Pavlof having a Hekla moment

Eruption of Pavlof. Photograph by Colt Snapp (that may have to coolest name in history of photography).

Eruption of Pavlof. Photograph by Colt Snapp (that may have to coolest name in history of photography).

Hekla is famous for its short run-ups prior to eruption, typically the run-up involves a smattering of small earthquakes for an hour or so and then it goes boom. Pavlof has the same nasty habit of not announcing upcoming eruptions.

At beast you get a few harmonic tremor episodes in the hours prior to an eruption, and that is exactly what happened this time around. In the last 24 hours prior to onset of eruption two distinct minute long harmonic episodes happened and one Long Period charging episode.

Pavlof takes this enigmatic behavior one step further; it has no earthquakes shallower than 50 kilometers. At least that was true between 1973 and 1987 and in an area 30 kilometers out from Pavlof. This is a very unusual behavior for a highly active volcano. There are though a cluster of earthquakes that occurs at depths larger than 100 kilometers below the volcano.*

Another thing is that in 22 volcanic events in the period 1973 to 1987, 13 events where phreatomagmatic and distributed fairly evenly across the year, but the 9 magmatic events was highly constrained temporally. All of the 9 occurred between September 9 and November 20. And in one run Pavlof had a magmatic event 4 years in a row, these four eruptions was constrained even harder between November 11 and November 15, one each year.*

This little funny sequence of calendarial eruptions stopped directly after the publication of this particular paper, so it is a bit less surprising now with a late March eruption than it would have been prior to the publication.


Onset of eruption with the two brief HT-busts and the LP-event. Image captured by Tyler Mannison from AVO.

Onset of eruption with the two brief HT-busts and the LP-event. Image captured by Tyler Mannison from AVO.

Pavlof Volcano in the Aleutian Arc is part of an NE trending local chain of volcanoes starting at Emmons Lake Caldera that forms the Emmons Lake Volcanic Center. This volcanic center contains Pavlof Sister, Pavlof, Little Pavlof (forming a triple volcano), Double Crater, Mount Emmons, Emmons Lake Caldera and Mount Hague.

If we restrict ourselves to the Pavlofian sub-system we find that surprisingly little study has been made about this frequently erupting system. One would think that one of the most frequently erupting volcanoes on the planet with a threat rating of 96 (out of 100) would merit quite a lot of scientific study. One would be wrong to assume that, there have literally been more eruptions than studies of Pavlof itself.

And in an eye-watering neglect Little Pavlof and Pavlof Sister has not been studied at all. And here it becomes hoary, it is actually unknown when Pavlof Sister last erupted, it is believed, but not tested scientifically that Pavlof Sister was highly active up until the massive 1786 eruption. This last eruption is contested if it was Pavlof or Pavlof Sister that erupted and apparently nobody has deigned to shlog up the slope of Pavlof Sister to take samples and spend a day in a laboratory to check. To me that seems like a pretty straightforward thing to do and something that would get you a paper published.

Today’s eruption

At 23:53 UTC eruption commenced at Pavlof after the above mentioned miniscule precursor signals. This basically made any eruption prognostication impossible at the current level and type of monitoring.

At 00:18 UTC an airline pilot noticed and reported in an ash column reaching 6 100 meters (20 000 ft), and later quite a few happy passengers on passing airplanes got to photograph the eruption. The ash was dispersed northwards due to a convenient southerly wind.

Judging from earlier eruptions this eruption could last anything from a couple of days up to years and it will be time that decides the size of the eruption. Going by the looks of it we are looking at a VEI-2 or a VEI-3 if it continues for a while. Anything larger is unlikely.

Grump mode on

The Pavlofians. To the left i Pavlof Sister, to the right is Pavlof and the small one behind to the right is Little Pavlof. Wikimedia Commons, Photograph by T. Miller, U.S. Geological Survey, July, 1975.

The Pavlofians. To the left i Pavlof Sister, to the right is Pavlof and the small one behind to the right is Little Pavlof. Wikimedia Commons, Photograph by T. Miller, U.S. Geological Survey, July, 1975.

First of all, I would like to state that what I am writing next is not aimed at the AVO and only partially at USGS. It is mainly a rant about the foibles of politicians.

Most of the volcanoes in the Aleutian Arc are grossly understudied and many are not monitored, and those that are monitored are under-monitored on a scale that is ridiculous. This is a sad fact. A happy volcano in the Aleutian Arc has a seismometer and a GPS that works at best half the year and the volcano get a visit every year and perhaps a paper written about it every two or three years. Pavlof is such a volcano.

