Greip: A prequel on instrumentation

This volcano has nothing to do with the article, except that it is a young pretty beauty. Photograph by Angela Rucker, USAID. Wikimedia Commons

This is both an informal start of our series about a promising central proto-volcano, and a story about the problems of sifting through the bewildering number of signals that the instruments yield for us to peruse.

Let me start out in the stars. A friend of mine work with SETI, the search for extra-terrestrial signals. In that field you must sift through enormous amounts of data to get very few promising signals. Now and then the computers cough up a signal that it can’t explain, and the scientists involved get to check it out.

So far, no signal has been from an extra-terrestrial intelligent source. And just a handful has been unexplainable.

One could say that they are walking in Sahara. In Icelandic volcanology you are instead walking in the Garden of Eve in regards of signals, you are drowned in delicious dangerous fruits every day.

In this article I will go through the most common instruments to try to explain their limitations, and how they can fool you if you do not know how to interpret them. As such this is not a guide to how they work, it is a guide to avoid the traps that they throw up in a setting as massively complex as in Iceland.

 

The ideal volcano conundrum

Let us start with stating something that should be obvious. All current theories are based on the concept of an ideal volcano. This hypothetical volcano is sitting in the middle of a uniform piece of crust and it will not be affected by anything else. All signals will be pristine and only belong to the volcano.

Even at this hypothetical clean and well-behaved volcano the theories start to diverge slightly if you start to compare let us say seismometers and GPS-trajectories. This divergence comes from the theories not really hooking up as they should.

For this volcano, this is such a minute issue that you can just look aside, after all you would be able to prognosticate it to a T given enough instruments to peruse. My point is that even here we have sources for misinterpretation unless you know the theories well.

The main point is that for this hypothetical volcano you can pick your favourite type of instrument and leave the others be, and you would still be able to understand the volcano fairly well.

 

The regular volcano mess

Problem is that regular volcanoes are quite messy, even a single volcano will be affected by the method it receives energy, local tectonic setting, the tectonic of the plate it is sitting on and so forth. And this is only for a solitary volcano.

Most volcanoes seem to be in relations, many of them even practice polygamy. This means that the volcanoes will start to scuffle about, squeezing and pushing each other, while they at the same time are affected differently by the local tectonic setting.

Here you are forced to employ an array of different methods to understand what volcano is doing what, and if they are about to erupt. A single method does not cut it. Problem is just that the human brain is lazy, in other words, most humans try to employ single-method solutions to a problem. The more simplistic and simpletonian the better in their world.

When trying to prognosticate one of these volcanoes you employ a linear approach. Let us say that you notice an earthquake swarm under volcano X, but you do not know in the beginning if it is caused by magma, the faultline under the volcano, or a combination of both.

So, you go and look at the GPS-trajectories and see that it looks like the mountain is indeed inflating (or not) from magma entering the system. Since the other volcanoes around are not rambunctious at the moment, you can fairly safely assume that all of the signals are coming from volcano X.

You then look at something specific like volcanic gas readings inside the crater, and when the volcano starts to emit higher values of these gases you will feel confident alerting various government agencies that something might happen.

Various volcanoes will obviously give off different signals before going boom, but the general process applies.

 

The Icelandic Signal Festivity

In Iceland on the other hand you have herds of volcanoes galumphing about, in a tectono-palooza setting. And that is just where the problem starts.

You also have to contend with global tectonic forces, two major continental plates, bonus platelets (micro-continents), a plume shoving Iceland upwards and outwards, Isostatic rebound from the last ice-age, glacial isostatic variations, glacial noise, Jökulhlaups, weird hydrothermal signals and effects, and so on and so forth ad nauseam.

All of these causes effect every single point of Iceland in an ever-changing pattern. What was true yesterday will not be true tomorrow.

Either it will be knocking things about, or it will make weird and confusing noise to content with. Many find this to hard, and they go for a simpler volcanic setting. Or, they find it to be a grand mental exercise trying to put it all into their brains at the same time.

