Scientists decode hidden seismic signals beneath Alaska's unstable landslide

Since 2020, researchers have been listening to the ground beneath Alaska's Barry Landslide in Prince William Sound. What they're hearing might give them crucial minutes—or hours—of warning before a catastrophic collapse sends half a billion cubic meters of rock into a fjord and triggers a tsunami.

The Barry Landslide is genuinely dangerous. It's massive, it's been creeping for decades, and it sits on fractured bedrock in a steep fjord that's lost the glacial buttress that once stabilized it. If it fails suddenly, the material would fall directly into the water. Nearby communities like Whittier, plus kayakers and cruise ships in the area, would be at risk.

A New Signal in the Noise

What makes this research significant is what Gabrielle Davy and her team at the University of Alaska Fairbanks discovered while sifting through a year of continuous seismic recordings. They found a previously unrecognized signal—sharp, high-frequency pulses that follow a strict seasonal pattern. They show up in late summer, intensify through winter, then vanish by early spring.

The researchers propose these signals come from water freezing and thawing inside tiny cracks in rock beneath the nearby Cascade Glacier. It's a subtle process, but it reveals something important: changes in underground water conditions that could eventually destabilize the slope.

This wasn't obvious at first glance. The seismic data is noisy—full of vibrations from small earthquakes, glacier motion, and general background rumble. Davy's team had to manually review the recordings to train their eyes to recognize what "normal" looked like before anything unusual would stand out. "By spending time with the raw data, you train your eye," Davy explained, "before developing classification tools and detection algorithms."

Building an Early Warning System

The Alaska Earthquake Center is now testing a regional landslide detection system at Barry Arm that will alert authorities to any slope failures in real time. This work matters because it's part of a broader shift in how scientists think about landslide hazards. Precursor seismic activity—if it occurs—can provide precious early warning.

The freeze-thaw signals themselves aren't signs that the landslide is moving. But they're a window into changing conditions beneath the slope. Similar signals have been documented in Norway near other unstable rock slopes, suggesting this pattern might be recognizable elsewhere too.

There are other sites in southern Alaska with similar hazards, and researchers are now investigating whether this detection approach could work there as well. The goal isn't to predict the unpredictable—it's to listen carefully enough that when something does shift, we hear it first.