Mountain of the Night: the lost Mars volcano

It should be easy to recognize a volcano. They stand high above the surrounding land, a singular cone which couldn’t really be anything else. Of course, they may not stay that way. Erosion may destroy the shape. A big explosion may replace the cone with a crater. Or there may never have been a cone, for instance when erupt as an Icelandic fire rift, although even they do build cones in the end, just not ones that stand out well. But now it seems that the 6th highest volcano on Mars has been missed. It was lost in a maze.

A note on its height may be needed. Volcanos should really be ranked by their height above the surrounding land. But that can be difficult to precisely define, so instead the height above sea level is normally used. Sea level can present problems as well, as on Mars where there is no sea to define a sea level. (In fact even on Earth we need to be a bit careful with this definition or we could suddenly discover later this century that all volcanoes on Earth have become 1 meter lower, because of the rising sea.) On Mars, instead of the ever-lasting but non-existing sea, a zero level is defined by taking a level of constant air pressure, originally taken as 0.6% of sea level pressure on Earth. That didn’t quite work because air pressure on Mars varies a lot between summer and winter, as so much of the atmosphere freezes out in the southern winter. So nowadays we use a level where the force of gravity is equal to that on the equator at a height which corresponds to the average radius of the planet. (It contains a small contribution from the rotation of the planet causing the centrifugal force). According to this definition, famous Olympus Mons is 21 km high. But it stands 27 km above the surrounding plain, so if people want to make the mountain bigger they will quote the latter number. Olympus Mons is about as big as a mountain on Mars can get, before it crumples the crust below under its weight.

The tallest volcanoes on Mars according to the official definition are Olympus Mons (21 km), Ascraeus Mons (18 km), Arsia Mons (16 km), Pavonis Mons (12 km) and Elysium Mons (12 km). Tharsis Tholus should be added to this list: it is a small(ish) prominence at just 9 km high. ‘Tholus’ means hill, by the way, whereas ‘Mons’ is used for a singe mountain – a mountain range would be a ‘Montes’. The line which contains three of the highest volcanoes (Ascraeus, Arsia and Pavonis) is therefore known as ‘Tharsis Montes’. When colonizing Mars it is important to first brush up on your Latin, otherwise you can expect to get quickly lost in the landscape. This is an oft -overlooked aspect of Mars exploration, and is perhaps the reason why Musk (whose occasional use of Latin on twitter has not been fully successful) has been unable to get his Mars colony off the ground. ‘Musk Mons’ would have a ring to it, though, while ‘Tholus Musk’ sounds a bit silly.

Mars (like Musk) is basically a simple planet. Being much smaller than Earth, there was lalways ess room for variety. The planet consists of two halves: a northern hemisphere which is low lying and rather featureless and boring, and therefore the preferred place for exploration, and a southern half which is high and mountainous, contains all the interesting bits and is therefore ruled out for landings as they would be too risky. The northern plains are covered in sediment – it seems that the surface buried below the sediment is more diverse and interesting. The area in between the two halves shows evidence for old rivers flowing from the highland to the low basin. There are a variety of impact craters mainly in the southern hemisphere, and there are many, mainly ancient, volcanic deposits and a much smaller number of very large volcanoes.

The most dominant feature is the Tharsis Rise, an enormous bulge which sits on the equator and has three of the four highest volcanoes sitting on it, and the fourth one sitting adjacent. It is so large that geology lacked a word for such a feature. The three volcanoes together form the Tharsis Montes, but this is only a part of the Rise. (To be fair to Mars, I should point out that the Tharsis Rise arose mainly in the low-lying hemisphere.) This Tharsis Rise is so large that it forced Mars to change its rotation axis. This process is called ‘true polar wandering’, and it ended with the bulge sitting on the equator so that Mars could rotate in peace. Finally, there is the big crack, starting from the side of Tharsis Rise which runs a quarter of the way around the planet. It is called Valles Marineris, and it puts the Grand Canyon to shame.

There is little or no evidence for plate tectonics (there is one place where a bit of oceanic crust may have formed at one time). And it is old. All these features formed in the first billion years or so of Mars’ existence. Little has happened since.

Map of Mars made with UAE Hope space mission

An elevation map, from www.planetary.org

Valles Marineris

Source: Sivasankari, T., Arivazhagan, S. Topographical and morphological studies of Valles Marineris, Mars by using Mars Colour Camera onboard India’s first Mars Orbiter Mission with MOLA data. J Earth Syst Sci 132, 75 (2023). https://doi.org/10.1007/s12040-023-02083-4

NASA calls the Valles Marineris the ‘Grand Canyon of Mars’ but that is like calling the Grand Canyon the Lathkill Dale of America. NASA can be a bit silly at times. The 4000 km length and 7 km depth of the Valles Marianeris are far beyond the Grand Canyon and are similar to the sizes of the largest subduction trenches on Earth, such as the Mariana trench, but those of course have a very different origin and are also not visible from space. The African Rift valley is almost as long (3000 km) as the Valles Marineris but is much less deep or impressive. The only rift on Earth that really competes may be the political division in the US! For would-be colonizers, the Valles Marineris is crying out for a roof: it would make the perfect walk-in greenhouse. And for science-fiction lovers: you heard it here first. And for record-seekers: the deepest point of the Valles is 11 km below the surroundings. It is like a 4000 km long version of Lake Baikal, at least after removing the many kilometers of sediment from Baikal.

The canyon consist of several parts, with one part following a straight line (the Coprates Chasma) and others are more complex. The structure begins almost as a double, with the Lus Charma running in parallel to the Tithonium Chasma and later the Cando Chasma. At one point near the Melas Chasma there seems to be an impact crater straddling the canyon, although this could also be a collapse feature. At the end, the Valles runs in the Capri Chasma, broadens and turns into the chaotic structure of Eos Chasma. And at the top end lies the even more chaotic labyrinth of dark faults, the Noctis Labyrinthus.

How such a structure could have formed has been a long-standing question. 120 years ago, the answer would have seemed obvious. If the Valles Marineris had been known, it would been seen as a canal, an artificial structure to transport water from the mountains. You heard it here last. After its discovery it was viewed as a river channel, slightly complicated by the fact there can be no liquid water on Mars. Lava channels were suggested. Nowadays it is seen as a tectonic structure, an actual crack in the crust somehow caused by the rise and (slight) fall of the Tharsis Rise. Plate tectonics has been invoked, with the claim of a transform fault with as much as 150 km displacement although the evidence for that movement is fairly slim. There is a collapse model, involving withdrawal of a magma from an underlying reservoir, presumably a massive dike . A rift seems most plausible but rift models also come in many varieties. Some models make this a pull-apart basin, either through spreading rift or through gravity causing one side to slope away. There are simple rift and complex rift models. It is quite messy.

