By Franziska Müller
Published on
Around 2,000 cubic metres of rock broke away from the Hochvogel mountain in the Allgäu Alps in June. Now researchers are warning that another major collapse could be imminent, potentially sending up to 400,000 cubic metres crashing down the mountainside.
The summit itself is at risk of breaking apart, with a fissure that has existed since the 19th century steadily widening. Records suggest the crack was once about shoulder-width, but the gap is now several metres across.
Scientists have been monitoring the hotspot for twelve years, initially on field trips and, since 2018, with permanently installed sensors and measuring equipment. A drone with a laser scanner has also been deployed to the area.
In spring, measuring instruments recorded movement rates of up to five millimetres per week. In geological terms, that is extremely fast; normally the Alps shift by an average of around 1.8 millimetres per year. Readings from the early-warning system are now prompting the researchers to raise the alarm.
Hochvogel
The Hochvogel sits on the border between Germany and the Austrian region of Tyrol. It is part of the Allgäu High Alps and stands at 2,592 metres high.
The mountain has been closed to climbers approaching from the Austrian side for some time, but the ascent from Germany remains open.
At the beginning of October, a team led by geology professor Michael Krautblattler from the Technical University of Munich (TUM) climbed the peak once again to inspect the terrain and measuring instruments.
Krautblattler specialises in debris flows and rockslides and wants to "equip areas that are dangerous with intensive early-warning systems and thus be able to read properly the warning signs the mountain gives us," as he said in an interview with the German Alpine Club (DAV) in February.
Instruments transmit data around the clock
There are now more than 30 sensors on the Hochvogel, measuring the entire summit to millimetre precision and documenting movements.
In 2024, TUM described the main fissure as up to six metres wide, around 35 metres long, and about 60 metres deep.
A new crack on the south-west ridge is now regarded as a key weak point where the highest rates of movement are recorded. The scientists refer to this hotspot as "Fissure 6."
According to Krautblatter, similar early-warning systems are currently in use at only two other locations - the Partnach Gorge and the Höllental Gorge.
"There we are learning in great detail which signals the mountain gives off and how long in advance. Often, it is just days or hours. Systems like this will be vitally important in high mountain areas, because there things are going to change dramatically, beyond anything we know from experience," Krautblatter told DAV.
The researchers receive the data from the instruments systematically, several times an hour, in their offices. Krautblatter hopes the technology will help keep the Alps accessible while allowing authorities to close off danger areas before disaster strikes.
Hochvogel rockslide could be imminent
Researchers believe the mountain could be reaching a critical point and that between 250,000 and 400,000 cubic metres of debris could break away and crash down the mountainside.
Scientists believe extreme weather could be partly behind increasing movements on the mountain.
On the Hochvogel, "we can see a clear influence from heavy precipitation events, in other words intense rainfall, thunderstorms and snowmelt," Johannes Leinauer from the TU Munich team told Deutschlandfunk.
"And these thunderstorm events are currently becoming more frequent and more intense as a result of the climate change, and that can of course affect how quickly and how often such rockfalls occur," he added.