A Follow-up on the Scientific Project

Digital Elevation Map of Mount St. Helens, the archetypal flank collapse and lateral blast volcano, with the pre-1980 topography and subsequent deposits annotated. Her 1980 eruption opened our awareness to what has since been recognised as a very common phenomenon of stratovolcanoes. (USGS)

Digital Elevation Map of Mount St. Helens, the archetypal flank collapse and lateral blast volcano, with the pre-1980 topography and subsequent deposits annotated. Her 1980 eruption opened our awareness to what has since been recognised as a very common phenomenon of stratovolcanoes. (USGS)

Last month, prompted by VC-reader VerboselyLaconic’s observation about the volcanoes of Colombia and Ecuador seemingly exhibiting a trend to suffer flank collapses in a preferred direction, we invited our readers to search worldwide in order to establish whether or not this was a general observation or if it only applied to the volcanoes mentioned by VerboselyLaconic.

The first result was a nice discussion, a sort of barn-storming session, as to what could be the causes of the observed phenomenon. Cbus proposed gravity in combination with structural weakness: “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.”

This is a sound observation, not only because non-volcanic landslides follow this rule, but also because volcanoes, strato- (or layered) volcanoes in particular, are not homogenous, strong bodies of rock, but rather a pile of debris held in place by loosely welded pyroclastic deposits and lava flows. If the solid bedrock upon which the volcanic edifice is built tilts significantly so that in one direction it is significantly higher, say 300-500 m, than in the opposite, there will be so much more loose material on the downslope that a structural weakness in that direction is inevitable. If this is true, volcanoes on such a slope ought to display a preferred direction of collapse while volcanoes on level bedrock would tend to collapse whichever way.

    Flank collapse at Kharimkotan volcano, Kuriles, Russia. This was the result of the January to April 1933 VEI 5 eruption. There have been several more flank collapses at this volcano, in many different directions. (Photo by Alexander Belousov, 1994, GVP)

Flank collapse at Kharimkotan volcano, Kuriles, Russia. This was the result of the January to April 1933 VEI 5 eruption. There have been several more flank collapses at this volcano, in many different directions. (Photo by Alexander Belousov, 1994, GVP)

DownUnder replied that: “But gravity only helps with the west side already being structurally less stable or more prone to collapse. If the volcano has more instability on its east flank, that’s were it will collapse if it shall collapse.” This too is a valid observation and led to a discussion on hidden, interior weaknesses caused by magmatic intrusions, so-called “cryptodomes” or “failed eruptions”, or by chemical alteration caused by volcanic gasses in combination with hydrothermal activity.

At this point, Edmdas asked us if we had considered weathering? “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.” Biologique replied that “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… …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.”

Map showing that for Equador and Colombia, the prevailing winds are from the east and average between three and six meters per second (Down Under @recretos)

Map showing that for Equador and Colombia, the prevailing winds are from the east and average between three and six meters per second (Down Under @recretos)

Here VerboselyLaconic intervened: “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… …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….”

Several readers including Azost wondered how to identify a lateral blast or how to differentiate a flank collapse from glacial erosion by just looking at topographical maps and images. Indeed! Although never explicitly specified, we searched for flank collapses whatever the cause. Here is an example of a “cirque, caused by glacial erosion - Broken Top Mountain (near South Sister) Oregon, USA. (fr.mobilytrip.com)

Several readers including Azost wondered how to identify a lateral blast or how to differentiate a flank collapse from glacial erosion by just looking at topographical maps and images. Indeed! Although never explicitly specified, we searched for flank collapses whatever the cause. Here is an example of a “cirque, caused by glacial erosion – Broken Top Mountain (near South Sister) Oregon, USA. (fr.mobilytrip.com)

Thus in no time at all we had identified two main underlying (pun intended) causes as well as a possible minor outside influence in the form of weather. By the time Lucas added: “Anyway, could the alignment of a volcano on a fault influence where it collapses?”, something definitely to keep in mind, we were still confused albeit at a higher level of understanding. Thanks to Irishzombieman, who located a paper bearing on the subject, we could read the following:

