Tim Hageman, Jessica Mejía, Ravindra Duddu, Emilio Martínez-Pañeda
{"title":"Ice viscosity governs hydraulic fracture that causes rapid drainage of supraglacial lakes","authors":"Tim Hageman, Jessica Mejía, Ravindra Duddu, Emilio Martínez-Pañeda","doi":"arxiv-2409.05478","DOIUrl":null,"url":null,"abstract":"Full thickness crevasses can transport water from the glacier surface to the\nbedrock where high water pressures can open kilometre-long cracks along the\nbasal interface, which can accelerate glacier flow. We present a first\ncomputational modelling study that describes time-dependent fracture\npropagation in an idealised glacier causing rapid supraglacial lake drainage. A\nnovel two-scale numerical method is developed to capture the elastic and\nviscoelastic deformations of ice along with crevasse propagation. The\nfluid-conserving thermo-hydro-mechanical model incorporates turbulent fluid\nflow and accounts for melting/refreezing in fractures. Applying this model to\nobservational data from a 2008 rapid lake drainage event indicates that viscous\ndeformation exerts a much stronger control on hydrofracture propagation\ncompared to thermal effects. This finding contradicts the conventional\nassumption that elastic deformation is adequate to describe fracture\npropagation in glaciers over short timescales (minutes to several hours) and\ninstead demonstrates that viscous deformation must be considered to reproduce\nobservations of lake drainage rate and local ice surface elevation change. As\nsupraglacial lakes continue expanding inland and as Greenland Ice Sheet\ntemperatures become warmer than -8 degree C, our results suggest rapid lake\ndrainages are likely to occur without refreezing, which has implications for\nthe rate of sea level rise.","PeriodicalId":501270,"journal":{"name":"arXiv - PHYS - Geophysics","volume":"2 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Geophysics","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.05478","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
Full thickness crevasses can transport water from the glacier surface to the
bedrock where high water pressures can open kilometre-long cracks along the
basal interface, which can accelerate glacier flow. We present a first
computational modelling study that describes time-dependent fracture
propagation in an idealised glacier causing rapid supraglacial lake drainage. A
novel two-scale numerical method is developed to capture the elastic and
viscoelastic deformations of ice along with crevasse propagation. The
fluid-conserving thermo-hydro-mechanical model incorporates turbulent fluid
flow and accounts for melting/refreezing in fractures. Applying this model to
observational data from a 2008 rapid lake drainage event indicates that viscous
deformation exerts a much stronger control on hydrofracture propagation
compared to thermal effects. This finding contradicts the conventional
assumption that elastic deformation is adequate to describe fracture
propagation in glaciers over short timescales (minutes to several hours) and
instead demonstrates that viscous deformation must be considered to reproduce
observations of lake drainage rate and local ice surface elevation change. As
supraglacial lakes continue expanding inland and as Greenland Ice Sheet
temperatures become warmer than -8 degree C, our results suggest rapid lake
drainages are likely to occur without refreezing, which has implications for
the rate of sea level rise.