On Saturday, September 9, part of the Trift glacier in the Swiss Alps broke off and crashed into a glacier below it. About 220 people of Saas-Grund, a small nearby ski town, evacuated the area as a precaution, said local police spokesman Simon Bumann. The collapsed piece measured approximately 500,000 cubic meters. Local authorities who had been surveilling the glacier found that the glacier’s tongue, a long and narrow extension of ice, was moving at about 130 centimeters per day, according to the Valais canton police.
It was during the night that the glacier’s movement began to increase. Eventually, more than two-thirds of the glacier’s front edge broke off on Sunday morning, but the debris that hit the glacier below didn’t reach the surrounding inhabited areas. Authorities feared that the broken piece could have triggered an ice avalanche, potentially impacting the town. In August, eight hikers were buried when a rockfall triggered an avalanche in Bondo, Switzerland. The avalanche in Bondo moved about four million cubic meters of mud and debris, which is the equivalent of 4,000 houses, about 500 meters, according to the regional natural hazards office.
Since the evacuation ended in Saas-Grund, residents have been able to return to their homes, and local roads around the glacier have reopened. As a precaution, the area underneath the glacier, including hiking trails, remains closed to walkers.
Thanks to Martin Funk, a glaciologist at the technology institute ETH Zurich, the surrounding villages were able to evacuate in time before any damage had been done. Funk had recommended that an expensive radar system be reinstalled just three days prior to the incident to keep an eye on the glacier. Rangers in the Saas-Grund area have monitored the Trift glacier since 2014, when they first noticed that the north face of the Weissmies mountain had broken off. But an earlier radar system that had been installed in the area was later removed due to the high price of its innovative technology. The system is said to have cost authorities around 400 francs a day, or about 417 dollars.
“In 2014, it was found that the Trift glacier in the Weissmies area moves faster than is usual for glaciers in our region. Afterwards, the behavior of the Trift glacier was closely monitored,” said Sandra Schnydrig, head of housing control at the municipality of Saas-Grund, to GlacierHub. “In the years 2015 and 2016, the glacier was permanently monitored with a radar arm and the behavior of the glacier was analyzed. At the beginning of 2017, a more simple measurement method was installed via photo analysis.”
Part of Swiss glacier breaks off after residents evacuated – Washington Post #science
— Science Online (@USscienceOnline) September 10, 2017
There was no imminent threat until this year, when Funk saw that the glacier had begun moving again in the photos. “On Tuesday, September 5, the photo analysis showed that the Trift glacier started to move faster. Immediately afterwards, it was decided to reinstall the wheel arm measurement and to observe the behavior of the glacier more closely,” said Schnydrig. But when Funk urged authorities to reinstall the radar system, there was none available. The last radar in Switzerland had been sent to Bondo, another valley in the Swiss Alps, which recently suffered damage from an avalanche and mudslide.
Pictured: Damage caused by avalanche in Swiss town of Bondo
— Jacquie (@JacquieRobert20) September 11, 2017
Fortunately, on September 7, a radar system was sent from Germany and installed on the Trift glacier. With the proper equipment, Funk was able to predict the imminent collapse. “The degree of monitoring of this glacier is much greater than for most other glaciers in the world,” Jeff Kargel, senior associate research scientist and adjunct professor at the University of Arizona, told GlacierHub. “Technology is getting close to a point where satellite-based monitoring can detect the precursory movements of ice and result in semi-automated alerts. We are not far from being able to do that all over the world.”
The glacier will continue to be under constant evaluation. A third of the glacier’s snout remains and is unstable. Bruno Ruppen, president of the commune, was reportedly satisfied with the way the evacuation was carried out for this incident because the glacier did not cause any damage. “It could not have gone better,” he told local reporters.
The village of Saas-Grund was fortunate the recent event didn’t cause damage or casualties, but if the glacier continues to retreat at its current rate, it is assumed that more pieces of ice could break off. “The loss of ice below these remnants and the withdrawal of physical support from these pieces of the glacier means that they are very likely to fracture and slide off, especially during warm weather episodes when the ice melts, water gets in between the ice and the bed, and the whole mass becomes very slippery and weakened by fractures,” Kargel explained. “Therefore, the very common style of climate-change-driven glacier thinning, retreat, and seasonal melting is very often accompanied by this type of ice avalanche.”