Hochvogel, a solitary 8,504 ft (2592 m) high peak in the Eastern Allgäu Alps on the border between Germany and Austria, can collapse anytime due to a crack say the scientists. This mountain peak has extensive vertical fracture’s which run perpendicular to the general dip, giving rise to an intensely fractured fabric. These large fractures in the summit area were first noticed in the late nineteenth century. The growing mountain has a progressively accelerating rock slide which developed since the 1950s. As per the recent measurements, the crack at the summit is about 40 metres long, 8 metres deep and 3 metres wide. The study is by the Helmholtz Centre Potsdam – German Research Centre for Geosciences and the Technical University of Munich.
In the event of the collapse, up to 260,000 cubic metres, limestone debris could fall into the Hornbach Valley in Austria. About six subunits of rocks, ranging from 8000 to 148000 cubic metres are located along a failure plane on two large, NE–SW trending fracture systems. The rock falls have already begun but the authorities say that there is no threat to the population living around it. The threatened areas lie in Zugspitze area in Germany, Hornbach Valley in Austria and Central Apennines in Italy.
In 2018, the main fracture at the south east had already opened by 2–4 m, had a dimension of about 5 m width and 30 m length, and since then it continued to open at a rate of a few mm per month. The main fracture is more than 60 m downwards with a minimum sliding plane surface area of 2000 square meter. The authorities have installed a number of seismic stations with round the clock monitoring with a real-time high alpine monitoring system. The scientists are using a seismic approach for the measurements of the activities.“we can now for the first time sense, record and process this cyclical phenomenon continuously and almost at real time”, says Michael Dietze, the lead author and post-doctoral researcher at the GFZ Helmholtz Centre Potsdam.
The researchers have observed a recurrent sawtooth-like frequency pattern of seismic activities and have attributed the rise in frequency of activity to a so-called stress increase within the rock mass. When the frequency drops, the sensors record an increased rate of crack cues, as they are known to happen when rock is being torn apart. This cyclical increase and decrease of stress by jerky movement is also called stick-slip motion – something considered to be a typical precursor of large mass movements.
The researchers are divided if the rock falls will continue in a gradual manner or in a single collapse. But in the recent years, the southern part of the mount has subsided by several metres, and at some point, it will collapse in the form of a landslide say the researchers.