Intro

After writing two Io articles I return to Io  again my favourite moon, looking at one single lava flow field. But read Alberts and my two other Io posts first. Jupiter’s moon Io is the most volcanically active place in our entire solar system. The most powerful active volcanoes ever seen by cameras are not found here on Earth, but on Io, a major moon of Jupiter, and thats why Io is my favorite object in the solar system. Because of Jupiters tides, Io is a volcanic powerhouse, so volcanic it is very much a real-world Mustafar. Io is a sci-fi world come real: a moon completely consumed by raging volcanic eruptions and never ending volcanic fury thanks to Jupiter’s enormous tides. Volcano planets are common in games and fiction and here is one in real life after all.

The volcanic eruptions seen on Io are enormous in volume, extent and in eruption rates compared to any recent historical basalt eruption here on Earth. The largest lava lakes and lava flows are at Loki Patera; the largest lava lake in the solar system and some huge lava flows are at Lei Kung Fluctus, Amirani and Masubi. Some of the silicate lava flows on Io’s surface are likely 1550c / 1600 c ultramafic “komatites” rather than just normal basalt. Higher than normal basalt temperature eruptions have been confirmed by Galileo spacecraft. Io hosts the only other “hot” glowing silicate lava eruptions in our local solar system, making this moon special: it is the volcanologists paradise.

The Voyager probes revealed a young volcanic surface for Io covered in sulfur snow and dark lava flows. The Galileo Spacecraft surprised the entire science community by discovering very high temperature silicate volcanism. Ionian lavas could be similar to the early archaean lavas on Earth if the tidal heating is hot enough. The Galileo spacecraft mapped many active lava flows and lava lakes and saw many intense lava fissure eruptions and confirmed ultramafic minerals in its sensors. The later Juno Spacecraft that still orbits Jupiter have seen many new regional lava flow changes and the most intense eruptions seen so far.

The sheer amounts of volcanic eruptions on Io makes it impossible to write a whole article on every eruption and lava flow change on Io that have happened since 2000. So in this post we will have a look at one of the lava flows that were closest photographed by Galileo Spacecraft: the Prometheus lava field. In this article I will give you a tour of this extraterrestrial lava flow and explain what you see in the images of it. As alien as it is, it is also very similar to lava flows on Earth which is quite fun: geology works similar elsewhere if you have similar mantle rock material to melt! Io has two types of lava flows: fast open fountain feed lava channels and slower fed eruptions. Prometheus is a tube-fed eruption. in this post I will explain what you see in these spaceprobe images of Prometheus. I will show the most interesting images at the end of this post: the most fun things are put lowest down.

Prometheus lava flow field: hot pahoehoe invading a sulfur snow field a general explanation

First we does a comparison with Io: on Earth volcanoes with a constantly active surface lava flows flowing at mantle supply rates are extraordinary rare. They only exist at a very few places, typically Hawaii and Africa ( Kilauea and Nyiramuragira ) even if Earth has in theory 1000 s of possibly active systems underwater. Most active volcanoes on Earth are not in constant eruption nor in constant lava flow since most the magma systems here are quite or very weak.

But on Io a majority of all volcanic centers are in constant effusive activity with the average Ionian volcano having a magma supply that is many 10s to a few 100 times larger than Kilauea. The largest Ionian lava lake volcanoes can have a magma supply rate of 100 km³ per year. This of course translates into constant lava eruptions all over Io. Lava flow eruptions are common and one such constant surface lava flow is Prometheos. It is not the largest lava pahoehoe flow field on Io ( those are the Amirani, Lei Kung Fluctus and Masubi lava flows ), nor the most violent eruption, but it is one of the best studied. And it is much larger than any recent lava flow in Kilauea, Africa or Iceland. Compound pahoehoe lava flows like Prometheus appear to be the standard type of constant lava flow activity on Io, with channel-fed fountain Aa flows ( pillan, surt, thor ) being rarer but still common. This lava flow was named after one of the titans in greek mythology that titan stole the fire from the gods. Because of Io’s extreme volcanism all features on Io are named after mythological beings of fire and sunlight. The moon is cooking after all.

