Volcanism on Io II GLY 424/524 April 22, 2002 Eruption Plumes on Io Ionian Plumes: SO2 Source • Low gravity, atmospheric pressure • Liquid SO2 “pockets” beneath the surface • Plumes on Io ~60 - 450 km – Superheated upon contact with magma – Old Faithful would be 35 km tall on Io – Boil, erupt • Powered by SO and SO2 • Vertical crustal recycling of SO2 “snow” – Tvashtar plume detected August 2001 and “frost” deposits – 500 km tall • Most plumes from lava flow front rather – Particles determined to be SO2 “snowflakes” than vent – Interaction of hot lava with old SO2 “snow” Sulfur gas (S2 or SO2) lands on the cold surface. Atoms rearrange into (S3, S4), which give the surface a red color. Eventually, S8 forms ordinary pale yellow sulfur. 1 Io Volcanic Styles Io Volcanic Styles Continued • Promethean • Pillanian – Prometheus = type locale – Pillan = type locale • Also Amirani • Also Tvashtar • Zamama • I-31A hot-spot • Culann – Short-lived, high-effusion-rate eruptions – Long-lived, steady eruptions • Large pyroclastic deposits • Produces compound flow field • Open-channel or open-sheet flows • Takes years to decades • Associated with “wandering” plumes • Lava lakes – Extensive plume deposits – Loki = type locale – Extensive, rapidly emplace flows • Also Emakong, Pele, Tupan – High temperatures Prometheus Prometheus Prometheus Prometheus • Io’s “Old Faithful” – Active since 1979 – Observed by Voyager 1 • Eruption Plume – 80 km tall – Plume source migrated 85 km to the west since 1979 • Lava flow – ~100 km long – Apparently originates in caldera 2 Prometheus Caldera & flow-front plume Prometheus Pillan Pele & Pillan April, 1997 September, 1997 July, 1999 12 km/px 5 km/px 12 km/px Pillan ~400 km diameter Pillan eruption • http://www.digitalradiance.com/sng/Io_volc ano.htm 3 Pillan Lava flows High-res images near Pillan Patera 7.2 km long ~9 m/pixel Pillan lava flows; 19 m/px Tvashtar Bright regions are saturated pixels, indicating HOT fire- fountaining on Io Temps >1600K F.o.v. ~300 x 75 km 4 Loki Loki, March 4, 1979 Pele Loki as seen by NIMS Image A: Brightness temperatures in K; Image B: color temperatures in K Loki temps: lava flooding? Emakong Caldera Emakong 5 Lava channel Voyager Io Results Emakong Emakong ~70 km long Tupan Caldera Culann 6.