Numerical modeling of tectonics and fault activity of icy satellites.

摘要

Enceladus, one of the satellites of Saturn, exhibits evidence of recent fault activity, which may be due to gravitational fluctuations, or tidal stresses, generated by its orbit around Saturn. Recent Cassini spacecraft observations of Enceladus reveal water-ice plume activity at the south polar region, originating from locations that correlate with four geologically young, linear fracture-like features, named the "tiger stripes". It is the goal of this investigation to determine the ideal geophysical and geological factors (e.g., fault depths, frictional coefficients, ice layer thickness, ocean layer thickness, tidal stress sources) that support fault activity on Enceladus. The core of this work is a synthesis of stress predictions provided by a numerical tidal stress model (SatStress) and a quantification of failure scenarios based on Coulomb failure laws. We determine that constraining the ice layer thickness to 40 km, ice coefficients between 0.1 and 0.3 and fault depths 3 km promote fault activity along the tiger stripes. Based on these results, I suggest a plan to employ these techniques to understand Europa, an icy moon of Jupiter that exhibits similar fault systems. Agenor Linea, a fault in the southern hemisphere of Europa, is the target for identifying mechanisms for fault activity. This study will lead to a more comprehensive understanding of the fault behavior on icy satellites of the outer solar system.