Looking at it in detail shows several aspects. The rift is deep and sharp. On earth, rifts come in two forms: wide and narrow. Wide rifts form basins, as in the western US. Narrow rifts form long, thin and deep breaks, as in Lake Baikal. The difference comes from the strength of the crust. Shallow, warm (young) crust gives wide basins, while deep, cold and stiff crust gives the narrow, deep rifts. The Valles Marineris is an extreme version of the latter. This might be expected from the deep, cold Martian crust. It really is like a dry Lake Baikal.

The Valles Marineris runs away from the Tharsis Rise and is clearly related to it, though perhaps younger, i.e. a late consequence of the Rise. The sides of the canyon show evidence for numerous collapses, small and large. This is not unexpected from a 7km high cliff and the slides likely continue to this day – the colonizers should be aware, stay away from the sides of the canyon and build their settlement more to the centre. There may have been flows of various forms (mud, perhaps) through the canyon, which did not form the canyon but, much like the Rio Grande, made use of a pre-made channel. And one more aspect: a rift like this is begging for filler and glue to stick the planet back together. Lava could have provided both the filler and the glue and the Tharsis volcanoes could have provided plenty, but there is little evidence for this. This is another reason to assume that Valles Marineris was a later addition, coming after the volcanoes had begun their decline.

The Valles Marineris is typically dated to 3.7 billion years ago, a long time ago for us but on Mars this is the ‘Late Noachian’ and the more recent Hesperian epoch. The formation may have been as fast as 200 million years or as slow as a billion years, through a combination of faulting and uplift. After formation, it did not lie down quietly. As mentioned, there were many landslides. Erosion took its toll. Mars’ ever-present winds got in on the act, caused erosion but also formed sand dunes throughout the canyon system. In one place there are multiple volcanic cones on the bottom of canyon, thought to date to perhaps 400 million years ago. Meteorites impacted and apparently badly damaged the western ‘Eos Chaos’ region, near the end of the canyon. Glaciers were present at one time and left their signs. There are various sulphate deposits in and around the canyon, possibly coming from pyroclastic flows – but from which volcano? In the top part of the canyon, there is a linear ridge running along the centre line of the canyon, called Geryon Montes, which reaches almost as high as the surrounding plateau and separates the Valles here into a double canyon. It is not a spreading ridge as might have been surmised: the rise does not stay in the centre but moves closer to one side, and further down there is a similar structure which does in fact merge with the wall of the canyon. The Geryon Montes is a sign of a double canyon, a remnant of the original plateau cut by two closely spaces rifts.

In fact there are as many as seven parallel canyons, in various stretches, that run alongside Valles Marineris. They may be precursors to the real thing.

The Valles Marineris cuts through several kilometers thick lava flows, deposited before the Valles formed. The Geryon Montes shows a number of parallel ridges along the crest, more than 10 km long: they are thought to be the remains of dikes associated with lava eruptions, brought to the surface by erosion (i.e. collapses into the Valles).

There is no structure like it in the Solar System. Neither is there anything like the Tharsis Rise. Two two must be connected, somehow. On Earth, a big bulge may form before a flood basalt, as for instance happened at Steen Mountain prior to the Colombia basalt eruptions. The terrestrial crust can adjust to increased surface area by thinning a bit. Perhaps on Mars that was not possible, and the bulge had to render the crust to create space: hence the Valles Marineris.

Clearly this was a very complex structure which formed over time in phases with some changes taking place even now, but it may have had simple beginnings. Still, a glass-roof cover sounds quite attractive. What a place it would be to call home.

Noctis Labyrinthus

Somehow, the beginning of the Valles Marineris is tied to the labyrinth of faults at the top. Here is where the Valles begins with a sharp multi-kilometer drop to much lower elevation. The name is not promising (Musk beware): the name means ‘the labyrinth of the night’. Wikipedia calls it a maze of steep-walled valleys and a spider-like network of grabens. The bottoms of the valleys or grabens have the surface of the plateau, so clearly this is a rather complex collapse feature. Do realize the scale: the valleys are 2 to 3 km deep! They go off in all directions and take no notice of the Valles Marineris. Some of the grabens cross the initial grabens of the Valles Marineris at right angles, as if they are oblivious of each other. The Valles is much deeper though: From the top of the labyrinth to the start of the Valles Marineris is a drop of 6 km, and it quickly goes several kilometers lower.

Wikipedia points out that the Labyrinth is the most chemically diverse region of Mars, including lapilli-like minerals and water-sulphates that are not stable under conditions on Mars. Evidence has been seen for deposits coming from a glacier. Other deposits have been interpreted as volcanic air fall. The minerals have been suggested to come on part from the combination of volcanic ash and a glacier, even though this is on the Martian equator – Mars’ climate is highly variable and glaciers can form anywhere at different times. In any case, the strangeness adds to the puzzle of the Vallis Marineris.

The landscape of Noctis Labyrinthus. Source: https://www.esa.int/ESA_Multimedia/Images/2016/01/Perspective_view_in_Noctis_Labyrinthus

The image below show a light coloured layer on the top of a terrain in the Noctis Labyrinthus, interpreted as a pyroclastic deposit with a thickness up to 150 meters. Wind has moved it into dunes, which cemented due to the interaction with ice. Similar pyroclastic deposits have been found in places around the Vallis Marineris and on Arsia Mons.

Source: https://www.hou.usra.edu/meetings/lpsc2022/pdf/2595.pdf

The mysterious Oudemans crater

Adjacent to Noctis Labyrinthus lies a large impact crater. It is called Oudemans and it has a diameter of 120 km. On Earth this would be among the largest known impact structures. On Mars, there is rather more competition: it does not appear on most lists of large craters – there are unnamed craters larger than this.

Oudemans crater has the usual raised rim, a flat floor (as is common for craters of this size) and a central rise although this seems slightly off-centre. It is the only crater of this size on Mars which has no ejecta blanket around it. The rim has a gap where the crater floor connects with the lower-lying basin which starts off the Valles Marineris. This gap is unusual. The off-centre peak suggests that not only the northern rim but half the central rise is missing. This has been attributed to an oblique impact but that seems a less likely coincidence. Another explanation may be that the crater was emplaced on a sloping terrain. But it appears that the region around the crater and to some degree the crater itself have been modified, recovered, and to the north, perhaps collapsed. The crater floor would have been affected but may have been covered with later deposits.

Inside the Oudemans crater are some smaller craters, left by later impacts. One of these shows an almost identical shape as its big parent, with a missing part of the northern rim. This crater is only 1 km wide rather than the 120km of Oudemans, but it seems unlikely that it happened to come in under the same oblique angle. Something else wiped out part of the rim.

