A Relationship Between Jet Activity and Strike-Slip Motion over the Tiger Stripes on Enceladus

Abstract

Abstract At 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. We show that this traction may produce quasi-periodic strike-slip motion with two peaks in activity during each orbit. To the extent that friction modulates the response of Tiger Stripes to driving stresses, the tidal traction on the faults result in a difference in the magnitudes of peak strike-slip motion and cause a delay in the timing of the first peak in fault motion. The predicted double-peaked and asymmetric strike-slip motion of the Tiger Stripes closely tracks diurnal variations in jet activity inferred from Cassini images of plume brightness. The spatial distribution of strike-slip motion also matches Cassini infrared observations of heat flow which indicate maximal activity along Baghdad Sulcus and near the center of the Tiger Stripes. We hypothesize that strike-slip motion may open 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.