An Invitation to a Volcanocafé Scientific Project

Photograph taken some time after the October 25th 1902 VEI 6 eruption of Santa Maria, Guatemala. The eruption killed more than 5,000 people as well as causing an economic disaster by destroying most of the country’s coffee crop. The eruption column reached 28 km. Note absence of the Santiaguito cone which has subsequently grown where the post-eruption crater used to be.

Photograph taken some time after the October 25th 1902 VEI 6 eruption of Santa Maria, Guatemala. The eruption killed more than 5,000 people as well as causing an economic disaster by destroying most of the country’s coffee crop. The eruption column reached 28 km. Note absence of the Santiaguito cone which has subsequently grown where the post-eruption crater used to be.

A couple of days ago, VC reader VerboselyLaconic posted an interesting observation about the Andean Volcanos of Equador and Columbia. Here is what he said:

It seems almost a rule that when they erupt BIG, it is a lateral blast, and all but a few of them blow in a westerly direction. Now, I have no documentation supporting this, but just a cursory look at Google Earth and you will see what I mean. The place is absolutely littered with Mt St Helens look-alikes. I have compiled a (non-exhaustive) list of a few volcanoes located there, just to illustrate:

-Cerro Altar; LATERAL, W
-Chimborazo; FLANK COLLAPSE (?), W
-Carihuairazo; LATERAL, E
-Iliniza Sur; FLANK COLLAPSE(?), SW
-Corazon; LATERAL, NW
-Ruminahui; LATERAL, W
-Pasochoa; LATERAL, SW
-Atacazo; LATERAL, SW
-Pichincha; LATERAL, WSW
-Castiagua; LATERAL, WNW
-Mojanda; LATERAL, W
-Cotacachi; LATERAL, NW
-Imbabura; LATERAL, E
-Reventador; FLANK COLLAPSE(?), E
-Cerro Negro de Mayasquer; LATERAL, N
-The 3 unnamed cones to the SW of Cerro Negro; LATERAL NNE, LATERAL W, LATERAL NW
-Azufral; LATERAL, NE
-Dona Juana; LATERAL, SW
-Tungurahua; LATERAL, SW

Is this odd? Is this disproportionate to the rest of the major chains of volcanoes elsewhere? Of the 30 or 40 volcanoes located in these two countries, 22 of them have blown laterally and 17 of those in a westward manner. I guess if you must build in this area of the world, build on the eastern side of the volcanoes. You have a 57% chance of not getting shotgun blasted into the Pacific…and only a 23% chance of being shotgun blasted into the Amazon – if your mountain happens to blow. Of course, the lahars and pyroclasts may STILL get you, so there is that…

This observation is statistically significant. Roughly 50% of listed volcanoes have suffered a flank collapse, often in conjunction with a lateral blast, and of those 22 volcanoes not less than 17 (or 77.3%) have done so to the westward, in the direction of the subduction zone. Is this a coincidence, does it apply only to Andean volcanoes in Equador and Columbia, or is there a general physical principle involved, a rule that applies elsewhere? Why not start a scientific project of our own in order to find out and in the process, create our own data base!

Instantly obvious from the birds-eye view although not readily apparent from ground level, Galeras in Colombia is another volcano to have suffered several flank collapses in the past. Long-term extensive hydrothermal alteration has contributed to large-scale edifice collapse on at least three occasions, producing debris avalanches that swept to the west and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. (Ingeominas photograph)

Instantly obvious from the birds-eye view although not readily apparent from ground level, Galeras in Colombia is another volcano to have suffered several flank collapses in the past. Long-term extensive hydrothermal alteration has contributed to large-scale edifice collapse on at least three occasions, producing debris avalanches that swept to the west and left a large horseshoe-shaped caldera inside which the modern cone has been constructed. (Ingeominas photograph)

So on behalf of Volcanocafé, you are hereby invited to become one of our researchers! What we want you to do is to use Google Maps (topographical is best for our purposes) or Google Earth and hunt for volcanoes that have suffered a flank collapse. Once you find one, take a screen shot – just make certain north is up! – note down its name and location, then go to the Global Volcanism Program – – and search for the “Volcano Number”.

Armed with this information, you open a photo editor (MS Paint will work), crop the screenshot and enter the salient facts. Once done, upload the image to Facebook, TinyPic, InkFrog, PhotoBucket or any other image hosting site, copy the link and post your discovery on this topic! Unashamedly copy any background information found relating to the collapse event (give credit for where you found it though). As an example, I have done this for Mount Iriga in the Philippines, a volcano which appears in one of the photographs on the Mayon article:

Philippines, Luzon, Mount Iriga (Volcano Number 273041)

Screenshot from Google Maps

Screenshot from Google Maps

Mount Iriga is a small stratovolcano that rises to 1196 m immediately SW of Lake Buhi. The dominantly andesitic stratovolcano has satellitic cinder cones of basaltic composition. A large breached crater that opens to the SE was formed as a result of a major debris avalanche that buried several villages and formed a broad hummocky deposit that extends across the plain south of Lake Buhi. This catastrophic event was at one time considered to have occurred during 1628 CE, but later work has shown that the collapse and eruption occurred earlier at some unknown date during the Holocene. The avalanche was followed by phreatic explosions that created a small crater at the base of the scarp. (GVP entry on Mt Iriga)


Good volcano hunting!


