Seas of Hawaiʻi

Hawai’i’s paradise ocean

Hawai’i is an amazing place. And not just for volcanologists. This is a world-on-an-island, with (apart from the most accessible eruptions in the world) Mars-sized mountains, pristine beaches, coral reefs, a world class city for shopaholics and night owls, rain forest with world-class mosquitos, desert, archaeology, astronomy, volcanoes, agriculture, flying fish and diving birds. It is the only US state that once had a king or queen, and it gave us the first American president not born on the continent. It is both a paradise and a troubled place, with enviable life style clashing with grinding poverty, unequal opportunity and discrimination. It is paradise for the wealthy, and home for everyone else.

And that is just on the surface. There is much more here that doesn’t meet the eye.

Let’s look. Hawaiʻi is the largest, and southernmost island of Hawaiʻi. It is also the youngest. There are 8 major islands in the state. From southeast to northwest, these are Hawaiʻi, Maui, Kahoʻolawe, Lānaʻi, Molokaʻi, Oʻahu, Kauaʻi and Niʻihau. They vary greatly in size. Hawaiʻi itself is 10,000k km2 while Niʻihau, the ‘forbidden island’, is only 180 km2. Kahoolawe is even smaller, at less than 120 km2. But there are many more deserted islets. There is one fewer than there used to be: East Island (a name that promises too much) was wiped off the map by hurricane Walaka in 2018. Few had ever heard of it.

The Hawaiʻian chain

The unknown Hawaiʻian islands form the long chain to the northwest, trailing the hot spot. Just looking at the map indicates how they came to be. The chain runs from young volcanoes at one end to ancient ones at the other. All but the youngest are very close to sea level. Each volcano formed in a burst of activity, grew to a massive size, faded and died, eroded and sank. At the youngest end, the volcanoes have merged to form one combined island: the main island of Hawaiʻi consists of no fewer than five volcanoes. The islands are pushed up by the hot spot: this is one of the reasons why such a large area has appeared above sea level in a very deep ocean. Once the island migrates off the hot spot, the heat is no longer there and like a cooling souffle, the island begins to sink. Now the island begins to break up into the individual volcanoes as the lower areas between them sink below sea level. Erosion takes hold and the mountains take on a rugged appearance and grow lower. Dramatic events can happen, where an entire face of the island collapses into the sea. Niʻihau was originally a slope of a volcano of which the peak has disappeared into the ocean. We are left with a scattering of islands where originally there was only one.

But erosion must stop once the island reaches sea level: otherwise why is the entire northwestern chain so close to sea level? There are two aspects here. First, once sea level is reached, erosion by rain ends and only wave erosion is left. Wave erosion does not reach far below sea level. Second, coral reefs build on the sinking slopes and reef growth manages to keep up with the initial sinking. The two combined creates the atolls, circular or semicircular reefs often dotted with sandbanks. The hard core of the volcano, the volcanic plug, can stand up to the rain and waves longer than any other part of the volcano. Mixed with the atolls you can get one or more rock islets.

Midway atoll, the oldest of the northwestern chain.This is the end phase of the evolution of an Hawaiʻian volcano. Note that its Eastern Island is not the one that was lost to the hurricane. Source: wikipedia.

Midway atoll is a good example of the end phase. It has a ring of sand banks and islands, formed by the coral reef. The volcanic rock is 150 meters below: that is how much the coral has build over the 28 million years since this was an active volcano. Why 150 meter? That is much deeper than the ocean waves could disturb the sea bed! The reason lies in the ice age. Even a sub-tropical reef was not safe from that. During the depths of the ice ages the sea level was more than 100 meters below the current level. At the time, wave erosion was able to reduce the volcanic rock. When the ice melted and sea level rose, the coral managed to keep up and return the island to the surface – but not beyond. The highest point is 13 meters above sea level. Will this island survive the current sea level rise? Yes, because only the most pessimistic predictions get more than 10 meters of rise out of our on-going climate catastrophe. And the coral should be able to keep up with the rise in any case. However, if acidification of the ocean were to stop coral growth, Midway will have a problem.

The French frigate shoals show a younger phase in the decline and fall of Hawaiʻi. Like Midway, it is a large atoll. But at the centre is a solitary rock, perhaps 10 million years old, peaking at 35 meters above the sea. It is called La Perouse, and it is the last remnant of the volcanic plug. Soon it will be gone, victim of the sea.

La Perouse

The crescent of the French Frigate atoll contains numerous small islands. They are in continuous flux. Whale-Skate island, for instance, broke into two 30 years ago, and foundered. At high tide it is now submerged. One island here has the discouraging name ‘Disappearing island’. East Island was the second largest of the islands here, and it was lost to the hurricane. But change is a constant here. New islands will appear when the sand again comes together.

The French Frigate atoll. Source: wikipedia

North of the French Frigate Shoals is the Gardener Rock, a larger double pinnacle which reaches 50 meters above sea. It too is the plug of an ancient volcano, at 12.3 million years probably a bit older than La Perouse. There is no atoll here. But under water is another wonder. Gardener Rock is the peak of an immense subsea volcano. It is estimated at twice the volume of Mauna Loa. (The volume includes the part of the volcano that is below the ocean floor: it is based on the seismic reflection between sea floor and lava, 9 kilometers deep.)

Submerged emperors

The Hawaiʻian chain ends a little northwest of Midway atoll, at a place where the volcanoes are 43 million years old. Here begins the Emperor chain, a chain of seamounts extending north all the way to the Aleutian trench in which they disappear. The bend between the two chains is caused by a change in the movement of the Pacific plate. Plates are pulled in by subduction zones, and 45 million years ago there was a change in subduction around the Pacific. Exactly what happened is still being discussed. The problem is that the direction of the chain is not purely caused by the plate movement. The hot spot itself has also moved southward, but we don’t know by how much. If you are interested in the history of the Pacific, read all about it here.

The Emperor chain is named after emperors of Japan. Unlike the younger volcanoes of the Hawaiʻian chain, these are well under water. Take as an example Nintoku seamount. It is 56 million years old and is a typical subsea volcano with a conical slope, but with a flat top (such a top is called a guyot). From magnetic profiles we know that this volcano formed about 27 degrees north. But Hawaii is at 19 degrees north. This is one of the pieces of evidence that suggests that the hot spot has not been stationary, but has moved southward at some point during those 56 million years. It may have moved east or west as well: we have no data on that.

The flat top of Nintoku shows the effect of wave erosion: it spend a long time at sea level. But it is there no longer. Even though the volcano is 5 km tall, the sea here is deeper than that. The top is 1200 meters below sea level. There is some old coral on top, and some sedimentary rock. But clearly, this island did not manage to maintain its sea level position. And this is true for the entire Emperor chain. What happened?

Two things happened. First, the drift of the Pacific plate took the volcano northward – and it was never as far south as Hawaiʻi is now. Initially this did not matter: the climate was much warmer in those days than it is now. But soon, the old mountain found itself in waters too cool to support coral. And once the coral stopped growing, the mountain disappeared under water.

