Jet activity on Enceladus linked to tidally driven strike-slip motion along tiger stripes

• Published in: Nature Geoscience
• Main Authors: Berne, Alexander, Simons, Mark, Keane, James T., Leonard, Erin J., Park, Ryan S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group 2024
• Subjects: Aagaard; South Pole; South pole
• Online Access: https://doi.org/10.1038/s41561-024-01418-0; https://rdcu.be/dGjUE

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. © The Author(s), under exclusive licence to Springer Nature Limited 2024. This research was supported by the Future Investigators in NASA Earth and Space Science and Technology (FINESST) Program (80NSSC22K1318)(A.B., M.S.). We thank the Keck Institute for Space Studies (KISS) at the California Institute of Technology for organizing two workshops about ‘Next-Generation Planetary Geodesy’ which provided insight, expertise and discussions that inspired this research. We also thank M. Knepley, B. Aagaard and C. Williams for providing valuable advice on how to modify PyLith for our simulations. A portion of this research was supported by a Strategic Research and ...