In fact Prometheus is one of the best photographed of any of the dark silicate lava flows on Io’s surface. Galileo Spacecraft in the 2000s got high resolution close-ups of this compound tube-fed lava flow that turned out to be analogous to Puu Oo’s tube-fed lava flows on Kilauea. Galileo spacecraft also photographed hot glowing breakouts that we will talk about later. Lots was learned from Ionian lava flows by looking at Prometheus. An interesting interaction between hot silicate lava and sulfur snow was discovered, with the hot surface lava flows themselves vaporising the sulfur ice layers and redepositing them elsewhere on Io’s surface. The lava flow surfaces themselves are also snowed over when the dark mafic crust cools and gets coated by sulfur snow. Hot basaltic/komatitic lava flowing over thick layers of sulfur snow will produce a violent “phreatomagmatic” reaction sending plumes of sulfur gas skyward and jetting dark pyroclasts everywhere. Such sulfurous plumes were seen at Prometheus by the Voyager probes nearly 50 years ago. Back then in 1979 the dark lava flows that’s were seen when Galileo arrived in the 2000s did not exist; the lava field had been emplaced since the 16 years between the visits of the two space probes. Voyager saw just a sulfur rich deposit, later when Galileo Spacecraft arrived 16 years later an area of over 6000 square kilometers has been covered in tube-fed pahoehoe lava flows. The flow field emplaced in the sulfur ice desert would cover most of Vatnajökull if placed on our Earth and some other compound pahoehoe Ionian lava flows are much larger than that. Prometheus is a very different eruption compared to the fast violent “outburst” lava flows like those seen at pillan. Tube-fed lava flows on Io can be active for decades to likely centuries. They are persistent and the lava flows seen in 2000 s are still active today according to Juno’s instruments. Prometheus features fluid, low-viscosity mafic/ultramafic lavas. The flow field expands through thousands of small, distinct lobes called “lava toes” rather than moving as a single massive wall of rubble/ open river like Pillan.

Today in 2026 Prometheus lava flow could be over twice as large, at least 14 000 square kilometers. The Juno spacecraft’s thermal sensors have seen hotspots at Prometheus, a clear sign that the flow field is still active today. The superhot ( likely komatitic ) lava is constantly supplied by tubes to the flow fields edges where it violently interacts with thick layers of sulfur ice. This produces large fans of dark materials when trapped ice below the lava hot flow becomes high pressure gas that sprays hot lava everywhere along the flow front and leaves dark fans along the flow front edges. Such dark fans are common in pretty much all active surface lava flows on Io because of this interaction between hot fresh lava and sulfur ice. It feels strange that Io is a world where very hot lava is erupting onto – 140 C sulfur almost glacial enviroment. Most of the sulfur that is vaporized by the lava is not lost from the moon: it is just redeposited frozen elsewhere as snow. In the decades that Prometheus lava have flowed the tall sulfur plumes have moved together with the lava front, simply because the hot silicate lava has vaporized its way through the volatile frozen ices. But as one sulfur snow heap is vaporized by moving lava, the older crust behind the flow front that is little cooler than the fresh breakouts will start to accumulate its own sulfur snow cover.

The Galileo spacecraft spent not much time around Io due to Jupiter’s highly damaging radiation. It was not a built for Io’s environment but during its short flybys it captured so far the best archive images of Ionian eruptions so far. The best photos of Prometheus lava flow were photographed on February 22, 2000, by NASA’s Galileo spacecraft. During this flyby (orbit 27), mosaic images were captured with a resolution of down to 12 meters per pixel that allows you easily to see how the compound lava flow field is built: many dark fresh pahoehoe breakouts where the ( black lava ) flow is way too hot for sulfur snow to settle and little older surfaces ( lighter grey ) where sulfur snow has started to settle on the lava.