But a lot of volcanoes do not get even that miniscule attention, Pavlof Sister is such an example. We can drive a Panamax Supertanker through the gaps of knowledge about that volcano, and I guess it will surprise nobody when they learn that it is un-monitored.

Now most people will think that this is due to there being no people living in the area, but there are people living there even though they are pretty few.

Now remember the part of Pavlof being assigned a threat number of 96 out of 100? That is due to what occurs next to it every minute of every hour of every day across the year. And that is that an airplane flies by the volcano. This is the world’s premier flight route for all traffic between Asia and the continental US.

Now imagine that Pavlof or any other monitored or un-monitored volcano suffers a slightly larger eruption than normal at about midnight in northerly winds. Due to the airplanes flying extremely close to the chain of volcanoes you would have 1 wide-body airliner a minute suffering engine suffocation causing what the airline industry euphemistically calls a total hull-loss. In more human terms we are talking about up towards 300 people splashing into the ocean per minute.

What I described above is a worst case scenario, but sadly it is a fairly plausible one. Obviously not all airplanes would go down and it would just last a few minutes before airplanes where redirected. But it is a chilling thought all the same.

Here is something for politicians to ponder. The liability for a lawsuit per person would cover a volcanoes monitoring for ten years. So, in the long run it is far cheaper to give AVO the money it needs compared to having the FAA pay out massive amounts to grieving relatives that died unnecessarily.

And now a slightly milder barrage, I know that it is nicer to study volcanoes on Hawaii with a gin and tonic in your hand compared to freezing your butt off and getting eaten by huge bears in the Alaskan outback.

I also know that it is easier and better for the career to publish yet another useless on the comatose Yellowstone, or to spend a fortune on even more equipment there.

These might be comfortable places, but they are not the scientifically correct places to be at. I know you know this, I am just pointing it out in the open even though I know that it is easier to get grants for Hawaii and Yellowstone compared to the Aleutian Arc in the Alaskan Hinterlands. Once again it is mainly a political thing, but I have to grump a bit about it.


Update: The ash column is now reported at a height of 11 285 meters (37 000ft).

*Eruption characteristics and cycles at Pavlof Volcano, Alaska, and their relation to regional earthquake activity; S.R. McNutt

152 thoughts on “Pavlof having a Hekla moment

  1. I would like to thank Tyler Mannison who brought the eruption to my attention and supplied the SIL-image from the onset of eruption.
    He also gave the inspiration for the headline.
    Thanks Tyler!

  2. I think a lot of people, even on here don’t realize how potent the Aleutians are as a volcanic chain. This is definitely one of those volcanic chains where you’re happy that it is more remote (even if air-traffic goes right over it).

    Lots of beautiful peaks, even if it’s quite cold and remote however.

  3. Just a random thought; Grimsvotn doesn’t have many quakes because there is a more or less permanently open conduit: maybe something similar applies to Pavlof?

    Installing and maintaining monitoring equipment on the outer Aleutian islands will be a bit of a nightmare, given their ferociously inhospitable weather. But AFAIK the bears are not found west of Unimak Island, one small consolation.

    • It probably is a sign that the conduits are kept open between eruptions. It would be the only explanation that explains that there are no shallow earthquakes.

      Oh? So not even the bears are that crazy 😉

      • Only the bipolar bears. 🙂 (Yes that was pretty grizzly.)

        Sorry to introduce myself with horrid puns. I have been enjoying this blog the last couple of weeks. You all have helped reawaken the dormant geologist in me (Hydrogeology not vulcanology alas) and have me dusting off my college books again. Been reading the post archives here and I’ve got more out of these articles and the links to the sources than I got out of my college course. (Yes, I had another emphasis in my coursework, and my prof at the time was burned out…man was I ripped off in that class, but still. Hats off to all of you.)

        I’ll probably ask some questions as I get back into the swing of things. Isn’t the internet a wonder place occasionally? 🙂


        [Rescued from Akismet – Welcome at VC! / Lugh]

        changed displayed username as per request /Hobbes

        • Welcome to Volcanocafé!
          With that bad kind of jokes you are welcome 🙂

      • But….If the conduits are continually open, the ability of the system to build pressure is somewhat diminished, and thus a less likelihood of a large eruption…right? Certainly nothing catastrophic. If so, you are correct, it is a poor excuse for the lack of monitoring for Pavlof and a darn poor excuse for the rest of the system or arc.

