Trouble in Paradise: awakening Mauna Loa

An eruption has started at the summit of Mauna Loa. It has been a long wait! The inflation over the past month was notable, though not exceptional, but it was the drip that made the volcanic bucket overflow. We now need to see what happens. Commonly, eruptions migrate down the rift zone, in this case most likely (but not certainly) towards the southwest. But it is also possible that the eruption will be a smaller one which remains in the summit region. We will add information as it becomes available. Below, we republish a post from 2016 on Mauna Loa


 Radar image of Mauna Loa taken from space shuttle Endeavour in 1994. Colour indicates surface roughness, where red is smooth  (pahoehoe lava) and white is rough (a'a lava).  source: JPL

Radar image of Mauna Loa taken from space shuttle Endeavour in 1994. Colour indicates surface roughness, where red is smooth (pahoehoe lava) and white is rough (a’a lava). source: JPL

Mauna Loa keeps paradise interesting. It has erupted 33 times since 1843, with large eruptions happening on average once every 8 years. Over that time it has covered its slopes with 4 km3 of new lava. But those are just the most recent stirrings. Its older lava flows cover over half of the island of Hawaii. But after the large eruption in 1950, Mauna Loa became remarkably quiet. There have been only two eruptions since, one of which (1975) lasted less than one day and was the second smallest eruption of the 20th century. There was one significant eruption in 1984, but nothing since. But now the largest volcano on Earth is stirring. Inflation shows that magma is accumulating, just south west of the peak. Earthquakes are a daily occurrence and HVO has raised the alert level. There is trouble brewing in paradise.

Mauna Loa is the world’s second tallest volcano on Earth, after Mauna Kea. It started 5 km below the sea, taking perhaps a million years to reach its current height of 4.17 km above sea level. The total height, from base to summit, is therefore over 9 km, more than Mount Everest. To compare, the highest volcano on Earth is Ojos del Salado, on the Chile/Argentina border, which reaches 6,893 m above sea level. Mauna Loa is slightly cheating since the part that is under water benefits from the upward pressure from the water – it floats a bit. I can correct for this, and calculate how high a mountain would be that has the same pressure at its base, without the aid of water: this reduces Mauna Loa by 1800 m, and gives an equivalent height of 7200 m, almost the same as Ojos de Salado. This may not be entirely accidental. There is only so much weight a rock can bear, and both volcanoes will consist of very similar types of rock at their base. Rocks at the bottom, 9 km below the summit, are in danger of being crushed by the weight. On Mars, gravity is three times less and the same weight corresponds to a mountain three times taller – 22.5 km tall. In fact, Olympus Mons stands 22 km above the surrounding plain, almost exactly this number. So it seems this is indeed about the tallest a volcano can get. Mauna Loa and Mauna Kea are almost the same height, differing by only 24 meter. They are running into their limits.

Although it is slightly lower, Mauna Loa is a lot bigger than Mauna Kea. Mauna Loa is a shield volcano: its fast flowing lava has spread far, building a large mountain with a shallow slope. It is much wider at its base than Mauna Kea, has much more volume and therefore much more mass. Mauna Loa, the largest volcano on Earth, is so large, it is very hard to see. You can’t see it above the horizon: it IS the horizon. I remember reading the story of someone in Africa trying to chase an elephant out of their garden at night. In the flash light she failed to see any elephant, just the greyish sky. Only then did she realize the sky was the elephant, so large the eye couldn’t see it. Mauna Loa is this proverbial elephant. The only place from where you can get a good feeling for its tremendous size is from the summit of Mauna Kea (not an easy place to get to either.) From here, at night sometimes you can see the distant, angry eye of Pu’u’O’o, but in the day Mauna Loa dominates the sky line. (Unexpectedly for an astronomical observatory, you can’t see the stars that well from Mauna Kea. It is too high and the eye and the brain are badly affected by the lack of oxygen. You become half blind and too dim to realize.)

Mokuaweoweo crater, with south west rift in the foreground

Mokuaweoweo crater, with south west rift in the foreground

The top of Mauna Loa has its crater, called Mokuaweoweo Caldera. It consists of three partly overlapping craters, of which the central one is the largest. Together they are 6 by 2.5 km in size. The caldera isn’t that old. It formed because of a large flank eruption which emptied the shallow magma reservoir. This was the eruption which formed the Panaewa flow field, which Hilo is build on.

 Lava flows from Mauna Loa. Hilo is front centre, Mauna Kea right. Red and orange are flows since 1832.

Lava flows from Mauna Loa. Hilo is front centre, Mauna Kea right. Red and orange are flows since 1832.

Mauna Loa is a very elongated mountain, much longer in the south west-north east direction. In fact, the name Mauna Loa means ‘long mountain’. The long ridge follows a double rift zone. There is a caldera at the top (showing the mountain used to be a little higher); the rifts extend from the caldera towards the south west and towards the east, running from the south eastern point of Hawaii to (almost) Hilo, a distance of close to 100 km. The south west rift bends by 40 degrees where it reaches an altitude of 2400 m. At this point a number of eruptions have build a satellite shield.

