Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet
<p>In north-western Tibet (34.0° N, 82.2° E) near lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July and 21 September 2016. The masses transformed into ice avalanches with volumes of 68 and 83×10<sup>6</sup&g...
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-09-01
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| Series: | The Cryosphere |
| Online Access: | https://www.the-cryosphere.net/12/2883/2018/tc-12-2883-2018.pdf |
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| author | A. Gilbert S. Leinss J. Kargel A. Kääb S. Gascoin G. Leonard E. Berthier A. Karki T. Yao |
| author_facet | A. Gilbert S. Leinss J. Kargel A. Kääb S. Gascoin G. Leonard E. Berthier A. Karki T. Yao |
| author_sort | A. Gilbert |
| collection | DOAJ |
| description | <p>In north-western Tibet (34.0° N, 82.2° E) near
lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2)
suddenly collapsed on 17 July and 21 September 2016. The
masses transformed into ice avalanches with volumes of 68 and 83×10<sup>6</sup> m<sup>3</sup> and ran out up to 7 km in horizontal distance, killing nine
people. The only similar event currently documented is the 130×10<sup>6</sup> m<sup>3</sup> Kolka Glacier rock and ice avalanche of 2002 (Caucasus
Mountains). Using climatic reanalysis, remote sensing, and three-dimensional
thermo-mechanical modelling, we reconstructed the Aru glaciers'
thermal regimes, thicknesses, velocities, basal shear stresses, and ice
damage prior to the collapse in detail. Thereby, we highlight the potential of using
emergence velocities to constrain basal friction in mountain glacier models.
We show that the frictional change leading to the Aru collapses occurred in
the temperate areas of the polythermal glaciers and is not related to a
rapid thawing of cold-based ice. The two glaciers experienced a similar
stress transfer from predominant basal drag towards predominant lateral
shearing in the detachment areas and during the 5–6 years before the
collapses. A high-friction patch is found under the Aru-2 glacier tongue,
but not under the Aru-1 glacier. This difference led to disparate behaviour
of both glaciers, making the development of the instability more visible for
the Aru-1 glacier through enhanced crevassing and terminus advance over a
longer period. In comparison, these signs were observable only over a few
days to weeks (crevasses) or were absent (advance) for the Aru-2 glacier. Field
investigations reveal that those two glaciers were underlain by soft, highly
erodible, and fine-grained sedimentary lithologies. We propose that the specific
bedrock lithology played a key role in the two Tibet and the Caucasus
Mountains giant glacier collapses documented to date by producing low bed
roughness and large amounts of till, rich in clay and silt with a low friction
angle. The twin 2016 Aru collapses would thus have been driven by a failing
basal substrate linked to increasing pore water pressure in the subglacial
drainage system in response to increases in surface melting and rain
during the 5–6 years preceding the collapse dates.</p> |
| first_indexed | 2024-12-24T03:12:29Z |
| format | Article |
| id | doaj.art-f4c9a510f4394361892a598bad57d8a1 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-12-24T03:12:29Z |
| publishDate | 2018-09-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-f4c9a510f4394361892a598bad57d8a12022-12-21T17:17:46ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242018-09-01122883290010.5194/tc-12-2883-2018Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, TibetA. Gilbert0S. Leinss1J. Kargel2A. Kääb3S. Gascoin4G. Leonard5E. Berthier6A. Karki7T. Yao8Department of Geosciences, University of Oslo, Oslo, NorwayInstitute of Environmental Engineering, ETH Zurich, Zurich, SwitzerlandPlanetary Science Institute, Tucson, Arizona, USADepartment of Geosciences, University of Oslo, Oslo, NorwayCESBIO, CNES, CNRS, IRD, UPS, Université de Toulouse, Toulouse, FranceDepartment of Planetary Sciences, University of Arizona, Tucson, USALEGOS, CNES, CNRS, IRD, UPS, Université de Toulouse, Toulouse, FranceSociety for Ecological Restoration-Nepal, Kathmandu, NepalITP-CAS, Beijing, China<p>In north-western Tibet (34.0° N, 82.2° E) near lake Aru Co, the entire ablation areas of two glaciers (Aru-1 and Aru-2) suddenly collapsed on 17 July and 21 September 2016. The masses transformed into ice avalanches with volumes of 68 and 83×10<sup>6</sup> m<sup>3</sup> and ran out up to 7 km in horizontal distance, killing nine people. The only similar event currently documented is the 130×10<sup>6</sup> m<sup>3</sup> Kolka Glacier rock and ice avalanche of 2002 (Caucasus Mountains). Using climatic reanalysis, remote sensing, and three-dimensional thermo-mechanical modelling, we reconstructed the Aru glaciers' thermal regimes, thicknesses, velocities, basal shear stresses, and ice damage prior to the collapse in detail. Thereby, we highlight the potential of using emergence velocities to constrain basal friction in mountain glacier models. We show that the frictional change leading to the Aru collapses occurred in the temperate areas of the polythermal glaciers and is not related to a rapid thawing of cold-based ice. The two glaciers experienced a similar stress transfer from predominant basal drag towards predominant lateral shearing in the detachment areas and during the 5–6 years before the collapses. A high-friction patch is found under the Aru-2 glacier tongue, but not under the Aru-1 glacier. This difference led to disparate behaviour of both glaciers, making the development of the instability more visible for the Aru-1 glacier through enhanced crevassing and terminus advance over a longer period. In comparison, these signs were observable only over a few days to weeks (crevasses) or were absent (advance) for the Aru-2 glacier. Field investigations reveal that those two glaciers were underlain by soft, highly erodible, and fine-grained sedimentary lithologies. We propose that the specific bedrock lithology played a key role in the two Tibet and the Caucasus Mountains giant glacier collapses documented to date by producing low bed roughness and large amounts of till, rich in clay and silt with a low friction angle. The twin 2016 Aru collapses would thus have been driven by a failing basal substrate linked to increasing pore water pressure in the subglacial drainage system in response to increases in surface melting and rain during the 5–6 years preceding the collapse dates.</p>https://www.the-cryosphere.net/12/2883/2018/tc-12-2883-2018.pdf |
| spellingShingle | A. Gilbert S. Leinss J. Kargel A. Kääb S. Gascoin G. Leonard E. Berthier A. Karki T. Yao Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet The Cryosphere |
| title | Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet |
| title_full | Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet |
| title_fullStr | Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet |
| title_full_unstemmed | Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet |
| title_short | Mechanisms leading to the 2016 giant twin glacier collapses, Aru Range, Tibet |
| title_sort | mechanisms leading to the 2016 giant twin glacier collapses aru range tibet |
| url | https://www.the-cryosphere.net/12/2883/2018/tc-12-2883-2018.pdf |
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