Tsunami — City and Borough of Juneau, Alaska

2025-08-10 · City and Borough of Juneau, Alaska

Event narrative

The landslide generated tsunami scoured trees and vegetation from both sides of the Tracy Arm fjord. The National Tsunami Warning Center reported that the maximum tsunami wave height at the Juneau tide gauge was 36 cm (approximately 14 in) from the normal tide prediction, which occurred around outgoing and low tide, and continued to measure successive waves for 5 hours.

Wider weather episode

USGS and the Alaska Earthquake Center reported that seismic activity was measured at 526am AKDT on the 10th of August in vicinity of Tracy Arm south of Juneau. The seismic measurement had a landslide signature that they recognized and further USGS ground investigations confirmed that a large mass of the mountain fell into the water at the terminus of South Sawyer Glacier, generating a massive tsunami and successive waves that scoured trees and vegetation from both sides of the fjord and Sawyer Island. As a result, a significant amount of debris remained in the fjord and nearby areas for days after the event and disrupted navigation.

Source: NOAA Storm Events Database, event_id 1293399. Narrative written by the NWS forecast office that issued the report.