A small crater located inside Oudemans, which mirrors its shape. Source: Yin et al. 2021 https://doi.org/10.1016/j.icarus.2021.114332

The Tharsis Rise

The Tharsis Rise

All this happened on the slopes of the biggest bulge in the Solar System. In images, our attention is normally drawn to the sequence of three volcanoes, or the giant Olympus Mons at the top left, but these are not the Rise itself. The centre of the Tharsis is a plateau, 7-8 km high and 10,000 square kilometers, with the three volcanoes sitting on one edge. The full Tharsis plateau extends to lower altitudes and covers 4000 km by 6000 km, a very much larger area than the high summit region. Its height may be dwarfed by the three massive volcanoes, but the Tharsis Rise is far more massive than those volcanoes combined. It is continent-sized, on a planet that is rather smaller than ours.

And it has a problem. On Earth, continents stick out above sea level because they are lower density than the rest of the crust. They are like icebergs, floating with their heads above the water. But there are no such continents on Mars. All crust on Mars has the same basaltic density. Something is therefore pushing this bulge up, an enormous hot spot 20 times the size of any hot spot on Earth. And once the heat goes, the bulge will have to come down. So not only did this hot spot become enormous, it stayed in the same general area for 4 billion years, although probably not as active as it once was.

Yin et al in 2021 have argued that many features of this plateau and the crater can be explained if 3.5 billion years ago, a large ice cap was covering both the Tharsis Rise and the already existing Oudemans crater. The Rise is high enough to have supported such an ice cap at a time when Mars had a more significant atmosphere than it does now. An atmosphere rich in CO2 (climate deniers – look away now) traps heat through the greenhouse effect. But that does not create warmth, but redistributed it. It traps heat that would otherwise have gone up. So when the surface warms, the higher levels must cool. On Mars, the mountains are so high that they reach these once-cooled heights. The Tharsis Rise would have been colder at the top than it is now, and able to support glaciers.

Yin et al. suggest that the ice cap was 1 to 3 km thick. Volcanic activity and perhaps even mud volcanoes below the ice could have provided melt water, and form the hydrated minerals. And a moving glacier could have eroded the two missing crater rims, if the ice was flowing northward. Could this be a part of the puzzle?

The hidden volcano

Pascal Lee and Sourabh Shubham have now proposed that the Noctis Labyrinthus is the remains of a volcano., The evidence is still sketchy: you can find it in their short paper. It has attracted a fair amount of public interest. It is not everyday you find a 9-km tall volcano, even in potentia, in your backyard!

The larger region is shown here, from the Syria Planum on the left to the Valles Marineris on the right. This map extends about 1500 km. The Syria Planum is a 7 km high plain, sloping from 6.5 km on the left to 7.5 km on the right. The highest Montes in this image are (roughly) indicated by the red lines: these are around 8.5 km high. Although there are some peaks on the northern side of the Syria Planum (approximately at the label ‘Noctic Labyrinthus’) which also reach over 8 km, the highest region is the badly eroded and broken terrain above the Valles Marineris. And the Valles Marineris does not point at the centre of the Tharsis Rise. It points at this peak.

Lee and Subham propose that this region is the remains of an unknown volcano. It has been badly damaged by the arrow of time, much more so than other volcanoes. They point out the presence of the rough outline of a shield volcano, from the slope, the presence of summit depressions which look like th remnants of calderas, a circular depression at the centre, some low albedo material with the appearance of lava flows, and of course the variety of minerals which require mafic deposits. The volcano would be 250 km across – not quite as big a monster as the others, but still among the largest on Mars. Some features are indicated below.

They also point out the indications for glacial activity, as has been found by others as well. These are a field of rootless cones which may come from lava interacting with water below the surface, moraine bands, hydrated minerals, etc. The pyroclastic deposits seen in the region could have come from this volcano, although there are other suspects here! The volcano is called, at the moment still optimistically, Noctis Mons – the mountain of the night.

It raises questions, of course. Why the Labyrinth? Could that be caused by massive ice melt collapsing the surface? But why are the valleys so extreme deep? Why the Valles Marineris? Why the glacier on this mountain and not on the others? That last point may be answerable, as the other volcanoes are just too high. Glacier would have formed on their lower slopes rather than on the flatter summit, and therefore not grown as deep. Was the volcano a late addition to the Tharsis Rise? Why was it here and not closer to the centre of the rise?

The Tharsis Rise did not form in a single location. It formed over time, with the centre of activity extending over a 5000 km distance north to south. This does not seem to have a simple migration but was perhaps like a multi-headed plume with different heads being active at different times. One of the centres of activity, as indicated by the wrinkle ridges around the Tharsis Rise, was midway between Arsis Mons and the proposed Noctic Mons. The high plain of Syria Planum is often seen as the main centre. This is not far from the location proposed here.

The paper is meant to stake a claim. It does not present sufficient evidence that Noctis Mons is real. But it will stimulate a lot of discussion. And isn’t that what makes science is all about?

In the mean time, we can be excited about the possible discovery of a volcano that formed so long ago, that here on Earth not even Australia existed. And that says something.

Albert, March 2024

470 thoughts on “Mountain of the Night: the lost Mars volcano

    • Even the eruption of Grindavik has got a snow coverage, but not enough for a jökulhlaup …

  1. Very interesting to see that GPS stations to the east of the eruptive area are still showing inflation, albeit at about 1/4 of the previous rate [rough, unscientific calc based on current, short plot line gradient at various GPS stations]. In my mind, this means that there is still magma rising from the deep but the rate at which it can traverse the plumbing through to the sill, the dike and then out of the ground is lower than that at which the system is being fed.
    My thoughts, then. If nothing changes, the inflation will hit the point where it previously lead to either an eruption or to underground migration of magma to the east. What will happen then depends on whether the currently open conduits open further to allow the extra volume through or whether the pressure opens cracks elsewhere, perhaps those we saw in the first or second events, perhaps somewhere else. In the first scenario, we would see significant and spectacular fountains from the current cones. In the other, lava could appear anywhere from Eldvorp eastwards which would be a significant development for civil defence/lava control. The next two or three months should give us a clearer idea of what will happen next.
    Of course, the current plumbing might break down after a tectonic shift or pressure from below may reduce unexpectedly, closing the currently open conduits. In which case, the intermittent eruptive behaviour might continue or come to a halt entirely. However, the system inflating at the same time as lava is erupting is probably a sign that lava will flow for some considerable time from this point onwards. If it can be persuaded to stay in valleys or open countryside or ideally flow into the sea (VOG issues aside), all the better for both Grindavik, Svartsengi and Iceland tourism. The bulldozers now have a heap of experience in dealing with lava on the move so I believe that, if anyone can do it, these folks can.

