VOLCANIC-ERUPTIONS ON IO - HEAT-FLOW, RESURFACING, AND LAVA COMPOSITION

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 x 10(5) m(2) sec(- 1) and cooled from 1225 to 555 K over the 2.583-hr period of observati on. The inferred effusion rate of 3 x 10(5) m(3) sec(-1) for this erup tion is very high, but is not unprecedented on the Earth and is simila r to the high eruption rates suggested for early lunar volcanism. Erup tions occur similar to 6% of the time on Io. These eruptions provide a mple resurfacing to explain Io's lack of impact craters. We suggest th at the large total radiometric heat flow, 10(14) W, and the size and t emperature distribution of the thermal anomalies (McEwen ef al. 1992, Bull. Am. Astron. Sec. 24, 935; Veeder et al. 1994, J. Geophys. Res. 9 9, 17,095-17,162) can be accounted for by a series of silicate lava fl ows in various stages of cooling. We propose that the whole suite of I o's currently observed thermal anomalies was produced by multiple, hig h-eruptive-rate silicate flows within the past century. (C) 1995 Acade mic Press, Inc.