That explains why it became submerged. But why did that not stop at depths where wave erosion ceased? Here, the Pacific plate took over. For oceans too sink. As the ocean floor moves ages, it cools, and is it cools, it becomes denser. This causes it to sink a little deeper into the lithosphere. In fact this is what eventually causes the oceanic plate to begin subduction. So while the old volcano drifts with the plate, it finds its feet below it sink. This is why it ended up more than a kilometer below the sea, still a proud volcano but no longer meeting the eye.

Let’s go back to Hawaiʻi. Because there is more here too than meets they eye. There is a dramatic landscape below the sea.

The sea floor map shows the landscape. You probably want to see in full resolution: if so, click here. If this wasn’t hidden deep below water, it would be a world wonder all by itself. There is spectacular but invisible scenery. The underwater plateaus around the island have sharp edges, remnants of old sea shores. Beyond, the ‘land’ falls down steeply into a 5-km deep abyss, three times deeper than the (not so) Grand Canyon. There is the deep trough surrounding the southern islands, where the weight of the volcanoes has pushed down the lithosphere.


Very obvious are the immense debris flows where the sides of volcanoes have collapsed. The hummocky ‘terrain’ on the sea floor is a dead give-away. Even the smaller islands have these: for instance the North Kauaʻi Slide is larger than the island it left behind. The collapse happened at a time this island hosted a huge volcano; it is now a shadow of itself but the slide is still there.

The Nuʻuanu Slide extends almost 200 kilometers and is 200 meters thick on average. It even managed to travel through the trough and up the other side, gaining 300 meters in elevation. This slide took down half the volcano! A big part of the volcano came down as a single block, and is now known as the Tuscaloosa Seamount, 30 by 15 kilometers wide and almost 2 kilometers high. This single block contains almost 1000 km3! The rest of the 1-million-years old slide may contain several times as much. Fifteen major slides have been identified. There may have been a few more: slides that happen to go southward tend to get buried by the next volcano to develop. From the numbers, we can expect several such events per million years. To put that in context: it means that we have a chance of up to 1 in a thousand to see such an event during our life time. Don’t bother buying insurance: if this happens the insurance company will be bankrupt. The Alkali slides are thought to be around 100,000 years old, and these may be the youngest. They are relatively small, at a combined volume of ‘only’ around 500 km3.

Where would it happen? Looking at the sea map, the slides are most obvious around the northern islands. This is also where the volcanoes look like big bits are missing. Maui does not have them, and it’s volcanoes still look like volcanoes should. So one may guess that here is where the next such event may happen. It is part of the normal demise here. Maui and Hawaiʻi both do have smaller slides on their west side and perhaps this is normal behaviour for younger Hawaiʻian volcanoes. The Hilina slump on the south side of Hawaiʻi seems to come not from a fast land slide but from slower creep, with a bit of movement once a century after every major earthquake. It lacks the hummocks that characterize the real collapse slides.

(One may wonder about tsunamis. If a 5000 km3 slide tumbles into the ocean, the water displacement could in theory generate a tsunami tens of meters high on the American Pacific coast. That is the tsunami height on the coast: the run-up height can be several times higher. However, it is likely that such slides happen fairly slowly and not in a single block, and that would reduce any tsunami by quite a lot. However, when this happens do not be on the Hawaiʻian islands themselves. The Alaki slides have been associated with a major tsunamic deposit on Lanaʻi with run-up height over 300 meters!)

Underwater eruptions

Not all hummocks come from land slides. The rifts that extend from the main volcanoes continue under water. Eruptions on the subsea parts cause pillow lavas, and these also cause a rugged terrain. This can clearly be seen on the map, for instance on the Puna ridge. But these ridges themselves can have land slides, and the hummocks on their sides may be due either to lava or the slides – pick your choice. The most recent documented underwater eruption (apart from the next volcano to be discussed) was in 1877, in two places on the west slopes of Mauna Loa. There is some holocene volcanism in the Arch field, well south of Hawaiʻi: this appears to be caused by the buckling of the crust as it begins to be depressed by the weight of Mauna Loa, where the faults let some magma rise up. But this is minor activity that is not directly fed by the hot spot. The North Arch field, 300 km north of Oahu is much more significant, with many small cones and large lava flows. The cause is not well understood, but it appears to be fed by evolved magma from the islands. Once the islands cease to be volcanically active, it appears that the remnant magma finds a way around and surfaces far away and deep below. But the total volume is small compared to those of normal Hawaiʻian volcanoes.

The next volcano to be discussed in Hawaiʻi’s youngest. Loʻihi is located on the sea bed south of the main island. It is highly active with eruptions probably ever few decades. But it hasn’t made the surface yet: the summit is almost a kilometer down. Still, that makes it a big volcano which would be an eye catcher on land anywhere: it is between 3 and 4 kilometers above the sea bed where it began. The volcano is believed to be about 400,000 years old. It is not young by any standard but at this rate it won’t surface for another 100,000 years.


The missing volcano

An interesting aside is that if the current Pahala quakes indicate the centre of the hot spot (a big if), it is equidistant to the three most active volcanoes here. Loʻihi is a north-south ridge, pointing roughly at Pahala. Perhaps this is what it is: a deep Pahala rift reaching the sea bed here at an angle.

It is often assumed that Loʻihi will be the next volcano to develop. But is it? If you look at the island and measure the distances between the volcanoes, it is a fairly consistent 30 km: this is about the distance between the summits of Kilauea and Mauna Loa, Mauna Kea and Mauna Loa, and Hualalai and Mauna Loa. But Mauna Loa to Loʻihi is twice that. In fact if you continue the regular spacing of the other volcanoes, there is a clear gap where a new volcano would fit. And it is close to Pahala. This is illustrated in the map. If a new volcano were to form, you would expect it to be here, not in the sea but on land.

An ancient heritage

But Loʻihi is far from the only seamount in the area. Looking at the map, the place is littered with them. Close to Loʻihi are the Apuʻupuʻu, Hohonu and Green seamounts. Further west are the Dana, Charnell, Day and Palmer seamount. They have summits between 2 and 4 km depth, so well below Loʻihi, but in volume they are competitive. And if height is important, McCall’s seamount reaches less than 1 km from the surface and Pensacola seamount gets to 600 meters. These mounts extend south and west of Hawaiʻi. What is going on? Why are there so many more volcanoes below the sea than above? They are big beasts, up to 4 km above the sea floor. If the hot spot is creating that many other volcanoes here, how big is that hot spot?

It turns out, this has nothing to do with the hot spot. As the Pacific floor moved past the hot spot, it carried with it another volcanic field. It is an old one: these volcanoes formed in the Cretaceous, around 75 million years ago. They can be distinguished from the current volcanism by their rugged appearance.

The Pacific sea floor has several seamount chains, similar to Hawaiʻi. Each formed from a long-lived volcanic region. The seamounts around Hawaiʻi are different: it did not form a chain but a field. This was a different type of event. Was it a collision between two plates? Or (perhaps more likely) a phase of extension? Both can cause volcanic fields. Little research has been done. But all around Hawaiʻi are the massive remnants of its ancient volcanism.

