FRIENDS OF MUSTAFAR: TIDAL STRESSES ON JUPITER’S MOON IO

Are Io’s volcanic eruptions tidally controlled? Jupiter’s moon Io is subjected to some of the most extreme tidal stresses in the Solar System. These tides generate significant heat within Io, resulting in hundreds of active volcanoes and a very young surface. At and near the surface, these same tides also result in large stresses that will change in orientation and magnitude over the course of each orbit of Jupiter. Nearly all volcanoes on Io’s surface will experience periods of compression, tension, and shear stresses during every orbit (~43 hrs). Previous work has demonstrated that thermal activity at many of Io’s volcanoes is variable over time. Here we explore how the tidal stresses at several volcanoes change over Io’s orbital period with the aim of comparing stress changes to the timing of eruptions. Using the open source code SatStressGUI, we calculate the changing magnitudes and orientations of the tidal stresses at Io for a range of possible interior rheologies over the course of Io’s orbit at several locations on the surface. We will show how differing interior structures affects the timing and magnitude of the stresses. This work has implications for how the timing of the stresses compares to the timing of observed eruptions, as seen by the Voyager, Galileo, and Juno spacecraft and ground-based telescopes. Specifically, if volcanoes that are at a period in the orbit where they are experiencing compressional stresses the volcanic activity may be restricted and thus less likely to be observed to be active. Conversely, volcanoes that are in tension may be less restricted and thus more likely to be observed to be active. Finding a strong correlation between stress fields and volcanic activity would allow observations to be timed to coincide with periods of peak or minimal activity in a given region of Io.

We thank the SSW program for funding this work.