At Saturn’s moon Enceladus, jets along four distinct fractures called ‘tiger stripes’ erupt ice crystals into a broad plume above the South Pole. The tiger stripes experience variations in tidally driven shear and normal traction as Enceladus orbits Saturn. Here, we use numerical finite-element modelling of a spherical ice shell subjected to tidal forces to show that this traction may produce quasi-periodic strike-slip motion in the Enceladus crust with two peaks in activity during each orbit. We suggest that friction modulates the response of tiger stripes to driving stresses, such that tidal traction on the faults results in a difference in the magnitudes of peak strike slip and delays the first peak in fault motion following peak tidal stress. The simulated double-peaked and asymmetric strike-slip motion of the tiger stripes is consistent with diurnal variations in jet activity inferred from Cassini spacecraft images of plume brightness. The spatial distribution of strike-slip motion also matches Cassini infrared observations of heat flow. We hypothesize that strike-slip motion can extend transtensional bends (for example, pull-apart structures) along geometric irregularities over the tiger stripes and thus modulate jet activity. Tidally driven fault motion may also influence longer term tectonic evolution near the South Pole of the satellite.
Strike-slip motion along the tiger stripe fracture zones of Enceladus may act to modulate quasi-periodic jet activity, according to finite-element simulations of diurnal tidal deformation on the moon’s icy shell.