  2. Flow rates vs inflation rates.

    I was looking at the graph published by IMO were they plot the estimated inflation volume over time between the different events. These estimates are based on geodetic modeling from GPS measurements, and they range between 8e6m3 to 15e6m3 over a 20 day period. That translates to roughly 5-10m3/s for the inflation, where 5m3/s has been the sustained rate since January.

    Now the numbers are out for the measured lava flow between March 17 and March 20. That estimated flow is 14.5m3/s. Three times larger than the estimated magma supply during the last months.

    I guess there is a difference in volume between magma and lava, since as magma rises to the surface, gasses will expand and a lot of gas bubbles will remain trapped inside the lava, thus increasing its volume. But what is the usual ratio between magma volume and lava volume? A quick search did not give an answer, but I’m sure some of you will have good answers.

    • I dont know what the standard is, or even if there really is one but the DRE of Holuhraun is 1.2 km3 while the actual bulk volume is about 1.5 km3. The same is roughly true for Kilauea in 2018. So there is a difference but not nearly enough to explain how an eruption is ongoing at 3x the recent supply rate while inflation is still occurring at the sill… The sill is too deep to degas anyway, maybe CO2 slowly but that only comes out in significant volume above 4 km depth and SO2 and H2O are under 1 km. Notably the fumarolic activity near the first opening of the eruption was pretty visible but the actual visibility of the fume is down to atmospheric conditions so probably happens as standard in the final minute. At Kilauea in 1952 it was heard at the Volcano House on the north edge of the caldera, which is about as far as the erupting fissure is from the edge of Grindavik for reference.

      This is also why I think the supply appeared low because the input of magma had to fight the pressure within the chamber/sill complex. After November which was a big drain the supply was 75 m3/s or more from the source for a bit. At Kilauea this sort of very high supply after large deflation and low supply when the volcano is under pressure is very well documented, so I would expect this to be a factor at all open vent fluid lava volcanoes. Im personally a bit doubtful that the eruptions at Sundhnjukuagigar will end before next year, the cumulative volume so far is about 1/5 of what I have seen estimated for the original Sundhnjukur eruptions and also for the volume of Eldvorp + Arnarseturshraun/Illhraun, both being about 0.4-0.5 km3 in volume and probably similar volume underground. 1 km3 of magma at 10 m3/s would take about 3 years.

      • So in the four years I’ve read this site and been absolutely engrossed by geology / volcanology, there’s still something I genuinely don’t understand. Perhaps a basic question, but I can’t wrap my mind around it.

        When discussing these volumes, it seems we’re always looking at the inflow / inflation rate to determine the maximum possible eruptive volume. Doesn’t that ignore magma that may be already sitting in the crust? Why is there always an assumed hard limit on the size of an eruption based solely on what is calculated to have entered the crust recently? Don’t various volcanoes have magma chambers that may have formed and filled to various extents long before recent decades where we actually became capable of observing inflation and such obvious surface / topography changes?

        How do we account for that? Or is the answer simply that we cannot, and measuring inflation and estimating inflow rates is the best we can do in lieu of knowing what’s already residing underground from before the era we could measure this?

        Apologies if this is a silly question, for whatever the reason I just haven’t been able to wrap my mind around it.

    • The reason could be that not all the supply was going into the sill. I expect the magma system could be larger, drawing a comparison with Kilauea it is possible that there is a large deep dike body where most of the supply goes to, possibly under Sundhnukur, and that at shallow level, the sill/sills emerge outwards from the deep dike. At Kilauea, the main magma storage seems to be a large deep dike body several kilometres tall and 60 of kilometres long. Multiple sill complexes are located above the deep dike and result in elliptical areas of inflation. But the largest rates of magma accumulation are those that have been estimated for the deep dike body:

      https://hal.science/hal-03049436/file/Cayoletal_science2000.pdf

    • The problem with stating flow rates in volume is that they depend on density. I assume that the rate is measured from the expansion of the lava field, so is thoroughly degassed lava. What comes out at the vent is a low density mix of lava and gas bubbles, a bit like shaken fizzy drink. So that may appear much larger. The outflow rates can be quite uncertain and if measured accurately (lava field), may refer to what came out days ago.

      It is however possible for inflation to continue while the magma volume decreases. Three reasons: it takes time for rock to respond to slow changes, the inflation is different for shallow and deep magma, and the density may change. If magma is rising, there may be inflation seen above it even when the total amount of magma decreases. And if volatiles come out of the solution, the magma volume may increase even though the total amount of magma decreases- another aspect associated with rising magma.

      My suspicion is that the last two effects play a role here, and that we are seeing the deeper magma being depleted in order to feed the shallow magma which feeds the eruption.

    • Awwww … the landfill refill.

      By the speed of filling that landfill I’m certain scientists will be able to really accurately measure the effusion rate, given the supposedly known volume of that spot.

      I also estimated that 14.5 m3/s equals to about my bedroom except 14 meters high, filled with lava to the brim and pouring that out every second. My mind still cannot comprehend.

    • My hat is off to them. More power to these innovative Icelanders.

      • A bridge of longboats…?
        Asbestos wasn’t banned in those days.

    • The residents of Kalapana might disagree, that place has been buried twice by Pu’u O’o and people moved back immediately after the lava diverted.

  3. watching this cam closely, I noticed the middle (smalles) vent is just pouring out a continuous stream of lava, rarely broken up with gas emission, it’s just oozing out in a bulge
    at 20:20+

  4. I have a theory. Assuming these vents are erupting the magma of the previous intrusions, that magma must be relatively low in dissolved gases. That magma had been outgasing into surrounding rock. Meaning the pressure of the system increased since the gases don’t just disappear entirely. And now those gases are pushing back because the fluid pressure is relieved. Hence the prolongued eruption and stable outflow.

    • And the continuous outflow pulls magma in from Svartsengi because of relative underpressure, and perhaps that also helps to keep the feeder tunnel open.

  5. A somewhat off the wall thought that may never have an answer but will amuse.

    The earth decides to move apart or squash together and earthquakes and volcanos happen. What, why? So large plates [continent] are floating on a fluid [magma] that has inertia with lots of zero’s in the number.

    But how?– a glancing blow from an impact would give rotational movement, inertia will cause bumping over time hence the earthquake / volcano result. Continents floating around and making trouble.

    But why here / now? – so could a direct hit set off waves [think stones in lakes] that start on the inside and move outward and quite happily through fluid [magma] but when they hit a hard surface, the outer mantle they are reflected. Then they are reflected so we get interference waves, which are higher peaks and lower troughs expressed on the opposite outer surface of the sphere [Fourier analysis type headache]. Is the why here down to an interference peak just happened to bounce hard into one of those land masses that was moving apart and broke through.

    Are we watching the echo’s of a glancing blow that sets up rotation and then the interference waves of a direct hit?

    I came to the conclusion that the only thing that had lived long enough to know this were stars – and that they weren’t good at talking unless you believe in horoscopes – which I don’t.