  4. Pavlof’s one of the most well monitored volcanoes in the state. All of the seismometers are typically kept working and the webcam’s kept functioning, although clouds are an issue. InSAR studies have found that Pavlof’s also rude when it comes to deformation, so no one’s bothered to plop a GPS on it.

    Regardless, it and almost any other volcano in Alaska are grossly understudied and budget cuts only make things worse. Politicians seem to forget that Redoubt almost crashed a Boeing 747 with 300 people on it in 1989.

    • I know that Pavlof is one of the best monitored in the chain.
      I am actually more worried about those that are less monitored and studied since they are more likely to do something unexpected.
      Hm, I could have sworn I had seen a GPS-station listed for Pavlof, but I might be wrong or it has been taken away.

  5. And on a completely different tack…

    The photographer that took the photograph up above, Colt Snapp.
    Is it just me imagining him barraging about in remote Alaska with a gargantuan Hasselblad camera in a hip-holster? And when he shots a picture he takes it from the hip in such a lightning fast action that you only hear the shutter go off? And that when he takes photographs the birds start whistling movie-themes by Ennio Morricone? And that when he takes a photograph of a Kodiac bear it faints…
    Must be the best name of a photographer ever!

  6. does anybody know how to make/transfer the loop from the FAA webcam. The night part of the loop you can clearly see the lava fountain on Pavlof. I looped the Cold Bay cam NE 40. Very cool if we could capture it.

  7. Once a volcano erupts there is usually enough time to get an ash advisory going,even something well monitored,is not necessarily going to erupt on schedule.That sort of monitoring really only matters in areas that could affect nearby population and would not the Aleutian islands be sparsely populated?Also the effect of the ash on aviation is more affected by weather patterns and jetstreams?

    • Geyser, it takes 1 minute for an explosive eruption to reach flight altitude, with a northerly wind it would be in the flightpath 5 minutes later. And it would not be a diluted little thing as Eyjafjallajökull was, no this would be concentrated ash straight into the turbine.

      See it like this, the place is habited by 300 people every minute on a double chain going back and forth. That airspace is about as populated as any on Earth.

      • This is not 1982,its 2016,satellite coverages is universal,radars in aircraft are more sophisticated?But aside from all that ,if an aircraft is travelling 800 km/hr and the diameter of the top of the eruption cloud is 50km ,the aircraft is only going to be in that zone for a little over 3 minutes to catch that 1 minute eruption column,that erupts once in at least a few years.More chance of that plane crashing from other causes and that has been proved with time,when was the last time a volcano caused a crash or near crash of an airliner?

        • Aviation related radar CANNOT see ash. They can only see water drops above a certain size.

          • Quite true. Ash is mostly silica and is translucent to radar… much like glass is to light. Both cases are examples of electromagnetic radiation and how it reacts to silica.

          • If there is a certain water component to an eruption,
            the silica content is waay overriding
            any droplets that might be in the cloud. Carl is right to be concerned.

          • Well,even though doppler is made to see water, it has to be in some sort of condensation to pick it out. Pure vapor is background noise, if anything to a radar. It will change the scatter somewhat since the refractive index changes, but there is effectively no reflection.

          • Caveat: 20+ years working in and studying radar in a tactical environment.

          • Water is spherical and reflects RF easily back to the source (radar emitter). Ash is not spherical (usually) and refracts/scatters RF a lot, thus rendering the emitter blind. It never receives any RF back to the plane’s navigation or radar systems.

            The other issue comes from the ash itself and how it effects the engines. All jet engines work the same using the “suck, squeeze, bang, blow” principal; multiple groups of fans bring the air in, compress it, mix the fuel, and eject it out the exhaust as thrust. Commercial airlines utilize a high-bypass version of this engine. It operates just as it sounds. A large amount (~85-95%) of the air drawn into the engine bypasses the intake and is used as the primary thrust for the aircraft. That is why the nacelles are shaped the way they are and why there is such a large fan up front – the fan is “ducted.” Only a small part of the incoming air is directed into the internals of the engine.

            Now, all of these fans spin very fast (understatement of the year) and when they encounter particulates in the air, they tend to chop them up rather efficiently. Only, with ash, when the fans that compress (and heat up, due to the effects of The Combined Gas Law) the air and the fans that mix the fuel hit the ash particles, the combined kinetic, chemical, and compressional forces actually melt the ash back into glass and that glass begins to coat the inside of the engine. This coating, just like ice on a wing, begins to change the shape of the fan blade, making it less efficient, disrupting the airflow over it, and can choke the motor out completely; it can no longer squeeze or bang, so it stops sucking and blowing. It does not take much to do this, and one minute inside an ash cloud could be more than sufficient to bring down a two or four engine airliner.