But if so many of these mounts are around the island, why none on Hawaiʻi itself? Perhaps many cones are buried underneath. We always assume that deep under Hawaiʻi the lava flows lie on top of a smooth old crust. Perhaps it isn’t smooth at all. Perhaps the island is kept in place by these peaks sticking up and anchoring the lava above.

The sea mounts peter out to the north. There is little evidence of them north of the big island. Perhaps there is something about the big island. People have asked why the volcanism there occurs at a higher rate than it did when previous islands formed. Does the hot spot wax and wane? Perhaps it is not the spot. Perhaps the oceanic crust underneath the island of Hawaiʻi is different.

Do Mauna Loa, Kilauea and Loʻihi have some memory to those old times? Jurassic Park was filmed in part on Hawaiʻi. As commonly known, it was a complete misnomer: the dinosaurs in the movie were not Jurassic but Cretaceous. In a way, Hawaiʻi still is a cretaceous park. It has an undersea park of cretaceous volcanoes, dwarfing those dinosaurs. There is more here than meets the eye.

Albert, September 2020

This paradise ocean hides a violent secret

95 thoughts on “Seas of Hawaiʻi

  1. I like the idea of the pahala quakes being like hawaii’s Greip, but on HVO it looks like the quakes trend towards Kilauea, and actually only Kilauea. Maybe it could have been its own volcano but possibly the volcanoes cant directly erupt through the flank of their predecessors and must erupt at the base on the ocean floor to grow into their own edifice, which perhaps hasnt actually happened yet until now given the recent increase in activity in the last million years.

    There is one rather grave implication of the Pahala swarm being its own protovolcano though, that means Kilauea is not being fed from this location and is also going to get a second deep source, and with that a doubling of its already massive magma supply… Perhaps this is what happened at Gardner Pinnacle, the merger of two deep sources under the crust into one volcano that became as big as two ‘normal’ hawaiian volcanoes. Even if that doesnt happen the similarity of these events to the buildup to Holuhraun, only on a much larger and longer scale, is more than a little concerning, this looks like the beginnings of a laki-type event.

    • Kilauea does do Laki-sized events but it does this over decades rather than a year. The pressure to feed a fast large flow isn’t there. The lack of local inflation suggests that the magma at Pahala has ways to reach other volcanoes. But just like under Vatnajokul, it is not easy (make that ‘impossible’) to trace a separate conduit for each volcano down to the mantle. Each has its own magma chamber, but deep down, they are all connected through a set of interlinking sills and channels, I think. There isn’t a single conduit.

      • The pahala source is under the crust though, it is 30-50 km deep, further from the surface than its lateral distance from either Kilauea or Mauna Loa actually, I dont think that would show at the surface as any sort of deformation.

        In any case a thing that can cause so much seismic activity within the soft rock of a mantle plume is probably an impending big volcanic event in the near future. If not a true flood basalt, I expect another round of high fountaining, and for the caldera to be rather absent by 2050, perhaps another round of shield building is in the near future, like the Aila’au flows in the 1400s, or the Observatory flows before that.

      • Actually there is about 1000 km3 of space that the pahala swarm occupies, even if only 1% of that is magma that is still 10 km3 of magma on its way to the surface, and in this location probably a lot more than 1% of the mantle is liquid, which makes the strength of the quakes all the more interesting that they can even happen at all, there is a lot of energy there. I dont know if this is a good way of quantifying potential amounts of magma from earthquake swarms but this looks indeed quite a massive magmatic event, even if probably a lot wont reach the surface.

    • Its very hot down there too
      Perhaps 1600 C in Kilaueas deep basement ( hotter than liquid iron )

      Of course the basalt cools on the way up. Kilaueas summit is around 1240 C when it erupts.
      The 1974 eruption was feed by very very fluid and primitive basaltic magma with a composition quite diffrent from Puu Oo. The Overlook summit lava lake is pretty much a pipe down to the summit magma chamber.

    • Theres a little bit of silicic magma, for maybe a few thousand years about 100,000 years ago Hualalai was a trachyte volcano that did viscous flows and large VEI 5 eruptions, and actually this stage was not insignificant in volume, its entire surface was covered. Mauna Kea also has a large and very deep magma chamber under it that was only discovered this year, which is likely common to all the volcanoes and may become more prominent after the shield building stage. The Hawaiian volcanoes are probably too big for a caldera collapse though, which is probably what you are going for 🙂

      • I need hundreds of km3 for my attention! The hotspot doesn’t seem to produce a lot of sillic eruptions numerically speaking but how many km3 are there at Mauna Kea

        • Probably Hawaii or Iceland arent up to your standards then im afraid, though given the immense size of Hawaii there could easily be hundreds of km3 of magma under even the inactive volcanoes, though most likely it cant erupt on large scales, that being said some of Mauna Keas holocene eruptions were rather large, and with more viscous magma the eruptions were violent strombolian to subplinian with massive lava flows like Hekla.

          • If thats not what he wants maybe another Toba YTT would be even better!

        • Actually, there is possibly a way for you to get your big bang out of Hawaii Tallis. Stinn no silicic magma, so I dont know your opinions on this, but perhaps the ending will be satisfactory.

          The deep rifts of a mature Hawaiian volcano probably contain hundreds if not thousands of km3 of magma, Kilauea already has at least 400 km3 and it is only something like 1/8 of its fnal size. This is probably the equivalent structure to the massive magma chamber under Grimsvotn, the one that is supposedly in the 400 km3+ range, only in Hawaii this cant erupt on its own, at least not in large volumes, but if a major sector collapse incorporates part of the rift zones, or even the summit, of one of the volcanoes then you get 1000+ km3 of magma in contact with the ocean while also being decompressed rapidly. At the very least, say if the slide stops before water can get to the rift, then the pressurised cystal mush in the rift is suddenly at the surface, where it undergoes rapid decompression melting to create a flow so huge calling it a lava flood is not doing it justice, and really that is probably just as bad in the long run as a VEI 7, but most of the Earth is fine.

          Because bigger is better, if instead the collapse goes to completion and the deep interior of the island is exposed to the ocean, you end up with a lateral blast, a VEI 8 lateral blast… Hawaiian basalt can be twice as hot as silicic magma, so you get twice as much energy out of its interaction with the ocean. Adding to this, the decompression of so much magma, even a fluid basalt, is most likely a violent afair on its own which actually only serves to make its interaction with the ocean even faster by fragmenting the magma to begin with. So you get a VEI 8 lateral blast combined with a 1000x bigger grimsvotn 2011, and a megatsunami (gigatsunami?) in the middle of the Pacific basin where half the Earths population is in the firing line.


          • you coined a new term gigatsunami – wow !
            glad that such a collapse is ridiculously unlikely 🙂

            ps. fao dragons – facebook widget still doesn’t seem to be working

          • I guess if a megatsunami is 100-1000 meters, a gigatsunami would be a wabe taller than that, a 1+km tall wave 🙂

            Maybe the dinosaurs in Mexico saw one…

          • I still dont think that has ever happened in the history of the islands, not even in East Molokai or Koolau, though who knows Hawaii is very good at covering up evidence with new lava…

            I just dont see the deep rift blowing up, its just too dense (mafic) and crystallized (barely any melt in there). And if it happened to be exposed it would be under the pressure of 2+ km of water.