270 thoughts on “An Invitation to a Volcanocafé Scientific Project

    • By all means, do! But if you do so, please follow the stipulated rules! 😛

      • To tired tonight since I am suffering from acute Gothenburgensis. I will retung with Fuego.

        One thing though, I wonder if it might be that volcanoes to be frailer in the direction facing towards where the subduction faultline is. Might be a mechanical reason for this.

  1. There is a pretty obvious reason why these volcanoes erupt to the west – gravity.

    In almost all the Andes and Central America, the coastal plain / coast lies to the west, and to the east lies a highland region. When stuff collapses, it will typically topple towards the lowest lying area and area of greater structural weakness. Given the greater relief on the western side of these volcanoes, it’s only natural for them to collapse in that direction.

    • Well gravity could be. But gravity only helps with the west side already being structualy less stable or more prone to collapse. If the volcano has more instability on its east flank, thats were it will collapse if it shall collapse.
      Gravity is only the second link in the chain. The first one is obviously structural instability. Why are these volcanoes “weaker” on the W side rather than the E side? I think I have a theory that includes my main hobby, which is weather. I just need to refine it.

      • Good point! Precipitation + SO2 = H2SO4 which metamorphoses rocks to clay.

      • Structural instability is caused by the slope that a volcano is built on.

        Think of it this way, if you were to construct a sand castle on the side of a hill with a slope of 30 degrees, which part of that sand castle is probably going to experience the greatest structural weaknesses? It will almost always be the side that touches lowest on the slope.

        Speaking in a structural manner, more stress and load is placed at the foot of a volcano, and when that volcano is placed on an incline, the stress is greatly increased on the end that is at the bottom of the slope.

        You’ll notice that the volcanoes that are further inland on more level ground do not have similar predictabilities in terms of their slope failures or lateral blasts. But for volcanoes that are built on an incline, you almost always see them fail towards the weakest direction, which will generally be the downard slope.

        • I completely agree to a certain degree. Tho to collapse a side, it has to be generally weaker. If the side is stronger, well “cemented”, no incline, gravity or earth rotation alone will collapse it. If that were the case, we would see more such cases from more stratovolcanoes. The incline has an effect already with edifice building, where the downslope side tends to have more material, like an elongated foot. But that depends on the incline angle. It all comes down to the fact that the collapse side is generally weaker, before other forces collapse it. And I do embrace your theory because it is one of the likely forcings of collapse. But before we get to the forces of collapse, we have to understand what makes the edifice weaker on the collapse side.
          We should refer to known examples like St Helens, or Rainier which is prone to lateral colapse due to rock methamorphosis. And where it will collapse will be mainly decided by the fact which side is weaker or stronger. Of course among the other factors I mentioned already below. So far I am the only one trying to support my thesis with data and charts. 🙂

    • Hi, my first and possibly last post here.
      Have you thought about weathering? Be interested to know the direction of the prevailing weather systems, sun facing etc.

      Water flow (infiltration) can dissolve any minerals which would be holding the grains, ash, together weakening the cementation process from the pressure of ash layers above. This would make one side weaker than the other. There is also freeze-thaw action and also solifluction to consider which could all be playing a part in some way.

      Its many years since I did this stuff a Uni but a soil scientist might help you out if there is any mileage in my idea.

      • I certainly hope this isn’t your last post edmdas. We value all comments. This is just what Volcanocafe is all about. Ideas and theories.

    • It’s because of the direction the Earth rotates. Material rising from the interior has less kinetic energy in the Easterly direction than material at higher altitudes, so it pushes against the western side of the tubes.

  2. It may sound like a crazy idea, but I think the weather has to do with the westerly orientation of most lateral blasts. In most places the weather (wind, rain) is driven in from a generally westerly direction. Water draining into rock my lead to stronger weathering / leaching on that face, and hence weakening of the rock.

    Also, the added water would make for a good source for phreatic explosions.

    • Not crazy at all (see my above reply to Down Under) with the addendum “in that particular area”. Once results begin to come in from all over the world, we shall get an idea about the influence of gravity, local weather and any other influences we may think of.

    • In general, the highest rainfall is on the upside of prevailing winds and a rain “shadow” tends to be present on the down side of prevailing winds. Thus, in US where prevailing winds are from the west, rainfall is heaviest on west side. Some spillover of rain can occur near the peak of a mountain or range, however as one gets further away from the peak the rain shadow effect kicks in. The areas east of the coastal range are extremely dry.

      In northern Latin America the prevailing winds are from the east, therefore the eastern side of the Andes in the northern LA region are very wet. The western side tends to be much dryer.

      We have frequently seen these differences while traveling in Andean countries. For example just east of the Andes in Ecuador it is extremely wet and green. The prevailing winds from the east picks up loads of water from the Amazon basin. We traveled in a large canoe on a river on the east side of Ecuador for about 30 hrs. We could see raging thunderstorms over the mountains and not long after the river started to rise quite fast and become much more dangerous.

      Comparison of the two extremes west vs east prevailing winds may give interesting results re direction of lateral blasts.

      • The prevailing upper level winds are east (refer to my post below), but the surface winds are stronger westerlies from the ocean in the west. And they actually rise upslope from W and cause the precip maximum W of the range, with big diversity from N to S in Ecuador and Colombia.
        In the eastern lowlands and the E Colombia, there is an abundance of rain, but mainly due to the ITCZ.