Mauna Loa eruptions tend to begin near the summit, but quickly migrate to the rift zones, down slope. Both rifts can erupt anywhere along their length. Individual rift eruptions can occur along a section as short as tens of meter, to a staggering 20 km (as happened during the large 1950 eruption). Individual eruptions typically last a week, erupt 0.2 km3 of lava and cover 20 km2. The lava moves fast, covering up to 5 km per hour on the steepest slopes, and can reach the sea (on the west and south side, at least), in less than a day.

>Map showing areas covered by `a`a lava flows erupted during the eruption of Mauna Loa between March 24 and April 15, 1984. Source: HVO

Map showing areas covered by `a`a lava flows erupted during the eruption of Mauna Loa between March 24 and April 15, 1984. Source: HVO

The 1984 eruption is a good example. It began three years earlier, with slowly increasing earthquake activity, culminating in an M6.6 event. About 5 months after this, 25 March 1984, the eruption began, after 2 hours of tremors, initially at the summit, but within hours the eruption migrated first to the south west rift zone, changed its mind and moved to the north east rift zone. A few hours later, lava curtains erupted 7 km from the summit, and later that day, the eruption moved to a 2 km section 10 km from the summit. From here lava flows quickly advanced to Hilo. Eventually the flow reached a length of 30 km, coming to within 7 km of Hilo. As the eruption diminished, the active lava stayed closer to the point of eruption. After some tense days, the eruption ended on April 15.

Hawaiian Archipelago: trail of a hot spot

Hawaii is at the end of a long chain of islands and sea mounts. Close to Hawaii are the Windward islands, or Hawaiian archipelago. Further away are the Leeward islands, terminating near Midway. Beyond that, the chain becomes a series of sea mounts, which makes an angle of 120 degrees with the other chain: these are called the Emperor sea mounts (named after Japanese emperors). The mounts get progressively older further from Hawaii, with the oldest one about 80 million years. The chain terminates at the Obruchev Rise, very close to the Aleutian subduction trench, where it meets Kamchatka. There may have been more, older sea mounts, now subducted into oblivion.


The Hawaiian chain is the type specimen of a hot spot chain. The hot spot is supposed to have been stationary or near stationary, while the Pacific plate drifted over it. The sharp bend in the chain shows a sudden change of direction of the Pacific plate, about 45 million year ago. Previously, the plate was going north, but now it is moving to the north west. What caused this change? That is not really known. It happened at about the time India collided with Asia, and perhaps this is related although that was quite a distance away. It may also have been caused by the onset of subduction along the Asian plate boundary. After the change of direction, for a few million years no islands were formed.


Hot spots may come from plumes deep into the mantle, or they can be shallower, affecting mainly the upper mantle. Opinions differ. In the case of Hawaii, seismographs, used to map out the mantle, have detected the hot region to 1500 km depth, perhaps more. That is half the depth to the core-mantle boundary. It seems likely it extends to the bottom of the mantle. It came from the deep. But other data do not agree, and a more recent study has only found a pancake of heat, underneath the crust, not extending into the deep.

In any case, not all the lava it erupts comes from the deep mantle. It seems that over time, Mauna Loa has erupted a decreasing fraction of 3He, and that is a sign that a fraction of recycled crust is being included in the magma. Perhaps as the hot spot is moving away (and Mauna Loa is no longer directly over it, as it was when it began), the magma includes an increasing amount of shallower melt.

How and where did the hot spot get started? Its origins have sadly been lost in the subduction trench. Or perhaps not. Could the hot spot have started at the Obruchev Rise? The Rise is near an old spreading centre, abandoned in the Cretaceous when the centre jumped north. The ridge was at the western edge of the Fallaron plate, which has since largely been subducted underneath America. This puts the hot spot, at its earliest known location, directly underneath this spreading ridge. Much like Iceland! Did the spreading centre start the plume? Or did the plume split the plate? This is solidly in the realm of speculation. But it is interesting to think of tropical Hawaii starting off like Iceland. Perhaps there is hope for Reykjavik.

During its 80 million year history, the eruption rate has been remarkably constant, at about 0.015km3 per year. For comparison, over the past 200 years the eruption rate has been about 0.023km3 per year from Mauna Loa. Kilauea’s eruption rate should be added, which doubles the amount. So the current rate of activity is a bit above average for the hot spot.


Volcanoes provide a very temporary surface and are not the best place to build expensive structures. A good example was the Etna volcano observatory, build too close and unfortunately destroyed by the lava they were trying to observe. They wisely relocated to Catania, for safer viewing. It is surprising to find a scientific institute located near the top of Mauna Loa, and even more surprising that it is not there to study the volcano. The Mauna Loa Observatory studies our air and our Sun – not the shaky ground underneath their feet.

>The Mauna Loa Observatory. In the background is Mauna Kea - Mauna Loa is behind you.

>The Mauna Loa Observatory. In the background is Mauna Kea – Mauna Loa is behind you.

