This study focuses on the Pilatte hut (2,572 m a.s.l., in the Écrins mountain range, French Alps). At least three infrastructure are known to have been affected by paraglacial rock slides during the last two decades: the Gletscherbahn Moosfluh cable-car near the Aletsch glacier in Switzerland ( Kos et al., 2016 Grämiger et al., 2017), and the Mueller ( McColl and Davies, 2013) and Murchison huts in the New Zealand Alps ( Petley, 2017). Examples of infrastructure built on potentially paraglacial unstable rock slopes are rare ( Duvillard et al., 2015) but offer reliable cases to document the slope response in the initial years after de-icing. The response time for triggering paraglacial instability of rock slopes after the deglaciation period can be ten to one hundred years ( Ballantyne, 2002), although this remains poorly documented due to the difficulty in anticipating this process ( Zanoner et al., 2017).
#Cube world crack 2017 fr drivers#
Our understanding of the theoretical mechanics of paraglacial rock slope instabilities and their drivers ( McColl, 2012) is being continually improved through detailed case studies (e.g., Wieczorek and Jäger, 1996 Cossart et al., 2008 Krautblatter and Leith, 2015). These geomorphological processes can be the source of indirect threats to valleys through cascading processes ( Huggel et al., 2005), or direct threats to mountaineers ( Ritter et al., 2012 Mourey and Ravanel, 2017) and infrastructure built on moraines and rock slopes ( Strozzi et al., 2010 Ravanel et al., 2015b Kos et al., 2016). Widespread glacial shrinkage causes localized changes in the stress regime of the adjacent valley flanks which may cause deep-seated mass movements of rock (landslides) ( O'Connor and Costa, 1993 Blair, 1994 Haeberli et al., 1997 Kääb et al., 2005 Oppikofer et al., 2008). Deglaciation periods generally correspond to periods of intense geomorphological change, sometimes called “paraglacial morphogenic crisis” ( Mercier, 2010), and these trigger significant natural destructive events ( Deline et al., 2012). The paraglacial concept proposed by Church and Ryder (1972) describes the non-glacial processes directly conditioned by glaciation, as well as the period over which paraglacial processes are operating ( Ballantyne, 2002, 2013 Mercier, 2008 Cossart et al., 2013). Mountain permafrost, defined as ground that remains below 0☌ for 2 years or more, has experienced an almost continuous warming ( PERMOS, 2016) since the beginning of the 2000s. In the Alps, the glacierized areas shrank by half between 18, with a strong acceleration in recession since the 1980s ( Huss, 2012 Gardent et al., 2014). High alpine environments are strongly affected by this warming ( Beniston et al., 2018), especially with regards to glacial shrinkage ( Vincent, 2002) and permafrost degradation ( Harris et al., 2009). Above 4,000 m a.s.l., the mean annual air temperature increased by 0.14☌ per decade between 19 ( Gilbert and Vincent, 2013). Temperatures in the French Alps have risen by 1.5–1.8☌ since 1950 ( Einhorn et al., 2015).
#Cube world crack 2017 fr crack#
The relationship between observed crack propagation and glacier surface change suggests that the rock slope instability is a paraglacial response to glacier surface changes, and highlights that such responses can occur within a decade of glacier change. Reconstruction of the glacier surface using past images taken since 1960 and “Structure from Motion” photogrammetry showed that the glacier probably applied stresses to the rock slope during its short-lived advance during the 1980s, followed by debuttressing caused by rapid surface lowering until the present day. The current trend seems to be toward a relative stabilization. These movements initiated in the late 1980s and have accelerated since 2000.
Field observations and annual crack surveys have been used to identify the dynamics of past movements. We reconstructed the geometry of the unstable rock mass using Terrestrial Laser Scanning and quantified the unstable volume (~400,000 m 3). In this study we document the rock slope movement that has affected the Pilatte hut (2,572 m a.s.l.) in the Écrins range (French alps) since the 1980s.
Landslides triggered by shrinking glaciers are an expected outcome of global climate change and they pose a significant threat to inhabitants and infrastructure in mountain valleys.
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