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This is a sub-article to Io (moon)

Volcanism on Io, a moon of Jupiter, produces lava flows, volcanic pits, and plumes of sulfur and sulfur dioxide hundreds of kilometres high. This volcanic activity was discovered in 1979 by Voyager 1 imaging scientists.^[1] Observations of Io by passing spacecraft, such as the Voyagers, Galileo, Cassini, and New Horizons, and Earth-based astronomers have revealed more than 150 active volcanoes, with up to 400 expected to exist based on these observations.^[2] Io's volcanism makes the satellite one of only four known volcanically active worlds in the Solar System (the other three being Earth, Saturn's moon Enceladus, and Neptune's moon Triton).

First predicted shortly before the Voyager 1 flyby, the heat source for Io's volcanism comes from tidal heating produced by Io's forced orbital eccentricity.^[3] This differs from the heat source for Earth's volcanism, which comes primarily from radioactive isotope decay.^[4] Io's eccentric orbit leads to a slight difference in Jupiter's gravitational pull on Io between its closest and furthest points on its orbit, causing a varying tidal bulge. This variation in the shape of Io causes frictional heating in Io's interior. Without this tidal heating, Io may have been similar to the Earth's moon, a world of similar size and mass, geologically dead and covered with numerous impact craters.^[3]

Io's volcanism has led to the formation of hundreds of volcanic centres and extensive lava formations, making the moon the most volcanically active world in the solar system. Three different types of volcanic eruptions have been identified, differing in duration, intensity, lava effusion rate, and whether the eruption occurs within a volcanic pit (known as a patera). Lava flows on Io, tens or hundreds of kilometres long, are composed primarily of basaltic silicate lavas, similar to lavas seen on Earth at shield volcanoes such as Kilauea in Hawaii.^[5] While most lava flows on Io are consistent with basalt, flows consisting of sulfur and sulfur dioxide are also seen, as well as eruption temperatures that can be explained by high-temperature ultramafic silicate lavas.^[6]

As a result of the presence of significant quantities of sulfurous materials in Io's crust and on its surface, during some eruptions, sulfur, sulfur dioxide gas, and pyroclastic material are blown up to 500 kilometres (310 mi) into space, producing large, umbrella-shaped volcanic plumes.^[7] This material paints the surrounding terrain in red, black, and white, and provides for Io's patchy atmosphere and Jupiter's extensive magnetosphere. Spacecraft that have flown by Io since 1979 have observed numerous surface changes as a result of Io's volcanic activity.^[8]

Discovery

Prior to the Voyager 1 encounter with Io on March 5, 1979, Io was thought to be a dead world much like the Earth's Moon. The discovery of a cloud of sodium surrounding Io led to theories that the satellite would be covered in evaporites.^[9]

Hints of discoveries to come arose from Earth-based infrared observations taken in the 1970s. An anomalously high thermal flux, compared to the other Galilean satellites, was discovered during measurements taken at 10 μm while Io was in Jupiter's shadow.^[10] At the time, this heat flux was attributed to the surface having a much higher thermal inertia than Europa and Ganymede.^[11] These results were considerably different from measurements taken at wavelengths of 20 μm which suggested that Io had similar surface properties to the other Galilean satellites.^[10] It has since been determined that the greater flux at shorter wavelengths was due to the combined flux from Io's volcanoes and solar heating, while solar heating provides a much greater fraction of the flux at longer wavelengths.^[12] A sharp increase in Io's thermal emission at 5 μm was observed on February 20, 1978 by Witteborn, et al. The group considered volcanic activity at the time, in which case the data was fit into a region on Io 8,000 square kilometres (3,100 sq mi) in size at 600 K (327 °C; 620 °F). However, the authors considered that hypothesis unlikely, and instead focused on emission from Io's interaction with Jupiter's magnetosphere.^[13]

Shortly before the Voyager 1 encounter, Stan Peale, Patrick Cassen, and R. T. Reynolds published a paper in the journal Science predicting a volcanically-modified surface and a differentiated interior, with distinct rock types rather than a homogeneous blend. They based this prediction on models of Io's interior that took into account the massive amount of heat produced by the varying tidal pull of Jupiter on Io caused by the moon's slightly eccentric orbit. Their calculations suggested that the amount of heat generated for an Io with a homogeneous interior would be three times greater than the amount of heat generated by radioactive isotope decay alone. This effect would be even greater with a differentiated Io.^[3]

Voyager 1's first images of Io revealed a lack of impact craters, suggesting a very young surface. Craters are used by geologists to estimate the age of a planetary surface; the more impact structures a planetary surface has, the older it is. Instead of impact structures, Voyager 1 observed a multi-coloured surface, pockmarked with irregular-shaped depressions, which lacked the raised rims characteristic of impact craters. Also seen were flow features formed by low-viscosity fluid and tall, isolated mountains that did not resemble terrestrial volcanoes. The surface observed suggested that, just as Peale, et al., had theorized, Io was heavily modified by volcanism.^[14]

On March 8, 1979, three days after passing Jupiter, Voyager 1 took images of Jupiter's moons to help mission controllers determine the spacecraft's exact location, a process called optical navigation. While processing images of Io to enhance the visibility of background stars, navigation engineer Linda Morabito found a 300-kilometre (190 mi) tall cloud along the limb of Io.^[1] At first, she suspected the cloud to be a moon behind Io, but no suitably sized body would have been in that location. The feature was determined to be a plume generated by active volcanism at a dark depression later named Pele.^[15] Following this discovery, seven other plumes were located in earlier Voyager images of Io.^[15] Thermal emission from multiple sources, indicative of cooling lava, were also found.^[16] Surface changes were observed when images acquired by Voyager 2 were compared to those taken four months prior by Voyager 1, including new plume deposits at Aten Patera and Surt.^[17]

Heat source

Unlike the Earth and the Moon, Io's main source of internal heat comes from the dissipation of tidal forces generated by Jupiter's gravitational pull^[3] This external heating differs from the internal heat source for volcanism on Earth, the result of decompression in upwelling mantle convection currents, radioactive isotope decay, and residual heat from accretion.^[4] Such heating is dependent on Io's distance from Jupiter, its orbital eccentricity, the composition of its interior, and its physical state.^[18] Its Laplace-resonant orbit with Europa and Ganymede maintains Io's eccentricity and prevents tidal dissipation within Io from circularizing its orbit. The eccentricity leads to vertical differences in Io's tidal bulge of as much as 100 metres (330 ft) as Jupiter's gravitational pull varies between the periapsis and apoapsis points in Io's orbit. This varying tidal pull also produces friction in Io's interior, enough to cause significant tidal heating and melting. Unlike Earth, where most of its internal heat is released by conduction through the crust, on Io internal heat is released in the form of volcanic activity and generates the satellite's high heat flow (global total: 0.6–1.6 W). Models of its orbit suggest that the amount of tidal heating within Io changes with time, and that the current heat flow is not representative of the long-term average.^[18] The amount of heat released from Io's interior is greater than current estimates for the amount presently generated from tidal heating, suggesting that Io is cooling off from a period of greater tidal heating.^[19]

Composition

Analysis of Voyager images led scientists to believe that the lava flows on Io were composed mostly of various compounds of molten sulfur.^[20] The colouration of the flows was found to be similar to various allotropes of sulfur. Differences in the lava colour and brightness are a function of the temperature of polyatomic sulfur and the packing and bonding of sulfur atoms. An analysis of the lava flows that radiate out from Ra Patera revealed dark albedo material (associated with liquid sulfur at 525 K (252 °C; 485 °F)) close to the vent, red material (associated with liquid sulfur at 450 K (177 °C; 350 °F)) in the central part of each flow, and orange material (associated with liquid sulfur at 425 K (152 °C; 305 °F)) at the furthest ends of each flow.^[20] This colour pattern corresponds to flows radiating out from a central vent, cooling as the lava travels away from the vent. In addition, 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.^[16] However, the IRIS instrument was not capable of detecting wavelengths that are indicative of higher temperature components. This meant that temperatures consistent with silicate volcanism were not discovered by Voyager. Despite this, it was determined that silicates must play a role in Io's youthful appearance as suggested by the moon's high density and the need for silicates to support the steep slopes along patera walls.^[21] The contradiction between the structural evidence and the spectral and temperature data following the Voyager flybys led to a debate in the planetary science community regarding the composition of Io's lava flows, whether they were composed of silicate or sulfurous materials.^[22]

Earth-based infrared studies in the 1980s and 1990s shifted the paradigm from one of primarily sulfur volcanism to one where silicate volcanism dominates, and sulfur acts in a secondary role.^[22] In 1986, measurements of a bright eruption on Io's leading hemisphere revealed temperatures of at least 900 K (627 °C; 1,160 °F). This is higher than the boiling point of sulfur (715 K (442 °C; 827 °F)^*), indicating a silicate composition for at least some of Io's lava flows.^[23] Similar temperatures were also observed at the Surt eruption in 1979 between the two Voyager encounters, and at the eruption observed by Witteborn, et al., in 1978.^[13]^[24] In addition, modeling of silicate lava flows on Io suggested that they cooled rapidly, causing their thermal emission to be dominated by lower temperature components, such as solidified flows, as opposed to the small areas covered by still molten lava near the actual eruption temperature.^[25]

Silicate volcanism, involving basaltic lava with mafic to ultramafic (magnesium-rich) compositions, was confirmed by the Galileo spacecraft in the 1990s and 2000s from temperature measurements of Io's numerous hot spots, locations where thermal emission is detected, and from spectral measurements of Io's dark material. Temperature measurements from Galileo's Solid-State Imager (SSI) and Near-Infrared Mapping Spectrometer (NIMS) revealed numerous hot spots with high-temperature components ranging from at least 1,200 K (930 °C; 1,700 °F) to a maximum of 1,600 K (1,330 °C; 2,420 °F), like at the Pillan Patera eruption in 1997.^[5] Spectral observations of Io's dark material suggested the presence of orthopyroxenes, such as enstatite, magnesium-rich silicate minerals common in mafic and ultramafic basalt. This dark material is seen in volcanic pits, fresh lava flows, and pyroclastic deposits surrounding recent, explosive volcanic eruptions.^[26] Based on the measured temperature of the lava and the spectral measurements, some of the lava may be analogous to terrestrial komatiites.^[27] Compressional superheating, which could increase the temperature of magma during ascent to the surface during an eruption, may also be a factor in some of the higher temperature eruptions.^[5]

While temperature measurements of Io's volcanoes settled the sulfur-versus-silicates debate that persisted between the Voyager and Galileo missions at Jupiter, sulfur and sulfur dioxide still play a significant role in the phenomena observed on Io. Both sulfur and sulfur dioxide have been detected in the plumes generated at Io's volcanoes, with sulfur being a primary constituent of Pele-type plumes.^[28] Bright flows have been identified on Io, at Tsũi Goab Fluctus, Emakong Patera, and Balder Patera for example, that are suggestive of effusive sulfur or sulfur dioxide volcanism.^[29]

Eruptions Styles

Observations of volcanic eruptions on Io by spacecraft and Earth-based astronomers has led to the identification of differences in the types of eruptions seen on the satellite. The three main types identified include intra-patera, flow-dominated, and explosion-dominated eruptions. These eruptions differ in terms of duration, energy released, brightness temperature (determined from infrared imaging), type of lava flow, and whether it is confined within volcanic pits.^[6]

