It's happening again — a second Swiss glacier has just shown the same signs as Blatten.

Hinzugefügt: 2026-06-04

[00:00:10]Exactly 1 year ago in 40 seconds, an entire Alpine village ceased to exist. 9 million cubic meters of rock, ice, and mud came down this mountain at 200 km an hour. The people were already gone. The warning had worked and almost everyone believed the danger had left with them.

[00:00:25]It had not.

[00:00:26]Because today, just a few kilometers up the same valley, a second glacier is showing the same signs the first one showed in the weeks before it failed.

[00:00:34]This is the story of how a mountain can give a warning clear enough to save 300 lives and still leave the scientists who issued it admitting how little they really understand.

[00:00:43]This is the Lötschenthal, a narrow glacial valley in the canton of Valais in southern Switzerland. For centuries, it was considered one of the most isolated and untouched valleys in the entire Alps. Snow-capped peaks, streams of meltwater running clear over stone, wooden chalets that had stood for generations and passed from parent to child. And at the head of the valley sat Blatten, a village of about 300 people, the kind of place where families could trace their roots back hundreds of years. On the morning of May 28th, 2025, that village was buried under a wall of debris in less than a minute. To understand why it happened and to understand the warning that Swiss scientists are issuing at this very moment, we have to start with what came down that mountain and with the hidden process that set it loose.

[00:01:24]Above Blatten stood the Birch Glacier.

[00:01:26]And above the glacier rose a peak called the Kleines Nesthorn, a complex mass of nice and amphibolite, the kind of hard crystalline rock that builds the spine of the Alps.

[00:01:37]In the weeks before the collapse, that rock face was crumbling. Pieces of the mountain, some of the size of houses, were breaking off and falling onto the glacier below, loading the ice with an enormous and steadily growing weight.

[00:01:47]Swiss authorities were watching it happen almost in real time, and their response is the single reason this is not a story of overwhelming loss.

[00:01:54]On On 17th of May, 92 people were evacuated as the rock fall intensified.

[00:01:59]On the 19th, all 300 residents of Platten and the nearby Hamlet of Ried were ordered to leave within 2 hours before noon.

[00:02:06]The livestock were flown out by helicopter, one by one. A lame cow named Loni became the last animal airlifted to safety, and that single image, a frightened animal carried through the air away from a doomed valley, moved the entire country. And then everyone waited. There's something worth pausing on here because it is easy to hear evacuation and move on. These were not strangers passing through. The Litschental is one of those Alpine valleys where the same family names appear in the church records for five and six hundred years.

[00:02:33]People did not just lose houses. They lost the barn their great-grandfather built, the orchard a family had tended across generations, the view from a kitchen window that had framed the same mountain for a lifetime. When the order came to leave within 2 hours, families had to choose in minutes what fragments of centuries they could carry out by hand.

[00:02:50]That is the human weight sitting underneath the clean statistics of a successful evacuation. For nine long days, the mountain held. Nothing moved.

[00:02:59]And in those nine days, something very human happened.

[00:03:02]>> [music] >> People began to hope. Maybe the models had been too cautious. Maybe the worst had been avoided. Maybe they would be allowed to go home. It is worth remembering that this kind of waiting is its own ordeal.

[00:03:12]The scientists could not promise anything. They could only say that the mountain was unstable and that the safest place was anywhere but the valley floor.

[00:03:19]Then, on the 28th of May, the Birch Glacier gave way almost in its entirety.

[00:03:24]In around 40 seconds, more than 9 million cubic meters of rock, mud, and ice surged down the slope at roughly 200 km an hour. The debris flow slammed into the valley floor and blocked the Lonza River that runs through it, forming a new lake behind the rubble and raising the immediate threat of flooding for everyone downstream.

[00:03:42]One man, a 64-year-old shepherd who was outside the evacuation zone, did not survive.

[00:03:47]The early warning had protected 300 people, but the village itself was gone.

[00:03:51]Roughly 90% of Flatten was destroyed, and the later damage estimate reached around 255 million Swiss francs.

[00:03:58]An entire community, centuries in the making, gone in well under a minute.

[00:04:01]Now, why would a glacier collapse at all? This is where the science matters, because the truth is not the story most people carry in their heads.

[00:04:09]We tend to picture glaciers as slow, quiet rivers of ice that simply shrink and melt away over decades, gently and predictably. The reality in the high Alps is far more sudden and far more violent, and it begins with something you cannot even see from the surface. It begins with permafrost. High in the mountains, the rock itself is held together by ice. Not the glacier ice you see on top, but frozen water locked deep inside the cracks and joints of the bedrock. Ice that has been frozen solid for thousands of years. This frozen ground behaves like a glue, binding the fractured mountain into a single stable mass. It is the reason these steep faces have stood for so long.

[00:04:44]As the climate warms, that permafrost begins to thaw. The glue softens, and a rock face that was solid for millennia can, in a single warm season, lose the very thing that was holding it together. At Flatten, the thawing permafrost loosened the Klein Matterhorn, and the mountain began shedding rock onto the Birch Glacier.