            As you see, the engine does not just momentarily lose thrust, the ash changes the engine’s internal make up and once the plane gets into clear air, nothing says the engine MUST restart. When it does (as with a 747 back in the 80’s over AK that choked on an ash cloud) enough glass was ejected from the motor and blades due to centrifugal forces to allow the motor to restart.

            (Full disclosure: I was an Avionics and Fire Control Tech in the Navy working on F-14 Tomcats and S-3 Vikings for 11 years. I was also a flight-deck troubleshooter, so I was required to know a lot about everything on the jet.)

    • Geyser, have a look at the AVO report on Kasatochi in 2008: Had it not been for the presence of two scientists on the island in the run-up to the eruption, there would have been very little warning – Kasatochi is fairly isolated and off the main volcanic line. And that eruption was a humdinger

      • Let us now ponder Pogromni.
        It is a badly known post-caldera rebuilding volcano near Westdahl.
        No monitoring at all, and lo and behold the airlines fly over it.
        Nobody would basically know if it was bopping away on the road to an eruption.
        Next to it you find Westdahl that is known for hitting big from time to time. And it is not that restive either.
        Seriously, ponder why we have all these juicy pictures taken from the air, that is airline passenger snapping with smart phones as the whoosh past.

      • Risk vs benefit,heavily monitoring very isolated volcanoes,would cost a fortune and do little to mitigate the risk of flying on a daily basis,there is more threat from weather and bad weather is a more frequent occurence?

          • I get what you are trying to say,in an ideal world every country would actively monitor every volcano on their territory that is either active or could become active.Some countries may have the resources for this and lot will not,also monitoring requires a certain knowledge of a particular volcanoes pre- eruption behaviour to be more effective,fine for the frequent erupting systems ,where their patterns are well studied.But what of the long dormant system that becomes suddenly active ,there is no studied history to its behaviour and also calling an eruption will not necessarily predict the size of the eruption.Once the system has erupted there is enough monitoring to assess it’s danger to aircraft and alter flight paths,this has been proved time and time again.If a caldera erupts right under your plane and it crashes ,that is extreme misfortune of the highest order and not something that has worried me on a flight.

          • So, you are basically saying that we should not make the effort to study highly active volcanoes that threaten to shut down airline traffic between the US and Asia and that we should not bother with monitoring it even though it threatens the life of people?
            So, basically you are okay if we move all equipment from New Zeeland and emplace it on let us say Shishaldin? After all, there are few people living on those Islands too.

          • As I recall Icelandic airspace was closed, until it became obvious Holuhraun was just pushing lava and not throwing ash to the upper atmosphere in huge quantities.

          • Whoops, I was hoping my 20:01 would appear below Geyser’s 18:54

          • New Zealand volcano monitoring is not perfect,its only fortunate that eruptions there are infrequent.There were skiers on Mt Ruapehu in 1995 when it erupted and tourists on White island when it was threatening to erupt and school children on the Tongariro crossing when it erupted in 2012,if Tarawera 1886 occurred again I would not want to be reliant on the monitoring.

          • Geyser, we were actually diverted when Barda was in yellow state. A no-fly zone was established over a certain part of Iceland for some time.
            Jet airlines are not equipped with ash detecting devices and the Redoubt scenario is unfortunately still (2016) very possible, although we’d very much like it to be different. VAAC and ashtams is all we have. Predictions based on average windspeeds etc
            Add to this the fact, that if a jet does inadvertently enters an ashcloud it will only take seconds(!) to choke all engines, pollute the cabin air inside and sandblast all cockpit windows, reducing forward visibility to virtually zero for the flightcrew.
            It was my company’s 747 that was brought down by Redoubt. We know what ash will do and at what speed.
            I’ll post a link to the actual ATC – aircraft dialogue of the incident to give a sence at what speed things develop.
            Volcanic ash and jet aircraft do not mix. Timely warning and evasive action are the only way to mitigate the danger at this time.

          • tlfkaTsunami ,I never said ash was not a danger to jet aircraft,but that there are other tools ,satellite and better communication of hazards that were not as developed in the 1980s,my mistake with the radar being more effective.

