A narrow fjord in southeast Alaska, gray water, cliffs on both sides, low cloud sitting on them.<\/p>\n
High on one wall there is a line where the forest simply stops.<\/p>\n
Above it, trees. Below it, bare scoured rock and splintered stumps, for a thousand feet down to the water.<\/p>\n
Nothing burned and nothing was cut. Something came through and took the mountainside off.<\/p>\n
It happened before six<\/strong> in the morning.<\/p>\n There was nobody there<\/strong>.<\/p>\n A glacier filling a valley does more than sit in it. It presses outward against the rock walls on either side.<\/p>\n That pressure holds fractured slopes in place, and geologists call the support buttressing because the ice works the way a buttress on a cathedral does.<\/p>\n When the ice thins and pulls back, the support goes with it, and a slope that has been held for centuries is suddenly free to move.<\/p>\n The rock does not fall the moment the ice leaves. It creeps, opens its fractures, and finds the surface it will eventually slide on.<\/p>\n Here the glacier below the slope retreated sharply across a single week at the end of July, and the wall came down five days later.<\/p>\n The trigger was the ice leaving<\/strong>, not an earthquake arriving<\/strong>.<\/p>\n The mass that came off is put at roughly 84 million cubic yards, which is enough to bury a square mile of ground more than 50 feet deep.<\/p>\n Its crown sat over 3,280 feet above the water, so the whole block had that far to accelerate before it hit anything.<\/p>\n The landslide tsunami it pushed out broke at around 328 feet where it left the impact zone.<\/p>\n Two miles away, directly across the fjord, water climbed the opposite wall to about 1,578 feet above sea level and stripped it bare.<\/p>\n An island further down the arm lost nearly all of its vegetation, and the trimline left behind is visible from a boat today.<\/p>\n The scar is permanent<\/strong> and the fjord now has a different shape<\/strong>.<\/p>\n The event carried no earthquake, but it shook the ground hard enough to register across the regional seismic network.<\/p>\n Seismologists put the energy at the equivalent of a magnitude 5.4 earthquake, which is how the timing was fixed to the minute at 5:26 in the morning.<\/p>\n A federal tide gauge in Juneau, tens of miles away, logged a maximum of about 14 inches above the normal tide, with wave activity continuing for hours.<\/p>\n The runup figure of 1,578 feet is the second highest ever measured anywhere, behind a 1958 event in another Alaskan bay that reached about 1,730 feet.<\/p>\n The work was led from a Canadian university and published with eighteen authors, which is what a measurement of this kind takes.<\/p>\n One instrument network gave the clock<\/strong>, and field survey gave the height<\/strong>.<\/p>\n Here is the part that matters beyond this one fjord, and it was found in the seismic record afterward rather than at the time.<\/p>\n For days before the collapse the slope was producing small signals, each roughly the size of a magnitude 1 or 2 tremor, arriving about once an hour.<\/p>\n Six hours before failure the interval collapsed to every 30 to 60 seconds.<\/p>\n In the final two hours the signals merged into continuous vibration, which is a slope sliding on its failure surface rather than cracking.<\/p>\n That escalation is a recognizable pattern, and it means a slope of this kind can announce itself if somebody is watching the right instrument.<\/p>\n Careful measurement keeps replacing folklore, the way a catalog of sightings found no earthquake link for giant oarfish<\/a>.<\/p>\n The volume, the runup and the agencies involved are set out by the federal survey<\/a>.<\/p>\n A readable warning is worth nothing<\/strong> without a monitored slope<\/strong>.<\/p>\n This fjord is a cruise destination, and boats carrying hundreds of passengers work the same water most summer days.<\/p>\n Multiple ships had been in the arm the day before. On the morning itself the weather was wet and the hour was early, so nobody was ashore.<\/p>\n A seismologist on the study described it plainly as dodging a bullet, which is unusually direct language for a scientific coauthor.<\/p>\n What was lost was a kayak and a camp belonging to paddlers at the mouth of the arm, whose gear was swept off the shore.<\/p>\n Tour operators have since stopped running the fjord altogether and moved their trips to the arm next door.<\/p>\n Water can turn dangerous in places people treat as scenery, the way warm water<\/a> spins up funnels under ordinary fall clouds.<\/p>\n The precursor signals and the warning about retreating ice are described by the Alaskan institute<\/a>.<\/p>\n The scar is still shedding rock, and the next one will land in the same water<\/strong> with nobody watching<\/strong>.<\/p>\n","protected":false},"excerpt":{"rendered":" A narrow fjord in southeast Alaska, gray water, cliffs on both sides, low cloud sitting on them. High on one wall there is a line where the forest simply stops. Above it, trees. Below it, bare scoured rock and splintered stumps, for a thousand feet down to the water. Nothing burned and nothing was cut. … Read more<\/a><\/p>\n","protected":false},"author":28,"featured_media":37153,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"rank_math_focus_keyword":"Alaska","rank_math_title":"About 84 million cubic yards of rock came off an Alaska fjord wall and drove a landslide tsunami almost a third of a mile up the opposite slope, but the only things lost were a kayak and a camp","rank_math_description":"A landslide above Alaska's Tracy Arm on August 10, 2025 sent a wave 1,578 feet up a fjord wall. Three kayakers lost their gear but were unharmed. Here's t","footnotes":""},"categories":[24],"tags":[],"class_list":["post-37145","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-climate"],"_links":{"self":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/37145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/users\/28"}],"replies":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/comments?post=37145"}],"version-history":[{"count":3,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/37145\/revisions"}],"predecessor-version":[{"id":37285,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/posts\/37145\/revisions\/37285"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media\/37153"}],"wp:attachment":[{"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/media?parent=37145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/categories?post=37145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.ecoportal.net\/en\/wp-json\/wp\/v2\/tags?post=37145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Why a retreating glacier drops a mountain into the sea<\/h2>\n
What the fjord looks like now<\/h2>\n
Where the numbers come from and what they rank against<\/h2>\n
The days of warning nobody was listening for<\/h2>\n
How close it actually came<\/h2>\n