Tracy Arm, Alaska: the fjord where a wave surged 481 metres high
The glacial fjord of Tracy Arm in Alaska is a destination for expedition ships. A new analysis describes the landslide that triggered the second-highest tsunami on record there in 2025.
Photo: Lauren from San Jose, CA, USA / Wikimedia Commons, CC BY 2.0 (cropped and resized)
Video: YouTube · Alaska Earthquake Center · youtube.com
Tracy Arm is a narrow fjord in Alaska lined by steep rock walls, with South Sawyer Glacier among the glaciers at its head. Shortly after 5 a.m. on Aug. 10, 2025, a massive landslide crashed into it. Water and debris surged 481 metres (1,580 feet) up the opposite wall, higher than the top floor of the Taipei 101 skyscraper. The authors describe it as the second-highest tsunami in recorded history.
Passengers aboard the expedition ship Hanse Explorer had visited the glacier on the evening of Aug. 9, about 12 hours earlier, before heading back down the fjord. Seismologist Michael West and Ezgi Karasözen of the Alaska Earthquake Center describe the warning signs in The Conversation: heavy rain, rapid calving and thousands of small tremors in the days before the collapse. The glacier below the slope had retreated more than a third of a mile (over 500 metres) in the two preceding months.
A monitoring programme could have issued alerts at least a day in advance, and a warning system could have given people farther away about 10 minutes' notice, the authors say. “Alert systems do not remove the risk entirely, but they are a better option than no warning at all,” they write. No landslide monitoring system operates at this scale in the US yet. The underlying study was published in the journal Science.
This article is for information only and is not legal, tax, financial or medical advice. Figures as of the date stated.