The role of basal heating in lubricating icy landslides in the Solar System

A significant number of the major celestial bodies in the Solar System are characterized by high percentages of ice in their surface composition. Previous works have shown how the rheological behavior of ice-rock mixtures under different pressure, gravity and temperature conditions can be studied based on the morphologies of landslides. It has long been known that terrestrial landslides that occur on frozen surfaces show very low apparent friction, calculated as the aspect ratio between the fall height of the landslide and its horizontal movement. A possible mechanism to explain this low friction and consequently high mobility is the presence of a temporary meltwater layer at the interface between the debris and the impacted ground. This paper examines landslides on different planetary bodies of the Solar System composed of ice in varying amounts, from the ones containing ice only in the rock pores, to nearly completely icy mass flows.A mechanical-thermodynamic model of ice melting at the base of these landslides is investigated. Lubrication is explicitly introduced as a consequence of frictional melting of ice, which is found to be very sensitive to the gravity field, the topographic profile, and the temperature of the bodies. Results explain the decrease in friction coefficient, while the volume effect is seen to occur with more efficacy for bodies with high gravity and is absent for the very low-gravity comet 67/P. The results indicate the importance of initial temperature, ice content and especially gravity in ice lubrication dynamics of icy landslides in the different planetary bodies.