Now we have the backdrop to stand upon as we talk about the various instruments and what they measure and their problems.

 

Gravimeter

An Autograv CG5, photograph by Sandeep Vats. Wikimedia Commons.

As matter heats up the energy level increases, in turn pushing the atoms further apart, creating lower density.

This means that magma normally has a lower density than the surrounding host rock, and that you have a good indication that you have found a volcano, and that it contains something fairly hot. If you are lucky it will even yield a rough estimate of how large the volume of the hotness is.

This volume is obviously not the same as the magma volume, but it gives an upper limitation.

Iceland obviously did not read this rule-book, so upon occasion it produces a positive gravimetric anomaly in well-known volcanoes.

Either these volcanoes are colder than the host rock, or something else is going on. Since this happens only in old frequently erupting volcanoes with a large magma influx, we can surmise a more probable theory.

Magma is a mixture of various atoms and molecules with different weight. We know that as magma resides inside the volcano it will start to fractionate with lighter materials going upwards, and heavier materials going towards the bottom.

For a volcano frequently ejecting the lighter components the mass-balance will start to shift as the heavier substances increases its percentage. In other words, sticking a tube at the bottom of the chamber and sucking out the content would most likely be a viable form of mining, albeit technically almost impossible to perform.

The problem is that parts of a magma reservoir could be anomaly positive while others are anomaly negative, and in some magma reservoir topologies you could even get anomaly equilibria totally throwing things out of whack as you spelunk for volcanoes.

So, we need a way to verify any result of a gravitometer in Iceland. Thankfully there is an instrument suitable for that.

 

Magnetometer

Ground surveying in Surprise Valley California. Jonathan Glen, USGS. Wikimedia Commons.

Some materials and/or Chemical elements are magnetic. In the mining industry it is quite popular to run around measuring for positive magnetic anomalies, since this often indicates that you have a mineralisation in the ground. Iron is especially easy to find this way.

There is though a quirky effect to this, as you heat things up, they at various temperatures lose their magnetic charge. The specific temperature at which a chemical element becomes amagnetic is different between the elements. This point has a name, the Curie-temperature.

Pretty much all volcanoes contain ferrous materials, and we know the Curie-temperature for iron to be 1043K. That would be 769.85C for those of us who are sensible, and something weird in Fahrenheit.

The interesting thing is that at that temperature more than 15 percent would be melt in any reasonably pressurized magma reservoir, or that is very close to magma.

The problem is that it works well with large volumes, or smaller volumes close to the surface. Also, magnetometers do not really like large volumes of ice and water.

The problem is that large areas of Iceland are hot, really hot. This tends to produce results that are just to large (at least we think so), so at the same time as the Magnetometer is proving the Gravitometer, the same goes in reverse.

Well, at least a bit. Both are after all affected by heat. So, to further refine things we must go for a Volcanocafé tried classic, plotting earthquakes to chase for magma reservoirs.

 

Seismometer

The solid-state Güralp Fortimus Seismometer for early warning systems and volcanoholics. And no, you can’t get a discount.

The seismometer is the closest we have to being King of the instruments in practical volcanology. After all, all causes that we must contend with will emit noise (at least in theory but remember that this is Iceland).

Different causes will create an array of different acoustic signals, and the good news is that we can with a fair degree of certainty recognize a few of them. We also have a few solid theories about at what points those noises are generated, at least we have fair reasons to assume that our theories are relatively solid. Good news indeed!

For instance, we have fairly good grounds for a theoretical standpoint that most magma in Iceland is originating from the bottom of the crust, and that the magma has to travel upwards to erupt. At least at some point, and in some cases. Let us not get bogged down into intra-crustal decompression melt and other things that Iceland is quite capable of throwing our way.

After all, the hot area conducible for the intra-crustal melt is hot due to magma that probably came up from the bottom of the crust to start with.