  3. Like Tommy …Oh Dear! There will be reproducing dust Bunnies under my beds and sfa as I get practising on editing screen shots and generally getting immered in this project. It sounds fascinating. I think I may have a hunt around Africa. Just because….. 😀 .I may find fewer flank collapses… I can’t start tonight. Too tired but will start setting up tomorrow.

    Just to remind people that often finding nothing and noting down where negative sightings occur, is as important as long lists of positives.
    I agree with cbus about the South American Volcanoes to a certain extent and it is what is expected but here is this the case for all flank collapses? Is the collapse definitely due to gravity or something to do with the mechanics of the eruptions themselves?

    • I think that is more of an erosional feature. Lateral blasts tend to evacuate everything topologically in the explosive arc.

    • Thank you, Azost. I tend to agree with Lurking about it being a case of a breached summit crater being enlarged by erosion as rain would be funneled in that direction, not a flank collapse feature. But it is better to do as you have!

      (PS. With further entries, could you move the inset so that a full view of the mountain is possible? Cheers! 🙂 )

  4. Well, usually there is a number of factors. A good example is Mt. Saint Helens. It collapsed in the weaker direction, which was weaker for obvious reasons, since a cryptodome was building there, creating mass instability.
    So we have to look at magmatic systems under the volcano. Cotopaxi for example has an inflation area to the N/NE. And in my opinion, that area is most prone to a flank collapse than others. If SO2 degassing is more focused in one part, that part will could be weaker. Generally if there are more magmatic conduits under one part, that part would be more prone to collapse or would be generally weaker, mainly again due to increased degassing and “metamorphosis” in that part.
    If we add possible cryptodome building or local inflation in one part, that entirely changes the stress fields of the volcano.

    But of course another factor could be the weather. And let me present you the main points of my thesis.
    This is the plot I made, showing the 64 year long term average zonal wind at 700mb (~3-3.5km ASL, it varies). Positive zonal wind means west winds, and negative zonal wind means easterly winds. This is the wind higher up, that generally flows at the height of the height of the mountain range.

    It gets obvious right away that Ecuador and Colombia are directly in the major easterly belt. The values are not of big importance since this is climatology, but the direction of the wind is a direct negative correlation with the main side of the collapse.
    Now how could this be? Well, wind could be a drying mechanism. With prevailing easterly winds, each new layer of edifice would be drier on the eastern side rather than the western side. With each new layer, in total the eastern side would be generally less soaked than the west side.

    As far as the jet stream goes, this region does stand out.

    The precipitation patterns are clear. The main mountain/volcanic range is generally drier, with more precipitation in average on the western side. That is mainly due to the heavy effects the ENSO oscillations (1+2, 3/4) have on this region.

    In general weather terms, it is obvious that there is more stress on the W side, since the prevailing easterlies do potentially have a more drying effect on the edifice, while the W flanks are less exposed to the upper drier winds from inland and are more exposed to precipitation in general/average.

    • Part2:

      Looking at the surface winds tho, we can see that this region stands out again, but this time with westerly winds from the ocean to the mountain/volcanic range, creating a positive correlation with the flank collapses.
      But one might say that these winds could dry the W flanks. True, but not in this case. These winds are low level/surface, and they come from the warm ocean and are warm and moist. And what they actually do, is they lift on the ranges, creating more precipitation on the W side of the range due to orographic lifting, keeping the E part and the main range more dry. The upper level E winds do also help to keep more precipitation off the mountain range and the E sides generally drier.

      I am ending off with the lastest SST analysis from NOAA, showing the developing positive ENSO phase (El Nino).

      What to say, Weather is my thing, my main hobby, and since volcanology is my second hobby in the past year or two, I love such occasions where I can merge the two. 🙂

      Best regards

        • We must have messed up a setting when no one could comment… we’ll fix that too in due time once we understand this system better…

          • I think it’s more likely it’s logging in from phone using the same log in from the old site.

            Below the reply box you can change which account is used by clicking “change “

  5. Apparently, from what I have seen so far, the prevailing idea is that the “wet side” of the volcano is the one most likely to suffer a flank collapse.

    • Well, in a classical (textbook) stratovolcano model, that would hold merit. Tho things get a bit complicated with more complexity in the magmatic system under the volcano, and of course deformation, which can largely affect the stress fields. Not to mention secondary effects mentioned, like the plate subduction (which I kinda doubt would be a main factor) and gravity.
      And with time I think we could find more. We just first need a thesis and then test them all against different locations, which is why the hunt is on! 😀

    • True… Mount St Helens went in a direction away from the flow of prevailing weather.

      • Aye, and the last previous activity at St. Helens before it’s collapse was the building of the Goat Rock dome high on the north side. I would think that activity made the north flank structurally weaker.

        My guess is that weathering would not be near the top of the list of factors for weakening a volcano’s interior structure.

    • Wet side doesn’t sell well, though. This is what got me thinking: Look at the Cascades from BC to CA. All can agree that the west side of the Cascades are the wet side: 3/4s of Oregon and Washington are rain-shadow deserts. But, St Helens, Rainier, Baker, Shasta, and Lassen all have had major flank collapses to the north. So, wet vs dry can’t be the primary driver.

      The gravity theory is also off slightly. Glacier Peak and Garibaldi are both placed on high ridges, but any apparent flank failures appear opposite to the strong slope – in other words, toward the mountains instead of the sea.

      Washington State appears to be primarily northerly driven failures, Oregon is primarily southerly or easterly driven failures, and California switches back to north trending.

      Maybe there is no rhyme nor reason….

      I do like the conversation that I started though. Thanks all!