Intra-Patera eruptions

Intra-patera eruptions occur within volcanic depressions known as paterae.^[30] These volcanic centers generally have flat floors bounded by steep walls. They resemble terrestrial calderas, but it is unknown whether they form when an empty lava chamber collapses, like their terrestrial cousins. One hypothesis suggests that these features are produced through the exhumation of volcanic sills, with the overlying material either being blasted out or integrated into the sill.^[31] Some paterae display evidence for multiple collapses, similar to the calderas atop Olympus Mons on Mars or Kilauea on Earth, suggesting that paterae may occasionally form like volcanic calderas.^[30] Because the formation mechanism is still uncertain, the general term for these features uses the Latin descriptor term used by the International Astronomical Union in naming them, paterae. Unlike similar features on Earth and Mars, these depressions generally do not lie at the peak of shield volcanoes and are larger, with an average diameter of 41 kilometres (25 mi) and depth of 1.5 kilometres (0.9 mi).^[30] The largest volcanic depression on Io is Loki Patera at 202 kilometres (126 mi). Whatever the formation mechanism, the morphology and distribution of many paterae suggest that these features are structurally controlled, with at least half bounded by faults or mountains.^[30]

This eruption style can take the form of either lava flows, spreading across the floor of the paterae, or lava lakes.^[32]^[2] Except for observations by Galileo during its seven close flybys, it can be difficult to tell the difference between a lava lake and a lava flow eruption on a patera floor, due to the lower resolution and similar thermal emission characteristics. Lava flow eruptions on patera floors can be just as voluminous as those seen spreading out across the Ionian plains, such as the Gish Bar Patera eruption in 2001.^[32] Flow-like features have also been observed at a number of paterae, like Camaxtli Patera, suggesting that lava flows are an important resurfacing mechanism on the floors of these depressions.^[33]

Ionian lava lakes are depressions partially filled with molten lava covered by a thin crust of cooled, solidified lava. These lava lakes are directly connected to a magma reservoir lying below the lava lake.^[34] Observations of thermal emission at several Ionian lava lakes reveal glowing lava along the patera margin. These lava lakes are often crusted over by cooled lava, with that 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 flounder, triggering an increase in thermal emission at the volcano.^[35] For some lava lakes, like the one at Pele, this occurs continuously, making Pele one of the brightest emitters of heat in the near-infrared spectrum on Io.^[36] At other sites, such as at Loki Patera, this can occur episodically. During an overturning episode, Loki can emit up to ten times as much heat than when it is calmer.^[37] During an eruption at these more quiescent lava lakes, a wave of floundering lava crust spreads out across the patera at the rate of 1 kilometre (0.6 mi) per day, until the entire lava lake crust 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.^[38]

Flow-dominated eruptions

Flow-dominated eruptions are long-lived eruption events that build-up extensive, compound lava flows. The extent of these lava flows makes them a major terrain type on Io. In this style of eruption, magma erupts onto the surface from vents on the floor of paterae or from fissures on the plains, producing inflated, compound lava flows similar to those seen at Kīlauea in Hawaii.^[33] Images from the Galileo spacecraft revealed that many of Io's major lava flows, like those at Prometheus and Amirani, are produced by the build-up of small breakouts of lava on top of older flows.^[33] Flow-dominated eruptions differ from explosion-dominated eruptions by their longevity and their lower energy output per unit of time.^[6] Lava erupts in this style at a generally steady rate, and flow-dominated eruptions can last for years or decades.

Active flow fields more than 300 kilometres (190 mi) long have been observed on Io at Amirani and Masubi. A relatively inactive flow field named Lei-Kung Fluctus covers more than 125,000 square kilometres (48,000 sq mi), an area slightly larger than Nicaragua.^[39] The thickness of these flow fields was not determined by Galileo, but the individual breakouts on the surface of these fields are likely 1 metre (3 ft 3 in) thick. In many cases, active lava breakouts flow out onto the surface tens to hundreds of kilometres from the lava source vent, with low amounts of thermal emission observed between the breakout and the vent. This suggests that lava flows through lava tubes between the source vent and the breakout.^[40]

While these eruptions generally have a steady eruption rate, larger outbreaks of lava have also been observed at many flow-dominated eruption sites. For example, the leading edge of the Prometheus flow field moved 75 to 95 kilometres (47 to 59 mi) between Voyager in 1979 and the first Galileo observations in 1996.^[41] While generally dwarfed by explosion-dominated eruptions on Io, average flow rate at these compound lava flow fields is much greater than what is observed at similar, contemporary lava flows on Earth. Average surface coverage rates of 35–60 square metres (380–650 sq ft) per second were observed at Prometheus and Amirani during the Galileo mission, compared to 0.6 square metres (6.5 sq ft) per second at Kilauea.^[42]

Explosion-dominated eruptions

Explosion-dominated eruptions are the most pronounced of Io's eruption styles. These eruptions, sometimes called "outburst" eruptions from their Earth-based detections, are characterized by their short duration (lasting only weeks or months), rapid onset, large volumetric flow rates, and high thermal emission.^[43] These eruptions lead to a short-lived, significant increase in Io's overall brightness in the near-infrared. The most powerful volcanic eruption observed in historical times was an "outburst" eruption at Surt, observed by Earth-based astronomers on February 22, 2001.^[44]

Explosion-dominated eruptions occur when a body of magma (called a dike), from deep within Io's partially molten mantle, reaches the surface at a fissure. This results in a spectacular display of lava fountains.^[45] During the beginning of the eruption, the thermal emission from an outburst eruption is dominated by high, 1-3 μm infrared radiation. This thermal emission is produced by a large amount of exposed, fresh lava within the fountains at the eruption source vent.^[46] Outburst eruptions at Tvashtar in November 1999 and February 2007 centered around a 25-kilometre (16 mi) long, 1-kilometre (0.62 mi) tall lava "curtain" produced at a small patera nested within the larger Tvashtar Paterae complex.^[45]^[47]

The large amount of exposed molten lava at these lava fountains have provided researchers their best opportunity to measure the actual eruption temperatures of Ionian lavas. These temperatures (about 1,600 K (1,330 °C; 2,420 °F)^*), suggestive of an ultramafic lava composition and similar to Pre-Cambrian komatiites, are dominant at such eruptions, though superheating of the magma during ascent to the surface cannot be ruled as a factor in the high eruption temperatures.^[5]

While the more explosive, lava-fountaining stage may last only a few days to a week, explosion-dominated eruptions can continue for weeks to months, producing large, voluminous silicate lava flows. A major eruption in 1997 from a fissure north-west of Pillan Patera produced more than 31 cubic kilometres (7.4 cu mi) of fresh lava over a two and a half to five and a half month period, and later flooded the floor of Pillan Patera.^[48] Observations by Galileo suggest lava coverage rates at Pillan between 1,000 and 3,000 square metres (11,000 and 32,000 sq ft) per second during the 1997 eruption. The Pillan lava flow was found to be 10 metres (33 ft) thick, compared to the 1–metre-thick flows observed at the inflated flow fields at Prometheus and Amirani. Similar, rapidly emplaced lava flows were also observed by Galileo at Thor in 2001.^[2] Such flow rates are similar to those seen at Iceland's Laki eruption in 1783 and in terrestrial flood basalt eruptions.^[6]

Explosion-dominated eruptions can produce dramatic (but often short-lived) surface changes around the eruption site, such as large pyroclastic and plume deposits produced as gas exsolves from lava fountains at these eruptions.^[46] The 1997 Pillan eruption produced a 400-kilometre (250 mi) wide deposit of dark, silicate material and bright sulfur dioxide.^[48] The Tvashtar eruptions of 2000 and 2007 generated a 330-kilometre (210 mi) tall plume, which deposited a ring of red sulfur and sulfur dioxide 1,200 kilometres (750 mi) wide.^[49] Despite their dramatic appearance, without continuous resupply of material, these changes often revert back to their pre-eruption appearance in months (in the case of Grian Patera) or years (as at Pillan Patera).^[8]

Plumes

Sequence of *New Horizons* images showing Io's volcano Tvashtar spewing material 330 kilometres (210 mi) above its surface

The discovery of volcanic plumes at Pele and Loki in 1979 provided conclusive evidence that Io was geologically active.^[1] Generally, these plumes are formed when volatiles like sulfur and sulfur dioxide are ejected skyward from Io's volcanoes at speeds reaching 1 kilometre per second (0.62 mi/s). Additional material that might be found in these volcanic plumes include sodium, potassium, and chlorine.^[50]^[51] Despite their dramatic appearance, volcanic plumes are relatively uncommon. Of the 150 or so active volcanoes observed on Io, plumes have only been observed at couple of dozen of these hotspots.^[7]^[47] The relative confinement of Io's lava flows suggest that much of the resurfacing needed to erase Io's cratering record must come from volcanic plume deposits.^[8]

The most common type of volcanic plume on Io are dust plumes, or Prometheus-type plumes, produced when encroaching lava flows vaporize underlying sulfur dioxide frost, sending the material skyward.^[52] Examples of Prometheus-type plumes include Prometheus, Amirani, Zamama, and Masubi. These plumes are usually less than 100 kilometres (62 mi) tall with eruption velocities around 0.5 kilometres per second (0.31 mi/s).^[53] Prometheus-type plumes are dust-rich, with a dense inner core and upper canopy shock zone, giving them an umbrella-like appearance. These plumes often form bright circular deposits, with a radius from the plume source ranging between 100 and 250 kilometres (62 and 155 mi) and consisting primarily of sulfur dioxide frost. Prometheus-type plumes are frequently seen at flow-dominated eruptions, helping make this plume type quite long lived. Four out of the six Prometheus-type plumes observed by Voyager 1 in 1979 were also observed throughout the Galileo mission and by New Horizons in 2007.^[15]^[47] While the dust plume can be clearly seen in sunlit visible-light images of Io acquired by passing spacecraft, many Prometheus-type plumes have an outer halo of fainter, more gas-rich material reaching heights approaching that of the larger, Pele-type plumes.^[7]

Io's largest plumes, Pele-type plumes, are created when sulfur and sulfur dioxide gas exsolve from erupting magma at volcanic vents or lava lakes, carrying silicate pyroclastic material with them.^[7] The few Pele-type plumes that have been observed are usually associated with explosion-dominated eruptions, and are short-lived.^[6] The exception to this is Pele, which is associated with a long-lived active lava lake eruption, though the plume is thought to be intermittent.^[7] The higher vent temperatures and vent pressures associated with these plumes generate eruption speeds of up to 1 kilometre per second (0.62 mi/s), allowing these plumes to reach heights of between 300 and 500 kilometres (190 and 310 mi) above Io's surface.^[53] These plumes form red (from the short-chain sulfur) and black (from the silicate pyroclastics) deposits on the surface. Most Pele-type plumes form large, 1,000 kilometres (620 mi)-wide red ring deposits, as seen at Pele.^[8] They are generally fainter than Prometheus-type plumes as a result of the low dust content, causing some to be called stealth plumes. These plumes are sometimes only seen in images acquired while Io is in the shadow of Jupiter or those taken in the ultraviolet range. The little dust that is visible in these plumes in sunlit images is generated as sulfur and sulfur dioxide condense as the gas reach the top of their ballistic trajectories.^[7] That is why these plumes lack a dense central column, seen in Prometheus-type plumes whose dust is generated at the plume vent. Examples of Pele-type plumes have been observed at Pele, Tvashtar, and Grian.^[7]