So, a starting point for using our seismometers would be to look for deep origin magma rising upwards, indicating a fresh batch of magma arriving into our volcanoes.

If that magma enters a magma reservoir it will increase the pressure, if fluid dynamics is a solid scientific theory, and thankfully it seems to be just that.

And as the pressure rises it will cause creaking and groaning in the host rock. These earthquakes are defined as short brittle earthquakes caused by fracturing rock. If the pressure is high enough the crack created will be large enough for magma to enter and there will be a discernible coda to the signal as magma rushes into the crack.

As magma enters a reservoir it can also create a monochromatic tone, exactly like an organ pipe, this is called charging tremor or tornillo.

So, according to our theories we should be able to “hear” magma moving. And the creaking and groaning should also give us the shape of the magma reservoir since magma is to hot and “fluid” to be able to cause earthquakes. In other words, if there is a void covered by earthquakes, we can assume that this is the 3-dimensional outline of the magma reservoir, especially if the gravitometer and the magnetometer has told us that there should be one there.

The problem here is that some regions and volcanoes in Iceland are to varying degrees aseismic in Iceland. The reason for this is that the host rock is to hot and ductile to crack in any way we know how to recognize. Say goodbye to the earthquakes that we are chasing.

So, all the tools so far in the toolbox is affected by temperature variations, variations that can render them more or less useless at some volcanoes. How about we leave the ground and go for something that is not affected by heat?

 

GPS

Icelandic researchers happily bolting down more GPS-stations.

The Global Positioning System is a technological marvel based on the most fundamental scientific theory that humanity has come up with. The theoretical precision of a good GPS-network is astounding, and the practical side of it is not that far behind.

The problem is that the level of sensitivity when employed on Iceland is akin to poking a 3-dimensional anthill with a stick. Things will continuously be running around at high speed trying to bite you in the ass.

First you must choose your reference station to which you are measuring. If your volcano is in American Iceland you have to use Reykjavik as a reference, and if you are in the Eurasian part of Iceland you have to use a station named HOFN. This way at least the worst continental movements will be removed.

Problem is just that REYK and HOFN are moving about on their own. Upon occasion this will throw an entire half of the network out of whack since it would seem like half of Iceland is rapidly inflating. The way to catch this is to cross reference everything against this possibility.

Next you must cross reference away local tectonic effects by using a number of GPS-stations. The same goes for local tectonic effects from earthquakes and movements in fissure swarms.

After that we will have to contend with large spatiotemporal isostatic rebound from the last ice age, and the seasonal variations caused by the glaciers in Iceland.

And, let us not forget that ice and dust on the antennas will have quite drastic effects. At this point in your search your hair will file for divorce and emigrate on its own to Australia due to the frustration.

Now, time to make things even worse, this is after all Iceland. As you are looking at the GPS-network for your favourite volcano you must always reconcile yourself with the not so unimportant fact that your GPS-stations are impacted by what is going on at the same time in quite a number of volcanoes.

At this point you are reduced to becoming a medieval scholar divinating truths out of a concoction mostly resembling a good bowl of chili while drinking heavy amounts of agave spritus. Life as you used to know it is after all gone down the mental drain.

And to top it off, GPS-es do not do well if placed upon glacial ice, and most likely your volcano of interest is hidden below a large honking glacier, so you are reduced to relying on distal GPS-stations.

 

4-dimensional saviour

After eating the content of your divination bowl and fortified by fortified fluids life once more will start to feel worth living and you throw yourself against the problem with renewed gusto.

You start to work your way down the list of instruments at your disposal removing every erroneous signal, starting at the gravimeter and working yourself towards the GPS-trajectories.

If you are methodical you will end up with a surprising amount of information that you feel that you are fairly certain about.

You enter this into the best computer for this particular kind of work that you have at hand, your brain, and out comes a 3-dimensional static image of what is happening, then you start to spool this image backwards and forwards along the fourth dimension (time), and after a while you should have a pretty good inkling at what is happening not only at your volcano, but in the volcanic vicinity (or more).

