While the 'Chasing Ice' video is a great example of ice cliff failures at Jakobshavn, I am primarily concerned about slumping calving failures (see the first linked article & associated first linked reference & the associated image) in the BSB/Thwaites that would produce somewhat shallow draft icebergs (at least shallower than tabular icebergs) that can readily float out of the Thwaites gateway that would allow more calving leading to an MICI-type of collapse. Also, see the second linked reference on ice cliff failures of Jakobshavn and see also the linked video:
Title: "Tall ice-cliffs may trigger big calving events -- and fast sea-level rise"
https://www.sciencedaily.com/releases/2019/03/190322163342.htmExtract: "Glaciers that drain ice sheets such as Antarctica or Greenland often flow into the ocean, ending in near-vertical cliffs. As the glacier flows into the sea, chunks of the ice break off in calving events. Although much calving occurs when the ocean melts the front of the ice, and ice cliff above falls down, a new study presents another method of calving: slumping. And this process could break off much larger chunks of ice at a quicker rate.
The ice-cliff research was spurred by a helicopter ride over Jakobshavn and Helheim glaciers on Greenland's eastern coast. Helheim ends abruptly in the ocean, in near-vertical ice-cliffs reaching 30-stories high (100 meters). On the flight, scientists viewed large cracks (called crevasses) on top of the ice that marched towards the end of the glacier."
See also:
Byron R. Parizek, Knut Christianson, Richard B. Alley, Denis Voytenko, Irena Vaňková, Timothy H. Dixon, Ryan T. Walker, David M. Holland. Ice-cliff failure via retrogressive slumping. Geology, 2019; DOI: 10.1130/G45880.1
https://pubs.geoscienceworld.org/gsa/geology/article/47/5/449/569567/Ice-cliff-failure-via-retrogressive-slumping&
Xie, S., Dixon, T. H., Voytenko, D., Deng, F., and Holland, D. M.: Grounding line migration through the calving season of Jakobshavn Isbræ, Greenland, observed with terrestrial radar interferometry, The Cryosphere Discuss.,
https://doi.org/10.5194/tc-2017-231, in review, 2018.
https://www.the-cryosphere-discuss.net/tc-2017-231/Abstract. "Ice velocity variations near the terminus of Jakobshavn Isbræ, Greenland were observed with a terrestrial radar interferometer (TRI) during three summer campaigns in 2012, 2015, and 2016. Ice velocity variations appear to be largely modulated by ocean tides. We estimate a ∼ 1 km wide floating zone near the calving front in early summer of 2015 and 2016, where ice moves in phase with ocean tides. Digital Elevation Models (DEMs) generated by the TRI show that the glacier front here is thin (ice surface is < 125 m above local water level). However, in late summer 2012, there is no evidence of a floating ice tongue in the TRI observations. Ice surface elevation near the glacier front was also higher, > 140 m above local sea level within a very short distance (< 1 km) from the ice cliff. We hypothesize that during Jakobshavn Isbræ's recent calving seasons, the ice front advances ∼ 3 km from winter to spring, forming a > 1 km floating ice tongue. During the subsequent calving season in mid- and late-summer, the glacier retreats by losing its floating portion through a sequence of iceberg calving events. By late summer, the entire glacier is likely grounded. In addition to ice velocity variations driven by tide rise and fall, we also observed a transverse velocity variation in the mélange and floating ice front. This across flow-line signal is in phase with the first time derivative of tidal height, and is likely associated with tidal currents or bed topography."
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