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^ Geissler, P. E. (1999). "Global Color Variations on Io". Icarus. 140: 265–282. doi:10.1006/icar.1999.6128. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Williams, D. A. (2000). "A komatiite analog to potential ultramafic materials on Io". J. Geophys. Res. 105 (E1): 1671–1684. doi:10.1029/1999JE001157. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Spencer, J. (2000). "Discovery of Gaseous S₂ in Io's Pele Plume". Science. 288: 1208–1210. doi:10.1126/science.288.5469.1208. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Williams, D. A. (2004). "Mapping of the Culann–Tohil region of Io from Galileo imaging data". Icarus. 169: 80–97. doi:10.1016/j.icarus.2003.08.024. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b ^c ^d Radebaugh, D. (2001). "Paterae on Io: A new type of volcanic caldera?". J. Geophys. Res. 106: 33005–33020. doi:10.1029/2000JE001406. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Keszthelyi, L. (2004). "A Post-Galileo view of Io's Interior". Icarus. 169: 271–286. doi:10.1016/j.icarus.2004.01.005. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b Perry, J. E. (2003). "Gish Bar Patera, Io: Geology and Volcanic Activity, 1997–2001" (PDF). LPSC XXXIV. Clear Lake, Texas. Abstract #1720. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b ^c Keszthelyi, L. (2001). "Imaging of volcanic activity on Jupiter's moon Io by Galileo during the Galileo Europa Mission and the Galileo Millennium Mission". J. Geophys. Res. 106: 33025–33052. doi:10.1029/2000JE001383. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Davies, A. (2007). "Effusive activity: landforms and thermal emission evolution". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 142–152. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)
^ Matson, D. L. (2006). "Io: Loki Patera as a magma sea". J. Geophys. Res. 111: E09002. doi:10.1029/2006JE002703. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Radebaugh, J. (2004). "Observations and temperatures of Io's Pele Patera from Cassini and Galileo spacecraft images". Icarus. 169: 65–79. doi:10.1016/j.icarus.2003.10.019. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Howell, R. R. (2007). "The nature of the volcanic activity at Loki: Insights from Galileo NIMS and PPR data". Icarus. 186: 448–461. doi:10.1016/j.icarus.2006.09.022. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Rathbun, J. A. (2006). "Loki, Io: New ground-based observations and a model describing the change from periodic overturn". Geophys. Res. Lett. 33: L17201. doi:10.1029/2006GL026844. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Davies, A. (2007). "The view from Galileo". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 155–177. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)
^ McEwen, A. S. (2000). "Galileo at Io: Results from High-Resolution Imaging". Science. 288 (5469): 1193–1198. doi:10.1126/science.288.5469.1193. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ McEwen, A. S. (1998). "Active Volcanism on Io as Seen by Galileo SSI". Iacrus. 135: 181–219. doi:10.1006/icar.1998.5972. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Davies, A. (2007). "Prometheus and Amirani: effusive activity and insulated flows". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 208–216. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)
^ Davies, A. (2007). "Between Voyager and Galileo: 1979-1995". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 27–38. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)
^ Marchis, F. (2002). "High-Resolution Keck Adaptive Optics Imaging of Violet Volcanic Activity on Io". Icarus. 160: 124–131. doi:10.1006/icar.2002.6955. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |laydate= ignored (help); Unknown parameter |laysource= ignored (help); Unknown parameter |laysummary= ignored (help)
^ ^a ^b Wilson, L. (2001). "Lava Fountains from the 1999 Tvashtar Catena fissure eruption on Io: Implications for dike emplacement mechanisms, eruptions rates, and crustal structure". J. Geophys. Res. 106: 32, 997–33, 004. doi:10.1029/2000JE001323. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b Davies, A. (2007). "Pillan and Tvashtar Paterae: lava fountains and flows". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 192 207. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)
^ ^a ^b ^c Spencer, J. R. (2007). "Io Volcanism Seen by New Horizons: A Major Eruption of the Tvashtar Volcano". Science. 318: 240–243. doi:10.1126/science.1147621. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b McEwen, A. S. (1998). "High-temperature silicate volcanism on Jupiter's moon Io". Science. 281: 87–90. doi:10.1126/science.281.5373.87. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Turtle, E. P. (2004). "The final Galileo SSI observations of Io: orbits G28-I33". Icarus. 169: 3–28. doi:10.1016/j.icarus.2003.10.014. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Roesler, F. L. (1999). "Far-Ultraviolet Imaging Spectroscopy of Io's Atmosphere with HST/STIS". Science. 283 (5400): 353–357. doi:10.1126/science.283.5400.353. {{cite journal}}: |format= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Geissler, P. E. (1999). "Galileo Imaging of Atmospheric Emissions from Io". Science. 285 (5429): 448–461. doi:10.1126/science.285.5429.870. {{cite journal}}: |format= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ Milazzo, M. P. (2001). "Observations and initial modeling of lava-SO₂ interactions at Prometheus, Io". J. Geophys. Res. 106: 33121–33128. doi:10.1029/2000JE001410. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)
^ ^a ^b McEwen, A. S. (1983). "Two classes of volcanic plume on Io". Icarus. 58: 197–226. doi:10.1016/0019-1035(83)90075-1. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

External links

[Morabito1979-1] Morabito, L. A. (1979). "Discovery of currently active extraterrestrial volcanism". Science. 204: 972. doi:10.1126/science.204.4396.972. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Lopes2004-2] Lopes, R. M. C. (2004). "Lava lakes on Io: Observations of Io's volcanic activity from Galileo NIMS during the 2001 fly-bys". Icarus. 169: 140–174. doi:10.1016/j.icarus.2003.11.013. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Peale1979-3] Peale, S. J. (1979). "Melting of Io by Tidal Dissipation". Science. 203: 892–894. doi:10.1126/science.203.4383.892. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[USGSweb-4] Watson, J. M. (May 5, 1999). "Some Unanswered Questions". United States Geological Survey. Retrieved 2008-10-11.

[Keszthelyi2007-5] Keszthelyi, L. (2007). "New estimates for Io eruption temperatures: Implications for the interior". Icarus. 192: 491–502. doi:10.1016/j.icarus.2007.07.008. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IobookChap7-6] Williams, D. A. (2007). "Active volcanism: Effusive eruptions". In Lopes, R. M. C. and Spencer, J. R. (eds.) (ed.). Io after Galileo. Springer-Praxis. pp. pp. 133–161. ISBN 3-540-34681-3. {{cite book}}: |editor= has generic name (help); |pages= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)

[Geissler2008-7] ^ ^a ^b ^c ^d ^e ^f ^g Geissler, P. E. (2008). "Galileo observations of volcanic plumes on Io". Icarus. 197: 505–518. doi:10.1016/j.icarus.2008.05.005. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Geissler2004-8] Geissler, P. (2004). "Surface changes on Io during the Galileo mission". Icarus. 169: 29–64. doi:10.1016/j.icarus.2003.09.024. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Fanale1974-9] Fanale, F. P. (1974). "Io: A Surface Evaporite Deposit?". Science. 186 (4167): pp. 922–925. doi:10.1126/science.186.4167.922. PMID 17730914. {{cite journal}}: |pages= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Morrison1973-10] Morrison, J (1973). "Thermal Properties of the Galilean satellites". Icarus. 18: 223–236. doi:10.1016/0019-1035(73)90207-8. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Hansen1973-11] Hansen, O. L. (1973). "Ten-micron eclipse observations of Io, Europa, and Ganymede". Icarus. 18: 237–246. doi:10.1016/0019-1035(73)90208-X.

[IobookChap2-12] Cruikshank, D. P. (2007). "A history of the exploration of Io". In Lopes, R. M. C. and Spencer, J. R. (eds.) (ed.). Io after Galileo. Springer-Praxis. pp. pp. 5–33. ISBN 3-540-34681-3. {{cite book}}: |editor= has generic name (help); |pages= has extra text (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)

[Witteborn1979-13] Witteborn, F. C. (1979). "Io: An Intense Brightening Near 5 Micrometers". Science. 203: 643–646. doi:10.1126/science.203.4381.643. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Smith1979-14] Smith, B. A. (1979). "The Jupiter system through the eyes of Voyager 1". Science. 204: 951–972. doi:10.1126/science.204.4396.951. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Strom1979-15] Strom, R. G. (1979). "Volcanic eruption plumes on Io". Nature. 280: 733–736. doi:10.1038/280733a0. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Hanel1979-16] Hanel, R. (1979). "Infrared Observations of the Jovian System from Voyager 1". Science. 204 (4396): 972–976. doi:10.1126/science.204.4396.972-a. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Smith1979b-17] Smith, B. A. (1979). "The Galilean Satellites and Jupiter: Voyager 2 Imaging Science Results". Science. 206 (4421): 927–950. doi:10.1126/science.206.4421.927. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IobookChap5-18] Moore, W. B. (2007). "The Interior of Io". In Lopes, R. M. C. and Spencer, J. R. (eds.) (ed.). Io after Galileo. Springer-Praxis. pp. 89–108. ISBN 3-540-34681-3. {{cite book}}: |editor= has generic name (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)CS1 maint: multiple names: editors list (link)

[IoVolcanismChap4-19] Davies, A. (2007). "Io and Earth: formation, evolution, and interior structure". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 53–72. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[Sagan1979-20] Sagan, C. (1979). "Sulphur flows on Io". Nature. 280: 750–753. doi:10.1038/280750a0.

[Clow1980-21] Clow, G. D. (1980). "Stability of sulfur slopes on Io". Icarus. 44: 268–279. doi:10.1016/0019-1035(80)90022-6. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Spencer1996-22] Spencer, J. R. (1996). "Io on the Eve of the Galileo Mission". Annu. Rev. Earth Planet. Sci. 24: 125–190. doi:10.1146/annurev.earth.24.1.125. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Johnson1988-23] Johnson, T. V. (1988). "Io: Evidence for Silicate Volcanism in 1986". Science. 242: 1280–1283. doi:10.1126/science.242.4883.1280. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Sinton1980-24] Sinton, W. M. (1980). "Io: Ground-Based Observations of Hot Spots". Science. 210: 1015–1017. doi:10.1126/science.210.4473.1015. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Carr1986-25] Carr, M. H. (1986). "Silicate volcanism on Io". J. Geophys. Res. 91: 3521–3532. doi:10.1029/JB091iB03p03521.