This should not take more time than it will take a pair of Turdus Merula to burrow a nest and hatch in your newly grown beard. Time is after all both relative and geological in our case, so why care?

 

A final comment or two

Obviously, there are other instruments, but they are not good when dealing with an intra-glacial volcano. So, I omitted those.

The direct reason for writing this prequel is to put the level of mental strain, problem solving, raw learning, theory building, and time that lies behind the upcoming series of articles. This has after all been in the making since 2013.

Even though I wrote this prequel this is a group effort. At the dawn of time there was obviously Lurking, who plotted the beginnings before spawning an entire lineage of plotters. Without Lurking we would never have been even remotely as adept at reading and using plots for everything.

Albert is happily waiting in the background to kick us in our scientific nuts if we can’t produce a convincing case, misinterpret data, or take a theoretical downturn. It is a boon to have someone of that implacable scientific moral around forcing us to do the job correctly.

The heavy writing work will be done by me and Gaz, while Andrej Flis is doing the heavy plotting. There will also be an unusually high number of sources for this article, normally we write more in the popular science style, but here we will at least try to reference things.

CARL REHNBERG

 

55 thoughts on “Greip: A prequel on instrumentation

  1. Why is Grimsvötn area blue anomaly on these other maps?
    Thats a mystery for a whole PHD to figure out

  2. Both grav and mag can be problematic when trying to figure out what is happening at depth because they are strongly affected by what is happening at the surface. With gravity the glaciers are a problem as you need a really good determination of the thickness of the ice as well as a super accurate (centimetric) elevation data. Glacial till can also create negative anomalies.. As well glaciers are noisy environments and gravimeters dont like vibrations.
    With mag you can have local anomalies in the thousands of nT at ground level. This can be filtered by things like upward continuation/low pass fltering, but if you have things like large areas of remanent magnetism (common case for basalts) it can get quite tricky to find the lows created by hot magma at depth.

    • Yup, isn’t life wonderful?
      The more precise and luxurious instruments (toys) we get to play around with, the larger the amount of problems and errata will grow.

      • Carl, a great post. Real life just isn’t clarity and shows what real scientists have to deal with to winkle out the actual reality. Nice!

  3. Thanks for interesting and entertaining guiding into this exciting field! looking forward for more and applied on specific volcanoes!

  4. Noise in the data is very important. An example is below, the inflation at Mauna Loa. Points on consecutive days can differ quite a bit. Some of this is real: the mountain can move a bit in response to events, some of it is thermal (a sunny day can make a difference especially if the GPS itself is in the sun) or rain (water on the antennae slightly delays the signal and makes it appear that the receiver has moved),. Some is scatter: measurement uncertainties, which include uncertainties in the position of the GPS satellites. The points may in fact change after a few days when the positions of the satellites are updated, backdated. Mauna Loa has been inflating since October but whether constant or in spurts you can’t tell. Before that, the draining of the magma reservoir at Kilauea affected the GPS on Mauna Loa as well so it is more difficult to know what the mountain itself was doing.

    Very important not to overinterpret the data. It takes time for a real signal to emerge from the noise.

  5. Well… since I am being credited (blamed) with spurring along the idea of volcano aficionado plotting efforts, a topic I would like to bring up with anyone interesting in exploring it is the idea of finding the dimensions of magma chambers or intrusions while plotting quakes.

    Something that was broached on VolcanoCafe years ago, was the idea that magma chambers can be conceptually thought of as a somewhat diffuse cotton ball, with each fiber of the ball representing a tendril or intrusion of magma. I don’t know who tossed the idea about, but they discussed it with Carl at length. I didn’t have anything to add to the conversation so I kept my mouth shut and just read the discussion, taking mental notes. Now, after a bit of rumination, I think the general conceptual model is quite handy and is probably not that different than the geological reality of it.