The Observatory is located 5 km north of the summit, 700 meter below it. It is so high up in order to stay away from any pollution (natural or otherwise) coming up from below. The inversion layer in the atmosphere normally keeps that locked up. The air comes in from the sea, again as clean as anywhere on Earth. It is an ideal pace to measure how our air is changing. Since 1956 the amount of CO2 in our atmosphere has been measured. There are several places around the world where this is done, but Mauna Loa has the cleanest record. The buildings, offices and domes are build on stark, black lava fields and even after 50 years, gives an impression of a temporary incursion in an unforgiving land. The total lack of any vegetation is an advantage, as plants affect the local CO2. The famous Keeling curve, showing how rapidly we are changing our atmosphere, is measured here, a monument to our fragility and willingness to take inordinate risks. It fits the environment, but if Mauna Loa were to erupt this direction, the scientists may only have an hour to get away. There is also a solar observatory here. In general, only astronomers put their most expensive instruments on top of active volcanoes. A certain disregard of the world they live in may play a role. There is a massive astronomical observatory on Mauna Kea. Again, their only access road goes over the recent flows from Mauna Loa. One could question the wisdom of building the one escape route where it is most likely to be cut off.

The Keeling curve

The Keeling curve

The mid-life crisis of Mauna Loa

I mentioned that Mauna Loa seems to be losing its hot spot. How do we know? Part of the evidence comes from the changing isotopes, the reducing fraction of 3He compared to 4He. But there is a more direct indication. Mauna Loa has stopped growing.

Mauna Loa’s lava covers half of Hawaii, to the coast and into the sea. The eruptions still often reach the sea, at least on the west side of the island, but they only rarely reach the Hilo area, even though this area is entirely build on Mauna Loa’s lavas. Over the past 100,000 years, the lava flows have not been as vigorous and have not reached as far as previously. Still, Hilo should not be complacent. In 1880 lava reached with 2 km of Hilo Bay.

How far lava can flow depends on the cooling rate. The flow stops where the lava solidifies. The higher the flow rate, the slower the cooling (large bodies stay warm for longer), and the further the lava flows reach. This process is very clear in Kilauea. When the eruption rates go up, the lava flows extend, as they did last year. When they decline, lava stays closer to the point of eruption, mostly less than 5 km this year. Holuhraun did the same thing: when the flow began to diminish, the flow field stopped expanding. Lava from Mauna Loa now rarely reaches Hilo Bay, perhaps only once per 4000 year. It mostly stops 5-10 km from Hilo. One flow did cover the entire urban area and the bay, perhaps 1000 year ago, but this one erupted from a vent very close to Hilo to begin with. Most of the lava now flows closer to the rift, and less lava reaches the sea. This makes the mountain grow steeper: it is beginning to enter its post-shield phase. This may be related to the growth of Kilauea, competing with it for lava resources.

The weight of the mountain pushes the crust below down. The whole island subsides, at around 2 mm per year. So far lava deposition has just about kept up with this, but it may not for much longer. The baton is being passed and Mauna Loa will sink.

The 30-year silence of Mauna Loa has coincided with the continuing eruption of Kileauea at Pu’u’O’o. This eruption started in 1984 and is still going. But eruption rates have slowly declined. The central crater of Kilauea shows inflation and this may be due to an ebbing flow through to Pu’u o’o. It is argued that Mauna Loa and Kilauea are separate volcanoes, from two different hotspot tracks, Kilauea connecting to Mauna Kea. This seems less likely, and although the feed systems are not identical, they are not independent either – they are too close together. The question will be settled soon: if they are independent, a Mauna Loa eruption would not affect Kilauea. If there is connection between them, you would see Kilauea changing when Mauna Loa erupts. Will in the future Kilauea take over and rival Mauna Loa in size? Perhaps they really are too close. There is another candidate waiting out at sea, which is more likely to become the next giant.

Towards eruption?


After 20 years, activity underneath Mauna Loa resumed in 2004, with a series of deep earthquakes. The mountain began to inflate at the same time. Things calmed down again, but in 2014 earthquakes moved to shallower levels, and inflation increased. Magma is now accumulating at 3-5 km depth, below the south west rift. Activity is continuing at an elevated but non-critical level: it has all the appearance of building up to an eruption, but it does not appear to be imminent. Will it be a year, five years, longer? After the previous burst, in 2004, nothing happened for a decade. The current episode could equally go off the boiler. But the magma is now shallower, and the inflation more focussed. This is beginning to look as if it is closer to deciding to erupt.

Inflation and earthqauke activity at Mauna Loa. Source: HVO

Inflation and earthquake activity at Mauna Loa. Source: HVO

An eruption is likely to start within hours of strong tremors. Initially it will be close to or at the summit, before rapidly migrating. As the current inflation is a little south west, the most likely migration is in this direction. The lava could flow either side of the ridge. For a normal-size eruption, Highway 11 will be cut within one or two days, possibly at several locations if the eruption is large, and lava will flow into the ocean shortly after. Judging from the time line of the various flows since 1843, Kealakekua Bay would seem next but this is guess work – Mauna Loa does not work like that. As the magma chamber empties, the risk of larger, possibly damaging earthquakes increases. The south side of the mountain is prone to slipping and the risk of this increases when the pressure changes. Conversely, earthquakes can also affect internal magma flows and an earthquake can hasten or stop an imminent eruption. The double 1868 earthquake (M7.1, M7.9) disrupted the magma supply for decades.