    Life is too short.

  6. Updated 360° view of the flow field, showing the lava flowing into the quarry. But I also noticed up the top and out of view the lava channel has become perched and quite defined, and has a surface of pahoehoe overflows. So the volume of stored lava is considerable now, a similar channel at Kilauea in 2007 sent a’a flows up to 7 km from the vent rapidly so things could move fast now if a breakout occurs.

  7. How close is Grindavik to a lava flood? The lava is running and running, but (for me) it’s uncertain how long the levees will keep the lava out of the village/town of Grindavik. The levee contains the risk that if it breaks, there can happen a sudden and voluminous lava flood towards the areas it protected before. I’d estimate that the greatest risk for a possible levee break is the point, where the levee changes from W-E to N-S direction

  8. Anyone care to estimate how long the current 5 fissure cones will continue to emit lava? 1 week? 2 weeks? 1 month? 2 months? I have seen some slight decrease in the gas content, but the vents are staying fairly active the past 4 days. See https://livefromiceland.is/webcams/thorbjorn2

    • The eruption seems to have decreased quite a lot over night, so perhaps a day or two at most. But then things can change in the other direction as well.

      • There is lava ponded over the vents so the fountains are drowned, and the cones have also got much bigger, so it is likely the output is unchanged

    • Today it releases a big gas and steam cloud:
      https://www.youtube.com/watch?v=8bfcTBLvPiM
      Is this a sing of strength or weakness of the eruption?

      Earthquakes above Magnitued 1.0 occured today along the whole way from Fagradalsfjall to Askja. Is there a “national” Icelandic tectonic movement connected to current volcanism near Grindavik?

      • Weakness. It indicates less heat coming out. It may be reaching the end

        • I agree, this might be an indicator that the ongoing influx at Thorbjörn might not be sufficient to maintain a constant eruption at the present position. If the conduit between sill and the eruption site, we might see fluctuations and an ON-OFF thing like in the first Fagradallsfjall episode, but if it clothes we’ll have to wait for 3-4 weeks for the next cycle.

      • Its probably because it is 2° and 75% humidity in Grindavik right now, the same intense steam clouds appear in summit eruptions at Nyiragongo, Mauna Loa and Etna, all where similar low temperatures are common.

        • Yes, I agree with you. Probably more related to current weather conditions.

      • It looks distinctly mucky now. Ash or change in the gas composition?

      • Carefully watching for over 15 mins, around 18:25 pm local Iceland time frame, I have witnessed new “white smokers or “white steamers” popping up in the lava field of the left middle foreground of the cones on the Husafel camera https://www.youtube.com/watch?v=8bfcTBLvPiM so something definitely is happening with the situation.

    • For all I know, it could die out tomorrow or make a 1 km3 shield. Arnarsetur eruption 1000 years age did start as a lava flood but had a sustained phase of pahoehoe lavas. There are also some young pahoehoe lavas from the Eldvorp area. It’s a good question, but I’m afraid I don’t know where this is going. One thing I’ll say is that the supply is enormous. Doing dike intrusions and eruptions at intervals of less than a month is beyond what Krafla or Manda Hararo did. I would like to see a volume estimate of all the lava flows and all the dikes intruded. That would give an idea of just how much magma is involved in this episode. I know the November dike volume was 0.13-0.14 km3, and that this recovered in one month.

      • The supply after the November dike, judging from how fast it recovered, could have well been 10 times the long-term supply of Kilauea and 100 times that of Piton de la Fournaise. Also, much higher than the effusion rate now. A 0.1 km3 dike is not something you erupt back from in a month. Kilauea’s dike intrusion at the start of February was probably smaller that the November dike of Sundhnukur, yet the volcano still looks spent.

        • There were a number of intrusions in the area over the last 5 years. It is possible that the eruptions are being fed from those magma intrusions

        • Kilauea has been quaking again for the past weeks though, similar to what it was doing late last year. Interesting that the expansion of the caldera has slowed at the same time while SDH has 20 microradian of uplift just visible on the 1 month plot, seems like magma is flowing into the SWRZ. The UWEV tiltmeter seems to roughly correlate to about 1 million m3 per microradian (shows how big the DI events are really) but I dont know what sort of correlation there is for SDH and the connector might be too diffuse to really make use of it that way anyway.

          • Indeed, the SWRZ episode continues. Though it’s only starting to swarm properly, so it will take a while.

          • I think April is a good time for next significant intrusion, three months after the major (and very voluminous) intrusion in January. Maybe Kilauea waits until Grindavik ends?

            Apart from Iceland and Hawaii, I miss Etna’s activity a bit. It’s been a long dormant period for Etna since last eruption.

      • Did Arnasetur erupt in one single steady eruption or in a series of many episodic eruptions as Grindavik saw them since December?

        • As far as I can tell, Arnarsetur was a single flood that grew a short-lived shield around the vents. Arnarsetur did probably follow the Eldvörp eruptions. Eldvörp erupted multiple times given that it has overlapping sheets of lava from successive eruptions (can be seen in Google Earth or ArcticDEM), although there are not that many. I think maybe 2-3 events, though I would need to check more closely. There could also have been small early eruptions that were buried by larger later eruptions. Then another dike formed offset from the others that made the Illahraun and Arnarsetur lava flows in a sort of culminating event of substantial volume. I had assumed though that the sill deflated throughout all the Arnarsetur eruption, but maybe this was wrong assumption.

  9. https://www.facebook.com/share/p/hDAitmvyGPZQ91Tp/?mibextid=A7sQZp

    From about 3 hours ago apparently. There seems to be a defined lava channel now even with pahoehoe overflows. The channel makes a near right angle turn to go towards the quarry too which might mean the flow direction could change abruptly at some point and go back down towards the ocean the expected way. The cones are getting pretty big now about as big as any of the pre-existing Sundhnjukur cones, will be interesting if this is an actual sort of trend and the eruption stops or changes character, or if this time is just a different style altogether. Im more inclined to the latter, seems no obvious reason why the eruption should stopso suddenly now.

    • My best guess is steady state for the next 2-3 weeks, then perhaps a change. Most of the GPS elevation readings show stability, but 2 or 3 showed a slight rise yet in elevation (apparently still seeking a static balance?)

      • Small changes are impossible to see with the eye. It’s possible that the eruption has already decreased a bit, but this needs professional observation. IMO has so far not noticed a decrease.

        • ??? I am not sure of what you mean “small changes are impossible to see with the eye”? I think we can record the camera video from the Iceland cameras and do a compare. I have seen the eruption vigor diminish.