[GeisslerColor1999-26] Geissler, P. E. (1999). "Global Color Variations on Io". Icarus. 140: 265–282. doi:10.1006/icar.1999.6128. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Williams2000b-27] Williams, D. A. (2000). "A komatiite analog to potential ultramafic materials on Io". J. Geophys. Res. 105 (E1): 1671–1684. doi:10.1029/1999JE001157. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Spencer2000b-28] Spencer, J. (2000). "Discovery of Gaseous S₂ in Io's Pele Plume". Science. 288: 1208–1210. doi:10.1126/science.288.5469.1208. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Williams2004-29] Williams, D. A. (2004). "Mapping of the Culann–Tohil region of Io from Galileo imaging data". Icarus. 169: 80–97. doi:10.1016/j.icarus.2003.08.024. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Radebaugh2001-30] Radebaugh, D. (2001). "Paterae on Io: A new type of volcanic caldera?". J. Geophys. Res. 106: 33005–33020. doi:10.1029/2000JE001406. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Keszthelyi2004-31] Keszthelyi, L. (2004). "A Post-Galileo view of Io's Interior". Icarus. 169: 271–286. doi:10.1016/j.icarus.2004.01.005. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Perry2003-32] Perry, J. E. (2003). "Gish Bar Patera, Io: Geology and Volcanic Activity, 1997–2001" (PDF). LPSC XXXIV. Clear Lake, Texas. Abstract #1720. {{cite conference}}: Unknown parameter |booktitle= ignored (|book-title= suggested) (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Keszthelyi2001-33] Keszthelyi, L. (2001). "Imaging of volcanic activity on Jupiter's moon Io by Galileo during the Galileo Europa Mission and the Galileo Millennium Mission". J. Geophys. Res. 106: 33025–33052. doi:10.1029/2000JE001383. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IoVolcanismChap5-34] Davies, A. (2007). "Effusive activity: landforms and thermal emission evolution". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 142–152. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[Matson2006-35] Matson, D. L. (2006). "Io: Loki Patera as a magma sea". J. Geophys. Res. 111: E09002. doi:10.1029/2006JE002703. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Radebaugh2004-36] Radebaugh, J. (2004). "Observations and temperatures of Io's Pele Patera from Cassini and Galileo spacecraft images". Icarus. 169: 65–79. doi:10.1016/j.icarus.2003.10.019. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Howell2007-37] Howell, R. R. (2007). "The nature of the volcanic activity at Loki: Insights from Galileo NIMS and PPR data". Icarus. 186: 448–461. doi:10.1016/j.icarus.2006.09.022. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Rathbun2006-38] Rathbun, J. A. (2006). "Loki, Io: New ground-based observations and a model describing the change from periodic overturn". Geophys. Res. Lett. 33: L17201. doi:10.1029/2006GL026844. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IoVolcanismChap9-39] Davies, A. (2007). "The view from Galileo". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 155–177. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[McEwen2000-40] McEwen, A. S. (2000). "Galileo at Io: Results from High-Resolution Imaging". Science. 288 (5469): 1193–1198. doi:10.1126/science.288.5469.1193. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Mcewen1998a-41] McEwen, A. S. (1998). "Active Volcanism on Io as Seen by Galileo SSI". Iacrus. 135: 181–219. doi:10.1006/icar.1998.5972. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IoVolcanismChap12-42] Davies, A. (2007). "Prometheus and Amirani: effusive activity and insulated flows". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 208–216. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[IoVolcanismChap2-43] Davies, A. (2007). "Between Voyager and Galileo: 1979-1995". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 27–38. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[Marchis2002-44] Marchis, F. (2002). "High-Resolution Keck Adaptive Optics Imaging of Violet Volcanic Activity on Io". Icarus. 160: 124–131. doi:10.1006/icar.2002.6955. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help); Unknown parameter |laydate= ignored (help); Unknown parameter |laysource= ignored (help); Unknown parameter |laysummary= ignored (help)

[Wilson2001-45] Wilson, L. (2001). "Lava Fountains from the 1999 Tvashtar Catena fissure eruption on Io: Implications for dike emplacement mechanisms, eruptions rates, and crustal structure". J. Geophys. Res. 106: 32, 997–33, 004. doi:10.1029/2000JE001323. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[IoVolcanismChap11-46] Davies, A. (2007). "Pillan and Tvashtar Paterae: lava fountains and flows". Volcanism on Io: A Comparison with Earth. Cambridge University Press. pp. pp. 192 207. ISBN 0-521-85003-7. {{cite book}}: |pages= has extra text (help)

[Spencer2007-47] Spencer, J. R. (2007). "Io Volcanism Seen by New Horizons: A Major Eruption of the Tvashtar Volcano". Science. 318: 240–243. doi:10.1126/science.1147621. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Mcewen1998b-48] McEwen, A. S. (1998). "High-temperature silicate volcanism on Jupiter's moon Io". Science. 281: 87–90. doi:10.1126/science.281.5373.87. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Turtle2004-49] Turtle, E. P. (2004). "The final Galileo SSI observations of Io: orbits G28-I33". Icarus. 169: 3–28. doi:10.1016/j.icarus.2003.10.014. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Roesler1999-50] Roesler, F. L. (1999). "Far-Ultraviolet Imaging Spectroscopy of Io's Atmosphere with HST/STIS". Science. 283 (5400): 353–357. doi:10.1126/science.283.5400.353. {{cite journal}}: |format= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Geissler1999-51] Geissler, P. E. (1999). "Galileo Imaging of Atmospheric Emissions from Io". Science. 285 (5429): 448–461. doi:10.1126/science.285.5429.870. {{cite journal}}: |format= requires |url= (help); Unknown parameter |coauthors= ignored (|author= suggested) (help)

[Milazzo2001-52] Milazzo, M. P. (2001). "Observations and initial modeling of lava-SO₂ interactions at Prometheus, Io". J. Geophys. Res. 106: 33121–33128. doi:10.1029/2000JE001410. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

[McEwen1983-53] McEwen, A. S. (1983). "Two classes of volcanic plume on Io". Icarus. 58: 197–226. doi:10.1016/0019-1035(83)90075-1. {{cite journal}}: Unknown parameter |coauthors= ignored (|author= suggested) (help)

