2015 GSA Annual Meeting in Baltimore, Maryland, USA (1-4 November 2015)

Paper No. 340-12
Presentation Time: 4:45 PM


WALKER, Catherine C., School of Earth and Atmospheric Sciences, Georgia Tech, 311 Ferst Drive, Atlanta, GA 30332, cat.walker@eas.gatech.edu

An often-posed query in the study of Antarctic iceberg calving by ocean water infiltration into fractures is, where is Antarctica's Crescent City? That is, where are the conditions just right where an ocean wave or tide could be the tipping point, after which a fracture propagates? The same idea can be apply at Europa.

Where are the conditions right for sub-surface ocean water to punch through to the surface? The fracture/failure of Europa’s icy shell are not only observable scars of variable activity throughout its evolution, they also serve key as mechanisms in the interaction of surface and subsurface material, and thus crucial aspects of the study of crustal overturn and ice shell habitability. We investigate the settings in which sub-surface water–both in the form of Great Lake-sized perched water pockets in the near-surface and the larger global ocean below–drives the deformation, fracture, and failure of the surface. We will use a 2D/3D models, adapted from terrestrial hydraulic fracturing ("fracking") to investigate the propagation of vertical fractures upward into the ice shell, motion of water within and between fractures, and the subsequent break-up and/or fragmentation of ice over shallow water, forming the chaos regions and other smaller surface features. We will present results from a cohesive fragmentation model to determine the time over which chaos formation occurs, and use a fracking model to determine the time interval required to allow water to escape from basal fractures in the ice shell. In determining the style, energy, and timescale of these processes, we constrain temporal variability in observable activity and topography at the surface. Finally, we compare these results to similar settings on Earth–Antarctica–where we have much higher resolution imagery and observations to better understand how sub-surface water can affect ice surface morphology, which most certainly have implications for future flyby and surface lander exploration.