Spatial distribution of volcanoes on Io: Implications for tidal heating and magma ascent

Abstract

22Extreme volcanism on Io results from tidal heating, but its tidal dissipation mechanisms and

Global near-IR maps from Gemini-N and Keck in 2010, with a special focus on Janus Patera and Kanehekili Fluctus

“…Based on Galileo magnetometer data, Khurana et al (2011) suggest that Io must have a partially molten asthenosphere, which advocates that most volcanoes are at low latitudes. Although this broadly agrees with observations (e.g., Lopes-Gautier et al, 1999;Schenk et al, 2001;Radebaugh et al, 2001), recent studies (Veeder et al, 2011Hamilton et al, 2013) show a much more complicated pattern. Veeder et al (2012) quantified the thermal emission from over 240 volcanic sites on Io, creating a Galileo-epoch distribution of volcanic thermal emission that showed that Io's volcanic heat flow is offset eastwards from that expected from a model of internal heating concentrated solely in the asthenosphere.…”

“…Most of Io's detectable volcanic heat flow ($45% of Io's total thermal emission of 1.05 Â 10 21 W -see Veeder et al, 1994Veeder et al, , 2012 comes from paterae. By examining the distribution of volcanic features on Io, Hamilton et al (2013) show that sites of volcanic activity appear to be globally random, although closer to the equator, active hot spots are more widely spaced than a random distribution would predict. Moreover, some of the most energetic eruptions have been found at high latitudes (e.g., Marchis et al, 2002;Laver et al, 2007;Spencer et al, 2007;de Pater et al, 2014).…”

The collapse of Io's primary atmosphere in Jupiter eclipse

“…The atmospheric densities at eclipse ingress longitudes (~340°W) are a factor of 2 lower than at eclipse egress longitudes (20°W) [ Tsang et al ., , ]. Egress longitudes also contain ~40% more volcanically active hotspots and paterae than at ingress longitudes as seen by the Galileo spacecraft [ Feaga et al ., ; Hamilton et al ., ]. We postulate that at ingress longitudes, the atmosphere is dominated by ice sublimation, but at egress longitudes where the atmosphere is twice as thick, SO 2 emission from the larger number of volcanoes largely masks the sublimation response to sunlight.…”

Dynamics and Thermal History of the Terrestrial Planets, the Moon, and Io

“…The process of getting heat to the surface, however, is influenced by mantle convection, which will act to smooth out variations, and melt transport, which will be sensitive to lithospheric structures. Hamilton et al (2013) analyzed the distribution of volcanic centers based on clustering statistics and found that an asthenospheric model was preferred; however, a consistent 30-60 eastward offset of the observed pattern indicated that lithospheric structure, perhaps offset by nonsynchronous rotation, played an important role. Hamilton et al (2013) analyzed the distribution of volcanic centers based on clustering statistics and found that an asthenospheric model was preferred; however, a consistent 30-60 eastward offset of the observed pattern indicated that lithospheric structure, perhaps offset by nonsynchronous rotation, played an important role.…”