            When Kilauea would be very “cool” is in a Pahala Ash-like period when summit and rift storage reach its maximum size, its hard to know anything about that obscure period of Kilauea, but it ended 11000 years ago in what probably was an eruption way bigger than Laki from the tip of the Puna Ridge 5500 m underwater. The resulting caldera was so broad that it left the Kaoiki collapse scarps imprinted on the slopes of Mauna Loa, the storage of Kilauea is still nowhere near recovered from that collapse.

            How would Kilauea look like during the Pahala ash? Well I think VEI5 (maybe even VEI 6) phreatoplinian eruptions would happen occasionally, big shields would be active long the ERZ and Puna Ridge frequently, like Puu oo or even dwarfing it, and bigger short lived eruptions than Kilauea is capable now though probably deep underwater. Always or almost always dominant over Mauna Loa.

          • I always thought the Pahala ash was caused by the relatively low altitude at that time resulting in calderas that easily sank below sea level, so that the summit was basically always phreatomagmatic, and that after 11000 years ago or so the mountain had built enough that most collapses avoid this. I recall reading that distal rifts formed early for Kohala, and that growth above sea level only began to dominate after a certain point. This sounds very much like what we see at Kilauea, which has a totally inactive distal rift and seemingly very rapidly (by geological scales) growing proximal rift and summit region. That being said some of the Hilina basalts do look like ignimbrite formations, even though I guess a basaltic ignimbrite is just a spatter fed flow scaled up a bit… I want to read your sources it sounds very interesting.

            Historical time is just too short for Hawaii 🙁 Theres a lot of evidence that both Kilauea and Mauna Loa have erupted in ways that are very different to recent observations, even in the past few centuries. The deep quakes also look to be the beginning of something seriously enormous which I already commented on before, and it is ever so slowly inching towards Kilauea. I dont know if theres still a lack of articles but maybe I can make one about this subject to save a lot of walls of text 🙂

          • Yes, thought you would find that interesting. I have just tied a series of clues based on my understanding of how Kilauea’s system works.

            I cannot link anything right now but you can easily find a work of Holcomb about an enormous very voluminous flow field at the tip of the Puna Ridge, 50 km3 if I recall right, of sheet, fast emplaced tholeeitic lava flows, I think that at least half of it was emplaced 11000 years ago in a single rapid event based on indirect evidence. The implications of such a massive eruption at an elevation of 5500 m are that the whole storage of Kilauea: The deep south caldera reservoir (which contains most of the eruptible magma aswell as feeding the deep rift?) the MERZ and LERZ magma reservoirs (which allow acces to erupt in the LERZ and Puna Ridge), and the parts that most often drain which are Halemaumau and the UERZ magma chambers, all collapse. Gone, zero, reset, no storage, and the ERZ has no way to receive magma or spread, Kilauea would behave drastically different before and after.

            Thing is, has this happened? Kilauea had been in 10000 years of dominance over Mauna Loa before the Puna Basalt (this is clear when you plot radiocarbon ages of Mauna Loa, all the published ones). This period has abundant explosive activity (Pahala Ash) from Kilauea in fact there is one exposure of 26 meters of ash in a pali 12 km away from the summit, this I know from an abstract, sadly the Pahala Ash is not much studied. During this period Kilauea was more explosive than in the preceeding Hilina Basalt discarding elevation as the main factor. Additionally there where no overflows from the summit meaning a caldera existed all the time at the summit (Kilauea gained no elevation but still mantained dominance over Mauna Loa) presumably deep and water filled much of the time. The Puna Ridge had quite a growth spurt if you ask me.

            11000 years ago behaviour changes entering 3000 years of Mauna Loa dominance, the strongest period of dominance visible in the Holocene (again I just plotted radiocarbon dates). This also roughly the upper end of the Pahala Ash. The Kaoiki scarps are known to be older than 9000 years and I do believe represent the outer rims of a large collapse of the South Caldera Reservoir.

            What I reason is this: those 3000 years of Mauna Loa dominance are easily explained by a recovery period of Kilauea, to form back the summit storage and restart ERZ spreading. The last several thousand years are characterized by Kilauea and Mauna Loa turning frequently the control over the hotspot ruled by shorter, centuries-long ERZ cycles, so we are sort of in the middle of a longer term cycle… The last cycle ended 11000 years ago in what must have been, in the only way it matches evidence, a big, REALLY BIG, eruption from the tip of the Puna Ridge. Before 11000 years ago the storage of Kilauea must have been much bigger compared to now and after 11000 years there must have been barely none. I think Puu oo is a consequence of the enlarging ERZ storage as it is something new that hadnt happened in the last few thousand years.

            I hope that is understandable, it is a theory lacking good direct evidence, problem is that Kilauea has barely any surface that is older than 1000 years so with the few facts known I think this is the best understanding that can be gained. If may be too much to take in still…

          • I guess we will never know for sure, unless it happens again. The rate of resurfacing is quite incredible really.
            I think there is going to be something big when the Pahala swarm reaches an outlet though, not 50 km3 but not just a run of the mill summit eruption. 1959 was fed out of a massive new intrusion, 1960 was at least 0.25 km3 of lava erupted in a month, and then at least 0.2 km3 in the dike maybe even twice that, and that eruption didnt induce a caldera so even more stayed in the summit to prevent that. Total could have been in the range of 1 km3 intruded in 1959, probably setting off the high activity subsequent including up to Pu’u O’o indirectly. That is what I expect at a bare minimum from the pahala swarm if it really is what it looks like, but im not going to spoil any more of my future post and to avoid text walls, theres a lot of those on here now… 🙂

          • Well, with Kilauea you never know, even a phreatoplinian eruption is in the menu, but also a biggish non-eruptive dike that pospones its next eruption another year. I am afraid to predict because it is way too complex, however, the last 3 times the caldera got waterlogged a prolonged period of surtseyan eruptions followed, so that would be my guess, maybe not its next move, but that is coming soon.

            This short-term cycle is coming strong, with the biggest rift shield structure in who knows how long, part of me hopes this means we will see the darker face of Kilauea, not the friendly lava lake volcano Thomas Jaggar spoke of. The other part of me prefers not because at this rate HVO and local inhabitants would underestimate what is capable of.

            As for the Pahala Swarm I agree it is a hotspot surge but there is no sign of it coming anywhere close to the summit yet. Maybe we need to wait for 2021.

