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Volcanic eruptions on IoNine eruption plumes which were observed during the Voyager 1 encounter with Io are discussed. During the Voyager 2 encounter, four months later, eight of the eruptions were still active although the largest became inactive sometime between the two encounters. Plumes range in height from 60 to over 300 km with corresponding ejection velocities of 0.5 to 1.0 km/s and plume sources are located on several plains and consist of fissures or calderas. The shape and brightness distribution together with the pattern of the surface deposition on a plume 3 is simulated by a ballistic model with a constant ejection velocity of 0.5 km/s and ejection angles which vary from 0-55 deg. The distribution of active and recent eruptions is concentrated in the equatorial regions and indicates that volcanic activity is more frequent and intense in the equatorial regions than in the polar regions. Due to the geologic setting of certain plume sources and large reservoirs of volatiles required for the active eruptions, it is concluded that sulfur volcanism rather than silicate volcanism is the most likely driving mechanism for the eruption plumes.
Document ID
Document Type
Reprint (Version printed in journal)
Strom, R. G. (Arizona Univ. Tucson, AZ, United States)
Schneider, N. M. (Arizona, University Tucson, AZ, United States)
Terrile, R. J. (Arizona Univ. Tucson, AZ, United States)
Hansen, C. (California Institute of Technology, Jet Propulsion Laboratory, Pasadena CA, United States)
Cook, A. F. (Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Date Acquired
August 10, 2013
Publication Date
September 30, 1981
Publication Information
Publication: Journal of Geophysical Research
Volume: 86
Subject Category
Distribution Limits