TY - JOUR
T1 - A large frozen debris avalanche entraining warming permafrost ground—the June 2021 Assapaat landslide, West Greenland
AU - Svennevig, Kristian
AU - Hermanns, Reginald L.
AU - Keiding, Marie
AU - Binder, Daniel
AU - Citterio, Michele
AU - Dahl-Jensen, Trine
AU - Mertl, Stefan
AU - Sørensen, Erik Vest
AU - Voss, Peter H.
N1 - Funding Information:
The governments of Denmark and Greenland funded the projects ‘Screening analyses of the risk for severe landslides in Greenland’ in 2018, and ‘Study of the risk for severe landslides in Greenland’ from 2019 to 2022. Majken Djurhuus Poulsen, GEUS Nuuk, is thanked for assistance in communication with locals in Greenlandic. Thanks to Edvard Paornánguaq Kruse for information that helped further constrain the timing of the event and for use of his image in Data Repository . The regional seismic network in Greenland is operated by the international network GLISN ( www.glisn.info ) and supported by the Integrated Arctic Observation System (INTAROS) project which is funded by the European Union’s Horizon 2020 Research and Innovation Program under GA No. 727890. NOW (‘Noise of Thaw’) is funded by the Geocenter Denmark within the 2020 call. NOW provided data of the local seismic monitoring at Paatuut. The Thawing Mountain project provided active layer thickness observations and is funded by the Danish Energy Agency through DANCEA (Danish Cooperation for Environment in the Arctic). The paper is published with permission of the Geological Survey of Denmark and Greenland (GEUS). Thanks are due to Dr. Marten Geertsema and an anonymous reviewer for reviewing the manuscript and making helpful suggestions.
Publisher Copyright:
© 2022, The Author(s).
PY - 2022/11
Y1 - 2022/11
N2 - A large landslide (frozen debris avalanche) occurred at Assapaat on the south coast of the Nuussuaq Peninsula in Central West Greenland on June 13, 2021, at 04:04 local time. We present a compilation of available data from field observations, photos, remote sensing, and seismic monitoring to describe the event. Analysis of these data in combination with an analysis of pre- and post-failure digital elevation models results in the first description of this type of landslide. The frozen debris avalanche initiated as a 6.9 * 106 m3 failure of permafrozen talus slope and underlying colluvium and till at 600–880 m elevation. It entrained a large volume of permafrozen colluvium along its 2.4 km path in two subsequent entrainment phases accumulating a total volume between 18.3 * 106 and 25.9 * 106 m3. About 3.9 * 106 m3 is estimated to have entered the Vaigat strait; however, no tsunami was reported, or is evident in the field. This is probably because the second stage of entrainment along with a flattening of slope angle reduced the mobility of the frozen debris avalanche. We hypothesise that the initial talus slope failure is dynamically conditioned by warming of the ice matrix that binds the permafrozen talus slope. When the slope ice temperature rises to a critical level, its shear resistance is reduced, resulting in an unstable talus slope prone to failure. Likewise, we attribute the large-scale entrainment to increasing slope temperature and take the frozen debris avalanche as a strong sign that the permafrost in this region is increasingly at a critical state. Global warming is enhanced in the Arctic and frequent landslide events in the past decade in Western Greenland let us hypothesise that continued warming will lead to an increase in the frequency and magnitude of these types of landslides. Essential data for critical arctic slopes such as precipitation, snowmelt, and ground and surface temperature are still missing to further test this hypothesis. It is thus strongly required that research funds are made available to better predict the change of landslide threat in the Arctic.
AB - A large landslide (frozen debris avalanche) occurred at Assapaat on the south coast of the Nuussuaq Peninsula in Central West Greenland on June 13, 2021, at 04:04 local time. We present a compilation of available data from field observations, photos, remote sensing, and seismic monitoring to describe the event. Analysis of these data in combination with an analysis of pre- and post-failure digital elevation models results in the first description of this type of landslide. The frozen debris avalanche initiated as a 6.9 * 106 m3 failure of permafrozen talus slope and underlying colluvium and till at 600–880 m elevation. It entrained a large volume of permafrozen colluvium along its 2.4 km path in two subsequent entrainment phases accumulating a total volume between 18.3 * 106 and 25.9 * 106 m3. About 3.9 * 106 m3 is estimated to have entered the Vaigat strait; however, no tsunami was reported, or is evident in the field. This is probably because the second stage of entrainment along with a flattening of slope angle reduced the mobility of the frozen debris avalanche. We hypothesise that the initial talus slope failure is dynamically conditioned by warming of the ice matrix that binds the permafrozen talus slope. When the slope ice temperature rises to a critical level, its shear resistance is reduced, resulting in an unstable talus slope prone to failure. Likewise, we attribute the large-scale entrainment to increasing slope temperature and take the frozen debris avalanche as a strong sign that the permafrost in this region is increasingly at a critical state. Global warming is enhanced in the Arctic and frequent landslide events in the past decade in Western Greenland let us hypothesise that continued warming will lead to an increase in the frequency and magnitude of these types of landslides. Essential data for critical arctic slopes such as precipitation, snowmelt, and ground and surface temperature are still missing to further test this hypothesis. It is thus strongly required that research funds are made available to better predict the change of landslide threat in the Arctic.
KW - Assapaat landslide
KW - Global warming
KW - Slope temperature
KW - Fjeldskredsprojektet
UR - http://www.scopus.com/inward/record.url?scp=85135123559&partnerID=8YFLogxK
U2 - 10.1007/s10346-022-01922-7
DO - 10.1007/s10346-022-01922-7
M3 - Article
AN - SCOPUS:85135123559
SN - 1612-510X
VL - 19
SP - 2549
EP - 2567
JO - Landslides
JF - Landslides
IS - 11
ER -