Io's Volcanism: Thermo-Physical Models of Silicate Lava Compared with Observations of Thermal Emission
✍ Scribed by Ashley Gerard Davies
- Book ID
- 102568339
- Publisher
- Elsevier Science
- Year
- 1996
- Tongue
- English
- Weight
- 476 KB
- Volume
- 124
- Category
- Article
- ISSN
- 0019-1035
No coin nor oath required. For personal study only.
✦ Synopsis
posed to sulfur volcanism. With these new data available, it is now necessary to consider the fluid and thermodynamic Analyses of thermal infrared outbursts from the jovian satelbehavior of lava eruption and emplacement in order to lite Io indicate that at least some of these volcanic events are due to silicate lava. Analysis of the January 9, 1990 outburst explain the temporal evolution of these outbursts, and indicates that this was an active eruption consisting of a large reevaluate the role active volcanism plays in the Io therlava flow (with mass eruption rate of order 10 5 m 3 sec ؊1 ) and mal budget.
a sustained area at silicate liquidus temperatures. This is inter-
The largest class of outbursts on Io are characterized by preted as a series of fire fountains along a rift zone. A possible a large increase in the 4.8 Ȑm emission over a short period alternative scenario is that of an overflowing lava lake with of time (i.e., hours to days). The first report of such an extensive fire fountaining. The January 9, 1990 event is unique event was the pre-Voyager 5 Ȑm enhancement reported as multispectral observations with respect to time were obby Witteborn et al. (1979). Other events were subsequently tained. In this paper, a model is presented for the thermal observed (see Veeder et al. 1994). In particular the events energy lost by active and cooling silicate lava flows and lakes of August 7, 1986 and January 9, 1990 are characteristic on Io. The model thermal emission is compared with Earthof the largest of the outbursts seen: during the August 7, based observations and Voyager IRIS data. The model (a) pro-1986 event the 4.8 Ȑm emission from Io increased by a vides an explanation of the thermal anomalies on Io's surface; factor of 10, and almost doubled at 8.7 Ȑm (Veeder et al. (b) provides constraints on flow behavior and extent and infers 1994). From analysis of the observations of the January 9, some flow parameters; and (c) determines flow geometry and change in flow size with time, and the temperature of each part 1990 event, the most likely position of the hotspot is in of the flow or lava lake surface as a function of its age. Models the Loki Patera region on Io (Blaney et al. 1995).
of heat output from active lava flows or inactive but recently
The Loki infrared outburst of January 9, 1990 is characemplaced lava flows or overturning lava lakes alone are unable terized by a large increase in the 4.8 and 8.7 Ȑm fluxes to reproduce the observations. If the January 9, 1990 event is above the Io background flux, which in December 1989 the emplacement of a lava flow, the equivalent of 27 such events and January 1990 was already exhibiting a higher than per year would yield a volume of material sufficient, usual emission from the Loki Patera region (Blaney et al.
if uniformly distributed, to resurface all of Io at a rate of 1 1995). Assuming this increase was due to volcanic activity, cm/year.