  6. ” alt=”” />

    Meet Matthew Fontaine Maury (January 14, 1806 – February 1, 1873), United States Navy, [he] was an American astronomer, historian, oceanographer, meteorologist, cartographer, author, geologist, and educator.

    I bring him up because he originated the idea of Synoptic Charts. These charts tell you the prevailing winds and weather conditions that you may encounter world wide, based on the historical data and from ships logs.

    This set of charts (which are still in production and are kept up to date by mapping organizations) might come in handy for anyone who has a set of them when doing the final analysis of this data set on flank collapses.

    • Cool, I share birthday with the Sir.
      Tho his charts are of great value, his data is included into much bigger datasets, where satellite data is included, synoptic station data, weather buoys, ships, airplanes, weather baloons, etc…

      The real time data from these sources is used together as initial condition, to create an image of the real-time state of the atmosphere, from which numerical weather models are then initiated.
      This analysis is also included into these “Reanalysis” datasets, which I use and which are the standard of past weather reconstruction, and climatology. Not only his data, but data/logs from many others is used in the creation of these datasets.

      • Well, I ran across a set of those charts while on a deployment and spent hours marveling at the data and typical conditions for various areas. They would be ideal for planning a voyage by sail, and given the years he was active, that was still a prominent method of travel.

  7. And yet again my comment is in the dungeon. 🙂

      • Thanks.
        I have big problems commenting, since it seem I have 2 separate accounts for phone and PC. Looks like my old account is back on my phone, even tho I actually registered over the phone for the new site and replaced the login info and everything. strange

  8. Personally, I am happy to get off of blogspot. Now when you refresh the page returns to where you left off instead of some seemingly random spot on the page.

  9. Hi all,

    long time since I have been on here. Very interesting project, once we have collected the data, what do we intend to do with it? If we get a great finding, perhaps there could be a paper in this?

    Anyway, could the alignment of a volcano on a fault influence where it collapses?

    • Yes, fault lines may certainly play a role. As for your first question, I expect that pretty soon, we shall find areas that show a similar bias towards collapsing in a preferred direction – and areas that are utterly chaotic. Once we’ve collectively had a look, we shall have to narrow down depending on what we find and limit our research to a few selected areas, setting up different hypotheses, testing them and hopefully arrive at some sort of generalised theory which we can then publish.

      No matter what the end result is, we shall teach ourselves a heck of a lot about volcanology plus related sciences as well as have a lot of fun!

  10. Hakone

    A minor phreatic detonation has occured at Hakone. This has lead the local authorities to raise the level from 2 to 3 concerning the risk level. Phreatic detonation are a known feature prior to a real eruption, but it may at the same time be the only thing that will happen at the volcano.
    Phreatic detonations occur as the rising magma heats up water in the ground which causes steam driven explosions.
    The phreatic detonation has opened up several new fumaroles.
    It is time to start following Hakone closely.

    • I have been checking it morning and night, I thought it was just fog, there is one new fumarole just behind the buildings, one building is thinking looking from the camera angle the window ledge has disappeared now and the door is shorter, and it isn’t the angle.
      Indonesia has 4 volcanoes on the second highest level at the moment

    • Honest (but probably stupid) question here, but what are the chances that, if there is an eruption here, that it would be a caldera forming eruption?

  11. Hakone is steaming like hell from the main crater/vent.

    • On the second image there are of course also clouds.

    • I think it might be the onset of vent clearing phreatic episodes as a sign that it is nearing a real eruption. If not that area will still remain off limits for years. It is practically a large fumarole now.

  12. I have found graphics on my phone, which I made when I was explaining the deformation style at Hakone.
    1 is the clasical or “Icelandic” (as I call it) deformation, and 2 is what is likely happening at Hakone. The vent deformation, since the magma chamber is probably already inflated or deformed after at least 10.000 years of no surface magmatic eruption. This type of deformation was also evident at Pinatubo. Tho of course it is the only thing these two have in common. Besides the possible Dacite down under (pun intended) at Hakone. Tho as far as mote evolved evolved magmas go, I think Hakone is more of a Rhyolite system.

    There is decent amount of steam coming from the vent/quasi crater, and despite all the steam and pressure released so far, a phreatic detonation still ocured, and now there is even more steam coming out than before. That could mean that either the underground water supply is really big, or that the magma is getting closer to the surface. Or of course both, which would lead to more phreatic explosions and perhaps eventually a magma eruption.

  13. Is it just me, or does it look a bit ashy around the crater?

    • Looks like mostly steam / other gasses – lot of it. But there was a small phreatic eruption later

  14. Of course you will come across real jokers such as Avachinsky (Volcano Number 300100) with at least four probable flank collapses evident (note, some could be due to glacial erosion) and the entire area surrounding the mountain bearing the knobbly appearance of being a debris field. (I’ve made the picture large enough for the features to be evident):

    “Avachinsky, one of Kamchatka’s most active volcanoes, rises above Petropavlovsk, Kamchatka’s largest city. Avachinsky began to form during the middle or late Pleistocene and is flanked to the SE by the parasitic volcano Kozelsky, which has a large crater breached to the NE. It has a large horseshoe-shaped caldera, breached to the SW, that was formed when a major debris avalanche about 30,000-40,000 years ago buried an area of about 500 sq km to the south underlying the city of Petropavlovsk. Reconstruction of the volcano took place in two stages, the first of which began about 18,000 years before present (BP), and the second 7000 years BP. Most eruptive products have been explosive, with pyroclastic flows and hot lahars being directed primarily to the SW by the breached caldera, although relatively short lava flows have been emitted. The frequent historical eruptions have been similar in style and magnitude to previous Holocene eruptions.”
    (GVP background to Avachinsky)

    • This one is so hardcore, that it has a flank collapse inside a flank collapse, and a volcano inside a volcano.

