleys, destroying over 200 homes, 195 miles of roads and 27 bridges.
The danger of lahars in Washington has become so alarming that emergency officials now conduct massive evacuation drills designed to prepare residents for a disaster many experts believe is inevitable.