[00:05:03]And here is the cruel twist that surprised even the experts who study these systems for a living. That falling debris, at first, actually protected the glacier.

[00:05:12]A thick layer of rock on top of ice works like a blanket, insulating it and slowing the melt.

[00:05:17]So, for a while, the glacier looked almost healthier. But, all that rock had a second effect mattered far more.

[00:05:22]Its sheer weight began to push down on the ice and drive it forward.

[00:05:26]The glacier started to move, slowly at first, then faster, until in the final weeks, its speed climbed dramatically.

[00:05:33]The entire system, the broken rock above and the moving ice beneath, was sliding toward a single point of failure.

[00:05:39]Think of it like a shelf bracketed to a wall. For years, that bracket holds. You keep stacking more and more weight onto the shelf, and it keeps holding, and you start to believe it always will right up until the instant it doesn't and the shelf and everything on it comes down together. That is what a glacier collapse of this kind really is. It is not a melt and not a slow retreat.

[00:05:58]It is the sudden structural failure of an entire mountainside all at once. And there is a deeper layer to this that geologists think about constantly even if it rarely reaches the public. Because while Switzerland spent the past year mourning Bietschhorn and drawing up ambitious plans to rebuild it, glaciologists in Valais quietly turned their instruments toward a completely different glacier. Its name is the Eueschbielgletscher and it sits above the hamlet of Fafleralp just a few kilometers up the very same Lötschental Valley from the ruins of Bietschhorn.

[00:06:27]Over recent months, satellite data and field observations have detected what officials are carefully calling isolated collapses and anomalies [music] on this glacier.

[00:06:36]Those are not random words. They fall into the same categories of early signals that preceded the failure of the Bietschhorn glacier. As a precaution, the authorities have closed the road between Steg and Fafleralp, shut down a popular hiking trail, and delayed the reopening of tourism in the upper valley. The area above the destroyed village has become once again a watch zone monitored day and night.

[00:06:57]Now, an honest scientist has to be very careful here and so do we.

[00:07:01]The Eueschbielgletscher area is largely uninhabited and that single fact makes it profoundly different from Bietschhorn. There is no village of 300 people directly in the path. The signals detected so far are anomalies, not the announcement of an imminent collapse, and detecting early warning signs is genuinely not the same thing as predicting an event. We're not telling you a second disaster is about to happen.

[00:07:22]But that careful uncertainty is exactly what makes this moment so important because it points to a truth that reaches far, far beyond this one Swiss valley. So, could this affect where you live? If you're watching from outside the Alps, the direct answer is no. A Swiss glacier is never going to reach your town.

[00:07:38]But the mechanism behind it absolutely can reach you because that mechanism is not unique to Switzerland. Mountain permafrost is thawing across every major glaciated range on Earth.

[00:07:48]The exact same process that loosened the rock above Blett is at work right now in the Andes, hanging above growing cities in Peru. It is at work in the Himalayas, above villages and valleys in Nepal, India, and Pakistan, where sudden glacial floods already threaten entire communities. It is at work across Alaska and the mountains of Western Canada. In 2022, a chunk of the Marmolada Glacier in the Italian Dolomites broke off during a heatwave and swept through a popular hiking area with a severe human cost.

[00:08:15]The danger here is not that one Swiss valley is uniquely doomed. The real danger is that high mountain landscapes everywhere are entering a phase of instability that our historical experience simply did not prepare us for. When and where the next one happens is still, honestly, anyone's guess. That another one is coming, somewhere, is no longer in doubt. And here's the part that almost no one is willing to say out loud. The Blett warning is being held up around the world as a success story, and in human terms, it absolutely was one.

[00:08:43]300 people walked away from a disaster that flattened their homes. That is a genuine triumph of monitoring and of nerve. But listen closely to what the scientists themselves are now admitting in the aftermath. One glaciologist studying these very slopes described the situation as new, unexplored terrain, and called it chaotic, because every mountain behaves differently and no two failures are quite alike. They could see, clearly, that the Bersch Glacier was failing. They simply could not say when.

[00:09:10]>> [music] >> And when it finally went, the near-total breakup still came as a surprise to the very experts who were watching it in real time on their screens, expecting it.

[00:09:18]That is the uncomfortable truth sitting underneath the success. We have become good enough to know, with confidence, that a mountain is dying. Knowing the hour it will fall is still beyond us.

[00:09:27]And as the permafrost keeps thawing season after season, the number of mountains we are forced to watch only grows. The success at Blett was never the end of the danger. It the first clear full look at how much we still cannot predict. So I will leave you with the question this valley is forcing the world to confront. If a mountain can give a warning clear enough to save 300 lives and still take the people who issued that warning by surprise, then what does that tell us about every other peak we are not yet watching at all? That is the real weight of the Loetschental.

[00:09:57]If you're watching this on your television, search for the channel Geology Info on YouTube, where we track the planet's most important geological events as they unfold, with the science explained honestly and in full. And tell us in the comments below, >> [music] >> knowing everything we now know, should people be allowed to rebuild in a place like Blatten?

[00:10:15]There is no easy answer, and we read every single comment you leave.