      • “volcano inside a volcano.” → Somma, such as somma Vesuvius.

        And it is one of the “Bad Boys of Kamchatka” after all…

    • I never really looked into it before, but Avachinsky is a Decade Volcano? Why on earth? Do that many people live on Kamchatka to justify that? On a similar note, San Salvador is NOT a Decade Volcano? Please tell me that San Salvador made the new MDE list, at least.

  15. How about this one.

    Tharsis Tholus: a less studied volcano, height about 9km, size about 150km across, eruption history is not known but it has probably inactive for 2-3 billion years. It was discovered in 1972, about 2000km east of Olympus Mons. On Mars.

    There is a flank collapse visible to the northeast. This seems somewhat unusual for Mars, where most volcanoes show numerous land slips and caldera collapses but no clear flank collapses extending in to the caldera. And that is the serious aspect of posting this: flank collapses are typical of terrestrial volcanoes, but are not really seen on extraterrestrial volcanoes. You can argue this must be due to plate tectonics (absent from all other planets) but lava viscosity can play a role (martian volcanoes are not steep) and depth of the magma chambers (three times deeper on Mars than on Earth). Pick your choice..

    • what number is THAT on the GVP??


      I had an suspicion we’d see something like this from you. 😀

      • And there is nothing wrong with it. It does highlight that the phenomena is wide ranging. My issue is that water may be a difficult culprit to finger on Mars. But I am fairly certain that it’s hydrological cycle would be completely different than Earths.

  16. Haven’t posted a pic here before, so I hope this works. Old favorite listed below. I grew up in Nevada, which has plenty of extinct volcanoes. As a kid, I always sorta hoped one would come back to life unexpectedly.

    Mount Bezymianny
    Kamchatka, Russia
    Volcano Number 300250

    “Prior to its noted 1955-56 eruption, Bezymianny had been considered extinct. The modern volcano, much smaller in size than its massive neighbors Kamen and Kliuchevskoi, was formed about 4700 years ago over a late-Pleistocene lava-dome complex and an ancestral edifice built about 11,000-7000 years ago. Three periods of intensified activity have occurred during the past 3000 years. The latest period, which was preceded by a 1000-year quiescence, began with the dramatic 1955-56 eruption. This eruption, similar to that of St. Helens in 1980, produced a large horseshoe-shaped crater that was formed by collapse of the summit and an associated lateral blast. Subsequent episodic but ongoing lava-dome growth, accompanied by intermittent explosive activity and pyroclastic flows, has largely filled the 1956 crater.”

    GVP entry

    • Tolbachik
      Kamchatka, Russia
      Volcano Number 300240

      “The massive Tolbachik basaltic volcano is located at the southern end of the dominantly andesitic Kliuchevskaya volcano group. The massif is composed of two overlapping, but morphologically dissimilar volcanoes. The flat-topped Plosky Tolbachik shield volcano with its nested Holocene Hawaiian-type calderas up to 3 km in diameter is located east of the older and higher sharp-topped Ostry Tolbachik stratovolcano. The summit caldera at Plosky Tolbachik was formed in association with major lava effusion about 6500 years ago and simultaneously with a major southward-directed sector collapse of Ostry Tolbachik volcano. Lengthy rift zones extending NE and SSW of the volcano have erupted voluminous basaltic lava flows during the Holocene, with activity during the past two thousand years being confined to the narrow axial zone of the rifts. The 1975-76 eruption originating from the SSW-flank fissure system and the summit was the largest historical basaltic eruption in Kamchatka.”

      GVP entry

      Okay. Gotta get some work done now.

    • Yeaaaaa! What a nightmare this has been! I’ve been lurking though. So happy things are working out. Thank you Carl and everyone else involved for all your hard work. @ Diana – I love your little pink purse. It suits you. 😀

  17. Now, I have to make one thing clear. My presentation of the “wet side” theory, applies mainly to the presented region, which is Ecuador and Colombia, which has kinda a unique configuration. It was not meant on a general flank collapse basis, tho it might apply as a major forcing factor to some individual volcanoes.
    Point is, my general theory or thesis on which side will collapse first, as I have stated like 213432 times already 😀 , is that there is no “magic bullet” to do all the damage. There is usually a certain setup and a chain of events, over a certain geological period that creates the general stress field of the volcano. If you have a region like Ecuador and Colombia, where weather seems to be of importance on this matter since it has a unique configuration, one could expect more volcanoes in the region to be affected by it, which does to some degree explain why so many W slopes fail. But, there are also the more general factors, such as the before mentioned incline, gravity, orientation of “fissure swarms” (shall there be), setup of the magmatic system under the volcano and conduits, which is important because of the degassing, which would make the flank with more degassing more unstable, and of course the most obvious thing, deformation. Basically through inflation, emplacement and/or building a cryptodome. You can have a wet side on the west, but if you gonna start building a cryptodome on the E side, that will largely destabilize that flank. And it doesn’t even have to be a “mother of all cryptodomes”, like the size of it at Mt St. Helens. 🙂
    If you get inflation and/or deformation and movements of magma more focused under one flank, that will destabilize that flank through forming cracks and degassing mostly among other things, like general instability. And of course when the eruption starts and when pressurising occurs, the stress fields can also change. Of course the edifice itself plays a role, its composition and chemistry, which to some extent leads us back to weather.