          • Eruption vigour isnt really a good judge of the actual eruption rate when the vents are being submerged by lava ponded above them. The same thing happened at all of the Fagradalsfjall eruptions where it was always claimed the eruptions were slowing gradually but the lava flows and pond around the vents were pretty constant up until within a week of the end. Even in 2021 the fountains peaked in mid May 2021 and became episodic which lead to suggestion the eruption was ending and yet it ended up lasting another 4 months and the lava flows later on were more extensive than earlier too. The actual end was very abrupt too, and it wasnt even clear if it was actually over for weeks later really.

            If the lava pond starts freezing up without a lava tube forming then that is what I am looking for to show a decline. The eruption seems to be just getting more centralized to the two uphill vents where the large cones are instead of the long fissure.

          • A weak decrease of the output rate can’t be measured just by watching the Webcams. You need more professional scientific tools …. that IMO’s scientists have. I don’t know how they get their values, but they are valid unlike laymen’s feelings.

        • After reading the posts further down in the thread, it was volume rate that was referred to, not vigor of the busts. I agree with you that it is almost impossible to gauge flow rate changes by eye.

    • That is a fantastic shot. It put everything into context about the location and size of the flow. You can even see how close Fagradalsfjall is! Applause for whoever took that shot and annotated it.

  10. ( … Switching through the webcams I came along this spooky one:

    This is Búrfell. Or a just another demon … )

    Source: /watch?v=mXyOJpz6zeA

  11. Húsafell still shows a vital “Highway of Hell”. Maybe the decline of eruption force is slow currently. 21st March the eruption had a higher rate (14.5m³/s) than Fagradalsfjall (around 12m³/s). If it decreases slowly, it still has a long way to got until it dies.

    • In the Icelandic news IMO has published this series of photos taken by Civil defensive (?) webcam. The webcam looks from Hagafell over the lava field to Grindavik:

      “Melholsnama” is the shallow valley between Grindavik and Hagafell that has been filled with lava now.

    • All of the reasons I have seen for the eruption decreasing seem like either the lava pond rising and drowning the fountains a bit alongside the growing cones. Or it is weather related, which includes the SO2 which is very hard to measure in anything other than still air. Not to say I know better than the volcanologists of course but the eruption doesnt visually look anything like when the eruptions at Fagradalsfjall were erupting at the rate that is being claimed of recent. 4 m3/s is in the range of tube fed pahoehoe the eruption now looks a lot like the one at Litli Hrutur which was sat about 20-15 m3/s. So likely at that rate still.

      • The last number by IMO was 14.5 cubic meters per second on 21st March. It’s difficult for us to estimate the rate without scientific tools and methodological knowledge. We can only speculate about the development of the strengt.

        The volcano has flooded a stone pit (Melholnama) which now only allows the use of liquid stones …

  12. To compare the current eruption with the size of Holohraun I’ve looked for IMO’s report on September 7th 2014:
    “Magma flow is between 100 and 200 m3/s. The lava advances by about 1 km/day and its area yesterday afternoon was around 16 km2.”
    “The lava tongue now extends 11 km to the north and has reached the western main branch of Jökulsá á Fjöllum river”
    The extent of Holohraun’s lava field on 7.9.2014:

    A very different dimension of an eruption! The current eruption has a rate of ~10% of Holohraun.

    • I think you are comparing apples and bananas here. The magma in Bardarbunga had accumulated for quite a long time and originated from a hotspot. When magma intruded the dyke, the lid of the caldera acted like a piston and squeezed it out, hence the enormous volume and eruption rate.

      Here, we are seeing a fissure eruption originating from the mid ocean ridge. And for this type of volcanism the volume involved is quite large. We have seen 3 eruptions in a row at Fagradallsfjall and 4 eruptione at Svartsengi in less than 3 years. That’s quite substantial, I’d say.

      • I just wanted to compare the quantitive dimension, to get a feeling of the size of Grindavik’s effusion during the current episode. Also after nearly 10 years it’s time to remember Holohraun … Vatnajökull’s last eruption.

    • Leilani 2018 and Holuhraun 2014 are the two great hotspot lava floods during my lifetime, they both produced around 1,5 km3 of materials, very impressive in speed and apparence, Leilani had sourges of many 1000 s of cubic meters a second, large spectacular events that was going on for a long time with substained high eruption rates, hard to imagine that both hotspots have made similar past events that was 20 times bigger before modern history in Iceland and Hawaii. Galapagos have also made some enromous past mafic caldera collpases

      Im incredibley busy healing a broken bone, looking for career and screens makes me nearsighted so I avoids VC and screens overall are very addictive and thats the problem

      • So nice to see you posting again Jesper. Very many best wishes for faster healing now.

      • Very busy preparing my move to Iceland plan as Nordic Citizen, but first I really wants to find a career, job skill path so Iceland gets easier once I gets there, to be prepared as possible. But I have not gotten very far, not soure what I wants to do in life and the job market is hard in rich countries. Not everyone but almost lmost everyone in Nordics in younger years have high academic degrees and some majority of the adult population are millionares or even multi millionares, we are so very highly educated in Nordics that none in my family circle and in life friend outer circle have less than a beachlor and most of pepole I knows in person haves master degree. And even non academic jobs yeilds a more or less middle class living standards, and even most of these jobs requires requires years, years of voucational theory school training. Nordic countries like mine and Iceland are on per person avarge a phenomenaly rich and well educated well litterate population, I think only South korea is more academic and in a decade or so we nordics here will be just as litterate as them. So the job market is incredibley hard in Nordics, the only reason i wants even try for a career is that Im basicaly free Icelandic citizen as swedish resident, so i wants to find something that I can show up in Iceland. I think Nordics are the best countries to live in with cost free education, cost free healthcare and a good social saftey net and on avarge the worlds highest wages, but the job market feels almost impossible without spending 30 years in school we Nordics are “ultra first world economies”so the worlds elite. Even low skilled jobs also yeilds a good living, althrough its typicaly not whats easy to get here and in Iceland. But voucational euducation is usaly something that works everyhere, so im strongly looking into something like that. My grades are good, and possibilities are many but very unsoure what work skill that suits and not suits me, and the job market is hard in well developed countries like mine and Iceland. And I have no idea if my IQ is enough for complicated training…the possibilities are many for me, choices many, but many are hard to do even if I have degree reguirments for the schools. As told I strongly belivie in skilled voucational education but hard to chose what kind of work that suits me, but its easier than spending half a decade at university.

        Yes I really really really wants to move to Iceland thats gone hyperactive during a volcanic rift cycle, the lurid idea having an apartment room beside the volcanic night glow. and Im myself is basicaly almost free Iceland citizen, so Im desperately looking for a work skill, so I can have something to show up in Iceland, althrough probably needs to learn that speech thats not the same as mine as Icelandic nordic speech been isolated compared to Scandinavian mainland so is widley divergent compared to danish, swedish or norweigan. Everyone speaks english here in Nordics but learning the native speech is an enormous job perk.

