Dynamics of Hydrothermal Plumes on Europa: Implications for Chaos Formation

Introduction The apparent existence of a substantial liquid water layer beneath Europa’s icy crust [1, 2, 3] affects the transfer of energy from the tidally-heated rocky interior to the surface ice layer. Better understanding of the characteristic length, time, and velocity scales of flow in the liquid water layer can improve our understanding of the processes that reshape Europa’s surface. Of those processes, debate is especially intense regarding the formation mechanism for chaotic terrain. The “meltthrough” model proposes that chaos regions and/or lenticulae are formed when hydrothermal plumes rising from localized seafloor heat sources melt away the overlying ice layer [4, 5, 6]. Thomson & Delaney [5] (T&D, hereafter) suggest that the ocean currents at the top of the plume might drive the apparent drift of large ice blocks in chaos regions [7]. But do hydrothermal plumes have the right size, heat flux, and velocities to be compatible with the melt-through hypothesis?