    All in all, this is my theory. And I am 99% sure, that you will not find one forcing factor that you could apply to all volcanoes with collapsed flanks. I am convinced that there are many factors working together, but in regions like Colombia/Ecuador, as I have pointed out, there are external factors like weather that can affect more volcanoes at once, with the internal factors (mentioned above) still holding on to their part of the bargain.

    I hope that I wrote all this in an understandable way. 🙂

    • I like it. Don’t necessarily agree with it wholly, but then I don’t have to (plus, I have nothing more than a “feeling” as to why – so I cannot put up a cogent argument at this point.) It just seems too … simple.

      I do agree that there isn’t one answer for all, however. If there were, smarter people than I would have noticed this before now and already answered it. I think that a lot of the time the answer is going to be “because, at THIS PARTICULAR volcano, X happened.”

      And, “mother of all cryptodomes?” Would that be a MOAC? 🙂

      • Well, it might sound simple, but trust me, its not. Not by a long shot. All these forcings are always at work, but the relationship between them and the ratios, probably vary from a volcano to volcano, or a region to region. Heck, the magma composition itself also probably plays a role, and we know how diverse that is from volcano to volcano. But yes, I agree that this will be fun to explore, and in the end “because, at THIS PARTICULAR volcano, X happened” will prevail. 😀

        Instead of trying to find the magic bullet, we should focus on all the forcings first, and then start applying it to volcanoes and creating a certain sample size.

        I will also look at gravimetric fields, for gravity anomalies, but the data will be downloading for a while, so it will not be plotted today.

      • Not sure what MOAC usually stands for, but you can call it that way. 😀

        The fact is, as we have seen, that cryptodome building destabilizes the flank pretty badly and can override other forcings. Which is the point, that sometime one thing will override another, etc.

  18. Oh and I forgot, of course you dont have to agree with me, nobody has, that is the point, that we all have our own theories which we will test or at least try to test. This is just my basic theory also, and I will change and adapt it over time. 🙂 Tho when someone generally doesnt agree with ones theory or completely disapprove it, one is expected to at least present some counter data or another theory against it and try to back it up. That is how it usually works. The general “That theory is wrong because I dont like it” is the wrong approach, or dissing a theory just because it is opposite of what another believes, without present your own data, is also a false approach.
    We have a great opportunity to learn something new here, and we better not waste this chance and go in it head on, with everything we have. 🙂 😉

  19. And my last post of the day.
    Looking at Hakone caldera, I haven’t noticed before that Hakone is actually one big resurgent dome? It kinda seems that it could have one more caldera forming event in a certain near geological future.

    • It sure looks like it.
      And when a 10 000 year non erupter starts to inflate again, sprout fumaroles like a bunny pops kids and suffer phreatic detonations due to magmatic emplacements it is time to go and buy candy and beer.

    • So that’s where Yugawara is 🙂
      Thanks for posting this useful and interesting map Down Under! If there ever is a caldera-forming event, the type-locality of yugawaralite – one of my favourite zeolite minerals – would be destroyed 🙁
      I sincerely hope it doesn’t.

  20. If you are talking about gravitational slope failure, water would be one factor contributing to it. Water (or snow / ice at altitude) is one of nature’s chisels.

  21. Public notice

    Even though I am the resident Codiot amongst the Administrators and Editors I have somehow just succeeded with adding a log in and register Widget on the right sidebar without destroying the place.

    I hope everyone will find it useful.

    • I also inserted a Gizmo that will make it easier for people to upload and manage their Avatar images in here.

  22. GeoLurking
    Hey could you please give us a map of what is going on in Iceland.
    big swarm right now.

    Retrieved from Limbo /Lugh

  23. I believe, it’s my uneducated guess still, that an eruption might have just started under the ocean.
    I have been expecting an ruption on that location for many years. Last one there was in the 1920s I think.

    The graphs across Iceland are really very noisy for such a earthquake swarm. It almost looks like harmonic tremor, but I might be wrong.

    Big earthquake swarms in Reykjanes occur, but this one looks a bit odd.

    Retrieved from Limbo /Lugh

  24. I believe, it’s my uneducated guess still, that an eruption might have just started under the ocean.
    I have been expecting an ruption on that location for many years. Last one there was in the 1920s I think.

    The graphs across Iceland are really very noisy for such a earthquake swarm. It almost looks like harmonic tremor, but I might be wrong.

    Big earthquake swarms in Reykjanes occur, but this one looks a bit odd

  25. FWIW, the drum plot above doesn’t look crazy in comparison to Bardarbunga’s near m6 quakes, but that is far from the normal.

    This swarm in its very initial state looks to be about as energetic of a swarm as I can remember seeing at the Reykjanes ridge. Take that with a grain of salt since I haven’t exactly been watching for a super long time, but this definitely is a bit larger than the usual small swarm.

  26. Karen. I confirmed it. There is a volcanic/magmatic component to this swarm.

    Look at IM table. Many of the quakes are at great depth. At around 10-16km deep, and many of the earlier ones confirmed to 99% quality. Usually tectonic swarms at this part of Reykjanes never goes beneath 8km deep.