    In the paper “Caldera formation by magma withdrawal from a reservoir beneath a volcanic edifice” by Pinel and Jaupart (Earth and Planetary Science Letters 230 (2005) 273– 287) they mention that a tendril of magma exiting a magma chamber can only do so when the chamber pressure exceeds the maximum hoop strength of the chamber wall. This is going to be a function of the tensile strength of rock making up the wall, augmented by the confining pressure of the overburden. Once the chamber pressure drops below that level, the conduit will “slam shut” and propagation of the dike will stop. Note that a hard fast rule of that scenario, is that rock located at lower depth will have less confining pressure, so it is natural for a propagating dike to track towards the surface as it forms.

    Couple Paragraph 3 with Paragraph 2, and you have a pretty good mental construct of how things work with magma chambers… (in my opinion).

    Now for something I have yet to figure out… but I do have a general idea of how to approach it.

    In things military, there is the concept of likely target area. For passive intercept of signals, you make a few bearing plots and lay in tentative lines of bearings either side of the plotted bearing that represent the error of the equipment you are using. If you have another cooperating passive sensor at a known location that sees the same signal, you can plot out a line of bearing for them and place the tentative bearing error of their gear on either side of their detected bearing. Where their plot and your plots intercept, there will be a polygon. Fit an ellipse to that polygon and you have an area of uncertainty. That essentially gives you an ellipse that your sensed target has a high probability of being inside of. Over in the gunfire realm of things, you have a similar concept with shell placement. In the gunfire realm, this is called the CEP. (Circular Area Probable) that defines what percentage of the shots will hit within that distance from the aim-point. When you get down to the brass tacks of it all, it essentially assuming a Guassian Distribution of the actual hits compared with the aim-point. I think that it may be possible to use something like this to define an assumed boundary to a magma chamber as plotted with earthquakes. Software specifically for working with this does not exist as far as I know, but you can use a 2D slice of your 3D data to examine the boundaries of an inferred chambers outline. Where you put the boundary will depend on how you define it. If the inferred boundary encompasses 63.213% of the plotted quakes, you are probably in the ballpark with your assumptions. That would be equivalent to the “Distance root mean square (“DRMS”)” and there is a whole set of equations for converting back and forth through the different definitions of CEP.

    Just food for thought for anyone interested. And a VERY important note. Not everything inside the inferred chamber is going to be erruptible. It it highly likely that the inferred chamber is going to be very dependent on melt percentage. As a general rule, only about 5 to 10% of magma in a chamber is erruptible. Carl and Albert can clarify that if you need it. In general, the closer you get to the center of the “cotton ball” model, the higher the melt percentage will likely be.

    Feel free to use or refine any of these ideas in your rumination on the subject. You are only limited by your own mind. I do a lot of my thinking while driving stupid long stretches of road, so I don’t get much of an opportunity to jot things down.

    • I would expect volcanoes with hot basalt magma and high eruption and supply rates would probably have more molten chambers, those with lava lakes most of all. The lava in the former overlook crater was 1250 C which is a lot hotter than the melting point of basalt unlike the lava that flowed out of the end of lava tubes near the ocean which was often under 1100 C. It is estimated the temperature of kilaueas main magma chamber is around 1300 C, so it shouldnt be mostly solid like some models show, if it is deep enough the roof will be stable unless magma is drained like last year. Nyiragongo is probably this but even more with its lava being hotter.

      In these volcanoes rather than a cottonball it is more of a solid magma sphere but it is probably a squishy material that moves easily but is not the same as the erupting lava. For hawaii this might be olivine crystal mush for nyiragongo I dont know.

      • More evolved magma = lower melt fraction. Evolved magmas tend to be more explosive and less evolved is effusive, although there are exceptions (rhyolitic effusive lava should be rare, though). But it primarily depends on how old the magma chamber is, and volcanoes close to each other can have very different ages.