On Kamchatka, detailed geologic and geomorphologic mapping of young volcanic terrains and observations on historical eruptions reveal that landslides of various scales, from small (0.001 km3) to catastrophic (up to 20–30 km3), are widespread. Moreover, these processes are among the most effective and most rapid geomorphic agents. Of 30 recently active Kamchatka volcanoes, at least 18 have experienced sector collapses, some of them repetitively. The largest sector collapses identified so far on Kamchatka volcanoes, with volumes of 20–30 km3 of resulting debris-avalanche deposits, occurred at Shiveluch and Avachinsky volcanoes in the Late Pleistocene. During the last 10,000 yr the most voluminous sector collapses have occurred on extinct Kamen (4–6km3) and active Kambalny (5–10 km3) volcanoes. The largest number of repetitive debris avalanches (>10 during just the Holocene) has occurred at Shiveluch volcano. Landslides from the volcanoes cut by ring-faults of the large collapse calderas were ubiquitous. Large failures have happened on both mafic and silicic volcanoes, mostly related to volcanic activity. Orientation of collapse craters is controlled by local tectonic stress fields rather than regional fault systems. Specific features of some debris avalanche deposits are toreva blocks — huge almost intact fragments of volcanic edifices involved in the failure; some have been erroneously mapped as individual volcanoes. One of the largest toreva blocks is Mt. Monastyr — a 2 km3 piece of Avachinsky Somma involved in a major sector collapse 30–40 ka BP. (Ponomareva & al: 2006)

Table of 15 charted debris avalanches at Shiveluch volcano, Kamchatka. Two problems immediately become apparent: First, at what point does a “debris avalanche” constitute an “edifice” or “flank collapse”? Second, while it is clear from a topographical map that there are debris fields surrounding Shiveluch in all directions and particularly to the south, a visual examination by the untrained eye only reveals two or at the outside three flank collapses. (Ponomareva et al 1998)

Table of 15 charted debris avalanches at Shiveluch volcano, Kamchatka. Two problems immediately become apparent: First, at what point does a “debris avalanche” constitute an “edifice” or “flank collapse”? Second, while it is clear from a topographical map that there are debris fields surrounding Shiveluch in all directions and particularly to the south, a visual examination by the untrained eye only reveals two or at the outside three flank collapses. (Ponomareva et al 1998)

A second look at the volcanoes of Equador listed by VerboselyLaconic yields a slightly different picture. First of all, right through the middle of the Andes is the Guayllabamba river plain, a depression that separates the Andes into two distinct mountain ranges, each of which has erosion gullies caused by rivers flowing down into this plain. While there are exceptions such as Volcán Corazón, which indeed has suffered a flank collapse towards the WNW (even if the terrain to the east of Corazón shows unmistakable evidence of debris avalanches such as toreva blocks), most volcanoes seem to follow the principle suggested by Cbus, that is, collapse in the direction of lowest altitude where one is present.

The terrain of Volcán Corazón, Ruminahui and Cotopaxi. Features suggestive of toreva blocks and debris avalanches have been circled with red. Please note that these are my impressions, not scientific fact resulting from in-the-field investigations, and could thus be wrong!

The terrain of Volcán Corazón, Ruminahui and Cotopaxi. Features suggestive of toreva blocks and debris avalanches have been circled with red. Please note that these are my impressions, not scientific fact resulting from in-the-field investigations, and could thus be wrong!

To the WSW of Corazón lies Volcán Ruminahui, almost in the middle of the plain, and the topography suggests that it has suffered flank collapses to the west, the NNE, east, SE and SW. Even Cotopaxi itself, 15 km to the SE of Ruminahui, has feautures suggestive of toreva blocks and debris avalanches in several directions. Because volcanoes perpetually change the landscape, obliterating what was before, it is indeed very difficult to say anything definitive from the study of maps alone. Yet, kudos to VerboselyLaconic because he got us all thinking!

The bewildering array of flank collapses displayed by Avachinsky Volcano, Kamchatka, Russia. The greatest of those was about 20 – 30 km3 in size and occurred about 30-40 kA BP. (earthobservatory.nasa.gov)

The bewildering array of flank collapses displayed by Avachinsky Volcano, Kamchatka, Russia. The greatest of those was about 20 – 30 km3 in size and occurred about 30-40 kA BP. (earthobservatory.nasa.gov)

So where does this leave our project? Well, as we all soon realised, the subject is so complex and the search area so vast that I am afraid that there is little chance of us ever establishing a definitive data base, discover and quantify the underlying causes in every single case (or at least enough cases) in order to ascertain a set of guiding principles. Nevertheless, there is always our own, personal Oddysey of exploration and gaining of knowledge to consider, and the hours I spent familiarising myself with Kamchatcka and particularly the Kuriles gave me a lot of pleasure and a far greater familiarity with that region. So instead of feeling despondent, I feel a sense of satisfaction and personal accomplishment. I hope you share this feeling and thank you for your participation!