        Just the mind tought of having a home in Iceland and visiting eruptions at free time and Im basicaly citizen it is an immense rabbit hole, its simply too good to be missed really, its so very close, yet feels so distant, yet its so very possible for me. Its consuming me, so once I have my puzzle pieces I will go instantly to volcano land, but its kind of slow. I hopes to get the ball rolling soon. So thats what my mind is focused on… finding a way to Iceland, and Im basicaly free resident! So Im very busy

        • I hopes to do Iceland very soon, so possible and so close.. but what I should work with is very diffuse no idea..and many work skills are hard, but possibilites are many for me.
          So Im very busy

        • Finding careers in countries as rich as mine and Iceland are next to impossible but I wants to try really and education is free too

          The allure of living in Iceland is simply too tempting and Im free residence

  13. If I had to guess the lava output is at 8-11 cubic meters per second now. The eruption is certainly being fed by the failed magma intrusion on Nov. 10 and likely 3 to 3.5 cubic meters per second of magma from the upper mantle feed. Over the past 3 months the upper mantle feed is nearly unchanged at around 400,000 cubic meters per day of magma according to the IMO as of 2 weeks ago that I seen on Shawn Willsey’s livestream on youtube. I don’t see this eruption ending unless the lava output drops below 3 cubic meters per second. Even if that happens though it’s possible that new fissures open up along the dyke and a good indicator would be inflation seen on GPS data on or near the dyke.

  14. Is the eruption rate decreasing? What we see now on the surface is firstly partly hidden by the spatter cones that have built up and secondly is now pushing through an extra ~16m depth of lava to produce what we can see. It makes me wonder how much being produced hidden under the top of the lava.

    Also while the extent is growing very slowly the depth is increasing as each layer on lava add to the next.

    Production wise though, Fagradalsfjall did fill up several valleys to quite a depth, so there is a lot of lava over there for this one to catch up to….

    But is it just me or do the 8hr GPS look like the inflation is flattening out?

    • It may be flattening out, but the last few points are a bit all over the place, so there isn’t really any sort of obvious trend at the moment.
      If it is flattening out though, is it because an increased transfer rate to the dyke, decreased supply rate or due to extension of the reservoir?

    • As often in science it’s very difficult to get interesting valid statements, but always easy to get informations slightly above “knowing nothing”. Even good science usually makes statements with probabilities and uncertainties.

      Today the erupting cones in the Húsafell webcam look weaker than yesterday, but it’s indeed possible that a part of the lava effusion moves directly into tubes below the cones. How many cones are still acitve? On the Sundhnúkar webcam I count five cones. Two of them on the left hand tend to become the major vents. They do nice lava waves like a wave machine in a swimming pool. Until now the eruption hasn’t created a monopoly cone. I’d expect this before the end of the eruption.

      • He was really pushing it there, didn’t need to go that close!

        • Isak said he thought it was a bomb. But I wonder… How long can an FPV drone really survive in that sort of heat? Sensitive electronics and lots of plastic…

          Feel real sorry for Isak, he seemed gutted although he tried to not show it! But there were quite a few like 20 euro tips in a row there, so maybe he can get a new drone.

        • I agree Andy. He pushed his luck to the limit and the luck deserted him! He flew across the top of one cone that spattered up and just missed his drone, then he very strangely turned straight round and went back for a second try, when that cone erupted just as he was flying over it the lava spatter caught his drone. He really didn’t need to do that. I blame too many people who wanted to see the cones close up! Personally I am more interested in seeing where the lava is going that watching cones splatter out lava. I feel really sorry for him though as that is now the second drone he has lost in a matter of a few days
          now.

  15. GPS now showing clear recovery but at the rate it’s going it would take a couple of months. I’d expect the eruption to die off within the next week first and then we’ll see inflation start to increase.

    • Sundhnúkur webcam currently shows five active cones (are more active outside this view?): https://www.youtube.com/watch?v=rEMz0hwyfFs
      Two on the left side are becoming the dominating cones. Maybe there the eruption will build a “monopoly” of one cone which erupts until the end of the eruption (or the next magma pulse). Until now no cone has risen significantly in height. Fagradalsfjall built an impressive cone 2021. Maybe Grindavik’s volcano also can do this.

  16. To continue the Title of this article, Mars like Earth hosts a Grindavik. On Mars it’s an impact crater with 12 km diameter. It was named after Iceland’s Grindavik, but I don’t think as an exile during a volcanic crisis: https://en.wikipedia.org/wiki/Grindavik_(crater)

    On Vatnajökull Bardarbunga is currently seismically much more active than Grimsvötn. Is there a reason for this?

  17. I created my own timelapse video, more is going on on the current fissure eruption than we realize. See https://youtu.be/-PeZQtGEwfQ as the appearance of volcanic smoke around the 45 sec mark is telling.

    • Thank-you for the work on the timelapse video, Randall! It shows well the steady activity of the “volcanoes” and how daylight hocusses the human eye. When it’s getting dark, the lava effusion/fountains become more visibly.
      If I look on the night webcams currently, I don’t notice a significant decrease of activity. We have to wait for IMO’s next quantitive calculation.

  18. Curious – what’s the source of the yellow glare & smoke visible below Thorbjorn but north of the berm on MML’s Grindavík, varnargarðar cam? Something burning?

  19. The Svartsengi, Skipastigshraun and hs02-site crustal deformation (gps) readings have all trended upward at the same new rate (more mm/day) recently. I used to think perhaps lava would erode pathways or make the openings bigger. Maybe it does or has in some instances, but can magma also leave plaque/residue that would restrict flow? I didn’t time the increases in inflation rate with the smaller cones shutting off but I guess it could have been that. I don’t think those vents were flowing enough to cause that increase though. If the eruption continues to taper off to zero and inflation returns to its pre-eruption rates, that will answer a lot.

    • Maybe this was an attempt to create a more permanent vent, which will probably stop before the sill reinflates enough to open a new fissure. But the fact this one lasted past the initial stage for so long would suggest future eruptions will do so too should this one stop.

    • The lava that is between the new lava and Fagradalsfjall is Dalahraun, so apparently not at least not yet. The new lava so far has mostly just buried the older Sundhnjukshraun which maybe isnt too surprising being that it originates from the same place. It is not unlikely most or all of the land between the fissures and Fagradalsfjall will be buried eventually though.

      • The current eruption began on March 16th. If we count 20 days from then, the next wave of magma is possible around April 6th. Maybe then the lava field will hurry to expand fast to locations, where at present no lava has been added. The next wave of magma may rise through the conduit silently without any warning. It’s open now. The current erupting cones have open paths towards the sill (magma chamber) and can show the heartbeat immediatly like deep rooted lava lakes (f.e. Kilauea 2008-2018) do.