Notice in the photographs how the darkest fresh lava breakouts in Prometheus are mostly located at the edges in the central left of the flow field, while there are relatively few fresh pahoehoe breakouts to the right where the caldera ( prometheus patera) is located. That is because there is a well developed lava tube system connecting the magmatic vents at the dark lava filled caldera ( Prometheus patera ) and fault. These feed the lava tubes that in turn supplies the flow front to the left on these Galileo images. The lava tubes inside the flow field are about 100 kilometers long. This is much longer than on Earth where lava tubes rarely exceeds 10 kilometers long. Even longer lava tubes on Io are those that feed the Amriani flow field, 300 kilometers long. Io’s Masubis lava tunnel system could be over a 1000 kilometers long. Ionian flow have a length of 1600 km. All of these are tube feed pahoehoes gentle constant eruptions at mantle supply rates.

Prometheus Patera ( bean shaped dark caldera) to the right of the lava field is also very interesting. It is likely the main vent that supplies the lava flow field. All dark spots on Io are hot lava surfaces where temperatures are too high for sulfur snow to settle. Knowing that, we can directly say that there is active lava there. It is more difficult to tell if it is a lava lake that is constantly overflowing or just a caldera that has been filled to the brim by active flows that now supply the flow field to the left. The lava flows at Prometheus are connected to the caldera which you can see in these Galileo photos, so it is there where it is coming from. Magma is likely rising through a fault in Io’s crust which is visible to the right of the field if you look closely other lava lake pits on Io are often but not always found near faults.

Little is known about the structure of the magma chamber that resides below Prometheus but with the fast supply rate against the lower buoyancy than on Earth, it is certain that the magma local chamber dwarfs Kilauea and Icelandic chambers. And this is still a quite small magma chamber on Io. Little is known about the detail of the formation of Ionian calderas, other than that they are magmatic in origin for sure. The Ionian pateras/ calderas maybe formed by hot lava eating their way through icey volatile outer layers of Io with the likely combination of magma withdrawl. Layers of sulfur ices ( frozen volcanic gases ) are going to vary a lot depending how old the local Io surface is. At Prometheus the snowy icey layer around the flow field coud be quite thin, perhaps a few meters and the plume fallout is much thinner than that.

The Galileo Spacecraft observed Prometheus lava field many times between October 11, 1999 and February 22, 2000 with an estimated 13 square kilometer of surface per month covered by lava. Thats about 160 square km per year repaved with new surface flow breakouts. These eruptions are gentle and effusive: lava is not flowing in open raging rivers like Pillan Patera and there are no tall laca fountains either like at Pillan, instead it is a gentle ooze. Very fluid lava is always brought to the flow front by the tube system. There the lava breaks out in white hot sheets. These can be 10 s meters long and are so very fluid they are much less than a meter thick and likely much more fluid than even the lava in Kilauea’s summit. Prometheus lava flows at the front advances as sheets and lobes, not as a single river like Pillan or Thor. The semi-plastic crust swells when it accumulates incoming lava from the tube system and the lava breaks out white hot. The sheets cool quite quickly in the frigid environment. On the surface a thin dark crust form forms  which thickens and inflates and it repeats again when it brusts. It pushing the lava front forward identical to pahoehoe flows on Earth but the lava is faster and hotter than pahoehoe flows on Earth. Emission of thermal energy towards space is much less intense for these tube feed lava flows than major flood basalts on Io.