          • Well the next summit eruption is going to blow up, like in 1790. Im not convinced the lake will survive for long though, the whole caldera was deep in the past, but now its only that one part, and the volume of the lake is an order of magnitude lower than any summit eruption observed. Part of me wants to see a grimsvotn 2011 with no ice, 1 km3 of lava in a few days, straddling the line between a violent hawaiian fountain and a true plinian eruption with either a massive lava fall into the pit or a flood lava on the south flank, or both. 🙂

          • I on the other hand dont think there has been any lake in 1000 years, this is the more water there has been there since the K3 eruption (at least). If there was water in 1790 in the caldera why is it that no native told Ellis or any other early missionary? I think it is unlikely but without going back in time it is imposible to know so that it just my opinion. Some shallow groundwater combined with a caldera collapse resulted in a VEI4 eruption with a deadly base surge similar in style to Taal or Fernandina.

            And the explosive eruptions of the ~17th century were just borderline phreatomagmatic so less deep even, presumably. Those eruptions were first vulcanian (the drier equivalent of surtseyan), a subplinian event (layer D, like a slightly watered lava fountain) and Unit F which was like a mediocre version of 1790. So there was less water, which means less deep?

            From all that chaos of information which most people here lack the background to get, understandably, few people will reach this degree of obsesssion with Kilauea… just mean to say the lake wont blow away easily. The groundwater recharges the lake and activity is focused on the ERZ which means the caldera floor wont raise too much soon.

          • At risk of making this chain too long, the reason I think the next eruption will be at the summit is elevation, the bottom of the 2018 caldera is lower than even the bit of the rift at JOKA station, and probably there isnt enough pressure to drive another LERZ eruption yet so at least initially this seems more likely. I think that most activity will stay on the rift after that though. The quakes suggest that a complete connection to the rift like before 2018 still exists, perhaps the time between 1974 and 1983 is comparable to right now but theres less space to fill in the rift so a shorter recovery?

      • And I’m sitting right in the middle of the apocalypse cloud! It looks like Armageddon already happened outside, and everything smells like the whole west coast of US sat next to a campfire too long.

          • For now, fortunately, yes. The Big Hollow fire is about 12 miles from us, but the winds have shifted and the fire is moving more North West (towards Mount St. Helens, of all things).

        • I’m in the middle of it too on the Central OR coast. Not evacuated and safe, but air quality is terrifying and Newport is packed with Lincoln City evacuees as fires are burning on the coast.

      • Only when man bends to the sky and when hope is lost to even the most innocent of children
        Only when death is more abundant than life, and the yellow sun darkened
        Only then will I be satisfied Jesper

    • Chad is correct
      Hawaii is impressive as heck.
      These deep sea shield volcanoes are so immense. Kilaueas rift zone and underwater flanks are already 200 kilometers long north
      ( Puna Ridge ). Kilauea will probably grow larger than Mauna Loa when Kilauea is at her peak. Perhaps as large as 130 000 km3 she will grow in the future. Kilaūea is already a formidable beast, with its capabilities shown in 2018 in larger faster lava flows.
      Kilaueas version of Holuhraun it was.

      Hawaiian hotspot haves massive magma production at this time in Cenozoic.
      After Maui Nui ( Ancient Maui ) the volcanoes seems to just grow bigger and bigger.
      The size of Hawaiian volcanoes is determined by the speed of pacific plate moving away the Islands, and specialy how productive the Hotspot is in magma output.

      The now extinct mammoth of Pūhāhonu volcano grew to 140 000 km3! during a sourge in the hotspots output. Hawaii is haves now another sourge in magma output, so perhaps old Pūhāhonu is Kilaueas own future in size.
      Knowing the lenght of Kilaueas rift zone on land and water, ( longer than Mauna Loas )

      All other volcanoes are so very very invisible small compared to these Hawaiian volcanoes.
      Hawaii is probaly the most productive volcanoes on this planet.

      Thesw Hawaiian giant deep sea volcanoes starts off in one of earths deepest oceans
      6000 meters deep and when they surface the water, they are already larger than pretty much all other land volcanoes combined.
      At their peak, they grow 20 kilometers tall or more! and haves volumes of very small Dwarf planets . Hawaii are BIG volcanoes 🙂

      Hawaii is also enough to maybe erupt komatiite, if magma rises extremely quickly from depth into kilauea it woud erupt at a temperature high enough to keep olivine and other minerals competely molten in the magma which would most be as a komatiite or something similar as opposed to ”normal” Thoelitic Basalt.
      The plume head center under the big island is 1600 C. Hotter than liquid Iron and its very bouyant. Hawaii coud be the largest mantle plume today, and the most intense since Siberian traps and pre – opening of Atlantic.
      Hawaii is a real geological blowtorch

    • Subsidence is in there, twice – perhaps a bit hidden. It is the effect of the disappearing underground heat (first few million years) and the effect of sinking ocean floor (over tens of millions of years). There is another part that I did not include: spreading of the bulk of the island. I don’t know how significant that is, compared to the land slides which do the same job.

      • Localized sagging of the lithosphere also takes place , see Haleakala, the giant of Maui Nui, it has its ancient coast 2 km underwater 1 million years after its peak size, if that was at the coast the summit has probably subsided a couple of kilometers. Due to the inmense load it just collapses down into the planet.

  2. Grimsvotn is beginning to tick up again in activity, after its long summer sleep.This was expected but of course this may die down again. Let’s see.

  3. Hawaii is amazing
    And their waters are so crystal clear its absolutley amazing! Their water is as blue as azure – indigo saphire.
    Liquid saphire ocean with extremely blue transparent waves.

    Look at Big Island or Midway at Google Earth, the visibility is amazing.
    Probaly 100 meters visibility in the water. Hawaii is isolated from land runoff and nutrients

  4. Did they ever trace the origin of the hotspot (i.e. does it continue onto Kamchatka?)
    I’d be interested to see if there’s a link between the siberian traps or the NAIP to the hawaiian hotspot albeit the oldest seamounts still unsubducted are around 90myo whilst the traps are 250myo.

    These were the closest I could find but it seems a bit of a stretch:

    • On Wikipedia there is some good information on the hotspot. Despite the size of the early seamounts the supply was very low, they were active over many millions of years.
      It seems that perhaps the plume began small probably in the late Cretaceous and has grown in size quite significantly since the Miocene, today it has a magma generation rate about 2 orders of magnitude higher than in the rate that created the emperor seamounts, the past million years (creation of the Big Island) has erupted about 200,000 km3 of magma (some sources even higher), which is about a quarter of the whole Cenozoic volume, to put things into perspective. Another way to visualise this is to realise the eruption rate of Pu’u O’o after 1986 was actually the rate of magma generation in real time…

      The hotspot has also moved south since the Cretaceous.

      • Just a query; the northern end of the Emperor seamount chain disappears under the western end of the Aleutians. Where some of the volcanoes have produced that odd magnesium-rich andesite (more or less) called Adakite (indeed Adak Island, former home to a major US military base, is the ‘type locality’). So maybe some of those basalt shields have been chewed up, digested, and their lavas incorporated in magma fuelling Aleutian subduction volcanism

      • Thats right the slow Puu Oo eruption ( when Kupaianaha vent started up ) where feed and erupted same volume as Kilaueas input rate. It coud have lasted forever If nothing disturbed it.
        Erupting at input rate is why slow Hawaiian shield building eruptions, can last for 1000 s of years. Mauna Loas longest tube feed eruption lasted over 1000 years earlier in holocene

      • I dont know much about how rocks are made but that sounds interesting. Given the direction of subduction being westward moving and at an angle relative to the Aleutians if there were any older seamounts they would have subducted there, while today they subduct under Kamchatka and in future will do so under Japan. Maybe the composition is just from the crust being exceptionally old here though, ocean crust in the north Pacific was created in the early Jurassic.

