Glacier collapses are a growing but difficult to predict threat

Neither Maggi nor any of his colleagues were able to visit the site in person due to the risk of further ice falls, as well as the ongoing police investigation. But the statement they released at the end of their conference offers perhaps the clearest picture yet of the physical processes behind the collapse.

He identifies a number of contributing factors – the steepness of the slope below the secondary peak, Punta Rocca, from which the ice broke away; the fact that this section of ice had shrunk so much that it had separated from the main body of the glacier; and the presence of a large crevasse which, like the perforations of a postage stamp, became the fault line along which the serac sheared.

“What happened – well, what we think happened, because without the ability to do a full investigation, we can’t say for sure,” Maggi says, “is that there’s had water build up inside this crevice, which created pressure and pushed until it broke down.

The media made much of the heat wave that preceded the incident, with temperatures of 10 degrees Celsius recorded near the Marmolada summit, 3,343 meters above sea level, the day before the collapse. But while the conditions could have acted as a final trigger, Italian and international experts caution against assigning too much importance to the heat of that day or to short-term weather conditions. “I think it is quite important to say that this is not the only reason, as has sometimes been reported or implied,” says Matthias Huss, professor of glaciology at ETH, the Swiss Federal Institute of Technology in Zurich. . “It was the long-term evolution of this glacier that caused this event.”

Of course, these long-term conditions on glaciers can be monitored. In Huss’s native Switzerland, early warning systems had several notable successes, including predicting – until today – that the hanging Weissmies glacier would collapse in 2017. “They were able to project the date with relatively high accuracy, so that the downstream village of Saas Grund was only evacuated for one night,” says Huss.

In Italy, the imminent threat of the Planpincieux glacier in the Valle d’Aosta region led to the installation of the country’s first visual glacier monitoring system in 2013. Daniele Giordan, of the Italian Research Institute for the Protection Geohydrological, whose team designed it, explains that its system is remarkably simple. “We use a Canon DSLR, the type of camera you can buy on Amazon.” This feeds the images to the Turin office, where they are processed by a custom-developed algorithm. “It is a digital image correlation algorithm, from a family of well-known algorithms capable of detecting movements within a group of images. They are used, for example, to control the speed of cars on smart highways,” he says.

Because the camera began picking up visual clues of a potential collapse, it has since been augmented with synthetic aperture interferometric radar, similar to that used on the Weissmies Switzerland, which bounces waves off the ice to provide even more accurate readings of potentially dangerous accelerations. of movement. But such systems are expensive.

“The Valle d’Aosta has invested several hundred thousand euros in this surveillance system”, explains Giordan. “Maybe 10 times the original cost of our system.” And while the combination has proven effective, leading to early warnings in 2019 and 2020, the system is, of necessity, very specifically targeted.

Of course, for a monitoring system to work, “it has to focus on the glaciers, or the area of ​​the glacier, where it’s possible to have a collapse,” says Maggi. The problem is that “there are more than 900 ice cream parlors in Italy, and you have to know where to look”.

Most of the world’s glaciers that are currently monitored, Huss says, have large, obvious seracs, or overhanging sections. “Even if you’re not a scientist, you can see how dangerous they can be. But that was not the case with the Marmolada.

And even if a monitoring system had been in place, there is no guarantee that it would have detected telltale movements. “Inside the glacier there was definitely a lot of water,” Maggi says. “It’s easy to see on the videos. But outside of the glacier, no one saw more water than you would normally see. Meanwhile, the crevasse that flooded and played such a fundamental role in the detachment “had already been visible for several years,” according to the statement from the Glaciological Committee, and was not seen as ominous. Crevasses, the committee pointed out, “are an integral part of glacial dynamics.”

That’s not to say that any future monitoring effort, whether on the Marmolada or other similar glaciers, would be entirely in vain. “I’m not proposing our visual system as the solution,” says Giordan, “but having this data is definitely better than nothing.” He and his colleagues are currently working on a study that suggests their algorithms can provide useful results even when paired with basic webcams.

As glacier retreat worsens around the world, such low-cost solutions could potentially help save lives in countries with tighter budgets than Italy or Switzerland, in ranges from the Andes to Central Asia. For while very little was predictable about the collapse of the Marmolada, scientists who study these mountains and the guides and guardians who work there agree that such incidents will only become more frequent as that the planet will warm up – and the only way to truly mitigate the risk is through comprehensive international action on carbon emissions. “These are the effects of global warming,” says mountain guide Capa Zambanini. “We can say it wasn’t predictable, but that doesn’t mean it wasn’t our fault.”

At the foot of the Marmolada, police incident tape still blocks the way to the top, but the small bouquets of flowers left by mourners have already begun to wilt in the summer heat. The media circus has evolved and tourists have returned to the terrace of the Cima Undici restaurant. If you ignored the news cycle, you could be forgiven for thinking that nothing happened here. Except that every now and then someone points a phone up, where the deep scar is still too visible, 1,200 meters above our heads.

Comments are closed.