A ‘near-miss’ tsunami that occurred in Tracy Arm fjord, Alaska last year reached an incredible height of 481 meters. Remarkably, despite the fact that this fjord is heavily visited by cruise ships in summer, no boats were caught when it struck at 5:30 a.m. on 10 August 2025.
The event happened when more than 60 million cubic meters of rock collapsed into the fjord, triggering the wave which ran 481 meters up the wall of the fjord. Eyewitnesses in the area reported chaotic conditions: kayakers tens of kilometres away were awakened by surging water that swept away equipment, while observers elsewhere described waves and strong currents moving through the fjord system. The event has already led major cruise companies to cancel trips into Tracy Arm for the 2026 season.
However, nobody observed the wave directly. In the new study, an international team of researchers led by UC Calgary used a combination of satellite data, seismic recordings, and numerical modelling to understand exactly what had happened.
Engineering researcher Dr Thomas Monahan was part of the team that analysed seismic data to identify the signal of the wave. This revealed the surprising discovery of a series of long-lived oscillations that continued to reverberate through the fjord long after the initial impact.