Purely based on the past record, there is a 50% chance of an eruption within 8 years. I would expect something within a decade, most likely from the south west rift zone. When it happens, it would be advisable to run away, and not, as Hawaiians normally do, run towards the eruption to get a better view. Mauna Loa is not like Kilauea. It is fast and furious, best viewed from a large distance. Paradise can wait.

Background reading

Hawaiian Volcano Observatory; Much of the material and several figures in this post came from them

Hawaii’s island chain, with exam questions at the end! Source of some of the figures and material used in this post

207 thoughts on “Trouble in Paradise: awakening Mauna Loa

  1. It seems to have broken out near the vents of 1940 and 1949, summit eruptions often happen from this location. SWRZ eruptions as far as I know have broken out from the pit craters south of Mokuaweoweo (not where this eruption is happening), so it seems unlikely this intrusion will erupt in the SWRZ. It is not impossible that the eruption will propagate to the NERZ, but perhaps not the most likely option. Last eruption was in the rift and there is some tendency for Mauna Loa to alternate summit and rift eruptions, and NERZ eruptions sometimes first break out from the North Pit of Mokuaweoweo (not where this eruption is).

    My guess is that it will most likely stay at the summit. The second most likely option would be for it to propagate to the Northeast Rift. And least likely to go into the Southwest Rift.

  2. A significant portion of the caldera is already drowned in lava.

    • The first located earthquake was 2.5 hours ago, and the first M3 was 2 hours ago. Fast, as expected. But Albert was equally fast at publishing the article so we can enjoy the eruption.

      • Jesper caught it first. And the article was pre-written when it seemed the long wait might be drawing to a close, 6 years ago, so that doesn’t really count..

        The reason for proposing the southwestern rift is that that is where the inflation was centred for most of the past decade. The weakness is there. But let’s see. The actual intrusion (!) that caused this eruption was not large – it is the cumulative effect of the drop-feed over time

    • Two large lava fountains also also developing on the thermal cam

    • Mauna Loa is just so…enormous. Giant caldera makes large fissure look tiny.

  3. Actually, it does look like the 1940 cone has erupted, the fissure went right through it and probably did go past it. Not clear if it has gone beyond the caldera wall to the southwest but that would be somewhat expected in this early stage. The biggest fountain visible on the webcam right now seems to be either within or right on the north side of the 1940 cone.

    This eruption will probably only last a couple days, if it lasts longer then it might make a new cone to join in the two already there. The descriptions of the 1940s eruptions sound a lot like the lava geyser activity of Fagradalsfjall, low rate activity but episodic, so forms a large cone. Both had fountains up to nearly 300 meters, visible from HVO. But that seems to be somewhat unusual, and Kilauea was not erupting in the 1940s so perhaps the supply then was higher than average.

    • The earthquakes started under the centre of the caldera, but then propagated to the Upper SWRZ. So we know the intrusion rapidly propagated southward. This is normal for summit eruptions like 1949 or 1975, they usually open some fissure in the uppermost SWRZ.

      We have 2 M4 earthquakes under the caldera, and also two earthquakes in the Kaoiki area. The 1984 eruption produced a few small earthquakes in the Kaoiki area, but it is hard to know if it means anything.

  4. The fissure is actually a bit longer than this now, it has definitely extended a bit further northeast. it also has probably gone over the rim to the southwest but that will probably need an overflight to confirm. Well unless there is a lava flow racing down the flank towards Kona and someone takes a picture…

    • Quick lava map.

      I think I might have slightly overestimated the lava in the foreground as of right now but give it an hour and that wont matter 🙂

    • It certainly resembles the fissure opening pattern of summit eruptions like 1949 or 1940.

  5. Jesper sent me this image of the start of the eruption:

  6. Lava flows confirmed upper SWRZ. Ikaika Marzo on FB. Familiar name to some of use here 🙂 Also Hawaii PODD on YT

    Pretty serious flows, the slope is probably deceptively far away but no doubt about there beign a fissure outside Mokuaweoweo. Eruption seems to be very simialr to the 1949 eruption.

  7. I imagine that if the dike was growing it would probably cut the supply to the summit fissures. Taking into account that the summit eruption is still being sustained, that no fissures have opened in the northern side of the caldera, and that the fissure opening pattern is similar to summit eruptions in 1940 and 1949, then we are probably looking at a small summit eruption. Kona may not know yet, but they are probably safe. There is always a chance that something completely unexpected will happen though.

    • Hector and all,
      With some of these quakes relatively deep (near sea level) , .2-.4 miles deep, could there be more supply moving up to the summit?


      • Mauna Loa always has some supply, its just a lot less than Kilauea at the moment. But it does add up over time and today was the breaking point. But as this is a summit eruption it wont really take off the pressure, there will probably be another eruption after this one that is much sooner than 38 years…

        1975 took 9 years to have a flank eruption, but it did almost turn into a flank eruption itself, an intrusion went down the NERZ almost as far as the later 1984 vents opened, it was not really like a typical summit eruption when you look at the details (and what this is so far) which stay only right at the summit. There was also the major 1975 quake inbetween, which definitely took off a lot of pressure from Kilauea, and presumably took some off Mauna Loa in turn indirectly, so that probably contrinuted to the gap. Maybe it isnt a coincidence that when Kilauea did recover from that quake (Pu’u O’o) Mauna Loa was able to do its major eruption.

