The climate-driven disaster of the Marmolada Glacier (Italy)

On July 3, 2022, at 13:43:20 CEST (11:43:20 UTC), a mass of about 64,000 t of water, ice, and rock debris broke off from the Marmolada Glacier in the Dolomites (Northeastern Italian Alps), forming an ice avalanche that killed 11 mountaineers and injured 7 after flowing for about 2.3 km along the slope. The collapse occurred on the northern slope at an elevation of 3213 m above sea level and involved a major portion of a small isolated glacier. This small glacier was part of the glacial front until about a decade ago, and today, because of the fragmentation caused by the retreat, it remains isolated and contained within a niche on the north-facing slope just below the crest. The event was documented by several videos recorded by hikers who were at the site, which helped in the analysis of the causes. The seismic energy released by the event was comparable to an earthquake of 0.6 M. The detailed analysis of pre- and post-event stereoscopic satellite and aerial images led to a comprehensive insight on the failure. The detachment was largely caused by a failure along a median crevasse partly filled by a huge volume of meltwater induced by highly anomalous late spring and early summer temperatures that reached 10.7 °C at the time of the event. The dense pattern of crevasses along with the morphology and properties of the basal rock surface predisposed to failure, which was finally driven by the overpressure caused by the excess of melting water. A combination of hydraulic jacking and buoyant pressure within a thin layer of basal till were probably the two mechanisms that caused instability resulting ultimately in the sudden glacier collapse.