Recent structural evolution of Forni Glacier tongue (Ortles-Cevedale Group, Central Italian Alps)

Abstract

Structural glaciology yields important details about the evolution of glacier dynamics in response to climate change. The maps provided here document the occurrence and evolution of brittle and ductile structures on the tongue of Forni Glacier, Ortles-Cevedale Group, Central Italian Alps, between 2003 and 2014. Through the remote sensing-based analysis of structures, we found evidence of brittle fractures such as crevasses, faults and ring faults, and ductile structures such as ogives at the base of the icefall in the eastern glacier tongue. Although each of the three glacier tongues have evolved differently, a reduction in flow-related dynamics and an increase in the number of collapse structures occurred over the study period. Analysis of the glacier structural evolution based on the numbers and the locations of different structures, suggest a slowdown of glacier flow on the eastern tongue. The recent evolution of the glacier also suggests that the occurrence of a disintegration scenario is likely to worsen over the next decades.ARTICLE HISTORY

Combination of UAV and terrestrial photogrammetry to assess rapid glacier evolution and map glacier hazards

“…It has also undergone profound changes in dynamics in recent years, such as the loss of ice flow from the eastern accumulation basin towards its tongue and the evidence of collapsing areas on the eastern tongue (see Fig. 2d; Azzoni et al, 2017). Continuous monitoring of these hazards is important, as the site is highly touristic (Garavaglia et al, 2012).…”

“…Ice avalanches from hanging glaciers (Vincent et al, 2015) and debris flows caused by the mobilization of accumulated loose sediment on steep slopes (Kaab et al, 2005a) can also have serious consequences for downstream populations. Less severe hazards, but still particularly threatening for mountaineers, are the detachment of seracs (Riccardi et al, 2010) or the collapse of ice cavities (Gagliardini et al, 2011;Azzoni et al, 2017). While these processes are in part typical of glacial and periglacial environments, there is evidence that climate change is increasing the likelihood of specific hazards (Kaab et al, 2005a).…”

“…The orientation of fault structures is not coherent with glacier flow, with ring faults also appearing in circular patterns. Their location is limited to the glacier margins, medial moraines and terminus, whereas crevasses can appear anywhere on the glacier surface (Azzoni et al, 2017). After delineation, we also analyzed the height of vertical facies using information from the point clouds.…”

“…The latter develop as a series of circular or semicircular fractures with stepwise subsidence, caused by englacial or subglacial meltwater creating voids at the ice-bedrock interface, eventually leading to the collapse of the cavity roofs. While often overlooked, these collapse structures are particularly hazardous for mountaineers and they are likely to increase under a climate change scenario (Azzoni et al, 2017). They are more dangerous than crevasses because of their larger size.…”

“…Glacier and permafrost retreat, which has been reported in all sectors of the Alps Fischer et al, 2014;Gardent et al, 2014;Harris et al, 2009), is a major cause of slope instabilities, which can result in debris flows by debuttressing rock and debris flanks and promot-ing the exposure of unconsolidated and ice-cored sediments (Keiler et al, 2010;Chiarle et al, 2007). Glacier downwasting causes changes in water resources, with an initial increase in discharge due to enhanced melt followed by a long-term reduction, affecting drinking water supply, irrigation and hydropower production (Kaab et al, 2005b), along with a rising occurrence of structural collapses (Azzoni et al, 2017). Finally, glacier retreat and the increase in glacier hazards both negatively influence the tourism sector and the economic prosperity of high mountain regions (Palomo, 2017).…”