Alaska Tsunami Sent Water 1,580 Feet Up a Mountainside

The authors state plainly: "We believe that this combination of signs would have been sufficient to issue progressive alerts to any ships in the vicinity and homes and businesses that could have been harmed by a tsunami at least a day prior to the failure — had a monitoring program existed."

What would an alert system look like?

The researchers sketch a three-tier framework on a yellow-orange-red scale:

• Yellow: Weather plus rapid glacier retreat — conditions present in early August 2025 — would justify a notice that hazard levels were temporarily elevated in a general area.
• Orange: In the hours before the collapse, seismic events increased exponentially and shifted into a continuous "hum" of seismic energy known as seismic tremor. Those signals warranted immediate concern for a specific region, including keeping boats out of the fjord.
• Red: Once a large slide begins, the researchers' work shows the event can be detected and roughly sized within a couple of minutes from seismic waves alone — enough to signal an event in progress.

A warning would have offered little to ships in the immediate vicinity, but it could have given people farther away perhaps 10 minutes of notice. NOAA's tsunami warning program has spent decades refining exactly this kind of rapid message dissemination.

No landslide monitoring system operates at this scale anywhere in the U.S. Building one would require cooperation across state and federal agencies, plus stronger monitoring and communication networks. Even then, it will not be fail-proof.

What changes for people working in these regions?

The conditions at Tracy Arm are not unique. Landslides are common in Alaska's coastal mountains, where tectonic uplift and long-term ice loss converge with heavy precipitation and moving glaciers. As glaciers retreat across the Arctic, the hazard grows — sometimes with deadly consequences, as events from Alaska to Greenland and Norway have shown.

The authors frame the choice facing Arctic countries bluntly: avoid vast swaths of coastline, or live with a poorly understood risk. They argue for a third path: alert systems modeled on those used for avalanches and volcanic unrest. Those systems do not remove risk, but they have made winter backcountry travel safer for more people.

The same glaciers, ice-choked waters and steep mountains that create the hazard draw visitors to these places, and people will keep coming. As the authors put it, the question is not whether these places should be avoided altogether, but how to help people make more informed decisions.

On Aug. 9, tourists passed through a landscape on the cusp of failure without knowing it. An alert system might have given tour companies and residents the information they needed to avoid being caught by surprise.

Monitoring, not avoidance, is the first step.