Galileo Spacecraft’s sensors sees this type of activity like a series of many hot points that move forward, with older breakouts fading and cooling while new ones radiate intensely all advancing in a front. This is once again identical to how pahoehoe flow fields on Earth behave in a spacecraft’s thermal instruments. This earned these type of lava flows on Io the name “compound lava flows”. The flows are built by thin sheets and lobes and the lava flows hidden below a crust. The main lava river here is the lava tunnel but that is hidden from view. The hottest dark breakouts and lava tube skylights gave SSI instruments and NIMS at Galileo readings at about 1200 C. The crust was many 100 s of degrees c in many dark places but older crust freezing. More intense lava flows on Io like Pillan have radiated at over 1600 c. Sometimes, parts of the roofs of the lava tunnels collapse, forming so-called skylights. When the Galileo spacecraft observed these skylights, the instruments measured radiation straight from the protected, glowing flowing lava beneath the crust. This gave the researchers the unique advantage of measuring black body radiation without the lava surface cooling too quickly. Still the probe would perhaps needed to be closer to do the best readings. Lava tube skylights togther with intense lava fountains on Io are the best places to read the true lava temperatures. Because Galileo made measurements from a distance, heat pixels often covered several square kilometers per pixel. The spacecraft measured an integrated temperature. A pixel at the flow front contained a mathematical mixture of almost only recently warmed crust and 1% extremely hot, recently erupted lava. The researchers had to use complex two-temperature models to mathematically separate the components due to a lack of higher resolution. But temperatures at 1200 C is confirmed for Prometheus. It is likely that the Prometheus lava flows are true 1600 c ultramafic komatites as was seen at Pillan  but it is hard to know for sure. Superheated basalt is also a candidate thats similar to ancient lunar basalt. I think that all fresh lava flows on Io are very dark, which is a strong signature of an iron rich highly magnesian rock composition.

The lavas temperatures are much higher than the boiling point of the surrounding sulfur ices and that causes them to vaporize when hot lava meets the sulfur snow making gas jets. If you look closely at some of the close images ( photo below ) you can see something that almost look like sand dunes at the sulfur plains. Nasa experts think these formations are formed by the gas jets at the dark lava edge. These gas jets moves sulfur snow over the surface forming these “dunes” so a kind of wind sedimentation process in an otherwise airless space environment. Sulfur ices are constantly moved, vaporized and freezed out all over Io’s surface either by active lava flows and by deposition freezing out from distant volcanic vents.

Not all sulfur ice and snow on Io could always be vaporized by active lava flows when they flow over them. If that was the chase the moon would run out of volatiles to recycle back in its astenopshere and there would be no violent lava fountain eruptions that we seen elsewhere on Io. Some sulfur ice have to be buried together with the lava flows and remelted at depth. Thick sulfur ice layers can survive a hot lava flow on them by chilling the lavas underside and allowing the lava flow over it. Over time sillicate lava flows and sulfur snow get buried at together in a sort of weird layer pancake. It is still an overall violent interaction with hot lava that is much hotter than the boiling point of sulfur ice. Experts thinks that giant supercritical liquid boiling pockets of sulfur get trapped below the lava. When pressure gets too much the crust explodes and the sulfur vapor sprays hot lava chunks and gas everywhere. These explosions leaves dark halos of lava pyroclasts and plumes close to Ionian lava flow fronts. The faster the lava flow speed the more violent the interplay between hot lava and sulfur ice. At Prometheus that is a quite slow lava flow, this war between sulfur ice and lava is more gentle than at Pillan Patera and other faster Ionian flows.

The photos above are one the best and closest photos ever taken of the Prometheus lava flow and of any alien lava flow. Unlike the better photographed flows on Mars that are inactive this one is very much alive. The lava flow’s nature and behaviour is very clear by its shapes. It moves as lobes and sheets fed by the buried lava tubes. The lava is extremely hot and fluid so it forms smooth lobate, almost fractal shapes when it creeps along the ground. It reminds me so much of aerial photos of Kilauea’s lava flows and of the large older pahoehoes in the Craters of the Moon national monument. The various shades of black and grey are the result how old the lavas surface is and is determined how much sulfur snow it has accumulated. The dark breakouts are warm to superhot while the lighter grey older crust is cold enough for some sulfur snow and frost to settle on it. Cooling lava flows on Io tend to first go from black to green as the sulfur reacts with mafic silicate minerals forming a kind of pyrite frost. When the emplaced basaltic lava continues to cool and age, they slowly disappear under sulfur frost and snow, turning orange and later yellow and ultimately yellow-beige, until a new basaltic/ ultramafic lava flow comes along. Prometheus lava flow have two sources of volcanic gas plumes that condenses into sulfur snow. One is the patera ( caldera lava lake degassing ) the other is the lava flow front that vaporises sulfur snow forming the secondary plume thats moving togther with the lava flows. The snowy plains around Prometheus may not had much lava flow activity for hunderds of years.

