Preferential Orientations of Subjovian Patera and Northern Hemisphere Mountain Populations on Io

Abstract

Io's surface hosts numerous mountains and volcanic paterae generated by processes that occur at depth, including tidal heating and the resultant crustal recycling and subsidence stresses. Global trends in the shape and orientation of surface features could provide insight into these subsurface processes. Here, we present a global analysis of the shapes and orientations of Io's mountains and paterae. We find that both feature types exhibit distinctive elongate shapes, and in the case of paterae, a dominant planform aspect ratio of ∼2:3. These elongate features tend to be oriented randomly across Io's surface, with the exception of regional populations that have statistically significant preferential orientations: paterae in the subjovian hemisphere are unlikely to be oriented NE‐SW, and mountains in the northern hemisphere are unlikely to be oriented E‐W. We investigated whether tidal stresses play a role in preferencing certain orientations by modeling the maximum compressive and tensional tidal stress experienced at each mountain and patera location throughout Io's orbit, and comparing it to the orientation of the feature on the surface. There are no correlations between stresses and feature orientations on a global scale. It is likely that other factors, such as the presence of Loki Patera in the subjovian hemisphere, may influence the hemispherical preferential orientations of paterae.