        Jesper I would hold any assumption on the age and extent of Mauna Loa lavas for the future, HVO is mapping its surface in minute detail to get the best possible estimate of its behavior. To date they have mapped the distal ends of both rifts and the flank immediately above Kilauea, and some dates differ by several centuries to even millennia from the previous map that was made in the early 1990s.
        I have doubts that either Kilauea or Mauna Loa can sustain total stability in their eruptions for more than a few years without something disrupting it, and this has nothing to do with supply, look at how many different vents and flows erupted at Pu’u O’o, and there are multiple flow units in both the Aila’au flow field and Observatory flows, suggesting they behaved the same just at the summit where flows could move radially and cover more area. Mauna Loa has never erupted this way in historical time, not for years on end at a location outside its caldera, but prehistoric examples also show sequential flows suggesting variability, also with two instances of flank shields followed by a flood basalt in immediate succession 🙂

    • He is misreading the continental plate boundary as a hotspot track. The Hawaii hot spot has never been near Kamchatka or its plate. Only its debris was pulled in that direction. This is a bit like following the wind-blown smoke trail of a volcano. The volcano is at the other end.

      • I see what you mean now, the subduction and plate movement has created the chain rather than the hotspot itself – silly me.
        Is it possible that the hotspot came into being with the creation of the pacific plate (or is this all about the pacific LLSVP)?

        It’s notable that there are several fractures that look to have interacted with this (and other pacific hotspots), the Molokai fracture zone for instance. This is also evident in the atlantic with the canary/azores etc.

        Some of the investigations on make you question whether there are ever really hotspots or just leaky places where magma can take the path of least resistance to the surface. Our egg shell has been fractured that many times over it’s no wonder we get long lived powerful upwellings especially where there has been previously.
        Iceland for example – what came first, the MAR or the hotspot…

        • Some hotspots are probably shallow, but Hawaii is certainly deep, probably originating at the core/mantle boundary based on both its size and level of activity as well as the very high temperature of the magma.
          The Reunion, Comoros, Virunga and Afar hotspots are similar structures that are probably all related to rifting of the African continent, Iceland is probably another deep plume though is still young. It appears that Virunga is a near future flood basalt progenitor, much like Hawaii appears to be now, so maybe this is the closest comparison.

          Other so-called hotspots are probably just other effects, or perhaps the remnants of now dead plumes that can still erupt.

  5. I find Hawaii amazing especially the underwater topography. Lets just hope we don’ see any landslides like are evident in the topography north of Oahu and Molokai any time soon! I can’t imagine the tsunamis that might have created if it all happened at once.

  6. Something that I noticed on Google Earth, Hawaii today crosses over an old fracture zone on the Pacific Plate, which is aptly named the Molokai fracture zone. This structure isnt volcanic but I cant help but wonder if the crust is thinner here, which has lead to wholesale decompression of the mantle plume in the past few million years to reach the level it is at now, 0.21 km3 every year which is twice the rate of only a million years ago. Perhaps the relative rapidity with which the plate moves prevented that magma from erupting at Maui Nui, so it went on to create the Big Island in under a million years as all that magma found a new outlet. The rifts of all the Maui Nui volcanoes also immediately follow the fracture zone and major rifts are basically parallel to both each other and the fault zone, even to the point of crossing at right angles between Penguin Bank (distal rift of West Molokai?) and Oahu, which were probably active together, and also in contrast to the Big Island which has no particular rift orientation. It is just one of many things that may help explain the level of activity Hawaii experiences.

    Of particular note is that a fracture zone also crosses the hotspot track just north of Gardner Pinnacle volcano…

    • Just posted about this then scrolled down to see your comment – sorry!
      Do think thin stretched crust and fracture zones have a big part to play in this – volcanoes pop up wherever there is a weakness in the crust no matter where it is.

  7. Following the exploration of the Pacific with the team from RV Nautilus last year was fascinating. They were mapping seamounts near Samoa and also from Hawaii to San Francisco. Looking at the raw data as it unfurls shows the complex nature not only of the Hawaiian Archipelago but also the geology of the many fracture zones. For those interested in learning more about the discovery of volcanic and Tectonic features beneath the oceans I do recommend visiting There is a menu that covers not only all aspects of marine biology but also geology, Volcanoes /hydrothermal vents etc. The Exploration of Lōʻihi Seamount South of Kīlauea. was particularly fascinating.. I think it’s probably a new island in the making Thank you Albert for another very interesting read. During my enforced incarceration at home this last 6 months visits to the web cams of Hawaii and other tropical beaches kept me from going too stir crazy and gave me a few moments of sun, sand and sea to keep my spirits up. However I have no yearning to actually live on the side of a volcano not even one that is extict…ish. I may be fascinated by volcanic activity but I am a real coward and would spend my time worrying!

    • Nice to hear from you Diana! I hope you are keeping well in spite of the social isolation. Those tropical beaches must have felt a bit like home! There are a lot of seamounts. The Pacific is quite prone to volcanic activity. Most of which we will never see. Now a webcam on Lo’ihi could be really interesting.

      • Lol That thought takes me back to all the excitement of the surtseyan type eruption off El Hierro.

    • Been a long time since we had the pleasure of one of your posts, DIana. Hope to see many more in the future!
      You may not want to live where I do in northern California. Mt. Lassen, Mt. Shasta, Medicine Lake are all less than 50 miles away. Plus, I’m only a little over 100 miles directly east of the Mendocino triple-junction, with the Sierra Fault near Lassen.
      Nearby, the Battle Creek thrust fault (quite active), which is capable of M5, is literally 2 miles away. Couple all that with occasional tornadoes (both weather and fire caused), massive flooding rains intermixed with multi-year mega-droughts, threats of imminent dam failures and the occasional crippling snowstorm, and you get the idea. Almost anything is possible.

      Lastly, there is the smoke and fires to contend with. 3 of California’s largest wildfires in history are still burning in the immediate mountains around my place, with equally large fires in Central and Southern California. A total over 3 Million acres have now burned this year…i.e. much larger than the states of Rhode Island and Delaware (combined) and soon to be as large as Connecticut. The August Complex (now ~ 20 miles SW of me) just merged with the Elkhorn fire to form what is now the largest fire in Calif. history…over 700,000 acres. The famed Mendocino National Forest has been decimated, with as much 1/2 of it’s area going up in flames in this single event.
      And lest I forget the 111-113F temps we’ve endured on multiple occasions this Summer along with 51days =>100F. As I write, the air is so bad that it’s impossible just to get to your car without a mask… it’s basically SIP ver.2.
      Anyway, have a good day! It could be worse.

