Mechanisms leading to the 2016 giant twin glacier collapses, Aru range, Tibet

Abstract

Abstract. In northwestern Tibet (34.0°N, 82.2°E) near lake Aru Co, the entire ablation area of two glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July 2016 and 21 September 2016, respectively, and transformed into 68 and 83 10 6 m 3 mass flows that ran out up to 7 km, killing nine people. The only similar event currently documented is the 2002 Kolka Glacier mass flow (Caucasus Mountains). Using climatic reanalysis, remote sensing and 3D thermo-mechanical modeling, we reconstructed in detail the glaciers' thermal regimes, thicknesses, velocities, basal shear stresses and ice damage prior to the collapse. We 20show that frictional change leading to the collapses occurred in the temperate areas of polythermal glacier structures and are not linked to thaw of cold based ice. The two glaciers experienced a similar stress transfer from predominant basal drag towards predominant lateral shearing in the later detachment areas and during the 5-6 years before the collapses, though with a high friction patch on Aru-2 tongue which is inexistent on Aru-1. The latter led to distinctly disparate behaviour making the development of the instability more visible for the Aru-1 glacier compared to Aru-2 through enhanced crevassing over a 25 longer period and terminus advance. Field investigations reveal that those two glaciers are flowing on a soft, highly erodible, and fine-grained sedimentary lithology. We propose that specific bedrock lithology played a key role in the two Tibet, and also in the Caucasus gigantic glacier collapses documented to date by producing low bed roughness and large amount of till rich in clay/silt with low friction angle. The twin Aru collapses would have been driven by a failing substrate linked to increasing water pore pressure in the subglacial drainage system in response to recent increases of surface melting and rain. 30The Cryosphere Discuss., https://doi

Thermal Conductivity of Snow, Firn, and Porous Ice From 3‐D Image‐Based Computations

“…Many glaciers and ice sheets processes depend on thermal conditions: surface snow metamorphism, firn densification, ice deformation, or basal sliding, for instance. How temperature fluctuations are propagated through snow, firn, and porous ice is therefore crucial to understand, as its modeling is required in a variety of applications such as the interpretation of paleoclimatic data from ice cores (e.g., Barnola et al, 1991;Goujon et al, 2003;Salamatin et al, 1998;Schwander et al, 1997), past climate reconstruction from temperature profiles (e.g., Dahl-Jensen et al, 1998;Gilbert et al, 2010;Gilbert & Vincent, 2013;Van Ommen et al, 1999), interpretation of englacial temperature observation (e.g., Funk et al, 1994;Gilbert et al, 2014;Lüthi & Funk, 2001), climate-cryosphere interactions studies and future scenarios (e.g., Gilbert et al, 2014Gilbert et al, , 2016Seddik et al, 2012), glacier hazard assessment (e.g., Gilbert et al, 2015Gilbert et al, , 2018, or ice mass balance monitoring (e.g., Cummings et al, 2013;Reijmer & Hock, 2008).…”

The 1980 Aparejo Glacier catastrophic detachment: new insights and current status

“…Following Jacquemart and Cicoira (2021), the latter phenomena will be referred to as a glacier detachment. Nowadays, glacier detachments have gained more attention worldwide after the events of Kolka Glacier in 2002, resulting in the of 130 Mm 3 of ice in the Caucasus, killing 125 people (Kotlyakov et al, 2004;Huggel et al, 2005;Evans et al, 2009), and the detachment of twin glaciers in front of Aru Lake, Tibetan Plateau, during the summer of 2016, resulting in the death of 9 herders and hundreds of animals (Gilbert et al, 2018;Kääb et al, 2018). More recently, a minor glacier detachment of a volume of 4.2 ± 0.6 Mm 3 , which occurred in 2007, has been reported for Las Leñas Glacier in the central Argentinean Andes, fortunately without casualties or damages (Falaschi et al, 2019).…”

Different characteristics of two surges in Weigeledangxiong Glacier, northeastern Tibetan Plateau

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