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@@ Line 1: / Line 1: @@
+:''This is a sub-article to [[Io (moon)]]''
-{{Taxobox
+[[Image:PIA01081-Color Mosaic and Active Volcanic Plumes on Io.jpg|thumb|Io, with two plumes erupting from its surface]]
-| name = Thresher shark
+'''Volcanism on Io''', a moon of [[Jupiter]], produces [[lava]] flows, [[volcano|volcanic]] pits, and plumes of [[sulfur]] and [[sulfur dioxide]] hundreds of kilometres high. This volcanic activity was discovered in 1979 by ''[[Voyager 1]]'' imaging scientists.<ref name="Morabito1979">{{cite journal |title=Discovery of currently active extraterrestrial volcanism |journal=Science |last=Morabito |first=L. A. |coauthors=''et al.'' |pages=972 |volume=204 |issue= |year=1979 |doi=10.1126/science.204.4396.972}}</ref> Observations of [[Io (moon)|Io]] by passing spacecraft, such as the [[Voyager program|Voyagers]], ''[[Galileo (spacecraft)|Galileo]]'', ''[[Cassini–Huygens|Cassini]]'', and ''[[New Horizons]]'', and Earth-based astronomers have revealed more than 150 active volcanoes, with up to 400 expected to exist based on these observations.<ref name="Lopes2004">{{cite journal |title=Lava lakes on Io: Observations of Io’s volcanic activity from Galileo NIMS during the 2001 fly-bys |journal=Icarus |last=Lopes |first=R. M. C. |coauthors=''et al.'' |pages=140&ndash;174 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2003.11.013}}</ref> Io's volcanism makes the satellite one of only four known volcanically active worlds in the Solar System (the other three being [[Earth]], [[Saturn|Saturn's]] moon [[Enceladus (moon)|Enceladus]], and [[Neptune|Neptune's]] moon [[Triton (moon)|Triton]]).
-| fossil_range = {{Fossil range|56|0}} Early [[Eocene]] to Present<ref>{{cite journal
-  | last = Sepkoski
-  | first = Jack
-  | authorlink =
-  | coauthors =
-  | title =  A compendium of fossil marine animal genera (Chondrichthyes entry)
-  | journal = Bulletins of American Paleontology
-  | volume = 364
-  | issue =
-  | pages = p.560
-  | publisher =
-  | location =
-  | date = 2002
-  | url = http://strata.ummp.lsa.umich.edu/jack/showgenera.php?taxon=575&rank=class
-  | doi =
-  | id =
-  | accessdate = 2008-01-09 }}</ref>
-| image = Pelagic thresher shark.jpg
-| image_width = 200px
-| image_caption = [[Pelagic thresher]], ''Alopias pelagicus''
-| status = VU
-| regnum = [[Animal]]ia
-| phylum = [[Chordate|Chordata]]
-| classis = [[Chondrichthyes]]
-| subclassis = [[Elasmobranchii]]
-| ordo = [[Lamniformes]]
-| familia = '''Alopiidae'''
-| familia_authority = [[Charles Lucien Jules Laurent Bonaparte|Bonaparte]], 1838
-| genus = '''''Alopias'''''
-| genus_authority = [[Constantine Samuel Rafinesque-Schmaltz|Rafinesque]], 1810
-| subdivision_ranks = Species
-| subdivision = For species see text.
-}}
-{{Sharksportal}}
-'''Thresher sharks''' are large [[lamniform]] [[shark]]s of the family '''Alopiidae'''. Found in all temperate and tropical [[ocean]]s of the world, the [[family (biology)|family]] contains three [[species]] all within the [[genus]] '''''Alopias'''''.
+First predicted shortly before the ''Voyager 1'' flyby, the heat source for Io's volcanism comes from [[tidal acceleration#Tidal heating|tidal heating]] produced by Io's forced [[orbital eccentricity]].<ref name="Peale1979">{{cite journal |title=Melting of Io by Tidal Dissipation |journal=Science |last=Peale |first=S. J. |coauthors=''et al.'' |pages=892&ndash;894 |volume=203 |issue= |year=1979 |doi=10.1126/science.203.4383.892}}</ref> This differs from the [[Geothermal (geology)|heat source]] for Earth's volcanism, which comes primarily from [[Radioactive decay|radioactive isotope decay]].<ref name="USGSweb">{{cite web |last=Watson |first=J. M. |date=May 5, 1999 |title=Some Unanswered Questions |publisher=United States Geological Survey |url=http://pubs.usgs.gov/gip/dynamic/unanswered.html|accessdate=2008-10-11}}</ref> Io's eccentric orbit leads to a slight difference in Jupiter's gravitational pull on Io between its closest and furthest points on its orbit, causing a varying tidal bulge. This variation in the shape of Io causes frictional heating in Io's interior. Without this tidal heating, Io may have been similar to the Earth's moon, a world of similar size and mass, geologically dead and covered with numerous impact craters.<ref name="Peale1979"/>
-== Naming ==
-The genus and family name derive from the [[Greek language|Greek]] word ''alopex'', meaning [[fox]]. Indeed the '''[[long-tailed thresher shark]]''', ''Alopias vulpinus'', is named the '''fox shark''' by some authorities.
+Io's volcanism has led to the formation of hundreds of volcanic centres and extensive lava formations, making the moon the most volcanically active world in the solar system. Three different types of volcanic eruptions have been identified, differing in duration, intensity, lava effusion rate, and whether the eruption occurs within a volcanic pit (known as a ''patera''). Lava flows on Io, tens or hundreds of kilometres long, are composed primarily of [[basalt]]ic silicate lavas, similar to lavas seen on Earth at shield volcanoes such as [[Kilauea]] in [[Hawaii]].<ref name="Keszthelyi2007">{{cite journal |title=New estimates for Io eruption temperatures: Implications for the interior |journal=Icarus |last=Keszthelyi |first=L. |coauthors=''et al.'' |pages=491&ndash;502 |volume=192 |issue= |year=2007 |doi=10.1016/j.icarus.2007.07.008}}</ref> While most lava flows on Io are consistent with basalt, flows consisting of [[sulfur]] and [[sulfur dioxide]] are also seen, as well as eruption temperatures that can be explained by high-temperature [[mafic|ultramafic]] silicate lavas.<ref name="IobookChap7">{{cite book |title=Io after Galileo |publisher=Springer-Praxis |chapter=Active volcanism: Effusive eruptions |last=Williams |first=D. A. |coauthors=Howell, R. R. |editor=Lopes, R. M. C. and Spencer, J. R. (eds.) |pages=pp. 133&ndash;161 |year=2007 |isbn=3-540-34681-3}}</ref>
-== Distribution and habitat ==
-Although occasionally sighted in shallow, inshore waters, thresher sharks are primarily [[Pelagic zone|pelagic]]; they prefer the open ocean, staying within the first 500 [[metre|m]] of the [[water column]]. Common threshers tend to be more common in coastal waters over [[continental shelf|continental shelves]].  In the North Pacific, common thresher sharks are found along the continental shelves of North America and Asia.  They are rare in the Central and Western Pacific.  In the warmer waters of the Central & Western Pacific, bigeye and pelagic thresher sharks are more common.
+As a result of the presence of significant quantities of sulfurous materials in Io's crust and on its surface, during some eruptions, sulfur, sulfur dioxide gas, and [[tephra|pyroclastic material]] are blown up to {{convert|500|km}} into space, producing large, umbrella-shaped volcanic plumes.<ref name="Geissler2008">{{cite journal |title=Galileo observations of volcanic plumes on Io |journal=Icarus |last=Geissler |first=P. E. |coauthors=M. T. McMillan |pages=505&ndash;518 |volume=197 |issue= |year=2008 |doi=10.1016/j.icarus.2008.05.005}}</ref> This material paints the surrounding terrain in red, black, and white, and provides for Io's patchy atmosphere and Jupiter's extensive magnetosphere. Spacecraft that have flown by Io since 1979 have observed numerous surface changes as a result of Io's volcanic activity.<ref name="Geissler2004">{{cite journal |title=Surface changes on Io during the Galileo mission |journal=Icarus |last=Geissler |first=P. |coauthors=''et al.'' |pages=29&ndash;64 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2003.09.024}}</ref>
-== Anatomy and appearance ==
-[[Image:Pacifica thresher shark.jpg|thumb|left|200 px|
-Small purple colored thresher caught at [[Pacifica Pier]], [[California]].]]
-Named for and easily recognised by their exceptionally long, [[thresher]]-like tail or ''[[caudal fin]]s'' (which account for 1/3 of their total body length), thresher sharks are active predators; the tail is actually used as a weapon to stun prey. By far the largest of the three species is the [[Common thresher]], ''Alopias vulpinus'', which may reach a length of 20 ft and a [[weight]] of over 500 [[kilogram|kg]]. The [[Bigeye thresher]], ''Alopias superciliosus'', is next in size, reaching a length of 4.9 m (16 ft); at just 3 m (10 ft), the [[Pelagic thresher]], ''Alopias pelagicus'', is the smallest.
+==Discovery==
-Thresher sharks are fairly slender, with small dorsal fins and large, recurved pectoral fins. With the exception of the Bigeye thresher, these sharks have relatively small eyes. Coloration ranges from brownish, bluish or  purplish gray dorsally with lighter shades ventrally.
+[[Image:Io Volcanism Discovery image.jpg|right|thumb|Discovery image of active volcanism on Io]]
-The three species can be roughly distinguished by the main color of the dorsal surface of the body.  Common threshers are dark green, Bigeye threshers are brown and Pelagic threshers are generally blue.  Lighting conditions and water clarity can affect how any one shark appears to an observer, but the color test is generally supported when other features are examined.
+Prior to the ''Voyager 1'' encounter with Io on March 5, 1979, Io was thought to be a dead world much like the Earth's [[Moon]]. The discovery of a cloud of sodium surrounding Io led to theories that the satellite would be covered in [[evaporite]]s.<ref name="Fanale1974">{{cite journal |title=Io: A Surface Evaporite Deposit? |journal=[[Science (journal)|Science]] |last=Fanale |first=F. P. |coauthors=''et al.'' |pages=pp. 922–925 |volume=186 |issue=4167 |year=1974 |doi=10.1126/science.186.4167.922 |pmid=17730914}}</ref>
+Hints of discoveries to come arose from Earth-based [[infrared]] observations taken in the 1970s. An anomalously high [[heat flux|thermal flux]], compared to the other [[Galilean moons|Galilean satellites]], was discovered during measurements taken at 10&nbsp;[[micrometre|μm]] while Io was in Jupiter's shadow.<ref name="Morrison1973">{{cite journal |title=Thermal Properties of the Galilean satellites |journal=Icarus |last=Morrison |first=J |coauthors=Cruikshank, D. P. |pages=223–236 |volume=18 |issue= |year=1973 |doi=10.1016/0019-1035(73)90207-8}}</ref> At the time, this heat flux was attributed to the surface having a much higher [[Volumetric heat capacity#Thermal inertia|thermal inertia]] than [[Europa (moon)|Europa]] and [[Ganymede (moon)|Ganymede]].<ref name="Hansen1973">{{cite journal |title=Ten-micron eclipse observations of Io, Europa, and Ganymede |journal=[[Icarus (journal)|Icarus]] |last=Hansen |first=O. L. |pages=237–246 |volume=18 |issue= |year=1973 |doi=10.1016/0019-1035(73)90208-X}}</ref> These results were considerably different from measurements taken at wavelengths of 20&nbsp;μm which suggested that Io had similar surface properties to the other Galilean satellites.<ref name="Morrison1973"/> It has since been determined that the greater flux at shorter wavelengths was due to the combined flux from Io's volcanoes and solar heating, while solar heating provides a much greater fraction of the flux at longer wavelengths.<ref name="IobookChap2">{{cite book |title=Io after Galileo |publisher=Springer-Praxis |chapter=A history of the exploration of Io |last=Cruikshank |first=D. P. |coauthors=Nelson, R. M. |editor=Lopes, R. M. C. and Spencer, J. R. (eds.) |pages=pp. 5&ndash;33 |year=2007 |isbn=3-540-34681-3}}</ref> A sharp increase in Io's thermal emission at 5&nbsp;μm was observed on February 20, 1978 by Witteborn, ''et al''. The group considered volcanic activity at the time, in which case the data was fit into a region on Io {{convert|8000|km2}} in size at {{convert|600|K}}. However, the authors considered that hypothesis unlikely, and instead focused on emission from Io's interaction with Jupiter's magnetosphere.<ref name="Witteborn1979">{{cite journal |title=Io: An Intense Brightening Near 5 Micrometers |journal=Science |last=Witteborn |first=F. C. |coauthors=''et al.'' |pages=643&ndash;646 |volume=203 |issue= |date=1979 |doi=10.1126/science.203.4381.643}}</ref>
-== Diet ==
-Pelagic schooling fish (such as bluefish, juvenile tuna, and mackerel), squid and cuttlefish are the primary food items of the thresher sharks. They are known to follow large schools of fish into shallow waters. Crustaceans and the odd seabird are also taken.
+Shortly before the ''Voyager 1'' encounter, Stan Peale, Patrick Cassen, and R. T. Reynolds published a paper in the journal ''[[Science (journal)|Science]]'' predicting a volcanically-modified surface and a [[Io (moon)#Interior|differentiated]] interior, with distinct rock types rather than a homogeneous blend. They based this prediction on models of Io's interior that took into account the massive amount of heat produced by the varying tidal pull of Jupiter on Io caused by the moon's slightly eccentric orbit. Their calculations suggested that the amount of heat generated for an Io with a homogeneous interior would be three times greater than the amount of heat generated by [[radioactive decay|radioactive isotope decay]] alone. This effect would be even greater with a differentiated Io.<ref name="Peale1979"/>
-== Behavior ==