  20. Today since 8 o’clock Icelandic time, Askja has major earthquakes at “Lokatindur”. Is it a swarm or an ordinary earthquake with aftershocks? The depth of the earthquakes is around 3-4km. The location is on the NW side of Askja on the caldera rim. Is it an earthquake on the caldera ring fault?

    • I’ve looked for the GPS stations on https://gnss.vedur.is/
      While the station JONC close to the NW rim is unremarkable are Station OLAC shows a significant change recently since March 10th:

      • OLAC is on the western shore of Askja lake (Öskjuvatn). There was the center of uplift 2021.

        • The earthquakes happen on the caldera rim, possibly ring fault earthquakes: https://skjalftalisa.vedur.is/#/page/map
          At the same time the central GPS station of Askja caldera observes significant inflation. It is the same location, where 2021-2022 most inflation happened. Maybe there does something continue after a break. It’s possible that Askja does Fires like in the 1920s, but that they’re preceded by intrusions like today and around 2021. The longterm deformation graph shows the inflation since 2021. There was a pause 2023, but since March 20th inflation went sharply up again:

        • According to the Catalogue of Icelandic Volcanoes Askja has “an established shallow (2-5 km) magma chamber”. It’s the depth where the earthquake have occured today. So it’s likely connected to magma movements, but uncertain where the magma aims to.

          1920 to 1930 was a sequence of “Askja Fires” with five eruptions within ten years. If Wikipeadia is correct, they happened on the ring fault. This would indicate that possible intrusions can go from a central magma chamber directly to the ring faults and intrude/erupt there.

    • Certainly not an ordinary EQ with aftershocks; the largest event – M3.5 – came towards the end of the sequence, not at the start.

      • As you might expect from adjustment to an enlarging magma chamber

  21. The line of quakes along the west side of Fagradalsfjall is still active, even without the pressure of the sill at Svartsengi pushing on the area, so I am somewhat doubtful these are pressure quakes now. Fagradalsfjall is due to erupt around the middle of the year if it holds to the trend it has been going on, this area might well be where the next eruption happens. Or at least if not so soon then it is somewhere to watch for the next few years.

  22. Unusually strong quakes close to Lokatindur on the west side of the Askja caldera. Common with auakes in this region but not so strong. Nothing on tremor charts yet

    • Oh I really like that eccentric!
      Thank you so much for that link. I was watching lava last night heading for that area on the Grindavik varnargarðar cam. Thanks so much for the link to this cam. Although not video but static photographs it certainly shows what is happening in an area otherwise uncovered by video cams!

  23. The imo says that the eruption has subsided over the past day or two. Now in Fagradalsfjall 2021’s eruption, the lava output dropped from nearly 8 cubic meters per second to 4 cubic meters per second in the first 15 days of the eruption leading up to the new fissures opening https://jardvis.hi.is/is/fagradalsfjall-26april-2021 . After the new fissures opened in early April, a slow upward trend in lava output began to occur over the longer term trend https://jardvis.hi.is/is/fagradalsfjall-29-juli-2021. Now, it’s possible this decrease in activity leads to an end, but with the upper mantle feed and Nov.10 failed intrusion feed I think it’s slightly more likrly than not this eruption will continue for the next few weeks to months ultimately with a lava output stabilizing somewhere 4-10 cubic meters per second after the first month of this eruption. I also think that just like fagradalsfjall 2021 eruption, it’s possible that these original fissures will slowly decrease in intensity in the first 3 weeks and new fissures will open up once magma supply overtakes lava output.

  24. Significant outgassing occurring today, but over much of the fissure flow field. Apparently some gas emission is occurring in the field over to the extreme right, off the scope of the camera. See https://youtu.be/fTKY-Tkh1to. The outgassing needs to be monitored for a possible trend.

  25. To all:

    I recently posted a (sarcastic) post regarding earthquake hypocenters to the +/- 1 meter depth location. There were some who misunderstood my post and really took me to task. My attempt at sarcasm spectacularly failed.

    I contacted a seismologist with recognized credentials in the field, Professor Anthony Lomax, who, along with others, released a key scientific paper titled “High-Precision Earthquake Location Using Source-Specific Station Terms and Inter-Event Waveform Similarity” see https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2021JB023190

    Professor Lomax has his home page http://alomax.free.fr/science.html

    He was kind enough to respond to my email and ( I will summarize ) replied:

    > My question to you is this, can we actually determine the hypocenters now to ± meters location?

    His reply: Not for a regional network covering an area like Iceland.

    > I was told by 2 people that the cross velocity profile was the limiting factor in ALL such hypocenter determinations, but I would think that once we have been able to establish accurate velocity profiles, our determination can be accurate to the meter level.

    His reply: Yes, the errors in the velocity models used to get seismic wave travel-times between the hypocenter and the stations is one of the main sources of error and bias in earthquake location. Another source of error and bias is having too few stations poorly distributed around the event. For a regional network this error or bias can be the order of 1-2km for epicenter and several kilometers in depth. This is the absolute error relative to geographic features.

    I am posting this, so that no one misunderstands my posts and yes, I will try to not post hard to understand sarcastic posts anymore. I regret the angst that my post caused.

    Thank you for your patience with me.

    Randall

    • Yes, you were so sarcastic about it that you had to keep on repeating yourself in several replies and then apparently reach out with your question to an independent professor to verify the level of sarcasm.

      That’s a bit of sarcasm if you didn’t catch it.

      You got pretty much the same replies here as you got from the professor. You kept on trying to make a point that IMO had changed the way they report quake depths. I tried to say that they haven’t really, you only found a new place to get your data, but you ignored that. If you look at vafri.is/quake and click on a quake on the map to bring up the detailed information, you will find that the depth is given with three decimals. This is because that page also gets its information from the skjalftalisa API, and that API has always reported the depth rounded to three decimals. IMO didn’t change a thing as you so persistently insisted. Here’s a screenshot from November:

      https://www.facebook.com/photo/?fbid=10161205535007662&set=g.887053998798488

      If you really mean to be sarcastic and people misunderstand you, then say so immediately instead of keeping it going.

  26. I am re-reading this article and really do appreciate your explanation of how height is calculated on Mars. I have spent the past week digging deeper into the changing attitude about altitude and, while I completely understand the motives behind the way it’s done now, it has driven me batty looking through the various sources for volcano summit elevation data trying to figure out if it’s derived using the new +/- areoid, the old datum with hypethetical-sea-level, or if it’s just relief above local terrain. Then I go into wondering how the latter is calculated. Do they use key cols or is it based on average terrain elevation within a certain distance of the volcano. Basically I have a million nerdy questions about how “geographical” data has been standardized on a non-Earth body. If any of you wants to write an article about that sort of thing, you’ll have at least one reader geeking out about it.

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