        • You are forgetting the most important factor, volatiles content.
          Enough volatiles and even fairly benign basalt can become quite ashy. And the rhyolite flows that exist at some places are all devoid of volatiles.
          It is kind of a two-axis thing. 🙂

          • I hadn’t forgotten it – just didn’t say it.. Most explosive eruptions are evolved. Evolved magmas have lower density and therefore more buoyancy, and this may make explosive decompression easier – perhaps. But Kilauea also has done reasonable explosions, even if not at Krakatoa level.

          • I know that you know Albert, it is just that many readers… At least those who are not regularly gargling in the morning with lava, don’t know this concept. 🙂
            All old volcanoholics know, but there are always fresh ones around.

      • The lava was 1250 C ? In overlook crater?
        The numbers I gets from USGS is around 1185 C to 1210 C

        Puu Oo was around 1150 C

        • I found a paper earlier today that had some temperatures on it for lava erupted mostly around 1960, but it came to a conclusion that eruptions in the LERZ are around 50 C cooler than at the summit. It also lists a temperature for 1959 as 1240 C. 1960 was mostly reheated 1955 magma at 1180 C, quite hot especially that far from the summit. 1980s puu oo and the lava in the 1965 eruption was also around 1180-1200 C, if it was less later on in more recent flows that is interesting and indicates there might be a limit to how long these eruptions can last on the east rift. 2018 was probably around 1200 C on eruption at fissure 8, and puu oo temperature for other vents (and 1030 C at fissure 17) but HVO is doing a lot of study on this so there will probably be an official number soon.

          • Those numbers look good when comparing fluidity between the flows (but that is at best a ballpark figure).
            What I find interesting is that those numbers pan out pretty well with the temperatures in Icelandic central volcanoes and rifts.

            I always thought that Hawaii was a tad warmer since the Icelandic plume is fairly young and shallow, but comparing figures put them at what most likely is the same temperature. My guess would be that there is some in situ cooling going on in Hawaii compared to Iceland, but I am probably wrong.

          • Well lava going down the east rift is moving laterally, probably still at some depth (3-7 km for kilauea) but while the surroundings are very hot they still cool the magma, all the magma coming out of hawaii goes through the central magma system of said volcano. In iceland the rifts can probably erupt directly as well as through the mode above so are different than hawaiian rift zones and probably hotter at depth with a steeper heat gradient. Kilaueas east rift is about 100 times as active as the dead zone, since 1790 there have been 22 eruptions on the east rift, and more than 80 if distinct phases of mauna ulu and pu’u o’o are counted as separate eruptions, but the east rift still has much more earthquakes, probably because of this heat gradient.

            The great distance to the LERZ means eruptions usually only happen there after significant other eruptive activity on the east rift that basically extends the summit magma system down the rift and allows gravity to do the work so yes there probably is some amount of cooling, about 50 C according to HVO. Currently the active system goes as far downrift as highway 130, it probably cant go further as lava shields are not found below here but there are many above, most of them formed in the last 60 years. This is the source of inflation seen at JOKA station and I and several others think it will probably eventually result in a new pu’u o’o type eruption somewhere inbetween pu’u o’o and highway 130. More on all that when I can get to part 3 of my series though.

          • The LERZ closest Icelandic analogy would probably be Krafla, it tends to have sequential rifts/vents opening up along one of its fissure arms, and during a Fires episode it can have quite a few eruptions interspersed over a period spanning decades.
            The last Fires episode lasted 9 years and had 6 eruptions, the one before that lasted 22 years and consisted of a minimum of 6 eruptions (the minimum part is that any smaller activity would have been missed back in the day).
            Both of these eruptions occurred along the Leirhnjúkur Fissure.
            Krafla does though have differences, obviously. 🙂

