Just before dawn on August 10, 2025, a colossal slab of rock broke free from a mountainside above Alaska’s Tracy Arm fjord. The 63.5-million-cubic-meter landslide crashed into the fjord’s deep waters near the South Sawyer Glacier, unleashing an initial wave more than 100 meters tall. Within seconds, the surge sliced across the fjord at over 70 meters per second. Upon striking the opposite shore, it climbed the sheer cliffs to a staggering 481 meters above sea level—marking one of the highest runups ever documented.
A tsunami unlike any other
Most tsunamis triggered by earthquakes top out at a few dozen meters when they reach land. Landslide-generated tsunamis behave differently. Their violence stems from the sudden displacement of millions of tons of rock into a narrow, deep fjord. The abrupt shift in water depth and the direct force of the rock’s impact create waves that are both localized and extreme. Since 1925, researchers have recorded 27 such events with runups exceeding 50 meters. The most notorious remains the 1958 Lituya Bay event, which peaked at 530 meters.
A near-miss with global implications
“This was the second-highest tsunami ever recorded,” says Aram Fathian, a geoscientist at the University of Calgary and co-author of a recent study in Science. “Yet few people knew it even happened because it struck at 5:26 am, when the fjord was empty.” The absence of injuries or damage owed much to timing, but Fathian cautions that future events may not be so fortunate.
The landslide’s origin points to ongoing glacial retreat in Alaska. As glaciers melt, they reduce the structural support for surrounding rock faces. Combined with permafrost thaw, steep slopes become increasingly unstable. The Tracy Arm event underscores a broader trend: shrinking glaciers are raising the risk of catastrophic landslides in regions once considered stable.
What comes next for at-risk regions
Scientists are now racing to improve early warning systems for landslide tsunamis. Remote sensing, seismic monitoring, and high-resolution topographic scans can detect slope instability before collapse. Yet budget constraints and the remote nature of many glacial fjords limit widespread deployment.
Communities near Alaska’s Inside Passage, Norway’s fjords, and Patagonia’s glacial lakes must prepare for similar events. While rare, the stakes are life-altering when a 500-meter wave strikes. The Tracy Arm tsunami serves as a stark reminder: the next megatsunami could arrive without warning.
As glaciers continue to recede, researchers stress the need for global collaboration. Mapping unstable slopes, investing in monitoring tech, and updating emergency plans could prevent future tragedies. The question is no longer if another event will occur—but when.
AI summary
Alaska’nın Tracy Arm fiyordunda meydana gelen devasa heyelan tsunamisinin arkasındaki bilimsel nedenleri, iklim değişikliğinin rolünü ve gelecekteki riskleri keşfedin.
