G. J. Leonard

University of Arizona

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Jeffrey S. Kargel

Planetary Science Institute

Andreas Kääb

University of Oslo

Umesh K. Haritashya

University of Dayton

Bruce Raup

National Snow and Ice Data Center

Dan H. Shugar

University of Calgary

ÉB

Étienne Berthier

Laboratoire d’Études en Géophysique et Océanographie Spatiales

Adrien Gilbert

Université Grenoble Alpes

Simon Gascoin

Centre d'Études Spatiales de la Biosphère

Silvan Leinss

Gamma Remote Sensing (Switzerland)

J. Graham Cogley

Trent University

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Earth University

University of Arizona

Chinese Academy of Sciences

Centre National de la Recherche Scientifique

United States Geological Survey

University of Colorado Boulder

University of Zurich

Planetary Science Institute

International Centre for Integrated Mountain Development

Jet Propulsion Laboratory

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

Adrien Gilbert Silvan Leinss Jeffrey S. Kargel Andreas Kääb Tandong Yao

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 83 106 m3 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 show 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 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.

Lithology

Ice tongue

Bedrock

10.5194/tc-2018-45

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Citations (4)

The Chaotic Terrains of Mercury Reveal a History of Planetary Volatile Retention and Loss in the Innermost Solar System

Scientific Reports (2020)

J. A. P. Rodriguez G. J. Leonard Jeffrey S. Kargel D. L. Domingue D. C. Berman

Abstract Mercury’s images obtained by the 1974 Mariner 10 flybys show extensive cratered landscapes degraded into vast knob fields, known as chaotic terrain (AKA hilly and lineated terrain). For nearly half a century, it was considered that these terrains formed due to catastrophic quakes and ejecta fallout produced by the antipodal Caloris basin impact. Here, we present the terrains’ first geologic examination based on higher spatial resolution MESSENGER (MErcury Surface Space ENvironment GEochemistry and Ranging) imagery and laser altimeter topography. Our surface age determinations indicate that their development persisted until ~1.8 Ga, or ~2 Gyrs after the Caloris basin formed. Furthermore, we identified multiple chaotic terrains with no antipodal impact basins; hence a new geological explanation is needed. Our examination of the Caloris basin’s antipodal chaotic terrain reveals multi-kilometer surface elevation losses and widespread landform retention, indicating an origin due to major, gradual collapse of a volatile-rich layer. Crater interior plains, possibly lavas, share the chaotic terrains’ age, suggesting a development associated with a geothermal disturbance above intrusive magma bodies, which best explains their regionality and the enormity of the apparent volume losses involved in their development. Furthermore, evidence of localized, surficial collapse, might reflect a complementary, and perhaps longer lasting, devolatilization history by solar heating.

Landform

Antipodal point

Planetary science

10.1038/s41598-020-59885-5

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Citations (6)

Why did the Nepal Gorkha Earthquake Have so few Effects on Glacial Lakes

2015 AGU Fall Meeting (2015)

J. S. Kargel B. D. Collins E. J. Fielding K. Fujita Umesh K. Haritashya

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Reply on RC2

G. J. Leonard

Abstract. McMurdo Sound sea ice can generally be partitioned into two regimes: (1)Â a stable fast-ice cover, forming south of approximately 77.6^ââS around MarchâApril and then breaking out the following JanuaryâFebruary, and (2)Â a more dynamic region north of 77.6^ââS that the McMurdo Sound and Ross Sea polynyas regularly impact. InÂ 2019, a stable fast-ice cover formed unusually late due to repeated break-out events. We analyse the 2019 sea-ice conditions and relate them to a modified storm indexÂ (MSI), a proxy for southerly wind events. We find there is a strong correlation between the timing of break-out events and several unusually large MSI events.

Proxy (statistics)

10.5194/tc-2020-352-ac2

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The 2016 gigantic twin glacier collapses in Tibet: towards an improved understanding of large glacier instabilities and their potential links to climate change

EGU General Assembly Conference Abstracts (2017)

Adrien Gilbert Silvan Leinss S. L. Evans Lide Tian Andreas Kääb

Cirque glacier

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Glaciers along the Copper River, Alaska, Controlled by Landslides, Vegetation, Lakes, Rivers (and Climate)