            The Dead Zone is quite a bit different with eruptions being few and far apart, and emanating from 4 different volcanoes and have different lava sources.
            Veidivötn during the larger events tend to be a co-eruption between Bardarbunga and Torfajökull drawing magma out of both of them, giving lavas that can vary quite a bit along the length of the fissure, with the lava closer to Torfajökull being far more evolved and ashy compared to Bardarbunga. There are no clear signs that the magma is sourced directly from the bottom.
            Katla seems to source all magma from the chamber, there is little evidence of intermingling with MOHO derived magma.
            Laki swarm is something else completely. Probably due to being offset from Grimsvötn by four or even five other central volcanoes.
            The central volcanoes on this fissure swarm has large to small upper magma chambers, and a common very large deep upturned hull-like structure resting above the MOHO and that is open to the MOHO.
            This means that it is a far shorter way to suck up lava directly from the deep reservoir as the rift is pulled apart.
            We know that the source is common, but that the magma is significantly less evolved than in the central volcanoes from petrochemical evidence.
            This is probably the reason that both Grimsvötn and Thordarhyrna co-erupted repeatedly during the Skaftár Fires, lowered pressure at the common wedge-shaped reservoir caused pressure drop release of volatiles and decompression melt and off they went.

            It is a bit hard to get there, but walking across Lakí, Eldgjá and Veidivötn is mind-numbing. You truly walk along sleeping giant dragons. It changes you forever.
            And the chance is quite high that one of them will cough up a Fires-event in the next couple of decades, since both the plume-cycle and the rift-cycle for once in quite a few thousand years will co-peak soon.
            Which one of them?
            My money would be on either Raudholar (Grimsvötn), or Eldgjá. Grimsvötn as a volcanic field is fully recharged now after Lakí, and Katla has taken an unusually long nap and we know that it has had numerous intrusions during that time.
            That being said, only an idiot would write off Bardy.

      • Overlook lake contained tiny olivine crystals
        The 1300 C magma chamber below cools and convects the incomming magma and emerge in overlook lake at 1190 to 1210 C
        There is many magma chambers in kilaueas summit including a very large one deep below the upper chamber that was discovered a few years ago. https://www.sciencedaily.com/releases/2014/01/140129114925.htm
        This large deep chamber feeds directly from the 1500 C hotspot conduit deep down
        Kilaueas magma systems at the summit are as you say open and completely molten

  6. Part 1 of my series is nearly done, however I had to ditch the 3000 maximum to actually get all the relevant information, as well as making more pictures which takes up yet more space. I also discovered there is quite a lot of disagreement between the 2005 map and most of the data on prehistoric eruptions (mostly between 1970 and 1990).. :I
    Currently it stands at 4250 words, I will try to thin it out but even at minimum this will probably still be over 3500 words. I dont know if the pictures will send either if left in the word document.

    If there is an email link to send it over that would be good.

    • You can send it to the contact email of vc: volcanocafe.org @ gmail.com

  7. Nick Zentner covers a bit on scientific uncertainty and resolutions of it in his talk about Ice Age Floods in the Pacific Northwest.

    • The volcanic connection? Some ash horizons help establish timestamps to some of the floods
      (Jökulhlaups on steroids)

      • Nick’ has this one on the PANGA sensors around the Pac NW.
        There’s one about 4 blocks and up hill from me. (and not that many in NE
        Oregon ) The hope is that there can be early warning of the “big one”
        https://www.youtube.com/watch?v=YhGXYKvF-Jk&list=PLwNJg2mCrcQSWMxs2jvgp_lvpeffAUd6e&index=9&t=916s
        You couldn’t get me on the Old Alaska way viaduct or its underground replacement for lovin’ or money….
        But like Carl’s article this shows the value of sensors…

        • I am not that worried about big earthquakes or eruptions when I am in places where it can happen. Even in highly prone areas the likelihood of me being at a bad spot when it hits is so negligible that I write it off as “shit happens” if I go that way.