      • I’m not sure if supply rising up into the summit would make deep earthquakes or not. Mauna Loa has a known cluster of deep long period earthquakes at 30 miles depth, but so far there is no activity there.

  8. It looks like the eruption is already dying down in the caldera.

    • I wonder if it will focus into one vent and become a long lived eruption, like the eruptions of 1914, 1940 and 1949, which lasted 2-4 months, and happened from the same location. Or it might be a short day-long eruption like 1975. I don’t see any signs it is moving into the rifts, although that option still remains too.

      • It would be interesting if one of the fissures outside becomes the main vent instead of the fissures in Mokuaweoweo, there are some cones up there, like Pohaku Hanalei, which are exactly this sort of formation just not in Mokuaweoweo. And now that the caldera floor is high there is no specific stress field to keep eruptions strictly within the caldera, there was still in the 1940s but not after.

        I dont really think the supply exists to keep an eruption like that going though, the 1940s supply was a lot higher and Kilauea wasnt erupting, but then anything is a possibility at this stage.

        • Yes, I have wondered about that too. The fountains at the summit are almost gone now.

          • Although it might be an effect of the fog that makes the thermal emission look weaker in the MT cam. A line of fountains can still be seen in the ML cam.

  9. Headline from DailyMail, poor reporting.
    “World’s largest active volcano, Mauna Loa, erupts on Hawaii’s Big Island for first time in 38 years – triggering more than DOZEN earthquakes: Fears of major ash fall as sky over Honolulu turns flame red”

    I am not in Honolulu, but I am pretty sure the sky there is not red from this eruption.


    • Honolulu – Hilo. – easy mistake to make for the UK tabloids

      • Also that one of the places lava is flowing towards (far away still) is called Honaunau, next to Captain Cook. But probably just the case most people who havent gone to Hawaii or are familiar with it probably think Honolulu is on the same island as the volcanoes…

    • Youtube, of course.

      Impeccable article in the paper itsself, good photographs as usual, last paragraph:

      “The Big Island is mostly rural and is home to cattle ranches, coffee farms and beach resorts. 

      It’s about 200 miles (320 kilometers) south of Hawaii’s most populous island, Oahu, where the state capital Honolulu and beach resort Waikiki are both located.”

      Written 10h36 this morning.

      They are usually good in science reporting like most British papers.

  10. Just watching the time lapse footage of the M2cam. If you watch for the 03:00 image, it makes me think that there is some lava visible on that image. Heading to the left from the higher summit.


    • I saw that too, far away but it is definitely there. Its a shame the south pit cam is dead because that probably looks directly at the eruption from up close 🙁

  11. It does not seem like the eruption is slowing down. In this live stream there are fountains.

    • I asked them, these fountains are east of the summit, which means a fissure has probably opened down the NERZ too, not just to the southwest. This is what happened in 1975 and 1984 but actually not in most of the other summit eruptions. I thought it might have been dying down but it is just moving away from the webcam instead…

  12. Thank you guys for the comments, pics, discussion, and analysis. Very nice way to start my morning.

    Must be an adrenaline filled time for the younger residents of the big island who have never known ML in a state of eruption.

  13. It seems that there is a disconnect betw. HVO, Civil Defense and the media. True, there have been no vents opening in the recently-defined SWRZ (downhill from Lua Hou). But there almost certainly have been vents along the 1851-1940-1949-1975-1984 extension of the summit rift, and these will probably croak sometime today.

    So when HVO says the fissures haven’t extended outside the ‘summit’, they’re right but there are a lot of photos and video of flows visible from Kona and it’s as clear as a bell that they’re not in Mokuaweoweo any longer.

    But believe you me, when the traditional SWRZ unzips there’s not going to be any question about what’s going on!

    • After looking at the new fountains this looks like it goes down both sides of the volcano. It is like 1975, but it could change into a 1984 very fast if there is enough magma. I cant wait for aerial pictures, to get a sense of the locations. But the fountains on the wevcam are now small and weak, and I cant imagine the vents feeding the Kona flows are visible from the saddle road, the visible vents must be on the north end of the caldera.

        • More or less in the same place as the 1975 and 1984 fissures is my guess. But that is only assuming the same fissure in the middle of the caldera went down the flank. If a new dike firmed abd erupted then this could well be at your location.

  14. Things have been pretty active for the past few years with eruption at Mauna Loa, Reykjanes, La palma, and Tonga, I hope there’s more of this to come. (I am looking at you chiles-cerro negro

    • I was just thinking about that this morning, how it seems like there’s been a lot of interesting events the past few years. Hard for me to have much perspective because I didn’t pay attention live to this stuff before the La Soufriere eruption in 2020.

      If any event kickstarted my love for this, it was that eruption which caught my attention. Began googling different eruptions I knew about including Vesuvius 79AD and stumbled upon VC articles.

      Never left.

