Plumes Volcanology of Io

sequence of new horizons images showing io s volcano tvashtar spewing material 330 kilometres (210 mi) above surface

the discovery of volcanic plumes @ pele , loki in 1979 provided conclusive evidence io geologically active. generally, plumes form when volatiles sulfur , sulfur dioxide ejected skyward io s volcanoes @ speeds reaching 1 kilometre per second (0.62 mi/s), creating umbrella-shaped clouds of gas , dust. additional materials might found in volcanic plumes include sodium, potassium, , chlorine. although striking in appearance, volcanic plumes relatively uncommon. of 150 or active volcanoes observed on io, plumes have been observed @ couple of dozen of them. limited area of io s lava flows suggests of resurfacing needed erase io s cratering record must come plume deposits.

the common type of volcanic plume on io dust plumes, or prometheus-type plumes, produced when encroaching lava flows vaporize underlying sulfur dioxide frost, sending material skyward. examples of prometheus-type plumes include prometheus, amirani, zamama, , masubi. these plumes less 100 kilometres (62 mi) tall eruption velocities around 0.5 kilometres per second (0.31 mi/s). prometheus-type plumes dust-rich, dense inner core , upper canopy shock zone, giving them umbrella-like appearance. these plumes form bright circular deposits, radius ranging between 100 , 250 kilometres (62 , 155 mi) , consisting of sulfur dioxide frost. prometheus-type plumes seen @ flow-dominated eruptions, helping make plume type quite long-lived. 4 out of 6 prometheus-type plumes observed voyager 1 in 1979 observed throughout galileo mission , new horizons in 2007. although dust plume can seen in sunlit visible-light images of io acquired passing spacecraft, many prometheus-type plumes have outer halo of fainter, more gas-rich material reaching heights approaching of larger, pele-type plumes.

io s largest plumes, pele-type plumes, created when sulfur , sulfur dioxide gas exsolve erupting magma @ volcanic vents or lava lakes, carrying silicate pyroclastic material them. few pele-type plumes have been observed associated explosion-dominated eruptions, , short-lived. exception pele, associated long-lived active lava lake eruption, though plume thought intermittent. higher vent temperatures , pressures associated these plumes generate eruption speeds of 1 kilometre per second (0.62 mi/s), allowing them reach heights of between 300 , 500 kilometres (190 , 310 mi). pele-type plumes form red (from short-chain sulfur) , black (from silicate pyroclastics) surface deposits, including large 1,000 kilometres (620 mi)-wide red rings, seen @ pele. erupted sulfurous components of pele-type plumes thought result of excess amount of sulfur in io s crust , decrease in sulfur solubility @ greater depths in io s lithosphere. fainter prometheus-type plumes result of low dust content, causing called stealth plumes. these plumes seen in images acquired while io in shadow of jupiter or taken in ultraviolet. little dust visible in sunlit images generated when sulfur , sulfur dioxide condense gases reach top of ballistic trajectories. why these plumes lack dense central column seen in prometheus-type plumes, in dust generated @ plume source. examples of pele-type plumes have been observed @ pele, tvashtar, , grian.