Dilation of subglacial sediment governs incipient surge motion in glaciers with deformable beds.

ABSTRACT: Glacier surges are quasi-periodic episodes of rapid ice flow that arise from increases in slip rate at the ice-bed interface. The mechanisms that trigger and sustain surges are not well understood. Here, we develop a new model of incipient surge motion for glaciers underlain by sediments to explore how surges may arise from slip instabilities within a thin layer of saturated, deforming subglacial till. Our model represents the evolution of internal friction, porosity and pore water pressure within the till as functions of the rate and history of shear deformation, and couples the till mechanics to a simple ice-flow model. Changes in pore water pressure govern incipient surge motion, with less permeable till facilitating surging because dilation-driven reductions in pore water pressure slow

SUBMITTER: Minchew BM 

PROVIDER: S-EPMC7428031 | biostudies-literature | 2020 Jun

REPOSITORIES: biostudies-literature