The unstable ice masses in danger of falling on the hanging glaciers on the west side of the Eiger have fallen in small, individual pieces in the last couple of hours. The movements of the glacier have declined to normal levels. The infrastructure in the area of the Eiger glacier was not affected by the breakages. All hiking routes that were blocked off as a precaution, are open again from now.
Early warning thanks to the monitoring system
The current ice breakage was forecast to have been around 20,000 m3. Events of this magnitude have occurred in the past about once per decade. The event was recognised promptly in this case, as a modern monitoring system has been in place since March 2016. An interferometric radar system permanently measures the speeds of the glacier that, according to Dr Lorenz Meier, Managing Director of Geopraevent AG, have increased in about the last ten days from the usual 5 cm per day to over 60 cm per day. In March and April of this year, several smaller breakages could be recognised a few days in advance with the same radar. In winter, an avalanche radar is also in use, which promptly stops the Jungfrau Railways trains at a safe location in the case of a large avalanche.
The radar measurements are regularly monitored and interpreted by Geotest AG glaciologists. Risk areas and measures to be taken are established in a safety strategy. According to Manager Daniel Tobler, at-risk areas were blocked off on Sunday at the Eiger glacier station for safety reasons, based on the measurement data. With the drop in speeds after this morning's breakages, the block could be removed.
According to Prof. Martin Funk of the Laboratory of Hydraulics, Hydrology and Glaciology (VAW) at the Swiss Federal Institute of Technology in Zurich, breakages and ice avalanches regularly occur from hanging glaciers on the west side of the Eiger. Unlike snow avalanches, ice avalanches may happen at any time of year. An ice breakage occurs if a section of the hanging glacier breaks off and plunges downwards. Ice breakages are entirely normal occurrences for such high hanging glaciers, such as those on the Eiger. Smaller break-offs are much more frequent than large ones. Events with a few thousand cubic metres of ice arise at least once per year. However, events of a volume of more than 10,000 m³ are much rarer. The last large breakage, with almost 100,000 m³ ice, was in August 1990.