          • HeclaSu,yes you are right,I argued myself well out of my depth and my apologies to everyone concerned,just hope it was all somewhat constructive at some level☺

        • Glad you mentioned bad weather; Aleutian weather is notorious. Low cloud (and fog at ground level) sometimes for days at a stretch. So a satellite picks up the ash column only after it has punched through the clouds.Even a few minutes warning eg onset of harmonic tremor, could make a vital difference

          • So should all the air traffic over the North Atlantic have been diverted in 2014 when it was looking like Bardarbunga might have an explosive eruption?You are saying monitoring will make the difference in warning an aircraft in the time it takes an eruption column to break 10000ft?So you would have to decide if the system was going to erupt and then warn an incoming aircraft in under a minute,so you have to be able to pinpoint not only that an eruption is going to occur but also the exact time it will occur or otherwise re-route aircraft for an indefinite period of time?

          • Depends on the silica content of the ash. Bardabunga’s ash was less silicic that Eyjafjallajokul’s so less of a hazard.

            Silica can collect in the jet engines, which, when it cools, hardens to form glass – not good.

    • Last time Pavlof erupted, it took several hours for a VAA/VONA to be sent out because it was too cloudy to see the volcano on the webcam and satellite; a pilot only happened to see it erupting in the first place. Thankfully, nobody flew into the plume in the process.

      One of the reasons aviation rules for volcanoes exist is because a 747 flew into Redoubt’s plume in 1989, lost all four engines, and plummeted 13,000 feet. The next time the volcano erupted, people were well prepared, thanks to volcano monitoring. It doesn’t just help people on the ground, but also people in the sky be prepared.

  8. Carl, didn’t you mention a while back that four-peaked was worthy of more monitoring? What was your reasoning behind this?

    • It was due to it being a complex volcano, and complex volcanoes in Alaska tend to do rather nasty things. Even though Four-Peaked is not highly active it’s form and shape point to a rather high capacity when it finally get going.

  9. Well said, Carl!

    One of my pet gripes is how politicians are more concerned with expediency and the next opinion poll/election rather than doing the job us voters imagine they have been elected to do. How about a reduction in both the number of publicly elected officials as well as the size of the renumeration they award themselves in order to finance adequate monitoring and other vital scientific projects aimed at increased public safety?

    • The bureaucracy’s prime directive is to provide for the expansion and survival of the bureaucracy. Nothing else is a consideration.

  10. The VAA is to FL400 with ash drifting to the north. Flights heading to Anchorage are having to make hefty diverts to pass to the south of Pavlof as they descend into Anchorage. Other than that air traffic business appears to be as normal

    • To add to that remark, what I should have said is that trans-Pacific traffic is routing to the south of Pavlof, or a long way to the north of it.

    • Watch the video the whole way through – they took some random volcano video of a volcano that is NOT pavlof, and inserted it into their article. You can see a large city at the base of the volcano towards the end of the video. Unless some large city suddenly popped up in the Aleutians, I don’t really think this is the right volcano.

    • In addition to using video of the wrong volcano, I’m pretty sure they copy/pasted significant chunks of the article from a piece about the Nov. 2014 eruption, especially since Pavlof’s been quiet since then.

      From the FAA camera, it looks like it’s erupting from the NE summit vent. Can’t be sure.

      • That is a fairly typical example of UK tabloid press journalism. If a fact does not fit conveniently within what the ‘journalist’ wants, it is discarded.

      • The aircraft you mention just retired last year ( after many uneventful flights, flew a couple of them myself). Point is, we all still fly around with the same engines as in 1989. Some new engines were manufactured during the years, but make no mistake, they still operate the same and will react in the same fashion when in contact with ash.

        • Agree 100% with what you are saying.
          I was working for an Air Taxi outfit in Washington State during St. Helens.
          Had some training in Geology in College,
          so had a vague idea as to not play round in the ash. However there were people-some in government who had no idea what to
          expect. My Cousin who was an Engineer for Union Pacific Railroad was working a switch
          yard in Davenport , Wa. He had experienced
          volcanic ash in Alaska when he was in the
          US Army. Tried to tell the Yardmaster to shut down ops. Davenport got like 5in of
          ash. Yardmaster wouldn’t stop operations.
          Until the GP-9 switcher quit. It was so
          clogged up that it had to be scrapped…

  11. I wonder if there is any connection between Pavlof and the 4 volcanoes (at least) that are currently erupting in Kamchatka:

    n Kamchatka;




    and Brezmianny:

  12. Howdy all –

    In response to the question about AVO funding, the answer is Chicago-style politics. Chicago is a single party town. Has been that way for over half a century. The way the political game is played in Chicago is that if you aren’t part of the political machine, you get no money. Obama came from that political machine. As such, he plays by those rules and has done so while in office for the last 7+ years. The Alaska congressional delegation is all Republican, so when it is time to cut funds, states with Republicans in charge bear the brunt of those cuts and complete lack of interest from the Obama regime. This is why AVO has seen the budget cuts over the last several years.

