Rockfall and vulnerability of mountaineers on the west face of the Aiguille du Goûter (classic route up Mont Blanc, France), an interdisciplinary study

Abstract

Abstract. In high alpine environments, climate change leads to an increase in rockfall destabilizations. They represent a threat for sports and tourism activities in high mountain and especially for mountaineering. This danger of rockfall is particularly important on the classic route up Mont Blanc (4,809 m a.s.l., Mont Blanc massif, France), on the west face of the Aiguille du Goûter (3,863 m a.s.l.), and is responsible for at least 29 % of the accidents that occur in this sector. Despite the intensity of the geomorphological processes at work and the vulnerability of climbers, few scientific studies have been carried out on the occurrence of rockfalls and their triggering factors in the Goûter area. Based on a multi-method monitoring system (5 seismic sensors, an automatic digital camera, 3 subsurface temperature sensors, a pyroelectric sensor, a high-resolution topographical survey, 2 weather stations and a rain gauge) the objective of our study is therefore to quantitatively document the occurrence of rockfalls and their triggering factors in the Grand Couloir du Goûter in order to better assess the vulnerability of mountaineers in this sector. Our results show that in the high-Alpine and permafrost-affected Aiguille du Goûter west face, rockfalls are mostly frequent during the snowmelt period which favors the action of thermo-mechanical processes linked to the infiltration of liquid water into the cracks of the rock. During periods when the couloir is completely clear of snow, rockfalls are 2.5 times less frequent, and the thermo-mechanical processes involved in the rockfall triggering are limited by the absence of moisture in the ground. These results also show that climbers' awareness of the risk of rockfalls remains limited. What’s more, they do not adapt – or only slightly – their behavior to this risk, despite a particularly high accident rate. Important work on prevention and dissemination of the knowledge here acquired (newsletters, training for professionals and amateurs, awareness campaigns) among mountaineers is therefore still really necessary.

A Comprehensive Approach to Quantitative Risk Assessment of Rockfalls on Buildings Using 3D Model of Rockfall Runout

“…For instance, and because heavy rain events can trigger RFs, climate change could represent an additional risk to people, buildings, and infrastructure in terms of RFs [1] Earthquakes can cause RFs, as the ground shaking caused by an earthquake can destabilize slopes and trigger an RF. Earthquakes can also cause cracks in rocks, which can make them more likely to fall [2].…”

18-years of high-Alpine rock wall monitoring using terrestrial laser scanning at the Tour Ronde east face, Mont-Blanc massif

“…Rockfalls are a threat for alpinists (Soulé et al 2014, Mourey et al 2018, with mountain infrastructures subject to deterioration related to permafrost degradation (Duvillard et al 2019). The ongoing effects of global warming are likely to exacerbate these issues (Chiarle et al 2021), making long-term rockfall monitoring necessary for effective risk assessment and mitigation (Bommer et al 2010, Duvillard et al 2021.…”

Main results of permafrost monitoring in the French Alps through the PermaFrance network over the period 2010–2022

“…[21][22][23] As a result of these impacts, an adaptation strategy is also needed for mountain recreational practices, including mountaineering. 24,25 Various regional and international permafrost monitoring projects have been established around the world and are relayed by the Global Terrestrial Network for Permafrost (GTN-P). 26 Most of the monitoring systems have been in place since the 21st century, so the existing time series are still relatively short.…”

“…In the European Alps, the impacts of permafrost degradation have been documented, such as the increase in rockfall frequency 12,13 and high‐magnitude rock avalanches, 14,15 the acceleration of rock glaciers and their potential destabilization, 16–19 sudden drainage of thermokarst lakes, 20 and destabilization of infrastructure 21–23 . As a result of these impacts, an adaptation strategy is also needed for mountain recreational practices, including mountaineering 24,25 …”