    This looks like a tectonic-magmatic event. And I wonder whether magma has indeed already reached the surface (which is at the bottom of the ocean at significant depth at that location)

      • Not quite – these things tend to wax and wane.

        I’m with Irpsit here, I think this is the start of an eruption.

        • I don’t really like the “tectonic” dismissal. Of course they are tectonic, but on the MAR, “tectonic” is sometimea accompanied by decompression melt coming out. You can’t have millions of years of spreading without some of it eventually finding it’s way through the crust.

          On a side note, Lakagígar was probably “tectonic” at first. (but, Holuhraun does point at a different initiation method, one not that different than was kicked around on VC near it’s beginnings… that’s the initiation of rifting based on an intrusion from a central volcano. But remember, even Holuhraun was initiated by tectonic stress field changes that weakened the rock and allowed an intrusion from an already pressurized central volcano) In the Reykjanes ridge situation, we don’t really have a known central volcano to act as the magma source, just whatever accumulated decompression melt that happens to be available.

          Will there be an eruption? Beats me. I’m not the expert. If it’s like most of the MAR, there could be one going on right now but we would never know it. It might show up on instruments, but even that is a crapshoot.

          Like a post turtle, the Fuglasker islands didn’t get there by themselves ya know…

  27. Reply to Bill and to everyone:

    On the location of today strong swarm at Reykjanes, with conirmed magmatic activity, and even possibuility of an eruption already started or about to start in soon.

    It is around 130 meters deep there.
    This is 30km southwest of Reykjanes end of the peninsula.
    There was a rock standing above the water there, until the seventies. Clearly a leftover of a old Stursey-style eruption.

    The name of the place, after the rock, is… repeat after me: Geirfugladrangur
    Or also Geirfuglasker, the name of the volcano.
    It is a volcano just as it is Krisuvik, Bláfjoll or Hengill.

    So maybe we will have the next hard-to-pronounce erupting volcano of Iceland 🙂 Geirfuglasker
    Nothing confirmed so far…

    But I am pretty confident about magmatic movements. Quakes have been deep. Up to 17km. And about a third of the quakes. (Tectonic quakes there only go until 9km deep)

    Carl had a written post on it:

    This was during another swarm in 2013 and Carl at that time also shared of the opinnion that this was a magmatic event. So there you have it.

    Geirfuglasker wakes up.

    (Retrieved from Limbo /Lugh)

    • If, and big if, an eruption would start. It would be first underwater and then possibly Surtsey style. Possibly ashy (Reykjanes eruptions can be pretty ashy too )

      If that would happen, it would be the best touristic scenario for Iceland. Near airport, with a sight of an eruption some 30km away.I woudl book my flight right away!

      But it’s still a big “if”. I think it is more likely that we see a Grexit before a Geirfuglasker 😀

      (Retrieved from Limbo /Lugh)

  28. Good morning…Looks like we could have the start of Surtsey’s Sibling. It’s the most intense and widespread swarm I have seen since watching. (that’s only really a short time 5 or 6 years) I loved the response Lurking…..I have visions of aircraft targeting an emerging volcano :D. BillG I loved your description so please don’t take offence at our humour…… we had these “boils” at El Hierro with Bob. The IMO will no doubt make a comment fairly soon if it carries on and they know something definite. I am pretty sure it is being watched if an eruption is suspected because of shipping. Fishing boats will report as soon as something is seen.
    Certainly it is a big tectonic movement and for new watchers this means that the rift stretches an allows magma to surface…. not necessarily to the surface of the sea though. It would have to continue for quite a while for this to happen.
    here is a VC Post by Carl about Surtsey’s eruption which can be used as a sort of guide to depths and time span of eruptions in this area……..I hope everyone can get this link.

    • PS .I know Surtsey is off the South coast and the nearest surface volcano to the swarm seems to be centred around Geirfuglasker but Surtsey is easier to spell! The behaviour of most submarine eruptions on the MAR in this area will be similar. Irpsit and others please correct me if I am wrong .

  29. Quick note on Reykjanes before I rush off to work. The crust in that location is no more than 10 – 12 km which means that some of the CONFIRMED quakes, i.e. “99.0% quality”, occur in the astenosphere / MOHO. The signatures as revealed by the drumplot “RNE” are tectonic, not magmatic (yet).

    A few hints: Select quakes greater than M2.0 as smaller quakes are rather insignificant as well as their location being conjectural at best. Only look at confirmed quakes, those that have been reviewed by a seismologist and assigned a quality of 99.9%. Take a look at the closest drum plot (rne) and compare with the profiles that you can find on the menu bar under the heading “Volcanology Basics”; “What Is a Volcano”.

    Once the trend is upward and the majority of big quakes occur at depths significantly above (less) than 5.0 km plus the rne drum plot shows the unmistakable signature of a magmatic component is the time to wonder if an eruption may not be “imminent”.

    • Thank you Leon…. I will take heed of your advice and timely reminders of what to look out for if an eruption is pending and curb my excitement. I will watch closely and as always wait. Enjoy your day at work. 😀

    • Also look at the length of the coda of the earthquake signal visible. If the earthquake has a sharp onset it is more likely to be tectonic, but if it has a long decline of the signal or the decline is “lumpy” it is more likely to also be magmatic.

      When I look at RNE the initial swarm is as far as I can see tectonic. But, in Iceland tectonic has a tendency to change into magmatectonic (tectonic start, but magma rushes into the void). The type has a slightly different shape than at other places in the world and is harder to spot than the archetypical magmatectonic events. But, they where there before Bardarbunga and are easy to spot when you have looked at Iceland earthquake data for years.
      It was when I saw that change in data at Bardarbunga I called that eruption.