  15. Looking at the thermal webcams right now, it seems either the fissures died down are just really drowned in lava.

      • Only in the caldera, there is a powerful curtain of fire on the upper NERZ in the TwoPineapples live.

    • I think they’re croaked–and the fill is less than 40 feet deep and prolly a lot less. Too bad that the MLcam can’t rotate, I’d like to see how the NE half of Mokuaweoweo looks.

  16. I am curious as to where the lava flows are now. Currently watching the Two Pineapples livestream ad the lava flows are going far and sounds like USGS is sending a heli there.

    • Isn’t the observatory located somewhere in that area? Would be a nice spot for a livecam.

  17. EpicLava is at Kilauea, watching them both erupt together 🙂

    • I think these guys and Two Pineapples can wave at each other on Saddle Road! I don’t think it’s an overflow from North Bay, rather a fissure high up on ML just outside of North Bay. This is where the last fissure of 1975 was and hopefully not the last fissure of 2022…

  18. Been quite some quakes at Kilauea too in the past couple hours. South flank quakes.

    • I’m very interested to see how Kilauea behaves going forward now. Does ML enter a more productive phase for a while and Kilauea fades as has happened in the past, do both continue in a period of heightened activity?

      I certainly don’t know as much about these two as you guys, but I’m going to enjoy following along the next few months / years.

    • Almost exactly the same place as the 1975 vents. The first set of fissures in 1984 was in the same place too. The next set of vents in 1984 opened quickly which has not really happened now, this is probably not going to be a big or low altitude eruption but that is still on the cards for the coming years.

      And I now think that said eruption will be a NERZ eruption instead. If it stayed entirely in the caldera it would be a 50/50 but now a part of the eruption is down the NERZ it means that rift has partly opened. But we will see, this is sort of only the introduction and the main event is still to come…

      • Yes, Hector was right in going for the NE direction. Interestingly, most of the earthquakes were in the southwest rift

  19. Interesting passage
    “How and where did the hot spot get started? Its origins have sadly been lost in the subduction trench. Or perhaps not. Could the hot spot have started at the Obruchev Rise? The Rise is near an old spreading centre, abandoned in the Cretaceous when the centre jumped north. The ridge was at the western edge of the Fallaron plate, which has since largely been subducted underneath America. This puts the hot spot, at its earliest known location, directly underneath this spreading ridge. Much like Iceland! Did the spreading centre start the plume? Or did the plume split the plate? This is solidly in the realm of speculation. But it is interesting to think of tropical Hawaii starting off like Iceland. Perhaps there is hope for Reykjavik”

    For some others who don’t know the Obruchev Rise (like me), map here, left corner, near Kamtschatka:

    Dear Albert, letter place change which you might like to correct from Fallaron to Farallon.

    Interesting thought – the comparison with Iceland, creative, plausible.

  20. I just wanted to congratulate the “Mauna Loa Gang”!
    You really nailed this one, I saw how you guys followed this for 6 months until today.
    Very nicely forecasted.

    I would pat myself on my back if I where you 🙂

    • Looking back on my little attempt at predicting the eruption on October 4th, I was very close on when it would occur, but wrong about which rift zone it was going to be on. Trying to predict when a volcano is going to erupt is impossible, but forecasting an eruption, to the least, is at least somewhat easier.

  21. Extremely good piece, Albert, explaining the setting and its history very well.

    • I believe though that the older piece needs a second look and a bit of mending as in picture 3 the legend might be wrong as Mauna Kea should be north of Mauna Loa and Hilo in the east it seems.

      • The image is oriented with west at the top and north to the right

        • That’s what I thought first, but it was hard to figure it out as the island is like a triangle. It’s good though showing all the flows.

    • They are adding and building as they go. Some interesting timelapse up, especially the thermal one.

  22. Some-what off topic but, given recent land-slide casualties on Ischia, I’ve cross-posted link from VC’s *unsettling* 2017 ‘Ischia in motion’ report to Landslide Blog…

    That ~3 cm/yr resurgence uplift has delivered on the land-slide / mud-slide aspect. Sadly, I fear this is but a harbinger of many such steep slope-failures…

  23. Earthquakes seem to be following the dike intrusion, mostly at a depth of 1 km above sea level. The size and location of the intrusion now is similar to 1975, but if it continues propagating into the NERZ then we may end up having a major NERZ eruption like 1984.

    • The eruptive fissure in the NERZ is located at the northernmost tip of the dike judging from images.

    • The last earthquakes have been happening near the northern end of the intrusion. Intrusion only seems to be growing in the uppermost NERZ. The southern end and central parts of the intrusion seem to be done for.

    • I had never seen earthquakes to the north of the caldera. It is normal from the uppermost SWRZ and summit caldera to have earthquake activity, but the uppermost NERZ is usually quiet. The intrusion there is fracturing locations that are usually inactive.

    • The eruption sort of came as a surprise, as I did not expect for it to erupt. Matter of fact, there were not many reports of heightened amounts of earthquakes or deformation, similar to the other eruptions. Looking on the tilt and it seems to be uplifted during the time of the eruption. I guess Maunaloa wants to surprise us.

