Limits of Enceladus's ice shell thickness from tidally driven tiger stripe shear failure

Abstract

Enceladus's south polar thermal anomaly and water-rich plumes suggest the existence of a subsurface ocean, which is overlain by an ice shell of uncertain thickness. Our objective is to constrain Enceladus's ice shell thickness, through assessment of tidally driven Coulomb failure of Enceladus's tiger stripe faults. We find that thin to moderate ice shell thicknesses (<40 km) support shear failure along the tiger stripes, assuming low ice coefficients of friction (0.1-0.3) and shallow fault depths (<3 km). These results are marginally consistent with the minimum ice shell thickness which can permit convection within Enceladus's ice shell. A plausible scenario is one in which the heat loss and tectonic style of Enceladus has changed through time, with convection initiating in a thick ice shell, and tiger stripe activity commencing as the ice shell thinned. Copyright © 2011 by the American Geophysical Union.