-Thresher sharks are solitary creatures which keep to themselves. It is known that thresher populations of the [[Indian Ocean]] are separated by depth and space according to gender. All species are noted for their highly migratory or [[oceanodromous]] habits.
+[[Image:Loki Patera Color Voyager.jpg|left|thumb|''Voyager 1'' observation of Loki Patera and nearby lava flows and volcanic pits]]
-Thresher sharks are one of the few shark species known to jump fully out of the water making turns like [[dolphin]]s, this behaviour is called [[Whale surfacing behaviour|breaching]].
+''Voyager 1''<nowiki>'s</nowiki> first images of Io revealed a lack of [[Impact crater|impact craters]], suggesting a very young surface. Craters are used by geologists to estimate the age of a [[Geology of solar terrestrial planets|planetary surface]]; the more impact structures a planetary surface has, the older it is. Instead of impact structures, ''Voyager 1'' observed a multi-coloured surface, pockmarked with irregular-shaped depressions, which lacked the raised rims characteristic of impact craters. Also seen were flow features formed by low-viscosity fluid and tall, isolated mountains that did not resemble terrestrial volcanoes. The surface observed suggested that, just as Peale, ''et al.'', had theorized, Io was heavily modified by volcanism.<ref name="Smith1979">{{cite journal |title=The Jupiter system through the eyes of Voyager 1 |journal=Science |last=Smith |first=B. A. |coauthors=''et al.'' |pages=951&ndash;972 |volume=204 |issue= |year=1979 |doi=10.1126/science.204.4396.951}}</ref>
+On March 8, 1979, three days after passing Jupiter, ''Voyager 1'' took images of Jupiter's moons to help mission controllers determine the spacecraft's exact location, a process called optical navigation. While processing images of Io to enhance the visibility of background stars, navigation engineer [[Linda A. Morabito|Linda Morabito]] found a {{convert|300|km|adj=on}} tall cloud along the [[limb]] of Io.<ref name="Morabito1979"/> At first, she suspected the cloud to be a moon behind Io, but no suitably sized body would have been in that location. The feature was determined to be a plume generated by active volcanism at a dark depression later named [[Pele (volcano)|Pele]].<ref name="Strom1979">{{cite journal |title=Volcanic eruption plumes on Io |journal=[[Nature (journal)|Nature]] |last=Strom |first=R. G. |coauthors=''et al.'' |pages=733&ndash;736 |volume=280 |issue= |year=1979 |doi=10.1038/280733a0}}</ref> Following this discovery, seven other plumes were located in earlier ''Voyager'' images of Io.<ref name="Strom1979"/> Thermal emission from multiple sources, indicative of cooling lava, were also found.<ref name="Hanel1979">{{cite journal |title=Infrared Observations of the Jovian System from Voyager 1 |journal=Science |last=Hanel |first=R. |coauthors=''et al.'' |pages=972&ndash;976 |volume=204 |issue=4396 |year=1979 |doi=10.1126/science.204.4396.972-a}}</ref> Surface changes were observed when images acquired by ''[[Voyager 2]]'' were compared to those taken four months prior by ''Voyager 1'', including new plume deposits at [[Aten Patera]] and [[Surt (volcano)|Surt]].<ref name="Smith1979b">{{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&ndash;950 |volume=206 |issue=4421 |year=1979 |doi=10.1126/science.206.4421.927}}</ref>
-== Reproduction ==
-No distinct breeding season is observed by thresher sharks. Fertilization and embryonic development occur internally; this [[Ovoviviparity|ovoviviparous]] or live-bearing mode of reproduction results in a small litter (usually 2 to 4) of large well-developed pups, up to 150 cm at birth in thintail threshers. The young fish exhaust their yolk sacs while still inside the mother, at which time they begin feeding on the mother's unfertilized eggs; this is known as [[oophagy]].
+==Heat source==
-Thresher sharks are slow to mature, males reaching sexual maturity between 7 and 13 years of age and females between 8 and 14 years in bigeye threshers. They may live for 20 years or more.
+Unlike the Earth and the [[Internal structure of the Moon|Moon]], Io's main source of internal heat comes from the [[Tidal acceleration|dissipation]] of [[tidal force]]s generated by Jupiter's gravitational pull<ref name="Peale1979"/> This external heating differs from the [[Geothermal (geology)|internal heat source]] for volcanism on Earth, the result of [[decompression]] in upwelling [[Mantle (geology)|mantle]] [[convection]] currents, radioactive [[isotope]] decay, and residual heat from [[Accretion (astrophysics)|accretion]].<ref name="USGSweb"/> Such heating is dependent on Io's distance from Jupiter, its [[orbital eccentricity]], the composition of its interior, and its physical state.<ref name="IobookChap5">{{cite book |title=Io after Galileo |publisher=Springer-Praxis |chapter=The Interior of Io |last=Moore |first=W. B. |coauthors=''et al.'' |editor=Lopes, R. M. C. and Spencer, J. R. (eds.) |pages=89&ndash;108 |year=2007 |isbn=3-540-34681-3}}</ref> Its [[orbital resonance|Laplace-resonant orbit]] with Europa and Ganymede maintains Io's eccentricity and prevents tidal dissipation within Io from circularizing its orbit. The eccentricity leads to vertical differences in Io's tidal bulge of as much as {{convert|100|m|ft|-1}} as Jupiter's gravitational pull varies between the [[apsis|periapsis and apoapsis]] points in Io's orbit. This varying tidal pull also produces friction in Io's interior, enough to cause significant tidal heating and melting. Unlike Earth, where most of its internal heat is released by conduction through the crust, on Io internal heat is released in the form of volcanic activity and generates the satellite's high [[heat transfer|heat flow]] (global total: 0.6&ndash;1.6{{esp|14}}&nbsp;[[watt|W]]). Models of its orbit suggest that the amount of tidal heating within Io changes with time, and that the current heat flow is not representative of the long-term average.<ref name="IobookChap5"/> The amount of heat released from Io's interior is greater than current estimates for the amount presently generated from tidal heating, suggesting that Io is cooling off from a period of greater tidal heating.<ref name="IoVolcanismChap4">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 53&ndash;72 |chapter=Io and Earth: formation, evolution, and interior structure }}</ref>
-== Conservation ==
+==Composition==
+[[Image:Ra Patera Voyager.jpg|right|thumb|''Voyager 1'' image of volcanic pits and lava flows near Ra Patera]]
-All three thresher shark species have been recently listed as [[vulnerable species|vulnerable to extinction]] by the [[World Conservation Union]] (IUCN).<ref>{{cite press release |title=More oceanic sharks added to the IUCN Red List |publisher=[[IUCN]] |date=2007-02-22 |url=http://www.iucn.org/en/news/archive/2007/02/22_pr_sharks.htm |format= |language= |accessdate=2007-02-25 |quote= }}</ref>
+Analysis of ''Voyager'' images led scientists to believe that the lava flows on Io were composed mostly of various compounds of molten sulfur.<ref name="Sagan1979">{{cite journal |title=Sulphur flows on Io |journal=Nature |last=Sagan |first=C. |pages=750&ndash;753 |volume=280 |issue= |year=1979 |doi=10.1038/280750a0}}</ref> The colouration of the flows was found to be similar to various [[allotropy|allotropes]] of sulfur. Differences in the lava colour and brightness are a function of the temperature of polyatomic sulfur and the packing and bonding of sulfur atoms. An analysis of the lava flows that radiate out from [[List of paterae on Io|Ra Patera]] revealed dark [[albedo]] material (associated with liquid sulfur at {{convert|525|K}}) close to the vent, red material (associated with liquid sulfur at {{convert|450|K}}) in the central part of each flow, and orange material (associated with liquid sulfur at {{convert|425|K}}) at the furthest ends of each flow.<ref name="Sagan1979"/> This colour pattern corresponds to flows radiating out from a central vent, cooling as the lava travels away from the vent. In addition, temperature measurements of thermal emission at [[Loki Patera]] taken by ''Voyager 1''<nowiki>'s</nowiki> Infrared Interferometer Spectrometer and Radiometer (IRIS) instrument were consistent with sulfur volcanism.<ref name="Hanel1979"/> However, the IRIS instrument was not capable of detecting wavelengths that are indicative of higher temperature components. This meant that temperatures consistent with silicate volcanism were not discovered by ''Voyager''. Despite this, it was determined that [[silicate]]s must play a role in Io's youthful appearance as suggested by the moon's high density and the need for silicates to support the steep slopes along patera walls.<ref name="Clow1980">{{cite journal |title=Stability of sulfur slopes on Io |journal=Icarus |last=Clow |first=G. D. |coauthors=Carr, M. H. |pages=268&ndash;279 |volume=44 |issue= |year=1980 |doi=10.1016/0019-1035(80)90022-6 }}</ref> The contradiction between the structural evidence and the spectral and temperature data following the Voyager flybys led to a debate in the planetary science community regarding the composition of Io's lava flows, whether they were composed of silicate or sulfurous materials.<ref name="Spencer1996">{{cite journal |title=Io on the Eve of the Galileo Mission |journal=Annu. Rev. Earth Planet. Sci.|last=Spencer |first=J. R. |coauthors=Schneider, N. M. |pages=125&ndash;190 |volume=24 |year=1996 |doi=10.1146/annurev.earth.24.1.125}}</ref>
+Earth-based infrared studies in the 1980s and 1990s shifted the paradigm from one of primarily sulfur volcanism to one where silicate volcanism dominates, and sulfur acts in a secondary role.<ref name="Spencer1996"/> In 1986, measurements of a bright eruption on Io's leading hemisphere revealed temperatures of at least {{convert|900|K}}. This is higher than the boiling point of sulfur ({{convert|715|K|disp=s}}), indicating a silicate composition for at least some of Io's lava flows.<ref name="Johnson1988">{{cite journal |title=Io: Evidence for Silicate Volcanism in 1986 |journal=Science |last=Johnson |first=T. V. |coauthors=''et al.'' |pages=1280&ndash;1283 |volume=242 |issue= |year=1988 |doi=10.1126/science.242.4883.1280}}</ref> Similar temperatures were also observed at the Surt eruption in 1979 between the two ''Voyager'' encounters, and at the eruption observed by Witteborn, ''et al.'', in 1978.<ref name="Witteborn1979"/><ref name="Sinton1980">{{cite journal |title=Io: Ground-Based Observations of Hot Spots |journal=Science |last=Sinton |first=W. M. |coauthors=''et al.'' |pages=1015&ndash;1017 |volume=210 |issue= |year=1980 |doi=10.1126/science.210.4473.1015}}</ref> In addition, modeling of silicate lava flows on Io suggested that they cooled rapidly, causing their thermal emission to be dominated by lower temperature components, such as solidified flows, as opposed to the small areas covered by still molten lava near the actual eruption temperature.<ref name="Carr1986">{{cite journal |title=Silicate volcanism on Io |journal=[[Journal of Geophysical Research|J. Geophys. Res.]] |last=Carr |first=M. H. |pages=3521&ndash;3532 |volume=91 |issue= |year=1986 |doi=10.1029/JB091iB03p03521}}</ref>
-{{sport fish topics}}
-== Importance to humans ==
-Like all large sharks, threshers are slow growing and are therefore threatened by commercial [[fishery|fisheries]]. Other than for its meat, the sharks are hunted for their [[Shark liver oil|liver oil]], skin (for leather), and their fins, for use in [[shark-fin soup]].
+[[Image:NIMS Io map.jpg|left|thumb|Thermal emission map of Io by ''Galileo'']]
-They do not appear to be a threat to humans, although some divers have been hit with the upper tail lobe. There is an unconfirmed account of a fisherman being decapitated by a tail swipe as the shark breached. <ref name=dawkins>Dawkins, Richard. The Ancestor's Tale. Houghton Mifflin, New York: 2004.></ref>
+Silicate volcanism, involving basaltic lava with mafic to ultramafic (magnesium-rich) compositions, was confirmed by the ''[[Galileo (spacecraft)|Galileo]]'' spacecraft in the 1990s and 2000s from temperature measurements of Io's numerous hot spots, locations where thermal emission is detected, and from spectral measurements of Io's dark material. Temperature measurements from ''Galileo''<nowiki>'s</nowiki> Solid-State Imager (SSI) and Near-Infrared Mapping Spectrometer (NIMS) revealed numerous hot spots with high-temperature components ranging from at least {{convert|1200|K}} to a maximum of {{convert|1600|K}}, like at the [[Pillan Patera]] eruption in 1997.<ref name="Keszthelyi2007"/> Spectral observations of Io's dark material suggested the presence of [[pyroxene|orthopyroxenes]], such as [[enstatite]], magnesium-rich silicate minerals common in mafic and ultramafic basalt. This dark material is seen in volcanic pits, fresh lava flows, and [[pyroclastic rock|pyroclastic]] deposits surrounding recent, explosive volcanic eruptions.<ref name="GeisslerColor1999">{{cite journal |title=Global Color Variations on Io |journal=Icarus |last=Geissler |first=P. E. |coauthors=''et al.'' |pages=265&ndash;282 |volume=140 |year=1999 |doi=10.1006/icar.1999.6128}}</ref> Based on the measured temperature of the lava and the spectral measurements, some of the lava may be analogous to terrestrial [[komatiite]]s.<ref name="Williams2000b">{{cite journal |title=A komatiite analog to potential ultramafic materials on Io |journal=J. Geophys. Res. |last=Williams |first=D. A. |coauthors=''et al.'' |pages=1671&ndash;1684 |volume=105 |issue=E1 |year=2000 |doi=10.1029/1999JE001157}}</ref> Compressional superheating, which could increase the temperature of magma during ascent to the surface during an eruption, may also be a factor in some of the higher temperature eruptions.<ref name="Keszthelyi2007"/>
