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By Jason Perry
February 24, 2001
Imke de Pater, Franck Marchis, H. Roe, B. Macintosh, S. Acton and D. Le Mignant observed Io using Keck II's Adaptive Optics system on February 19, 20, and 22. On February 22, they observed an outburst at 334 ± 3 W, 40 ± 3 N, consistent with Surt, a plume site from Voyager 2. The J, H, and K' photometry suggests a temperature of 1000-1100 K but the H-band photometry suggests temperatures of up to 1700-1800 K, indicating ultramafic eruption. Follow-up observations are needed to look at the time evolution of this eruption.
This is the 2 major outburst in 2 months. In December 2000, Franck Marchis observed an outburst at Tvashtar Catena using the ADONIS Adaptive Optics system at the European Southern Observatory in La Silla, Chile.
Surt has been the site of short-lived eruptions before. Between the Voyager 1 and 2 encounters in 1979, a high temperature eruption may have been seen at this volcano. When Voyager 2 passed by in July 1979, a Pele-type plume deposit was seen around the volcano. Another eruption may have been seen in late March 1995. Faint activity at Surt was also noted in June 1996.
More information can be found in IAUC circular #7588 at http://cfa-www.harvard.edu/iauc/07500/07588.html. Figure 1 below shows Surt and and a nearby volcano, Manua Patera. This image is based on Voyager 1 data.
Two new images were officially released today, February 23. The first new image shows Tohil Mons. In addition to this image, stereo views of this 5.4 km tall mountain were also released. The other image shows new lava breakouts on the Amirani lava flow seen in February 2000 compared to images taken in October 1999.
To view the Tohil Mons, click here, and to view the Amirani image, click here.
Figure
1
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