Multiple-Temperature Component Fits to a Silicate Eruption at South Volund, Io, from Galileo NIMS and SSI observations.
A.G. Davies (JPL-Caltech), A.S. McEwen (University of Arizona), R.M.C. Lopes-Gautier (JPL-Caltech), L. Keszthelyi (Univ. Arizona / Univ. Hawaii), W.D. Smythe, R.W. Carlson (JPL-Caltech)
Analysis of data from darkside and eclipse observations of Io by
the NIMS and SSI instruments show that the South Volund hot spot is
a manifestation of high temperature active silicate volcanism. The
NIMS data are fitted with a two temperature model (developed from
modelling terrestrial lavas) which yields a better fit to the data
than a single temperature fit. The multispectral color
temperatures obtained from NIMS are compared with the brightness
temperatures obtained from the SSI instrument, and show excellent
agreement for the hotter of the two components fitted to the NIMS
data. The two components might correspond to a cooled crust which
has formed on the surface of an active flow or lava lake, at a
temperature of approximately 450 K, and covering an area of about
50 km , and a hotter and much smaller component, at a temperature
of approximately 1100 K and an area of less than 0.1 km . The hot
component implies the existence of cracks in the surface crust of
a flow or lake through which the hot interior radiates, a hot vent
area, or breakouts of lava forming new flow lobes. The ratio of
these areas is consistent with the crack-to-crust ratio of some
lava flows and lava lakes on Earth. The NIMS data has also been
fitted with a multiple-temperature thermal model, which implies
that part of the volcanic structure has a temperature in excess of
1450 K.