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

板状冰山崩解占南极洲冰质量损失的很大一部分，并且是冰架中全厚度裂缝（称为裂缝）传播的高潮。理解断裂的过程和驱动力，以及如何在大尺度冰流模型中最好地表示断裂，是现代冰川学面临的巨大挑战。迄今为止，许多工作集中在开发参数化的产犊定律，其考虑产犊前缘处或附近的速度、厚度、裂缝深度和/或损害代理以表示产犊（例如，尼克等人，2010; Duddu和Waisman，2012; Borstad等人，2012; Albrecht和Levermann，2012; Bibliya和Jacobs，2013; Ultee和Bibliya，2016）。最近的其他工作提高了我们对裂谷过程、驱动因素和影响的理解，通常强调裂谷路径与冰架应力场的关系，以及裂谷传播的平均速率与冰的机械特性的空间不均匀性的关系（例如，Hulbe等人，2005年; Khazhoun等人，2009; Larour等人，2014; Borstad等人，2017年）。尽管作出了这些努力，但仍存在一些基本问题。是什么驱动了裂缝的扩展？裂缝传播的速度有多快？是什么控制着传播的速度？举升尖端的非弹性变形有多重要？在这里，我们提出解决这些基本问题，从而显着有助于我们理解裂缝传播和冰架中的扁平冰山形成。更具体地说，我们提出测试的假设，大规模裂谷是由粘性stresseswithin冰架，裂谷过程可以很好地代表线弹性断裂力学，裂缝扩展的速率由冰的局部几何形状和机械性质控制，并且海洋诱导载荷（例如，膨胀和潮汐）在裂缝传播中起着重要的作用，通过遥感、地震和GPS观测与最先进的冰流和裂缝模型相结合。我们建议利用一个独特的情况，目前正在发展的布伦特冰架（BIS）和斯坦科姆-威尔斯冰川舌（SWGT），南极洲，研究几个活跃的裂谷系统的传播，通过遥感和原位观测和断裂建模。

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.