      Now back to the RNE drumplot. It started as tectonic and changed into a magmatectonic with a series of earthquakes at 04.59 local time. The magmatic component is weak.
      There is not ongoing eruption, and I am not sure there will be one unless the swarm continues for at least two days.
      A telltale sign would be that the larger (above M3) moves upwards. Smaller earthquakes are to low quality to track well.

  30. 14 quakes of 3+ magnitude as of this morning. Definitely magma-tecteonic in nature but is it volcanic in nature? Probable, maybe even likely given where it is. Is this another failed eruption and will we see any surtsey style action? Hope so but remember how long we saw quakes at B before we saw anything on the surface.

    However, one thing I will be doing is keeping an eye further up the MAR/SISZ for that big quake forecasted a little while ago.

  31. Just as a future reference, this swarm or something similar to this swarm, is what I would expect to see at Katla once it decides its time is near. 🙂

    • And I dont know for you, but these signatures look nicely magma-tectonic to me.

      • Not massively so, but at about 04.59 something changes and the signals start to show clearer magma signals.
        But it is always hard to tell in Iceland since pretty much every large earthquake at depth will be sucking a bit of magma with it.

        • very true. I forgot to add that not all look MT.

          • All of the larger swarms portraying M3+ quakes at that spot has shown at least some MT-component. I would therefore wait untill we see clear volcanic earthquakes moving upwards before we can say there will be an earthquake.
            That part of the MAR is messy. But, that being said, it erupts quite often with small effusive eruptions.

          • Strongest quake so far is an M5 at 3.5km depth.

          • Looking at the line of green stars on the IMO map, it looks like a fault is moving, perpendicular to the MAR.

            Dunno if it is an intrusion too.

          • Whether the signatures look magmatic or tectonic in origin, still depends on which drumplot you look at. This means that the seismic waves have to pass through magma to reach some stations but not others.

            Also you are looking at swarms which means that several eqs are “clumped” together in the drumplots.

          • @KarenZ: I agree about the drumplots. The further away you go, the more distorted the signal appears.
            But as far as the “clumping” goes, you have to take scaling into account. The new drumplots are for 24h constantly. So they are time scaled, and of course magnitude scaled because of that M5. So for a quake to be actually visible enough on the drums to make the “clumping”, it has to be at least an M2.7 and above.

            The latest larger quakes appear a bit different, having a more lower frequency component to it, which of course could easily be a magmatic component of the quake. And the baseline tremor seems to be a bit elevated lately.

          • This is actually a comment to KarenZ’s comment, but it’s not possible to comment on that one, maybe four levels of comments is the maximum?

            I also thought it looked like there was a line of stars perpendicular to the MAR, but now, after the quakes have been manually checked by IMO, they have moved back into the cluster, so the line was probably just a random effect of inaccurate positions.

            Nice to see the Café up and running again so quickly. I’ll keep lurking…

      • It’s been a while since we’very seen a 5 magnitude quake, it does look like things are getting interesting over there.

        Dragged out of Limbo /Lugh

  32. As for the earthquakes at ‘Reykjanes ridge’, are peoples around Keflavik / Grindavik able to feel the earthquakes you think?

    • Of course. There were already “feel reports” overnight from the M4 quakes and especially the M5. They dont fell all, but they do feel stronger quakes, I would say anything above M3.5 closer to the surface.

      • Ok :-).

        I said yesterday that i was expecting to see bigger earthquakes when the biggest one at that time was a 3.9. Then a 5.0 came later. I still think that we will see even bigger quakes coming very soon.

  33. I have a question. I didn’t actually know this before a week ago or so. I found this in a Norwegian web page (which i don’t remember who was) that there have been a massive super volcano 300 km west of Bodø in Norway about 55 million years ago.

    Now i did search it up again and here it is on what they said.

    The world’s third largest supervolcano.

    NGU and Statoil have found signs of the world’s third largest supervolcano under the sea in the Vøring basin about 300 km west of Bodø. The remains of the enormous crater – or caldera – measure 40×50 kilometres. It was created by an catastophic explosion 55 million years ago. Supervolcanoes are extremely rare and dangerous natural phenomena. An eruption can eradicate life and cause dramatic climatic changes. We also find many traces of smaller supervolcanoes in the geology of the Oslo field.

    Can someone who knows the exact location of that crater outside of Bodø link that place to me on Google Maps or something as i can’t seem to find it?

      • Yeah, most likely. I did try to search up some photos from where the location is, but the ‘Vøring basin’ area is pretty darn big. So it’s not that easy to find the exact location on where the crater is.

        However, i found that text i wrote over in this PDF file:

        On page 2, they have an arrow pointing where the crater is. But the question is still, where is that located in Google Maps 🙂

        • oh, its submerged. Havent registered that. That changes a thing or two.
          Since it is underwater, you wont find it on google maps, since its not on surface/land.

          As for the location itself, just find Bodo and go 300km west. I can perhaps find it on gravity anomaly data, to see how the caldera shows up.

          • Speaking of gravity anomalies, I wonder if data showing the the big whopping (impact?) crater under the SW corner of the Amazon basin is public yet 🙂

  34. Since it has been an exciting year for volcanic activity so far, i cant wait to see what the rest of the year has in store for us volcanoaholics. 😀

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