NSFGEO-NERC:A new mechanistic framework for modeling rift processes in Antarctic ice shelves validated through improved strain-rate and seismic obser

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Tabular iceberg calving accounts for a significant fraction of ice mass loss from Antarctica and is the culmination of the propagation of full-thickness fractures-known as rifts-in ice shelves. Understanding theprocesses and drivers of rifting and how best to represent rifts in large-scale ice-flow models are among thegreat challenges of modern glaciology. To date, much work has focused on developing parameterized calving laws that consider velocity, thickness, crevasse depth, and/or damage proxies at or near the calving front to represent calving (e.g., Nick et al., 2010; Duddu and Waisman, 2012; Borstad et al., 2012; Albrecht and Levermann, 2012; Bassis and Jacobs, 2013; Ultee and Bassis, 2016). Other recent work has improved ourunderstanding of the processes, drivers, and effects of rifting, often with emphasis on relating the rift path tothe stress field of the ice shelf and the mean rate of rift propagation to spatial heterogeneities in the mechanical properties of the ice (e.g., Hulbe et al., 2005; Khazendar et al., 2009; Larour et al., 2014; Borstad et al.,2017). Despite these efforts, several fundamental questions remain. What drives rift propagation? How fastdo rifts propagate and what controls the rate of propagation? How important is inelastic deformation at therift tip? Here, we propose to address each of these fundamental questions and thereby markedly contributeto our understanding of rift propagation and tabular iceberg formation in ice shelves.More specifically, we propose to test the hypotheses that large-scale rifting is driven by viscous stresseswithin the ice shelf, that rifting processes can be well-represented by linear elastic fracture mechanics, thatthe rate of rift propagation is controlled by the local geometry and mechanical properties of the ice, and thatocean induced loads (e.g., swells and tides) play an important role in rift propagation by combining remotesensing, seismic, and GPS observations with state-of-the-art ice-flow and fracture models. We propose toexploit a unique situation currently developing on Brunt Ice Shelf (BIS) and Stancomb-Wills Glacier Tongue(SWGT), Antarctica, to study the propagation of several active rift systems through remotely sensed and insitu observations and fracture modeling.