By comparing recent resurfacing rates between different dates of photography from Galileo Spacecraft astronomers have estimated the amount of lava feeding this lava field to be around 40 to 50 cubic meters of lava per second flowing through the tube system. That does not sound much but it is way much faster than the basal supply of any Earth volcano. Kilauea as example sits at around 3 to 7 m³ per second depending on supply rate. Other pahoehoe lava flows on Io haves higher supply rate. Amirani lava flow have a peak rate at 70 – 600 m³ per second during episodes of excess supply with basal supply rate at least 56 m³ per second. At time of photographing in early 2000 s the volume of the whole Prometheus lava flow was estimated to be around 120 km³ of basalt/komatite emplaced since 1979. Today in 2026 with constant activity, the Prometheus field could have a volume of 240km³. This is orders of magnitude larger than any recent compound holocene lava flow field on Earth, and this is still a relatively small lava flow field on Io.

Some estimates gives 100 s of cubic meters of lava per second through the tubes when many breakouts are active at once that woud then be a pulse in supply but the median lava supply rate is lower 40 – 50 m3 when you divide volume with time lava coverage for Prometheus. Magma output at these kinds of Ionian eruptions are quite notable. Kilauea, Earth’s most productive volcano in the long term, covered around 5 to 8 square miles every month during the Puu Oo eruption, but the Aminarani Ionian flow field covered 250 to 470 square miles in new lava surface during the same timespan, Prometheus is over 10 km2 per month. Io’s upper layers are probably full of lava tubes, that get compressed and crushed further down as new lava layers get added above. Prometheus flow field like pahoehoe flow fields on Earth are feed by lava tubes like roots of a tree there is one main lava artery “tree stem” this is 100 kilometers long and from that underground lava highway lava is delivered to the flow front and field in sub tunnel branches that feeds the flow fronts and inflating crusts that replaces the surface Ice. The subsurface pooled lava below the crust soon merges with the lava tunnel as the sides cool and builds the main tube channel longer.

The whole local area mantle output that feeds this lava field is squeezed into the main lava tube so while 40 – 50 m3 of lava per second does not seem huge it is an enromous flow speed when thats crammed into a narrow lava tube. A good example is the spectacular Kilauea firehose at Kamokuna in 2017 where around 4m3 per second made a spectacular river. The breakouts at Prometheus flow front move each much slower than the supply rate because the tube supply feeds many lava breakouts at once at the front. At night this area is a spectacular hellish landscape with numerous glowing breakouts ilumninating gas jets and lava glows sinister in inflation cracks in the crust.

 

Hot Prometheus: Io lava captured in action: the best shot of this flow field

This closeup cropped image of the lava field at Prometheus flow got my attention years ago : the real stuff which captured in glowing hot pahoehoe lava breaking out on this moon’s surface. The images, taken during a Galileo flyby of Io on February 22, 2000, have a resolution of 12 meters (39 feet) per picture element. This photo is a strongly zoomed view of a small part of the flow field and hot breakouts are clearly visible. It is very likely hot lava (because of its intensity) and not older sulfur-snowed ground. These hot scattered lava breakouts are responsible for the hottest local pixels in Galileos spacecrafts instruments. The closer the spacecraft gets to the surface the better the resolution of thermal data in the spacecrafts sensors. Flow front is compound lobate and seen as a series of moving hot points that comes and goes, but lava tube skylights in the middle of the flow field are always hot pixels that remain in place month after month.

It has to be one of the most stunning photos taken by any spacecraft: the only image pixel resolution of hot lava outside our Earth. The dark recent hot flow is about a kilometers wide and has many near fractal lobate rootlike pahoehoe fingers. the hot lava breakouts themselves are many 10 s to 100’s of meters wide based on the image scale, which agrees with of the flow rate of this breakout being much higher than anything you see at Puu Oo lava front videos. It is logical, knowing that the supply rate at Prometheus is far higher than that of Puu Oo. This is just one of many such breakouts that are scattered all over Prometheus flow. Fluid lava is breaking out not only at the edges but inside the flow field in the chase of this photo. Incoming lava from the tube system fills under the inflating cooler crust until it breaks the crust open and glowing lava rushes out like in this image. The lava field not only grows in area but also in height when breakouts pile on top eachother. The fluid glowing lava tongues are much less than a meter thick but as the crust grows, ages and the flows inflate the surface rises to over a meter in height.

