Surt (volcano)

Surt is an active volcano on Jupiter's moon Io. It is located on Io's Jupiter-facing hemisphere at 45.21° North Latitude, 336.49° West Longitude.cite web | last=Blue | first=Jennifer | date=October 1, 2008 |url=http://planetarynames.wr.usgs.gov/jsp/FeatureTypesData2.jsp?systemID=5&bodyID=7&typeID=11&system=Jupiter&body=Io&type=Eruptive%20center&sort=AName&show=Fname&show=Lat&show=Long&show=Diam&show=Stat&show=Orig | title=Io Nomenclature: Eruptive center | publisher=USGS | accessdate=2008-10-01 ] Surt consists of a oblong volcanic pit (known as a "patera"), convert|75|by|40|km in diameter, surrounded by reddish sulfur and bright sulfur dioxide deposits to its south and east.cite journal |title=Two classes of volcanic plume on Io |journal=Icarus |last=McEwen |first=A. S. |coauthors=Soderblom, L. A. |pages=197–226 |volume=58 |issue= |date=1983] cite journal |title=Surface changes on Io during the Galileo mission |journal=Icarus |last=Geissler |first=P. |coauthors="et al." |pages=29–64 |volume=169 |issue= |date=2004] The volcano was first observed in images acquired by the "Voyager 1" spacecraft in March 1979.cite journal |title=The Galilean Satellites and Jupiter: Voyager 2 Imaging Science Results |journal=Science |last=Smith |first=B. A. |coauthors="et al." |pages=927–950 |volume=206 |issue=4421 |date=1979] Later that year, the International Astronomical Union named this feature after an Icelanic volcano god, Surtr.

Several eruptions have been observed at Surt since it was discovered by "Voyager 1". The first eruption observed by Earth-based astronomers following the discovery of Ionian volcanism took place at Surt on June 11 1979, between the "Voyager 1" and "Voyager 2" flybys.cite journal |title=Io: Are Vapor Explosions Responsible for the 5-μm Outbursts? |journal=Icarus |last=Sinton |first=W. M. |coauthors= |pages=56–64 |volume=43 |issue= |date=1980] When "Voyager 2" encountered the Jupiter system in July 1979, the eruption appeared to have ceased, but a fresh, convert|600|km-wide plume deposit was observed surrounding Surt. This plume deposit was suggestive of an active Pele-type plume at Surt between the two Voyager encounters. In addition, dark material, thought to be lava erupted during the eruption, was visible within the eastern half of the patera. When the "Galileo" spacecraft first took images of the area in 1996, the appearance of Surt and the surrounding terrain had reverted back to its appearance as seen by "Voyager 1", again suggestive of a short-lived eruption.

Surt erupted again on February 22 2001 in the most powerful volcanic eruption ever observed, in terms of the amount of power (in watts) output by the eruption.cite journal |title=High-Resolution Keck Adaptive Optics Imaging of Violent Volcanic Activity on Io |journal=Icarus |last=Marchis |first=F. |coauthors="et al." |pages=124–131 |volume=160 |issue= |date=2002] The total power output observed at Surt (7.2–8.4esp|13 W) during this eruption nearly matches the average total power output for all of Io's volcanoes. Despite such a violent eruption, few surface changes were observed in conjunction with the eruption in images acquired by "Galileo" six months later, suggesting that any changes had largely faded. Fresh, sulfur-rich, reddish deposits were seen in images acquired by Galileo in August 2001 to the northeast of Surt.

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