Cooling Crusts Create Concomitant Cryovolcanic Cracks

Abstract

AbstractThe orbital and internal evolution of the ice‐covered ocean worlds orbiting Jupiter and Saturn are coupled, leading to time‐varying thicknesses of their ice shells. As the ice thickens and thins, thermal stresses in the ice shell and pressure in the underlying ocean will change, promoting and hindering fracturing of the ice shell. We identify when and at what depth cracks initiate and whether they can penetrate the entire ice shell. For an ice tensile strength of 3 MPa, cracks do not penetrate the ice shell of Europa. On Enceladus, time‐averaged ice shell thickness of less than 15 km and variations in tidal dissipation of more than 15% over approximately 100 Myr eccentricity cycles cause cracks to cross the ice shell and permit eruptions from the ocean. Ocean overpressure is never large enough to extrude water onto the surface, suggesting that eruptions on Enceladus are sustained by decompression boiling.