Ionian mafic/ultramafic lava is so hot that these pahoehoe flows viscosity may resemble liquid iron slag if the temperatures are high enough. The higher the temperature and lower the SiO2 are, the more fluid the lava will become. The simple fact that Prometheus’ compound lava flows on Io looks like this after many 100 s of kilometers away from the vent with little change gives an idea how hot and fluid and well insulated these pahoehoe lava flows are. Even over a 100 kilometers from the vent the dark fresh breakouts are looking like spilled stearine or liquid aluminium in shape. The lava is well insulated. The morphology of the pahoehoe field is very similar to large flow fields on Earth but I also think it looks smoother than most earthly flows and that agrees with models of Io’s lava having lower viscosity than oceanic basalt on Earth because it is hotter. Some models suggests both basalt and komatiite maybe able to erupt on Io in areas of different levels of tidal heating. Areas with higher heating will experience more mantle melting and more magnesian magmas. How hot the lava is determines the color for your eyes when the pahoehoe is breaking out. At 1200 c it’s shining light is yellow and at 1600 c it is a brilliant shining white hot just like liquid steel.

My own opinion on the surface morphology suggests the viscosity maybe much lower than typical earth oceanic basalt. Eruptions elsewhere on Io have been measured at 1600 c. Yhe breakouts may flow akin to liquid slag if the eruption temperature at Prometheus is well over 1200 c. When the lava sheet flows out it is a brilliant near white hot. It then cools to yellow, orange, red until it becomes glassy and black. The surface is always kept smooth and is likely very plastic when it is thin until it freezes into shape, because of the low viscosity allowing smooth surfaces. The pahoehoe crust is a very good insulator. It has low conductivity and the lavas high heat capacity mean little energy is lost even by flowing over cold sulfur ice and in the frigid cold vacuum. A visitor here woud have to content with the lethal radiation from Jupiter. There is not only hazards posed by flowing lava breaking out and rootless explosions caused by trapped sulfur ice boiling under the hot lava.

The exposed hot lava in space should cool much slower than a breakout does in Earth’s cooling  convective atmosphere, because it can only radiate energy by radiation. The lava glow will fade but slower so than it does in Earth’s chilling atmosphere. But older lava crusts on Io cools down to minus 130 c or lower. The crust is an excellent insulator and the cold vaccum on top steals little heat from the lava flows despite its low temperature. This allows tube fed lava flows on Io to flow vast distances despite the freezing conditions on Io s surface. Lava crusts haves excellent insulation traits. Submarine lava flows on Earth can flow kilometers underwater over the seafloor and Io s vacuum is much less chilling than the huge density of masses of cold deep ocean water.

Walking on the lava flows surface would be surreal. You would see a landscape very similar to the past pahoehoe lava flow fields at Puu Oo. You would see hot lava breakouts, you see ropey sheets, you see sheet lobes, you see inflation mounds, glowing skylights and pressure ridges. By looking carefuly you can see some of these features like inflation mounds and pressure ridges in these photos. The fractal lobate behaviour at the front is just like the flowing lava flows that I hiked in 2014 at Kilauea’s Kahauale’a 2 with my father. The Prometheus lava are much more vigorous and even hotter than that. Kahauale’a 2 lava flows were about 1150 c and the current ongoing summit eruption of Kilauea has risen to almost 1200 c. But Prometheus breakouts on Io could be 1500c /1600 c like the other Ionian eruptions. The pahoehoe tongues and sheets that I saw at Kilauea were at most a few meters long when the surface was incandescent but on Prometheus the glowing sheets could be a 100 meters long / wide or much more when the supply behind is larger. On Io we can observe volcanic activity that would be catastrophic on Earth and see large eruption processes that only happen every millions of years of years on Earth. And some of the larger Ionian pahoehoe flows would only happen during major LIPs on our planet.