    Over the last day or so, Alaska Airlines cancelled a couple hundred flights to interior Alaska due to Pavlof ash.

    I did an overview of Emmons Lake on the old VC site Nov 2014. Cheers –

    • this isn’t true. I looked at the budget tables, what ultimately is approved by Congress has been far lower than what the White House initially proposed, since 2011. the House and Senate have been doing the cutting. the biggest cuts were FY 13 and FY 14. I think the Alaska delegation should chat with their colleagues from other states who think volcano monitoring is silly (like my current congresscritter.)

  13. maybe someone has already brought forth the idea that the Aleutians also serve as an emergency landing spot for commercial flights across the Pacific…… i’m with Carl, the world would benefit from monitoring these volcanoes. Best!motsfo ………………. ps…………….. mosquitoes would eat You alive out there faster than a grizzly

    • I definitely fear mosquitos more than bears. At least our mosquitos and bears in northern Sweden.

        • Our mosquitos does not carry malaria, they instead kill people by swarming in their millions. Every year there is a drunk fool or two that has fallen asleep outdoors and been sucked dry.

          • If you get sucked by thousands five year long, you are immune to the itchy results … at least that’s what is my experience.
            Far more worse in our swamps are the small 2-3 mm ones (turkies we call them, no not Turks or turkey’s 🙂 ), they attack massive in cloudy weather in june, until the longest day. After that they are gone. They do not suck, but bite.
            At some point you can’t take any more, and start running.


          • We get the mosquitos in huge billowing clouds containing millions of them. When those clouds form at dusk you run for cover.

      • laid in the lingering twilight in Ft.Yukon listening to
        the mosquitoes buzz around the Mosquito nets in the
        hatch of a DC7(we slept in the aircraft-this was aerial
        firefighting) I swear I heard one say:”Should we eat him here or take him home?” The other said;”Let’s eat here if we take him home the big ones will take him away from us.”.-very old joke..

  14. If it is done I wonder what the VEI call will be, VEI-2 or VEI-3 ? There were reports of ash to 37,000 ft for a moment.

    • Depends on time.
      My guess is that it will become another smallish VEI-3. But that is just a guess.

      • I am surprised it could be that much with a 24 hour eruption. I assume it is just calculated on Volume?

          • I apologize in advance for my novice knowledge….Sounds like the VEI scale has a larger exponential component than the richter scale is that a correct assumption?

          • Yes. And, it’s a pretty crappy scale, but its about all that we have to gauge and compare eruptions.

            “The scale is logarithmic from VEI 2 and up; an increase of 1 index indicates an eruption that is 10 times as powerful.”


            Example of the crappiness. For the sake of argument, suppose Pavlof continues at it’s current rate beyond the 67 hour mark. That would put it at around VEI-4. Grimsvotn can easily do a VEI-4 in a just a few hours. Yet both would be called VEI-4 and generally counted as equivalent.

          • First of all, not all VEI-4s are equal.
            Grimsvötn had a large one, the largest in the Millenium so far. It was 5 times bigger than the Eyjafjallajökull VEI-4.
            Than we have Kelud, it was equal to Grimsvötn, but it was done and over with in 92 minutes.
            This makes things rather interestesting, nobody argues that Grimsvötn was all put together the largest eruption, but Kelud was the most explosive, even though both count as even on the VEI-scale.

          • If we got a do-over on defining terms, I’d probably go for VEI being defined by rate, so in DRE/s or something like that, logarithmic scale, and what’s called VEI in our time-line would be, say, ESI (eruption size index) instead or something similar. Or maybe even three measures: VII for DRE/s, ESI for total DRE over the duration of event, and VEI for maximum velocity of ejecta. With *those* definitions, it’s the big phreatomagmatic events like Krakatoa that would get the big VEI numbers.

      • I can work on that when I get home. Now it’s time for FISH!

        (Stuck out here with spring break traffic.)

      • If it maintains it’s current rate, it might make VEI-4 at roughly 67 hours after it started. Currently it’s plodding through VEI-3 territory. At it’s peak, it was ejecting at about 692 cubic meters DRE per second.

        Plume height taken from Anchorage VAAC reports, mass ejection rate calculated using Mastin et al.

