title: Fracture propagation to the base of the Greenland Ice Sheet during supraglacial lake drainage.
abstract: Surface meltwater that reaches the base of an ice sheet creates a mechanism for the rapid response of ice flow to climate change. The process whereby such a pathway is created through thick, cold ice has not, however, been previously observed. We describe the rapid (<2 hours) drainage of a large supraglacial lake down 980 meters through to the bed of the Greenland Ice Sheet initiated by water-driven fracture propagation evolving into moulin flow. Drainage coincided with increased seismicity, transient acceleration, ice-sheet uplift, and horizontal displacement. Subsidence and deceleration occurred over the subsequent 24 hours. The short-lived dynamic response suggests that an efficient drainage system dispersed the meltwater subglacially. The integrated effect of multiple lake drainages could explain the observed net regional summer ice speedup.
authors.affiliation: Department of Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA 02543, USA. sdas@whoi.edu
authors.forename: Sarah B
authors.initials: SB
authors.lastname: Das
authors.forename: Ian
authors.initials: I
authors.lastname: Joughin
authors.forename: Mark D
authors.initials: MD
authors.lastname: Behn
authors.forename: Ian M
authors.initials: IM
authors.lastname: Howat
authors.forename: Matt A
authors.initials: MA
authors.lastname: King
authors.forename: Dan
authors.initials: D
authors.lastname: Lizarralde
authors.forename: Maya P
authors.initials: MP
authors.lastname: Bhatia