-Thresher sharks are classified as prized gamefish in the United States and South Africa.  Common thresher sharks are the target of a popular recreational fishery off Baja Mexico.  Thresher sharks are managed in some areas for their value as both a recreational sport fish and commercial species.
+While temperature measurements of Io's volcanoes settled the sulfur-versus-silicates debate that persisted between the ''Voyager'' and ''Galileo'' missions at Jupiter, sulfur and sulfur dioxide still play a significant role in the phenomena observed on Io. Both sulfur and sulfur dioxide have been detected in the plumes generated at Io's volcanoes, with sulfur being a primary constituent of Pele-type plumes.<ref name="Spencer2000b">{{cite journal |title=Discovery of Gaseous S<sub>2</sub> in Io's Pele Plume |journal=Science |last=Spencer |first=J. |coauthors=''et al.'' |pages=1208&ndash;1210 |volume=288 |issue= |year=2000 |doi=10.1126/science.288.5469.1208}}</ref> Bright flows have been identified on Io, at Tsũi Goab Fluctus, Emakong Patera, and Balder Patera for example, that are suggestive of effusive sulfur or sulfur dioxide volcanism.<ref name="Williams2004">{{cite journal |title=Mapping of the Culann–Tohil region of Io from Galileo imaging data |journal=Icarus |last=Williams |first=D. A. |coauthors=''et al.'' |pages=80&ndash;97 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2003.08.024}}</ref>
-== Evolution ==
-The Thresher Shark has traditionally been said to be closely related to other sharks such as the great white and the mackerel from the Lamnidae family. However recent research has identified them as having a closer ancestral connection with the ragged tooth sharks (odontaspididae), the megamouth (Megachasmidae), and the crocodile sharks (pseudocarchariidae) then with the Lamnidae sharks. Due to the similarity between the second dorsal fin, tail and anal fin of the thresher and megamouth sharks these species have been said to be very closely related and have not diverged much from their common ancestor.
-==Homologous features==
-Two species of the thresher have been identified as having a modified circulatory system that acts as a counter-current heat exchanger, which allows them to retain metabolic heat. The mackerel sharks (Lamnidae family) have a similar homologous structure to this which is more extensively developed. This structure is a strip of red muscle along each of its flanks, which has a tight network of blood vessels that transfer metabolic heat inward towards the core of the shark allowing it to maintain and regulate its body heat.
-==Analogous features==
-Thresher sharks like many sharks are always believed to look a lot like dolphins. Their stream line bodies and their fins look and act in similar ways, showing convergent evolution. This is due to them both being exposed to the same conditions, and over time due to natural selection, these features becoming prominent in both these species.
-== Species ==
+==Eruptions Styles==
+Observations of volcanic eruptions on Io by spacecraft and Earth-based astronomers has led to the identification of differences in the types of eruptions seen on the satellite. The three main types identified include ''intra-patera'', ''flow-dominated'', and ''explosion-dominated'' eruptions. These eruptions differ in terms of duration, energy released, brightness temperature (determined from infrared imaging), type of lava flow, and whether it is confined within volcanic pits.<ref name="IobookChap7"/>
-* Genus [[Alopias]]
-** [[Pelagic thresher]], ''[[Alopias pelagicus]]
-** [[Bigeye thresher]], ''[[Alopias superciliosus]]
-** [[Common thresher]], ''[[Alopias vulpinus]]
+===Intra-Patera eruptions===
-==References==
+{{See also|List of paterae on Io}}
-* {{ITIS|ID=159915|taxon=Alopias |year=2006|date=4 May}}
+[[Image:Io Tupan Patera.jpg|right|thumb|Tupan Patera, an example of a volcanic depression]]
-{{Reflist}}
+''Intra-patera'' eruptions occur within volcanic [[Depression (geology)|depressions]] known as ''paterae''.<ref name="Radebaugh2001">{{cite journal |title=Paterae on Io: A new type of volcanic caldera? |journal=J. Geophys. Res. |last=Radebaugh |first=D. |coauthors=''et al.'' |pages=33005&ndash;33020 |volume=106 |issue= |year=2001 |doi=10.1029/2000JE001406}}</ref> These volcanic centers generally have flat floors bounded by steep walls. They resemble terrestrial [[caldera]]s, but it is unknown whether they form when an empty lava chamber collapses, like their terrestrial cousins. One hypothesis suggests that these features are produced through the exhumation of volcanic [[Sill (geology)|sills]], with the overlying material either being blasted out or integrated into the sill.<ref name="Keszthelyi2004">{{cite journal |title=A Post-Galileo view of Io's Interior |journal=Icarus |last=Keszthelyi |first=L. |coauthors=''et al.'' |pages=271&ndash;286 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2004.01.005}}</ref> Some paterae display evidence for multiple collapses, similar to the calderas atop [[Olympus Mons]] on [[Mars]] or [[Kilauea]] on Earth, suggesting that paterae may occasionally form like volcanic calderas.<ref name="Radebaugh2001"/> Because the formation mechanism is still uncertain, the general term for these features uses the Latin descriptor term used by the International Astronomical Union in naming them, ''paterae''. Unlike similar features on Earth and Mars, these depressions generally do not lie at the peak of shield volcanoes and are larger, with an average diameter of {{convert|41|km}} and depth of {{convert|1.5|km|1}}.<ref name="Radebaugh2001"/> The largest volcanic depression on Io is [[Loki Patera]] at {{convert|202|km}}. Whatever the formation mechanism, the morphology and distribution of many paterae suggest that these features are structurally controlled, with at least half bounded by faults or mountains.<ref name="Radebaugh2001"/>
+[[Image:Pele Io I32.jpg|left|thumb|Infrared image showing nighttime thermal emission from the lava lake Pele]]
-==See also==
+This eruption style can take the form of either lava flows, spreading across the floor of the paterae, or [[lava lake]]s.<ref name="Perry2003">{{cite conference |title=Gish Bar Patera, Io: Geology and Volcanic Activity, 1997&ndash;2001 |booktitle=[[Lunar and Planetary Science Conference|LPSC XXXIV]] |location=[[Clear Lake, Texas]] |last=Perry |first=J. E. |coauthors=''et al.'' |date=2003 |id=Abstract #1720 |url=http://www.lpi.usra.edu/meetings/lpsc2003/pdf/1720.pdf}}</ref><ref name="Lopes2004"/> Except for observations by Galileo during its seven close flybys, it can be difficult to tell the difference between a lava lake and a lava flow eruption on a patera floor, due to the lower resolution and similar thermal emission characteristics. Lava flow eruptions on patera floors can be just as voluminous as those seen spreading out across the Ionian plains, such as the [[Gish Bar Patera]] eruption in 2001.<ref name="Perry2003"/> Flow-like features have also been observed at a number of paterae, like [[Camaxtli Patera]], suggesting that lava flows are an important resurfacing mechanism on the floors of these depressions.<ref name="Keszthelyi2001">{{cite journal |title=Imaging of volcanic activity on Jupiter's moon Io by Galileo during the Galileo Europa Mission and the Galileo Millennium Mission |journal=J. Geophys. Res. |last=Keszthelyi |first=L. |coauthors=''et al.'' |pages=33025&ndash;33052 |volume=106 |issue= |year=2001 |doi=10.1029/2000JE001383}}</ref>
-* [[List of sharks]]
-* [[List of fish common names]]
-* [[List of fish families]]
-* [[Thresher]] for other meanings of the word
+Ionian lava lakes are depressions partially filled with molten lava covered by a thin crust of cooled, solidified lava. These lava lakes are directly connected to a magma reservoir lying below the lava lake.<ref name="IoVolcanismChap5">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 142&ndash;152 |chapter=Effusive activity: landforms and thermal emission evolution }}</ref> Observations of thermal emission at several Ionian lava lakes reveal glowing lava along the patera margin. These lava lakes are often crusted over by cooled lava, with that 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 flounder, triggering an increase in thermal emission at the volcano.<ref name="Matson2006">{{cite journal |title=Io: Loki Patera as a magma sea |journal=J. Geophys. Res. |last=Matson |first=D. L. |coauthors=''et al.'' |pages=E09002 |volume=111 |issue= |date=2006 |doi=10.1029/2006JE002703}}</ref> For some lava lakes, like the one at Pele, this occurs continuously, making Pele one of the brightest emitters of heat in the near-infrared spectrum on Io.<ref name="Radebaugh2004">{{cite journal |title=Observations and temperatures of Io's Pele Patera from Cassini and Galileo spacecraft images |journal=Icarus |last=Radebaugh |first=J. |coauthors=''et al.'' |pages=65&ndash;79 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2003.10.019}}</ref> At other sites, such as at Loki Patera, this can occur episodically. During an overturning episode, Loki can emit up to ten times as much heat than when it is calmer.<ref name="Howell2007">{{cite journal |title=The nature of the volcanic activity at Loki: Insights from Galileo NIMS and PPR data |journal=Icarus |last=Howell |first=R. R. |coauthors=Lopes, R. M. C. |pages=448&ndash;461 |volume=186 |issue= |year=2007 |doi=10.1016/j.icarus.2006.09.022}}</ref> During an eruption at these more quiescent lava lakes, a wave of floundering lava crust spreads out across the patera at the rate of {{convert|1|km|1}} per day, until the entire lava lake crust 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.<ref name="Rathbun2006">{{cite journal |title=Loki, Io: New ground-based observations and a model describing the change from periodic overturn |journal=Geophys. Res. Lett. |last=Rathbun |first=J. A. |coauthors=J. R. Spencer |pages=L17201 |volume=33 |issue= |year=2006 |doi=10.1029/2006GL026844}}</ref>
-==External links==
-* [http://filaman.uni-kiel.de/Summary/FamilySummary.cfm?ID=486 FishBase entry on Alopiidae]
-* [http://marinebio.org/species.asp?id=284 MarineBio: Thresher shark, Alopias vulpinus]
-* [http://news.bbc.co.uk/2/hi/uk_news/england/cornwall/7106976.stm A Monster 16ft Shark ]
+===Flow-dominated eruptions===
-[[Category:Alopiidae| ]]
+[[Image:Io Culann Patera.jpg|right|thumb|Culann Patera, an example of a flow-dominated eruption]]
-[[Category:Lamniformes]]
+''Flow-dominated'' eruptions are long-lived eruption events that build-up extensive, compound lava flows. The extent of these lava flows makes them a major terrain type on Io. In this style of eruption, magma erupts onto the surface from vents on the floor of paterae or from [[Fissure vent|fissures]] on the plains, producing inflated, compound lava flows similar to those seen at [[Kīlauea]] in [[Hawaii]].<ref name="Keszthelyi2001"/> Images from the ''Galileo'' spacecraft revealed that many of Io's major lava flows, like those at [[Prometheus (volcano)|Prometheus]] and [[Amirani (volcano)|Amirani]], are produced by the build-up of small breakouts of lava on top of older flows.<ref name="Keszthelyi2001"/> Flow-dominated eruptions differ from explosion-dominated eruptions by their longevity and their lower energy output per unit of time.<ref name="IobookChap7"/> Lava erupts in this style at a generally steady rate, and flow-dominated eruptions can last for years or decades.
-[[Category:Ovoviviparous fish]]
-[[Category:Commercial fish]]
+Active flow fields more than {{convert|300|km}} long have been observed on Io at Amirani and Masubi. A relatively inactive flow field named [[Lei-Kung Fluctus]] covers more than {{convert|125000|km2}}, an area slightly larger than [[Nicaragua]].<ref name="IoVolcanismChap9">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 155&ndash;177 |chapter=The view from ''Galileo'' }}</ref> The thickness of these flow fields was not determined by Galileo, but the individual breakouts on the surface of these fields are likely {{convert|1|m}} thick. In many cases, active lava breakouts flow out onto the surface tens to hundreds of kilometres from the lava source vent, with low amounts of thermal emission observed between the breakout and the vent. This suggests that lava flows through [[lava tube]]s between the source vent and the breakout.<ref name="McEwen2000">{{cite journal |title=Galileo at Io: Results from High-Resolution Imaging |journal=Science |last=McEwen |first=A. S. |coauthors=''et al.'' |pages=1193&ndash;1198 |volume=288 |issue=5469 |year=2000 |doi=10.1126/science.288.5469.1193}}</ref>
-[[Category:Sport fish]]