        NOTE: This is an estimate ONLY. 1st) VAAC reports focus on flight safety, and may over report ash cloud heights in order to be on the safe side.

        2nd) Mastin et al specifically states that their ejection rate calculation may be in error by up to a factor of four.

        3rd)Like many of you, I am just an amateur and may be completely off base in my number juggling. The spot ejection rates were calculated from the VAAC reports, then a straight second by second linear interpolation was done of the heights to fill in the data gaps. That curve was then summed to find the total ejecta to that point in the eruptive cycle.

        In a nutshell, I could be quite wrong. This is provided for discussion.

        As questioned earlier, yes, the VEI scale is exponential. VEI-5 does not even appear on my plot sine it is so far to that level. The red curve is the summed eruptive rate, the blue line is that rate projected into the future. The last VAAC report that I had availible was DTG: 20160330/0500Z

  15. The Alaska Earthquake Center published an article on Pavlof’s sneakiness:

    Elevated temperatures were observed at Cleveland overnight. If one had to choose a poster child for lack of funding, it may as well be Cleveland. It’s the only AK volcano with a direct fatality to its name, and it still took forever to put any seismometers on it.

  16. Interesting little stack of deep quakes under Katla…

    30.03.2016 03:45:18 63.627 -19.078 26.9 km 0.8 99.0 5.3 km NNE of Hábunga
    30.03.2016 03:41:41 63.619 -19.124 20.3 km 0.9 99.0 4.5 km NNW of Hábunga
    30.03.2016 03:40:55 63.614 -19.120 22.6 km 1.5 99.0 3.9 km NNW of Hábunga
    30.03.2016 03:40:38 63.625 -19.135 19.2 km 0.8 99.0 5.3 km NNW of Hábunga

  17. And a little something for those who are waiting for Katla.
    At that depth this should mean that there is magma entering the system at depth. This is the first clear depth intrusion in many years at Katla (do not remember how many years, but probably prior to Eyjafjallajökull).
    Do not expect an eruption in the next few days though. If anything happens it would be weeks, months or years before it happens.

    Wednesday 30.03.2016 03:45:18 63.627 -19.078 26.9 km 0.8 99.0 5.3 km NNE of Hábunga
    Wednesday 30.03.2016 03:41:41 63.619 -19.124 20.3 km 0.9 99.0 4.5 km NNW of Hábunga
    Wednesday 30.03.2016 03:40:55 63.614 -19.120 22.6 km 1.5 99.0 3.9 km NNW of Hábunga
    Wednesday 30.03.2016 03:40:38 63.625 -19.135 19.2 km 0.8 99.0 5.3 km NNW of Hábunga

      • The general consensus was 24km, but it seems like it was redefined here to 27. Or that the deepest of the earthquakes was not accurately set.
        My personal opinion is that the last of the earthquakes most likely was in the 20 to 22km depth range and that 24 km is fairly correct.

        • To further clarify.
          In the last 3 years the crustal depth has been redefined and become clearer for portions of Iceland and a much better understanding of the complexities of the crustal depth has emerged.
          Previously it was believed that the maximum crustal thickness was near the center of the Island and that it progressively got thinner as it got closer to the pure MAR. Maximum thickness was previously believed to be around 25km and around 10-12km at the tip of Reykjaness and out at Kolbeinsey.

          Due to better and more equipment small heat ductile earthquakes have been registered (hard to register) at larger depths defining parts as up to 40km and the MAR depth has increased to around 16km.
          The depth around the main fissure transecting Iceland (from Katla to Krafla via Grimsvötn/Bardarbunga) is now believed to be 25-26km deep in the main parts with 22 to 24km for the outer ends.
          As soon as you go outside the main faultline you get increased crustal thickness.

    • I have to correct you there on one thing 😉
      This is not the first such intrusion in several years, but atleast 3 or 4 such sequences occured last year alone that I can remember from the head, with more quakes in the pulse and some up to M2+ as far as as 20 to 27 kilometers down in the central region like today and undet the central east caldera rim. 🙂

      • This one sadly only goes till June 2014, but some depth sequences are seen even here, with some if not most, probably linked to intrusions at depth. It will probably be updated eventually.

        • Thanks for reminding me. The two around 2014 was indeed at Katla. The ones prior to that was at Godabunga that has a separate feeder system.
          My memory is not what it used to be. 🙂

      • Yes, I pointed one deep swarm in Hábunga out on here while Carl was away last year. I can’t remember when this was, but those who can search this site will be able to find the IMO data I posted.

