Warming primes Arctic and Nepal slopes as quakes trigger cascading hazards

In Aug. 2025, after bedrock and a glacier collapsed simultaneously on the Nepal-China border, massive debris flows and floods followed, causing heavy damage. About a year earlier in the Arctic, earthquakes likewise triggered rockslides and glacier collapses. The research team analyzed that long-term warming may have weakened permafrost, making mountain slopes more vulnerable to seismic shocks. An international research team including GEOMAR Helmholtz Centre for Ocean Research Kiel (GEOMAR) and the Geological Survey of Norway analyzed the magnitude 6.5 earthquake that struck Jan Mayen, a Norwegian territory, on Mar. 10, 2025, and the subsequent geomorphic changes, and published the results on the 8th in the Proceedings of the National Academy of Sciences (PNAS). Jan Mayen is a volcanic island in the North Atlantic, about 500 km east of Greenland and about 550 km north of Iceland. It is home to Beerenberg, the world's northernmost active volcano, and several glaciers extend from the volcanic summit to the coast. After the earthquake, a steep volcanic rock slope above Beerenberg's Scheruff Glacier collapsed, and large amounts of volcanic rock and debris fell, blanketing the glacier surface and spreading almost to the coast. On the nearby Weyprecht Glacier, researchers also confirmed a calving event in which part of the glacier broke off due to the earthquake's shock. The team reconstructed the immediate aftermath of the quake by integrating seismic observations, high-resolution satellite imagery, infrasound observations, and temperature and climate records. Analysis showed the rockslide occurred within minutes after the mainshock. However, the team said the earthquake alone could not fully explain the large-scale collapse. Although Jan Mayen is inherently seismically active, satellite records from the past 40 years show no earthquake-triggered rockslides comparable in scale to this event. The study found signs that the slope had been gradually weakening even before the earthquake. From 2019 to 2024, several small rock collapses occurred at the failure site, and long-term temperature data showed a warming trend, including an unusual increase in hot summer days since the late 1990s. The researchers focused on the possibility that these changes weakened the permafrost. Permafrost is ground or bedrock that remains frozen for at least two years. In particular, water frozen in rock fractures helps hold cracked rock together. When temperatures rise and the ice melts, the cohesion of the bedrock decreases, destabilizing slopes. The team interpreted the event as large-scale collapse caused when strong earthquake shaking struck slopes already weakened by warming. This case shows that 'cascading disasters,' in which one natural phenomenon triggers another, can emerge in the Arctic in conjunction with climate change. While earthquakes themselves are unrelated to climate change, warming can weaken mountain slopes, creating conditions for larger geohazards from earthquakes of the same magnitude. The researchers said, 'The recent disaster on the Nepal-China border differed from the Jan Mayen case in that bedrock and glacier collapse were the direct starting points, with damage then amplified by debris flows and floods,' while adding, 'In both cases, warming and permafrost weakening reduced the stability of glaciers and mountain slopes and increased the likelihood of multiple hazards occurring in sequence.' References PNAS (2026), DOI: https://doi.org/10.1073/pnas.2617210123