Models for the Crustal Structure of Io: Implications for Magma Dynamics. W

Introduction: Io, the innermost of the Galilean satellites, is the most volcanically active body in our solar system. While its volcanic eruptions can be studied directly, our knowledge of the underlying magmatic processes rests wholly on indirect inferences. Here we combine constraints from magma ascent and crustal density models to gain insight into the plumbing system underlying the Prometheus volcanic center. Magma Ascent Model: Prometheus was selected for focused study because it is the best known example of a long-lived flow field on Io. It also exhibits many similarities to the ongoing eruption of Kilauea Volcano, Hawaii [1]. However, despite their comparable eruptive styles, Prometheus and Kilauea have magma fluxes that differ by about an order of magnitude. During one ~6-month period (1996-1997), Prometheus erupted ~0.8 km of lava, with an estimated effusion rate peaking at ~70 m s, whereas Kilauea erupted 0.08 km over the same period. Building upon the work of [2-4], it is possible to relate the observed effusion rate to the subsurface plumbing system. For a cylindrical conduit, the effusion rate (QF) can be found by