Large lava flow activity on Io gives an insight to old ancient eruptions on Earth and therefore is of tremendous interest to planetary geologists to understand Earth’s previous large lava flows. Some geologists think that the Columbia River Basalt Flows CRB sequences are quite analogous to Prometheus and Amiarani lava flows, as they share many of their suggested morphologies such as huge inflated ”flood sheet pahoehoes” which are also seen in the Deccan Traps lava flows. Its hard to say exactly how Ionian flows compares to Earths LIP flows but both share many features how these lava flows work. Both fast fountain fed lava flows on Io like Pillan and the slower tube fed Ionian eruptions like Prometheus have likely analogues on flood basalts here on Earth. LIP province flows on Earth are badely eroded and we only see their interiors, but on Io we could perhaps see true analogues in action: that is why this is so interesting to think about. The longest recent Pleistocene pāhoehoe lava flow on Earth is the Pampa de Los Carrizales / Pampas Onduladas flow at 180 km in lenght and of middle late pleistocene in age. That one is Prometheus  in scale but Prometheus has a far bigger potential to become much bigger and the lava is also much hotter at Io. Such lava flow events on Earth are very rare but on Io it is the standard activity and Prometheus is a small lava flow for Io. The largest pahoehoe flow field on Io is Lei Kung Fluctus. It is mostly inactive  and it covers 125,000 km². Prometheous thats active maybe covers over 12 000 kmsup>2 today. Puu Oo s flow fields covers little over 100kmsup>2 and that is not a single lava flow. Kilauea’s very largest recent pahoehoe field Ailāʻau flow covered over 400kmsup>2 and that is still a small flow compared to Ionian lava flows.

This is about as much as I can write out in my own words out Galileo Spacecrafts images of Prometheus lava flow without making the the text too complicated for new readers with little background. At Kilauea me and father got to experience these Ionian flows processes on Earth. It is surreal to watch the same volcanological processes without a radiation blocking future spacesuit and without our suits becomming completely yellow of toxic snow. Space agencies needs to produce more space probes for Io the most volcanic and most  intresting body in our solar system. Information thats good and readable on Io s volcanic processes on Internet are almost completely lacking, only Jason Perrys blog is good information elsewhere, so I will keep making articles on Io for Volcanocafe.

 

 

 

Jesper Sandberg, May 2026

Recommended Sources

Two books: Volcanism on Io: A Comparison with Earth. Ashely Davies et al. https://www.amazon.com/Volcanism-Io-Comparison-author-published/dp/B01M2XT6XO/ref=sr_1_1?crid=141Y7PMY8CO6L HYPERLINK “https://www.amazon.com/Volcanism-Io-Comparison-author-published/dp/B01M2XT6XO/ref=sr_1_1?

Io a new view of Jupiter’s moon. Rosaly Lopes et al. https://www.amazon.com/Io-Jupiters-Astrophysics-Science-Library/dp/3031256697

Links

Read my and Albert’s other Io posts:

https://www.volcanocafe.org/a-quick-tour-of-volcanism-on-io/

https://www.volcanocafe.org/secrets-of-io/

https://www.volcanocafe.org/ios-pillan-patera-eruption-in-1997-the-largest-lava-falls-ever-seen/

https://www.sciencedirect.com/science/article/pii/S0019103598959723?via%3Dihub

https://www.jpl.nasa.gov/images/pia02557-lava-flows-and-ridged-plains-at-prometheus-io/

https://geology.illinois.edu/~skieffer/papers/PrometheusIo’sWanderingPlume_Science_2000.pdf

https://www.science.org/doi/10.1126/science.288.5469.1204

https://www.sciencedirect.com/science/article/pii/S0019103598959723?via%3Dihub

Click to access 1328.pdf

https://pirlwww.lpl.arizona.edu/~perry/io_images/i24.htm