          I am though right now quite flaky on flying with 787s or 373-Max (not that they are likely to ever fly in Europe again), or for that matter any Boeing plane built in the last 10 years. I await that the European flight authorities hands out a new airworthiness certificate before I get on any of them.
          I think the workers at Boeing should hang the leadership for forcing them to do shoddy work, and for cheating in collusion with the FAA on the certificates part. I hope the board is charged with murder for what they have done.

          Carl, parking his ass only on Airbuses for the time being.

          • I used to like Boeing and their planes due to their safety, but as things are now they have pretty much murdered their company.

          • 737 max was an example of poor engineering to cover a problem with the design. i feel if htere is no reasonable
            way of overriding a sytem for pilot control-or if the pilots don’t understand the system, that is where trouble starts.
            airbus has had similar issues in the past. My guess is that the stockholders will have a lot to say about why this mess occurred . I wouldn’t count Boeing out yet, but they shot hemselves in the foot big time.. i personally know one if the
            managers for Southwest. I know they aren’t happy either..

          • I hope they will sort it out in the end.
            Otherwise we will have at least a decade of only one builder of large airplanes, and that will make for expensive aircraft indeed…

          • and Trump forcing them to be grounded in the US is the first thing i’m supporting him on. (i’ll let You know if anything else turns up.) 😉 Best!motsfo

          • FAA/Trump was the last authority on the planet to ground the planes. So, giving praise to someone who wilfully risked lives for days more than the rest is a bit of a stretch.

          • Fat chance of that Carl, all mega companies in the USA have to do is pay off politicians and all is forgotten or hidden from view, workers have no say, it is consumers that can force issues and most of them have their heads up someplace where the sun don’t shine.

    • This was more of a Guide to problems with instruments, kind of deal.
      I have for years promised a guide to how to read them, or even how to operate them, but never seem to get around to actually writing them.

    • It is planed for Saturday, unless Gazmaster B is attacked by oiled up babysnakes again 🙂

  8. Gunung Agung might be up to something. Lately, there has been a number of strombolian eruptions, throwing incandescent rocks up to 3km from the crater. These have happened without much prior seismicity, meaning that the conduits are still warm and open. Now, over the last 48 hours, there has been a number of deep and shallow events, indicating more magma is on the move. Not sure if and when this might affect things at the surface, but I’ll continue to keep an extra eye on Agung for a while.

    • The earlier events probably were due to the cooling of the lava lake: the increasing stiffness of the lid allowed more pressure to build from degassing, so when it finally breaks through the crust it is quite explosive. Adding new magma in such a system can be quite dangerous. If this is the case, I would recommend closing off the areas of the mountain at danger from pyroclastics.

      • That sounds like a plausible explanation.

        I was under the impression that Pak Devy, Head of PVMBG’s Eastern Division, said in an interview in the beginning of April that the low number of seismic was due to open conduits. Now I did not read the interview myself, only a translated interpretation of the interview, so the information might have been distorted along the way.

    • There was another one at 5:35 AM local time 4/30/19 (a day ahead).
      I watch Agung, he’s been very seismically active the last couple of weeks.

  9. Today is April 29, 2018, tomorrow is the 1 year anniversary of the end of pu’u o’o. While not exactly the most thrilling or high intensity eruption ever, it is probably the one the most people have seen in action, and the only eruption of its size in the modern world. The picture below is the last picture of active lava from pu’u o’o, taken later on the same day, coated with ash.

  10. This has me quite a bit worried.
    I have never seen this at what for all points and purposes is schmack-bang on the extension of Veidivötn as it goes through Torfajökull. This is what I would expect to see prior to a runup.
    See my latest comment to Turtlebirdman up above… Never count out Bardy.

    • It is almost ridiculously picture perfect, like if someone at IMO was pulling our legs (they are not).

      • We might be leaving Kansas at speed if that intrusions hits the old Rhyolite chamber at the the southern tip of that lineament.

  11. for Carl…. clarification for way up the thread…. i’m NOT praising Trump… i’m just admitting it’s the first time that i agree with him. And i agree with You…. he was way late in doing so. Best!motsfo

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