  18. Thanks for this post, I’ve been away so imagine my surprise to find this
    happening . Now to look forward to fried green tomatoes and crepuscular sunsets…
    One thing-how about sulfur content into the upper atmosphere, what with the lower tropospause in those parts…?

      • But, at 55°25′ North, it’s right under the upwelling area between the Mid Latitude and the Polar circulation cells. That would tend to assist in getting whatever SO2 load that it has up to and potentially above the Tropopause. (via diffusion if not outright injection)

  19. Interesting quake somewhere else entirely: a 3.8 underneath the Loihi sea mount, the next Hawaian island to come out of the sea. It hasn’t erupted for years and one quake does not summer make, but curious nonetheless. It was a bit deep: 40km, but that seems the norm south of the main island.

    • Sadly that is a volcano we will not see sprout forth in our lifetime.
      It may well erupt several times, but at 975 meters depth it will take a good long time before it surfaces.
      It is though quite cool that it has a caldera on the top, and that pressure it should have been quite an event to cause a caldera to form.

  20. Rapid buildup of unrest at East of Hekla. Tremor and localized earthquakes.

    • Oh look, image is updating automatically, cool but confusing to discussion. I will capture a static image next time.

    • Spooky strain at Hekla, I immediately went to the Web Cam but it was still quite dark.

      BTW, I have captured that image and edited in the static image to your 02:59 comment.

    • It was the most interesting thing that Hekla’s done in the 6 years I’ve been watching her! 🙂

      • I think technically that was the 2013 earthquake swarm. It was the moment when Hekla went “time for an eruption, no I will nap instead”.
        Both me and Páll Einarson botched that one.

    • Related to geothermal energy extraction? Put your local volcano to good use?

      • Nope, in this case it is all natural.
        Before 2000 eruption there was unrest at this spot in the weeks prior to eruption. Nobody knows if it was related.

    • I do not buy it.
      I have seen a lot of IMO-repair sessions and they do them during office hours and they look different.
      Per chance it actually malfunctioned later in the night.
      All is there in the image.

      • Wouldn’t be the first time that a gremlin in the equipment waits until your back is turned before acting up. Those are the most irritating… and in fact, I’m going down to deal with one tomorrow. Taking a new controller, new drives, and a fresh firmware load in my bag-o-tricks.

        I’m leaving my talisman of chicken bones and memory sticks here. That was just an unfortunate joke that got spooky when it seemed to actually work. More times than not I have arrived to a dead system that worked perfectly when I fired it up. I blame the users ineptitude rather than some psychic thing. Psychotic? Maybe, but Psychic? No.

        • Hmmm, classic repair person. Dunno what it is but I drive family and friends bonkers by doing exactly what they claim they did, but works for me first time.


    • I think we will start a new trend especially for you.
      When you actually write something useful it stays, otherwise it will be binned.

      And just to be perfectly clear, we have cut you considerable slack. You are now up to 1 Permban (that was rewoked when we moved) and 3 1-week bans. You mostly just write crap and insults, and we have had it. So, let us say 3 binned items and then it is an automatic permban again. And this time it is permanent.

    • I think the activity also showed up on Ron’s Jon’s recorders. And the bigger quake was on the IMO confirmed quake map. (At least last time I checked.) To add to the confusion. There was also a short lived rumour going around just before it that IMO was worried about the volcano. But that was just bad journalism.

      Sometimes the gods just take a break and Murphy takes over.
      I appreciate the discussion on it however. It gives us Newbies some insight in these kind of things.

      GL Edit: Made the noted change. If you intended the original please state so and I will remove the edit.
      (I just had a 15 minute spat with a clerk about the correct of a name. I won, I was the customer.)

      And yeah, I was pretty close to just telling her to pack sand and leaving.

      • You are correct, it showed up on Jons helicorder, so that way we have confirmation on the signal.

  21. Out of curiosity – it there any consensus on the volcanoes in Italy north of Campi Flegrei / Vesuvius / Ischia?

    Are Vulsini, Bracciano, Alban Hills, and Lake Vico all assumed to be dead or dying volcanic complexes? Has subduction largely stopped here, or flattened out too much for melt to occur? Or are these volcanoes more assumed to erupt highly infrequently?

    If Alban Hills started to show any sort of significant activity, I would have to imagine it would rocket up towards people’s “please don’t erupt” lists due to the population of roughly 3 million people within 30 km.

    • If I remember correctly, the Alban hills have an issue with livestock turning up dead from time to time. (Gas emissions)

  22. Pingback: The Friday Update #9 (01/04/2016) | VolcanoCafe

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