Non-Newtonian topographic relaxation on Europa |
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| Authors: | F Nimmo |
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| Institution: | Department Earth Sciences, University College London, Gower St, London WC1E 6BT, UK |
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| Abstract: | Models of topographic support on Europa by lateral shell thickness variations have previously assumed a Newtonian ice viscosity. Here I show that using a more realistic stress-dependent viscosity gives relaxation times which can be significantly different. Topography of wavelength 100 km cannot be supported by lateral shell thickness variations for ∼50 Myr, unless the shell thickness is <10 km or the ice grain size >10 mm. Shorter wavelength topography would require even thinner shells, but may be supported elastically. Global-scale variations in shell thickness, however, can be supported for geological timescales if the shell thickness is O(10 km). |
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| Keywords: | Ice Rheology Shell thickness Grain size |
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