      • Note: The 3,000,000+ acres burned was for California alone in 2020. Up in Oregon, almost 600,000 acres and many small towns have been torched (including parts of bigger cities like Medford, Ashland and Portland) in the last 96 hrs as near hurricane force winds whipped up a series of mega-fires within a few hours of each other.The offshore winds have carried a dense bank of smoke 1,600 miles out into the Pacific before curving back towards California.
        Note also, the great Yellowstone fire of 1988, which has been widely documented, burned “only” 800,000 acres. As of now, the August/Elkhorn complex, plus the new Slater Fire and the Red Salmon complex (which are all in same general area) has now eclipsed Yellowstone.

        • As a sideline could you make any comments about firehardened homes in california? Is it normal or just confined to a few isolated settlements?

          • Not as many as you’d think. New construction codes now require fire-resistant materials (metal, stucco, cement board, etc.) but in the rural areas, existing properties, where a lot of the fires are, pretty much nada. One of the disincentives for retrofitting or securing perimeters are the costs (removing one tree by a professional can run upwards of $500.00), which is beyond the means of most folks. Also, the costs of fire insurance has skyrocketed, which puts further strain on limited budgets. However, it’s not all bleak, as there are now community-oriented ‘hardening” programs taking place, such as securing a perimeter around town, limiting tree density on lands inside city limits, and enforcing trash and debris ordinances.
            For those homes/businesses that have burned down, metal buildings and roofs, and tile roofs are on the rise, too….and in some places, are becoming mandatory.
            Regardless, in addition to common sense prevention, the real answer is to improve/expand the existing fire lines that are now carved into many of the forests, which if designed and maintained correctly, would limit the chances of a “normal” clearing-out-the-old-timber and brush fire from turning into a holocaust. What we saw here in August, was a lack of man power to deal with so many fires after they got established, but if adequate fire lines were in place, fires like the August Complex (and the Slater FIre now creeping into southern Oregon with 0% containment) still would probably not have reached such proportions.
            Lastly, in a broader attack, there is a growing consensus amongst locals that climate change is creating the basic ingredients for “normal fires” to literally explode (in addition to poor forest management and an overall increase in the number of human-caused ignitions).
            Autumn is our fire season out west (as you know), which used to last until the first fall rains made it to the coast…usually in mid-late September… becoming more widespread and extending southward by the end of Oct. But now, with climate change, our fall rains often don’t start until November, plus the rains shut down sooner in the Spring. In addition, temperatures in the mountains have been on the rise for several decades, and when coupled with a generalized drought pattern, is allowing the Bark Beetle population to explode….in old times, it was the “typical” cold temperatures of Winter in the mountains that held the beetles in check. But now, the beetles are free to expand their territory, and have killed millions upon millions of trees (some estimates are almost 1/3 of of the Sierra forests have been affected since 2010 alone), all just waiting to get torched in a fire.

          • Thank you for that report, it makes perfect sense and I wish those trying to deal with the problem my best wishes. Ultimately the problem will get solved and the thing about california is that they seem to be taking rational decisions even if implementation is difficult. Well done them. Sadly other places (eg australia) is a long way behind, in effect in denial. You cannot beat comments from people in the thick of it as against the UK press, which politicises and distorts everything.

          • Fires are an expected consequence of global heating. It happened in the Amazon and in Australia pretty much as predicted. And now in the US. It always was a matter of when, not if. As for fire hardening, one finding in Australia was that the most dangerous part was embers coming in through the windows. Metal wires on the windows can keep them out and make it more likely that a house will survive. Of course, a wooden house in a forest fire may not fare well regardless of window design.

          • What I cannot understand is why they do not build community fire shelters, similar to bomb shelters. A shelter built underground, with a power generator to provide power for lighting , air filtration and cooling. In the event of a fire people move from thier homes into the shelter until the fire is past. Seems there is an ostrich mentality, ignore the problem until it happens, panic, try to drive out through the fire and get roasted. Crazy.

  8. Chad: Hawaii coud be the worlds hottest magma right in eruption temperature? I knows it depends on also how fast its rises and how long the basalt is stoored undeground.
    But Hawaiian lavas haves a smoothness and shinyness that few basalts other than Galapagos, Erta Ale and perhaps Iceland Haves too. ( Hawaiian main plume basalts often displays extraodinary mobility ).
    But all basaltic magmas are generaly quite mobile. Kilaūea summit magmas specialy from South Caldera are a high magnesium, high olivine content basalt that erupts at full liquidus temperature.
    1974 and some of Mauna Iki in early 1900 s haves just centimeter thick flows in places. Thats well over 1200 C. Kilaūea can display amazingly mobility probaly because high temperatures breaks down the sillica polymers. The 2008 – 2018 summit lava lake was probaly the same magma, it too displayed amazingly low viscosity and made the most beautyful peles hairs that you can ever imagine, all very long golden and wool hair like. Very long thin gold peles hairs there.
    Close to 1240 C been estimated for the summit lava lake at Kilauea I think, with hardly any mineral crystals in the glass melt. Deeper down 70 kilometers or more the temperature rises to a bit over 1600 C.

    Kilaūea haves a very large yearly supply rate, so much of the magma inside Kilaūea at current are probaly less than 15 years old, but much of the summit magma chamber is intact, 20% drained in 2018. Deeper down its even hotter of course.

    If the Puu Oo eruption did not take place, but the Halemaumau eruption did in 2008, the summit lava lake woud not be robbed by the 0,2 km3 yearly supply down to Puu Oo. The summit woud perhaps overflow all the time, without any flank eruption robbing it.
    It woud overflow like crazy, without the 1983 – 2018 flank eruptions magma robbing from summit. Why Mauna Ulu stopped is a little strange, as it too was erupted during an era of very high supply. Volcanic gas is another important eruption driver. Hawaiian magmas are very gassy, But most of it bubbles out because of the low viscosity. The vog been terrifying during the years at some times.

    Nyiragongo coud be another candidate for the worlds hottest erupting lava, But its a completely diffrent compositon, while the sillica is lowest of all sillicate lavas on Earth it sometimes does not appear to be as hot as Hawaii. But 1977 and 2002 had very high temperatures at upper vents.
    Nyiragongo haves difficulty to produce peles hairs, probaly because the sillica content is so very low? Nyiragongo is very fluid, with lots of fluidal action, But I haves not seen the fantastic peles hairs there.Nyiragongo can produce glass If cooled rapidly, But how good a ultrabasic/ ultramafic Nephelinite is to produce glass threads I dont know.

    • The samples of Nyiragongo 2003 from the then new summit lava lake ( collected by Durieux ) by fishing in the lake from long chains, showed a 100% fresh competely crystal free melt under microscope.

      But I dont know the melting point of Nephelinite magma minerals! Its very diffrent from a normal basalt in minerals.
      Completely alien to ”normal” ubalkaline basalt magmas.

      Nyiragongo is also produced by smallest ammounts of partial melting to form souch very alkaline magmas.
      But very active for being Nephelinites, so huge forces behind

    • Viscosity – wise these two are quite similar, looking all over internet on viscosity data for Kilaūea and Nyiragongo.
      Hawaii is very fluid because its very hot, breaks down the sillica polymers despite 50% sillica.