    • Assuming a mean thickness of 2 m, the dike should have a volume of about 70 million cubic meters of magma right now. So we are looking at a supply of 1500 m3/s into the dike, plus the amount being erupted that is also important and could very well send this number to over 2000 m3/s.

    • Right now fissures are probably in the same location as the fissures from the “small” 1975 eruption, which is considered a summit eruption. It is also similar to the early fissures of 1984.

    • Looking at the webcams, however, the reports of a SW fissure is quite dubious.

      • Well, the fissure is steaming a little more than earlier this morning, but the infrared shows nothing. Although, the 1914, 1933, 1940 and 1949 eruptions lasted long enough to build sizable cones, so a resumption is unlikely but not impossible.

        • None of those went into the NERZ though, they did open southwest of the caldera but not on the proper rift. This is more like a NERZ eruption that leaves the summit rapidly. Although given where the eruption might be if it does extend downslope it could more likely diverge north of the rift rather than go where 1984 was, sort of half way between a radial and rift eruption. 1843 and 1935 eruptions were like this.

    • That video is taken from the same place as an earlier video of the known NERZ fissures. Importand difference though is that a new fissure broke out further down the rift. This could be getting pretty serious now.

      Maybe we shouldnt be surprised, a summit eruption is most likely, but there is 20+ years of magma supply, that was not the case before 1975. The amount supplied is comparable to the 1984 volume if not greater, and that was an above average eruption.

    • The picture in the article by Frederic Edwin Church is great.

  24. USGS has put out an early map of where the active fissures are. The two main ones seem to be the same as the 1975 fissures but there is a 3rd which is somewhat offset and quite a bit further down tbe rift, beyond where the fissures of 1975 ever got. Still high up but this looks like more than just a summit eruption to me.

    The video on Ikaika Marzo’s FB that some have said is a fissure above Kona is probably the lowest NERZ vent. There will be a better map made soon.

  25. Here is some helicopter footage, definitely there are fissures:

  26. Not sure why the code is still red, there is no ash at all. Kilauea got downgraded to orange almost immediately in all its recent eruptions. Seems HVO is kind of out of their comfort zone dealing with Mauna Loa.

    Maybe it is to keep the hoards of tourists out until the eruption stabilizes…

    • USGS guy in this interview is comparing the current eruption with 1984. That might be why?


    From 3:30 local time, so about 4 hours ago. There is only one vent but it is one vent to rule them all… massive fountain, probably going at least several tens to 100 meters tall. Looks like this eruption wont be like either 1975 or 1984, it is going to build a new cone high on the rift zone. This might be the best case really, although the eruption is probably still going to be followed by a bigger eruption in a few years anyway.

    • Looks like its forming a Fissure 8 like vent .. Perhaps we will get a New main vent there like 1984.

      The lava is flowing towards the Saddle Road now so main acess between Kona and Hilo coud get blocked If it continues

      • It will look like that in a couple of weeks as the flow wanes and the vent gets wider, but for at least the next few days we will get to enjoy this fountain in all its glory 🙂

        I have updated my map a bit. This eruption is at the very least bigger than 1975, possibly qute a lot bigger. The SWRZ fissure was also a lot bigger than I thought, it goes almost 6 km down the rift, past all of the pit craters on the west side. It is the furthest a summit eruption has gone in that direction. So I expect the flows towards Kona were probably bigger than we firs thought although nowhere near enough to be dangerous still.

        The fissure erupting now is in between ‘steamy cone’ and ‘dewey cone’ which were both created in 1899, which is probably the best analogue to what this will turn into. 1899 was the smallest proper NERZ eruption, although still twice as big as a typical summit eruption. No massive flows into Hilo, the longest flow is 17 km and stopped as it got to the saddle. But the size of the cones suggests there was probably some stronger fountaining than was seen in 1984, which is also what we see now too.
        So this will be a nice photogenic eruption, not the lava flood disaster it could have been, and now we know what Mauna Loa looks like when it erupts today the next one will be better expected.

        • I was confused that both cones are attributed to the 1899 eruption. It doesn’t make much sense to me. Maybe one them is from another historical or late prehistorical eruption.

          • Maybe, but the Dewey cone and associated flows overlie the 1880-81 eruption, and the Steamy Cone flows are on top of those, it is a strange progression but there isnt really any other option, the next eruption in the area wasnt until 1935 which was well mapped and I cant imagine a whole eruption was missed… The other option is that Dewey Cone is from 1880 or 1881 but then that still requires a jump back uprift at some point.

    • Not a few years if this ends up being a sizable eruption. The dike intrusion alone is substantial. And the erupted volume is probably going to end up being larger than 1975, if not already.

      • Would still be willing to bet the next eruption will be before 2060 🙂

        I dont think this vent is really low enough to drain out the volcano. It is more than a summit eruption but still at 3500m elevation there is not a lot to drain out, this might well end in the next week or at least slow down. 110 million m3 for the dike, if the eruption gets as big as 1899 (~70-80 million m3) then that is about 200 million m3 magma removed from the chamber. 1984 was 220 million m3 erupted, and a dike of the required length that is 3 km deep and 2m wide is about 180 million m3, or about 400 million m3 total. So 1984 was about twice as big in volume removed from the summit as what I think this could be at the upper end, and it took about 40 years to erupt again so 10 million m3 a year – slightly less than the known values given quiet gaps are known with no input in that time.

