Multi-phase volcanic resurfacing at Loki Patera on Io

• Published in: Nature (London) 2017-05, Vol.545 (7653), p.199-202
• Main Authors: de Kleer, K., Skrutskie, M., Leisenring, J., Davies, A. G., Conrad, A., de Pater, I., Resnick, A., Bailey, V., Defrère, D., Hinz, P., Skemer, A., Spalding, E., Vaz, A., Veillet, C., Woodward, C. E.
• Format: Article
• Language: English
• Subjects: 639/33/445/598; 639/33/445/847; Astronomy; Astrophysics; Aérospatiale, astronomie & astrophysique; Bulk density; Calderas; Cooling; Data processing; Emission; Emissions; Eruptions; Europa; Fizeau interferometry; Humanities and Social Sciences; Interferometry; Io (Satellite); Io volcanic activity; Jovian moon; Jupiter; Jupiter satellites; Lava; Lava flows; Lava lake; LBT; letter; Loki; Loki Patera; Moon; Moons; multidisciplinary; Natural history; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; Resurfacing; Science; Solar system; Space science, astronomy & astrophysics; Spatial discrimination; Spatial resolution; Surfacing; Temperature effects; Temperature gradients; Thermal emission; Thermal imaging; Volcanic activity; Volcano; Volcanoes
• ISSN: 0028-0836; 1476-4687; 1476-4687
• DOI: 10.1038/nature22339

Interferometric telescope observations of the Jovian moon Io reveal that the floor of the Loki Patera volcano has been resurfaced in two waves, with different starting times and velocities. Volcanic resurfacing on Io Jupiter's moon Io has the biggest active volcano in the Solar System. Inside the volcano, a warm floor surrounds a cool central island. Previous observations have indicated that volcanic resurfacing occurs every one to three years, but telescope observations have insufficient resolution to see how this progresses, and spacecraft observations have not been able to see the entire floor at once. Katherine De Kleer et al . used an occultation of Io by another of Jupiter's moons (Europa) to map the entire floor at a spatial resolution of 2 kilometres, using interferometric telescope observations. They find that the resurfacing happens in two waves, with different starting times and velocities, which then converge around the central island. They interpret the differences between the waves as evidence of either a non-uniformity in the lava or variations in the bulk density of the crust across the volcano. The Jovian moon Io hosts the most powerful persistently active volcano in the Solar System, Loki Patera 1 , 2 . The interior of this volcanic, caldera-like feature is composed of a warm, dark floor covering 21,500 square kilometres 3 surrounding a much cooler central ‘island’ 4 . The temperature gradient seen across areas of the patera indicates a systematic resurfacing process 4 , 5 , 6 , 7 , 8 , 9 , which has been seen to occur typically every one to three years since the 1980s 5 , 10 . Analysis of past data has indicated that the resurfacing progressed around the patera in an anti-clockwise direction at a rate of one to two kilometres per day, and that it is caused either by episodic eruptions that emplace voluminous lava flows or by a cyclically overturning lava lake contained within the patera 5 , 8 , 9 , 11 . However, spacecraft and telescope observations have been unable to map the emission from the entire patera floor at sufficient spatial resolution to establish the physical processes at play. Here we report temperature and lava cooling age maps of the entire patera floor at a spatial sampling of about two kilometres, derived from ground-based interferometric imaging of thermal emission from Loki Patera obtained on 8 March 2015 ut as the limb of Europa occulted Io. Our results indicate that Loki Patera is resurfaced by a multi-phase process