Radar interferometry for measuring tidal strains across cracks on Europa

Abstract

A major uncertainty in understanding the interaction between the surface of Europa and its ocean below is the present-day activity of fractures. Using well-constrained models for tidal strain and a force balance in a cracked shell, we estimate the shear and normal displacement of cracks that penetrate upward from the base of the shell. If more than half of the plate is fractured, then surface displacements having amplitudes of 3 to 30 cm will be localized in a band 1 to 100 km from the crack. Plate spreading will occur if more than ∼85% of the plate is fractured. The pattern of deformation is sensitive to both the percentage of plate that is cracked and the total thickness of the shell. Repeat-pass radar interferometry could easily detect and map the activity of the cracks during a short experiment from a variety of suitable orbits with repeating ground tracks. Copyright 2004 by the American Geophysical Union.