+While these eruptions generally have a steady eruption rate, larger outbreaks of lava have also been observed at many flow-dominated eruption sites. For example, the leading edge of the Prometheus flow field moved {{convert|75|to|95|km}} between ''Voyager'' in 1979 and the first ''Galileo'' observations in 1996.<ref name="Mcewen1998a">{{cite journal |title=Active Volcanism on Io as Seen by Galileo SSI |journal=Iacrus |last=McEwen |first=A. S. |coauthors=''et al.'' |pages=181&ndash;219 |volume=135 |issue= |year=1998 |doi=10.1006/icar.1998.5972}}</ref> While generally dwarfed by explosion-dominated eruptions on Io, average flow rate at these compound lava flow fields is much greater than what is observed at similar, contemporary lava flows on Earth. Average surface coverage rates of {{convert|35|-|60|m2}} per second were observed at Prometheus and Amirani during the ''Galileo'' mission, compared to {{convert|0.6|m2}} per second at Kilauea.<ref name="IoVolcanismChap12">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 208&ndash;216 |chapter=Prometheus and Amirani: effusive activity and insulated flows }}</ref>
+===Explosion-dominated eruptions===
+[[Image:Io Tvashtar I25.jpg|right|thumb|''Galileo'' images of active lava flows and fountains at [[Tvashtar Paterae]] in 1999]]
+''Explosion-dominated'' eruptions are the most pronounced of Io's eruption styles. These eruptions, sometimes called "outburst" eruptions from their Earth-based detections, are characterized by their short duration (lasting only weeks or months), rapid onset, large volumetric flow rates, and high thermal emission.<ref name="IoVolcanismChap2">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 27&ndash;38 |chapter=Between ''Voyager'' and ''Galileo'': 1979-1995 }}</ref> These eruptions lead to a short-lived, significant increase in Io's overall brightness in the near-infrared. The most powerful volcanic eruption observed in historical times was an "outburst" eruption at [[Surt (volcano)|Surt]], observed by Earth-based astronomers on February 22, 2001.<ref name="Marchis2002">{{cite journal |title=High-Resolution Keck Adaptive Optics Imaging of Violet Volcanic Activity on Io |journal=Icarus |last=Marchis |first=F. |coauthors=''et al.'' |pages=124&ndash;131 |volume=160 |issue= |year=2002 |doi=10.1006/icar.2002.6955 |laysummary=http://www.keckobservatory.org/article.php?id=54 |laysource=Keck Observatory Press Release |laydate=2002-11-13}}</ref>
+Explosion-dominated eruptions occur when a body of magma (called a ''[[Dike (geology)|dike]]''), from deep within Io's partially molten [[Mantle (geology)|mantle]], reaches the surface at a [[Fissure vent|fissure]]. This results in a spectacular display of [[Lava fountain|lava fountains]].<ref name="Wilson2001">{{cite journal |title=Lava Fountains from the 1999 Tvashtar Catena fissure eruption on Io: Implications for dike emplacement mechanisms, eruptions rates, and crustal structure |journal=J. Geophys. Res. |last=Wilson |first=L. |coauthors=Head, J. W. |pages=32,997&ndash;33,004 |volume=106 |issue= |year=2001 |doi=10.1029/2000JE001323}}</ref> During the beginning of the eruption, the thermal emission from an outburst eruption is dominated by high, 1-3&nbsp;[[micrometre|μm]] infrared radiation. This thermal emission is produced by a large amount of exposed, fresh lava within the fountains at the eruption source vent.<ref name="IoVolcanismChap11">{{cite book |last=Davies |first=A. |title=Volcanism on Io: A Comparison with Earth |year=2007 |publisher=Cambridge University Press |isbn=0-521-85003-7 |pages=pp. 192&nbsp;207 |chapter=Pillan and Tvashtar Paterae: lava fountains and flows }}</ref> Outburst eruptions at Tvashtar in November 1999 and February 2007 centered around a {{convert|25|km|adj=on}} long, {{convert|1|km|adj=on}} tall lava "curtain" produced at a small patera nested within the larger Tvashtar Paterae complex.<ref name="Wilson2001"/><ref name="Spencer2007">{{cite journal |title=Io Volcanism Seen by New Horizons: A Major Eruption of the Tvashtar Volcano |journal=Science |last=Spencer |first=J. R. |coauthors=''et al.'' |pages=240&ndash;243 |volume=318 |issue= |year=2007 |doi=10.1126/science.1147621}}</ref>
+The large amount of exposed molten lava at these lava fountains have provided researchers their best opportunity to measure the actual eruption temperatures of Ionian lavas. These temperatures (about {{convert|1600|K|disp=/}}), suggestive of an ultramafic lava composition and similar to [[Pre-Cambrian]] [[Komatiite|komatiites]], are dominant at such eruptions, though superheating of the magma during ascent to the surface cannot be ruled as a factor in the high eruption temperatures.<ref name="Keszthelyi2007"/>
+[[Image:Io Pillan Patera comparison.jpg|left|thumb|Two ''Galileo'' images showing the effects of an explosion-dominated eruption at [[Pillan Patera]] in 1997]]
+While the more explosive, lava-fountaining stage may last only a few days to a week, explosion-dominated eruptions can continue for weeks to months, producing large, voluminous silicate lava flows. A major eruption in 1997 from a [[fissure]] north-west of [[Pillan Patera]] produced more than {{convert|31|km3}} of fresh lava over a two and a half to five and a half month period, and later flooded the floor of Pillan Patera.<ref name="Mcewen1998b">{{cite journal |title=High-temperature silicate volcanism on Jupiter's moon Io |journal=Science |last=McEwen |first=A. S. |coauthors=''et al.'' |pages=87&ndash;90 |volume=281 |issue= |year=1998 |doi=10.1126/science.281.5373.87}}</ref> Observations by ''Galileo'' suggest lava coverage rates at Pillan between {{convert|1000|and|3000|m2}} per second during the 1997 eruption. The Pillan lava flow was found to be {{convert|10|m}} thick, compared to the 1&ndash;metre-thick flows observed at the inflated flow fields at Prometheus and Amirani. Similar, rapidly emplaced lava flows were also observed by ''Galileo'' at Thor in 2001.<ref name="Lopes2004"/> Such flow rates are similar to those seen at [[Iceland]]'s [[Laki#1783 eruption|Laki eruption]] in 1783 and in terrestrial flood basalt eruptions.<ref name="IobookChap7"/>
+Explosion-dominated eruptions can produce dramatic (but often short-lived) surface changes around the eruption site, such as large pyroclastic and plume deposits produced as gas [[Exsolution|exsolves]] from lava fountains at these eruptions.<ref name="IoVolcanismChap11"/> The 1997 Pillan eruption produced a {{convert|400|km|adj=on}} wide deposit of dark, silicate material and bright sulfur dioxide.<ref name="Mcewen1998b"/> The Tvashtar eruptions of 2000 and 2007 generated a {{convert|330|km|adj=on}} tall plume, which deposited a ring of red sulfur and sulfur dioxide {{convert|1200|km}} wide.<ref name="Turtle2004">{{cite journal |title=The final Galileo SSI observations of Io: orbits G28-I33 |journal=Icarus |last=Turtle |first=E. P. |coauthors=''et al.'' |pages=3&ndash;28 |volume=169 |issue= |year=2004 |doi=10.1016/j.icarus.2003.10.014}}</ref> Despite their dramatic appearance, without continuous resupply of material, these changes often revert back to their pre-eruption appearance in months (in the case of [[Grian Patera]]) or years (as at Pillan Patera).<ref name="Geissler2004"/>
+==Plumes==
+[[Image:Tvashtarvideo.gif|right|thumb|Sequence of ''New Horizons'' images showing Io's volcano Tvashtar spewing material {{convert|330|km}} above its surface]]
+The discovery of volcanic plumes at Pele and Loki in 1979 provided conclusive evidence that Io was geologically active.<ref name="Morabito1979"/> Generally, these plumes are formed when volatiles like [[sulfur]] and [[sulfur dioxide]] are ejected skyward from Io's volcanoes at speeds reaching {{convert|1|km/s|2}}. Additional material that might be found in these volcanic plumes include [[sodium]], [[potassium]], and [[chlorine]].<ref name="Roesler1999">{{cite journal |url= |title=Far-Ultraviolet Imaging Spectroscopy of Io's Atmosphere with HST/STIS |journal=Science |last=Roesler |first=F. L. |coauthors=''et al.'' |pages=353&ndash;357 |volume=283 |issue=5400 |year=1999 |doi=10.1126/science.283.5400.353 |format=fee required}}</ref><ref name="Geissler1999">{{cite journal |url= |title=Galileo Imaging of Atmospheric Emissions from Io |journal=Science |last=Geissler |first=P. E. |coauthors=''et al.'' |pages=448&ndash;461 |volume=285 |issue=5429 |year=1999 |doi=10.1126/science.285.5429.870 |format=fee required}}</ref> Despite their dramatic appearance, volcanic plumes are relatively uncommon. Of the 150 or so active volcanoes observed on Io, plumes have only been observed at couple of dozen of these hotspots.<ref name="Geissler2008"/><ref name="Spencer2007"/> The relative confinement of Io's lava flows suggest that much of the resurfacing needed to erase Io's cratering record must come from volcanic plume deposits.<ref name="Geissler2004"/>
+The most common type of volcanic plume on Io are dust plumes, or Prometheus-type plumes, produced when encroaching lava flows vaporize underlying sulfur dioxide frost, sending the material skyward.<ref name="Milazzo2001">{{cite journal |title=Observations and initial modeling of lava-SO<sub>2</sub> interactions at Prometheus, Io |journal=J. Geophys. Res. |last=Milazzo |first=M. P. |coauthors=''et al.'' |pages=33121&ndash;33128 |volume=106 |issue= |year=2001 |doi=10.1029/2000JE001410}}</ref> Examples of Prometheus-type plumes include [[Prometheus (volcano)|Prometheus]], [[Amirani (volcano)|Amirani]], [[Zamama (volcano)|Zamama]], and [[Masubi (volcano)|Masubi]]. These plumes are usually less than {{convert|100|km}} tall with eruption velocities around {{convert|0.5|km/s|2}}.<ref name="McEwen1983">{{cite journal |title=Two classes of volcanic plume on Io |journal=Icarus |last=McEwen |first=A. S. |coauthors=Soderblom, L. A. |pages=197&ndash;226 |volume=58 |issue= |year=1983 |doi=10.1016/0019-1035(83)90075-1}}</ref> Prometheus-type plumes are dust-rich, with a dense inner core and upper canopy [[Gas Dynamics Shocks|shock zone]], giving them an umbrella-like appearance. These plumes often form bright circular deposits, with a radius from the plume source ranging between {{convert|100|and|250|km}} and consisting primarily of sulfur dioxide frost. Prometheus-type plumes are frequently seen at flow-dominated eruptions, helping make this plume type quite long lived. Four out of the six Prometheus-type plumes observed by ''Voyager 1'' in 1979 were also observed throughout the ''[[Galileo (spacecraft)|Galileo]]'' mission and by ''[[New Horizons]]'' in 2007.<ref name="Strom1979"/><ref name="Spencer2007"/> While the dust plume can be clearly seen in sunlit [[Visible spectrum|visible-light]] images of Io acquired by passing spacecraft, many Prometheus-type plumes have an outer halo of fainter, more gas-rich material reaching heights approaching that of the larger, Pele-type plumes.<ref name="Geissler2008"/>
+Io's largest plumes, Pele-type plumes, are created when sulfur and sulfur dioxide gas exsolve from erupting magma at volcanic vents or lava lakes, carrying [[Tephra|silicate pyroclastic material]] with them.<ref name="Geissler2008"/> The few Pele-type plumes that have been observed are usually associated with explosion-dominated eruptions, and are short-lived.<ref name="IobookChap7"/> The exception to this is [[Pele (volcano)|Pele]], which is associated with a long-lived active lava lake eruption, though the plume is thought to be intermittent.<ref name="Geissler2008"/> The higher vent temperatures and vent pressures associated with these plumes generate eruption speeds of up to {{convert|1|km/s|2}}, allowing these plumes to reach heights of between {{convert|300|and|500|km}} above Io's surface.<ref name="McEwen1983"/> These plumes form red (from the short-chain sulfur) and black (from the silicate pyroclastics) deposits on the surface. Most Pele-type plumes form large, {{convert|1000|km}}-wide red ring deposits, as seen at Pele.<ref name="Geissler2004"/> They are generally fainter than Prometheus-type plumes as a result of the low dust content, causing some to be called stealth plumes. These plumes are sometimes only seen in images acquired while Io is [[Eclipse|in the shadow of Jupiter]] or those taken in the [[ultraviolet]] range. The little dust that is visible in these plumes in sunlit images is generated as sulfur and sulfur dioxide condense as the gas reach the top of their ballistic trajectories.<ref name="Geissler2008"/> That is why these plumes lack a dense central column, seen in Prometheus-type plumes whose dust is generated at the plume vent. Examples of Pele-type plumes have been observed at Pele, Tvashtar, and [[Grian Patera|Grian]].<ref name="Geissler2008"/>
+==References==
+<!--Intentionally left single column due to formatting issues-->
+{{reflist}}
+==External links==
+{{commons cat|Volcanoes of Io}}
+* [http://jupiter.berkeley.edu/volnews.html Summary of known Io volcanic activity, 1995-2001]
+* [http://pirlwww.lpl.arizona.edu/~geissler/Volcanic_centers/gif/ Io surface changes candidates]
+* [http://www.solarviews.com/eng/iovolcano.htm Io's volcanic features]
+[[Category:Volcanoes of Io|*]]
-[[de:Fuchshaie]]
-[[es:Tiburón azotador]]
-[[fr:Requin renard]]
-[[it:Alopiidae]]
-[[la:Vulpes marina]]
-[[ja:オナガザメ]]
-[[zh:长尾鲨属]]