        1975 was about 100 million m3 of magma total, and took 9 years to recover, which is within the same field as the above number. So to recover from this, assuming nothing changes, could take 20 years, but that is only under assumption of this getting as big as the 1899 eruption, right now the volume is probably about 1/4 of that or less, so if it stops now the next eruption could be only a decade off.

        But we will have t osee, this at least is not just a 1 day eruption, it has gone and done the one option none of us considered… 🙂

  28. Katla update:
    From Iceland Review, today, following another M3 last night.

    “Lovísa Mjöll Guðmundsdóttir, natural scientist at the Meteorological Office, stated to RÚV that the recent activity can be attributed to warmer-than-average weather. Glacial melt and flooding atop Iceland’s many volcanic systems have been known to trigger both seismic and volcanic activity, as often happens in the Grímsvötn system.”

  29. Map of all the vents that I have been able to locate. The caldera and SWRZ fissures I am confident in, the exact locations of the NERZ vents a bit less so excepting for the vent furthest downrift that is still active and has good images. I think there are fissures inbetween these areas, in the North Pit section of Mokuaweoweo, but there is no data on where those are so I didnt include them.

    I hope HVO can make a map of the flows soon, at least an accurate map of the vents. The SWRZ flows were short lived but I think could have been extensive, a lot more than 1975 or 84, and probably even more than 1949, probably much more of the eruption in the first few hours was on the upper southwest flank than in Mokuaweoweo, which gives a sense of what to expect when maps come out.

    • Thank you Chad, as always.

      Shouldn’t the long quiescence point to the possibility of a large eruption? Or is that fully mitigated by the belief that ML’s supply has lessened in recent decades and measurable intrusions / uplift weren’t spectacular since 1984?

      That’s a subject that’s difficult for me to reason around, and I know the ultimate answer is a “we don’t know for sure until it happens” kind of thing.

      • Not sure if you are watching one of the livestreams (TwoPineapples and ApauHawaiiTours, both same place on saddle road) but there are now two fissures that are certainly downrift of the fissure that was lowest during the day, the one USGS said is the only active area in their last update.

        So it is moving slower than 1984 but could be doing something similar

        • Very fascinating. Unfortunately at work and unable to watch, checking VC serves as my source of updates (and thus greatly appreciate yours).

          I think I meant a bit in hindsight as you, Héctor, and others tried to speculate about ML’s potential for its next eruption. The long dormancy to me superficially always suggested the risk of a larger event, but you guys have a much deeper and more complete of internal volcanic dynamics and I can see how and why there would be reasons against that.

          As always, trying to learn.

          • I expected a bigger eruption too but as a SWRZ eruption, and not before a summit eruption that stays at the summit, like the 1949-1950 pair.

            But it looks instead like this began as an eruption similar to 1975 but has enough pressure that it has gone directly into a rift eruption right away without a gap…

          • Makes sense, thanks!

            Perhaps she re-awakened with something more modest only to set the stage for the main event in a few years.

            Except perhaps she’s skipping the appetizer and serving the entree!


      ApauHawaiiTours live, and just as I post my map it looks like there could be yet another vent, a bit further down the rift from the main one… 🙂
      Still, looks like the eruption is staying in this area, the new vent is not as big.

  30. Actually I might have spoken too soon, there are actually several new fissures downrift of where the longest flow is coming from. It also looks like the area between could be opening up. This could end up being a big eruption after all.

    • I think it interesting that the pinched-off ML NERZ has been more active over the past 70-odd years than the relatively unbuttressed mid-to-lower SWRZ. I know, recency bias…

      • It isnt really pinched off to shallow intrusions though, the rift is almost 2 km above Kilauea, in which it is free to move. For major picritic flood lava eruptions there though it likely requires both a high supply and also Kilauea having recently collapsed to provide no resistance, this is probably very rare. There is one about 500 years old, flowing over Kulani prison, and the massive Pana’ewa flow that is 1450 years old, and the 1852 eruption, but picrites are rare, and all of these eruptions did happen at a time Kilauea could have had a deep caldera.

        The NERZ also trebds directly into Mokuaweoweo, while the SWRZ doesnt exactly. So a summit eruption with too much pressure can turn into a NERZ eruption like now, but a SWRZ eruption probably has to begin as its own thing. The NERZ was more consistently active in late prehistoric time too, only one eruption on the SWRZ is known between the 1710 Hapaimanu eruption and the 1868 eruption, and there isnt really a lot of evidence of SWRZ eruptions for a long time before 1710 either, while there are about 10 NERZ eruptions in the past 500 years outside of historic examples, likely more.

  31. Just like the eruption in Leilani Estates, the emissions from the eruption are creating its own weather. You can see it if you pull up the weather radar on the big island.


    • “Today’s Big Island forecast calls for moderate clouds with a chance of Mauna Loa.”

  32. In addition to the MOcam and SPcam which have been down for six weeks, the M2cam and M3cam went down overnight. Sigh.

Comments are closed.