Volcanic Eruptions on Io: Heat Flow, Resurfacing, and Lava Composition

Abstract

We model an infrared outburst on Io as being due to a large, erupting lava flow which increased its area at a rate of 1.5 × 10 5 m 2 sec -1 and cooled from 1225 to 555 K over the 2.583-hr period of observation. The inferred effusion rate of 3 × 10 5 m 3 sec -1 for this eruption is very high, but is not unprecedented on the Earth and is similar to the high eruption rates suggested for early lunar volcanism. Eruptions occur ∼6% of the time on Io. These eruptions provide ample resurfacing to explain Io's lack of impact craters. We suggest that the large total radiometric heat flow, 10 14W, and the size and temperature distribution of the thermal anomalies (McEwen et al. 1992, Bull. Am. Astron. Soc. 24, 935; Veeder et al. 1994, J. Geophys. Res. 99, 17,095-17,162) can be accounted for by a series of silicate lava flows in various stages of cooling. We propose that the whole suite of Io's currently observed thermal anomalies was produced by multiple, high-eruptive-rate silicate flows within the past century.