page_title: Loki Patera
hierarchical_section_title: Loki Patera
caption_attribution_description: English: A huge area of Io's volcanic plains is shown in this Voyager 1 image mosaic. Numerous volcanic calderas and lava flows are visible here. Loki Patera, an active lava lake, is the large shield-shaped black feature. Heat emitted from Loki can be seen through telescopes all the way from Earth. These telescopic observations tell us that Loki has been active continuously (or at least every time astronomers have looked) since the Voyager 1 flyby in March 1979. The composition of Io's volcanic plains and lava flows has not been determined, but they could consist dominantly of sulfur with surface frosts of sulfur dioxide or of silicates (such as basalts) encrusted with sulfur and sulfur dioxide condensates. The bright whitish patches probably consist of freshly deposited SO2 frost. The black spots, including Loki, are probably hot sulfur lava, which may remain molten by intrusions of molten silicate magma, coming up from deeper within Io. The ultimate source of heat that keeps Io active is tidal frictional heating due to the continual flexure of Io by the gravity of Jupiter and Europa, another of Jupiter's satellites.
context_page_description: Loki Patera is the largest volcanic depression on Jupiter's moon Io, 202 kilometres in diameter. It contains an active lava lake, with an episodically overturning crust. The level of activity seen is similar to a superfast spreading mid-ocean ridge on Earth. Temperature measurements of thermal emission at Loki Patera taken by Voyager 1's Infrared Interferometer Spectrometer and Radiometer instrument were consistent with sulfur volcanism.
  Io's lava lakes such as Loki Patera are depressions partially filled with molten lava covered by a thin solidified crust. These lava lakes are directly connected to a magma reservoir below. Observations of thermal emission at several of Io's lava lakes reveal glowing molten rock along Loki Patera's margin, caused by the lake's crust breaking up along the edge of the patera. Over time, because the solidified lava is denser than the still-molten magma below, this crust can founder, triggering an increase in thermal emission at the volcano. At sites such as Loki Patera, this can occur episodically. During an overturning episode, Loki can emit up to ten times more heat than when its crust is stable.
context_section_description: Loki Patera /ˈloʊki ˈpætərə/ is the largest volcanic depression on Jupiter's moon Io, 202 kilometres (126 mi) in diameter. It contains an active lava lake, with an episodically overturning crust. The level of activity seen is similar to a superfast spreading mid-ocean ridge on Earth. Temperature measurements of thermal emission at Loki Patera taken by Voyager 1's Infrared Interferometer Spectrometer and Radiometer (IRIS) instrument were consistent with sulfur volcanism.
  Io's lava lakes such as Loki Patera are depressions partially filled with molten lava covered by a thin solidified crust. These lava lakes are directly connected to a magma reservoir below. Observations of thermal emission at several of Io's lava lakes reveal glowing molten rock along Loki Patera's margin, caused by the lake's crust breaking up along the edge of the patera.  Over time, because the solidified lava is denser than the still-molten magma below, this crust can founder, triggering an increase in thermal emission at the volcano. At sites such as Loki Patera, this can occur episodically. During an overturning episode, Loki can emit up to ten times more heat than when its crust is stable. During an eruption, a wave of foundering crust spreads out across the patera at the rate of about 1 kilometre (0.6 mi) per day, until the crust of the lake has been resurfaced. Another eruption would begin once the new crust has cooled and thickened enough for it to no longer be buoyant over the molten lava.
  On March 8, 2015 a rare orbital alignment occurred between Io and Europa, two of Moons of Jupiter, that allowed researchers to separate heat being emitted. They were able to accomplish this because Europa's surface is coated in water ice which reflects small amounts of sunlight at infrared wavelengths. Scientists were able to determine that there were two waves of resurfacing lava, which explains the change in brightness on Loki Patera every 400–600 days. The images that helped researchers and scientist discover this were captured by the Large Binocular Telescope Observatory in southeast Arizona. The observation also revealed that there is a difference in the magma supply of the two halves of Loki.
  Loki Patera is located at 13°N 308.8°W. It is named after the Norse god Loki. Amaterasu Patera is located to the north and Manua Patera to the northwest.
caption: Voyager 1 observation of Loki Patera and nearby lava flows and volcanic pits
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