      Nyiragongo haves a extremely low sillica content and a high temperature too. The sillica content is as low as 35%
      Viscosity is very low, lower than almost any other sillicate lavas, as low as 2 Pa.s been estimated in experimental studies with eruption temperature in 1977.
      Nephelinite is a product of very little partial melting in the mantle and is common on the older dying hawaiian Islands as last gasp volcanism.
      You never finds any large volume nephelinite eruptions.
      Its never made in any large ammounts by the mantle.

      Hawaii and Icelands Thoelitic Basalts is on the other end of the partial melting scale
      These are the magmas of flood basalts and LIP s

    • That was a big firehose lava too and the longest lived one ever fimed and recorded in action. It went on like that from New year bench collapse 2016 – 2017 to summer 2017 before the bench started rebuilding itself. Rock in lava tubes are an amazing insulator, so the Kamokuna firehose flow erupted at vent temperatures of 1170 C. The flow was mostly lamminar but witt turbulent shear in it. The lava explodes into tephras when it hit the ocean and water gets trapped inside globs and explodes.
      By summer 2017 the fast moving low viscosity lava stream encased itself Into a shell.

    • Anyway the 1974 summit eruption of Kilaūea was fantastic, as it came directly from the south summit magma resovair. It started out with massive chain of lava fountains ( basicaly a mini flood basalt ) over a 1000 cubic meters a second, of very hot and primitive thoelite basalt high in magnesium and olivine. The 1974 halema’uma’u can be described as a lava ”flash flood” it moved very quickly. Forming ” shelly sheet pahoehoe”. 1974 was very hot and highly fluid, and fast eruptive rates. Almost No Aa lava was produced during 1974, despite high eruptive rates. Google Earth is a great way to explore the 1974 lava field.

      I guess I haves to find smaller pictures to post here

    • I think that a lot of the debate on magma temperature is best done on the bar because its not specific to Hawaii and looks to be quite a wall of text, but in general tholeiite basalt is very hot. I think any volcano capable of over 1100 C in a basalt upon eruption is probably going to look quite similar, though given its deep roots I would perhaps choose Hawaii over the others as the top of the list, someone really needs to do a proper comparison though. Maybe a future post 🙂

      Mauna Ulu stopped in 1974 because it diverted to erupt at the summit vents, more or less a repeat of what happened in 1971 even down to the summit eruptions being in the same places and in the same order at the same time apart, really almost a mirror repeat. The eruption in December 1974 was more or less 3-4 months afterwards, which is how long the pause in 1971-1972 was, only the location was different and perhaps it was quite random as to where the next eruption was until then and maybe the only reason it didnt return to Mauna Ulu was because its summit was by then the same height as the caldera floor. The eruption in December 1974 was only the beginning of a big intrusion so it was quite sizable as a volcanic event even if only 6 hours of it was an eruption.

      The reason things changed so much after that is probably because Mauna Loa erupted in mid 1975, again more of an intrusive event so bigger than it looked, and that probably lowered pressure a bit at Kilauea or otherwise seems to have effected it in some way. Then instead of a big eruption the whole south flank of Kilauea shoved south and this left a lot of space to fill that the available magma under Mauna Ulu was not sufficient to do so, requiring long term filling. GVP bulletin on Kilauea for early 1983 mentions the initial fissure erupted over an area where as much as 1 km3 of recent magma was sat, so the time between 1974 and 1983 was not of low supply but of difficulty in magma reaching the surface. This is rather a lot like right now actually, so maybe in a few months-years we get a new fissure on the east rift that turns in to another Pu’u O’o for the next generation, actually the quakes and GPS at Kilauea are looking interesting now, maybe not much longer 🙂

    • Actually, because I realise you have already asked this on the bar too 🙂 im going to try to answer this here but really I dont think the clear cut answer you want actually exists. Lava temperatures for mauna iki and both the 1974 summit eruptions were in the 1170 C range, the 1974 SWRZ eruption was about 1190 C, and some of the lava in Makaopuhi crater in 1965 was at 1200 C. Pu’u O’o was variable but typically about 1170 C, so pretty similar and this is probably the average. Eruptions over 1200 C are actually not common, in the 21st century only some summit lake records got to above that and not all. However 1959 was before direct measurement but significantly above 1200 C, with a recorded temperature of 1179 C on an optical pyrometer, probably close to 1300 C in reality. This was not universal to all 1959 lavas though, most were rather less.

      Nyiragongo as far as I know has no official tested temperature, only assumed temperature from surface morphology. It may be hotter or not, but as far as I know the hottest magma directly measured is in Hawaii, so go with that.

    • Its better for the VC Bar to ask this: but indeed heat and Hawaii are relevant.

      Have any lava lake measurements been done at Nyiragongo? I means penetrate the lakes skinn with probe and measure under the skinn crust? Nyiragongo have been visited many times

      • I suggest to Jesper that when Kilauea is erupting again that he go and test the temperatures of both volcanoes directly, then make a post on his findings.

  9. Hawaii ( coud be? ) the hottest erupting lava on the entire planet for now.

    Take a very close look at this daylight photo of 1974 Halema’uma’u caldera eruption. Look at the yellow hot lava
    almost yellow white there in daylight in the breakout. Its well over 1200 C.
    Most basaltic magmas erupt at over 1100 C but rarely go above 1200 C.
    Hawaii is hot, specialy near the summit.

    Holuhraun Iceland 2014 was hot too
    at 1188 C ( almost 1200 C ) making it the hottest Icelandic lava eruption thats been recorded in action so far in Iceland. Holuhraun had also the same composition and gas as Kilauea

    image removed. again. -admin

  10. May we please ask commenters to be succinct and to avoid repetition? We may begin to edit comments that are much longer than their content requires. Also, it is best if linked images fit a typical screen size. 500 pixels is normally plenty. Anything much bigger just eats up bandwidth.

  11. USGS allows you to manage pixel ammounts in links. Is this too large?
    Here is the 1974 summit eruption of Kilaūea ”mini flood basalt”
    If you where on the parking lot that day, it woud move supprisingly fast towards you.

    • At current the supply of fresh magma to the big island is exceptionally high compared to the long term geological average, and may have started really increasing some point in the last 2 million years since the huge Ancient Maui Nui formed. Especially since mauna loa and kilauea formed.
      Perhaps as large as 0,2km3 every year put in.

  12. Looks like Midway Atoll is one of the most northen coral reefs in the world.
    Its also as a volcano way smaller than any of the volcanoes south of it.
    Latitude 27.. isolation, I knows that many WW2 squabbles happened in the north of the Hawaii chain.
    Must be a heaven for seabirds: no rats or cats

  13. Look like TS/hurricane Sally is going to be bringing some big rains to GeoLurking’s neckadawoods?
    The core/eye will be west then north of the panhandle, so they’ll be getting multiple rain bands from the ENE then switching over to SSE with a lot of embedded convection training over the same area. Thinking good thoughts for the safety of all concerned.

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