Ponomareva, Melekestsev & Dirksen: “Sector collapses and large landslides on Late Pleistocene – Holocene volcanoes in Kamchatka, Russia”, Journal of Volcanology and Geothermal Research 2006

Click to access jvgr_landslides.pdf


Featured Image – Avachinsky from EOS
Categories – Science, Volcano
Tags – Debris Avalanche, Edifice Collapse, Flank Collapse, Lateral Blast, Reader Participation, Research Project

164 thoughts on “A Follow-up on the Scientific Project

  1. Speaking of Columbia did an eruption occur at Nevada Del Ruiz today?

  2. A most excellent and thought-provoking post. It seems to me that it’s not an ‘either-or’ solution. In that, in cases where a volcano is constructed on a sloping basement rather than on a more or less level surface, then flank collapses will more probably be directed ‘downslope’ for the reasons given in the discussion. It should be possible to get statistical evidence – look at the histories of a group of volcanoes where these conditions apply -East slope of the Andes, (eg Sangay,, Reventador) or the Aleutian Islands (on the northern margin of a steep ridge)- and compare with a control group known to have grown on a plain.

    Other factors also apply; for St Helens, (possibly Bezymianny also?) the collapse seems to have been triggered by magma intrusion into a structure where its progress has been diverted by the presence of a massive summit dome, to force a way into the less resistant flanks. And some collapses have certainly been influenced (in direction) by hydrothermal alteration – Rainier maybe, But there is no one-size-fits-all answer

    • Sure there is. No matter what happens… gravity wins… always.

      • I believe that US Congress is trying to get the law of gravity repealed, or at least watered down, in order to prevent the collapse of large edifices corporations which would dry up the flow of bribes donations.

        • The Indiana Pi Bill is the popular name for bill #246 of the 1897 sitting of the Indiana General Assembly, one of the most famous attempts to establish mathematical truth by legislative fiat. Despite its name, the main result claimed by the bill is a method to square the circle, rather than to establish a certain value for the mathematical constant π, the ratio of the circumference of a circle to its diameter. However, the bill does imply various incorrect values of π, such as 3.2.

          The bill never became law, due to the intervention of Professor C. A. Waldo of Purdue University, who happened to be present in the legislature on the day it went up for a vote.

          • Its quite possible that the Indiana Pi bill came about due to amateur mathematician Edward J. Goodwin trying to bypass the normal publication route. In the end, he did finally get his work published in American Mathematical Monthly with a disclaimer.

            … and Indiana gets the idiocy recognition as having had it’s legislature being haughty enough to try and legislate a mathematical constant.

            “it was nearly passed, but opinion changed when one senator observed that the General Assembly lacked the power to define mathematical truth.”

      • Back before I got kicked off of a loon site, I made the observation that Rome was also “Too big to fail” Some people just don’t like pragmatism.

        Everyone who touched it caught the disease
        For luscious bits of landfill
        It sparked an epidemic of self hate
        They wanted it so bad they could kill
        Everyone believing everything ain’t enough
        Trampling bodies on the treadmill

      • The problem with pragmatism, is that if you don’t pay attention to it or follow it, stuff can sneak up and bite you on the arse.

    • Hello! Unfortunately, a lot of studies have not been done in the Aleutian Islands. The USGS rated most Aleutian Islands volcanoes for a significant risk of flank collapse in the NVEWS framework due to many of them having steep slopes.

      The only one I can think of for sure is Shishaldin, and the collapse was to the north.

  3. Another small-ish but very deep quake going on at Katla. The depth is what is relevant here.

    • My access to the drumplots (Tromlurit) seems dead – URL changed? If anyone knows one that is working I’d be grateful to know.

      Meanwhile, you prompted me to go sniffing over the tremor charts for Godabunga and the area including Hekla. Writing as a volcano nut with crystallising rhyolite for brain cells, I’m wondering if things look…interesting? The Hekla strain chart has also been on a steady up for a couple of days now (so far as I can tell) and there was a tiddly quake right in the mountain a couple of days ago that I put down to melting ice. Might we be seeing the next phase of the current Icelandic high beginning to make itself felt?

      Or is that rhyolitic mush for brains reading too much into the charts?

      • Hi Clive, the drums still work for me at http://hraun.vedur.is/ja/drumplot/mapDRUM.php

        I’d say activity is up but whether we’re just seeing things clearer due to better instrumentation (any news on Hekla Cafe station?) Or it’s entered a new phase of increased activity, I couldn’t say. But it’s darn exciting to watch 😉

        I’ve just moved house, (finally saved up enough to buy our own flat), and we’re without internet so I hope she stays quiet for a while longer – the activity has been similar for a little while now. I won’t be booking my Hekla day off work just yet 😀

      • There is still residual activity at Bardarbunga and in that vicinity, but I don’t see anything “outside the normal” for the most part that we haven’t seen in the last few years.

        I will note that I feel I’ve seen dead zone earth quakes a bit more than I did 1-2 years ago, but that may just be a recency bias. I haven’t been actively tracking these quakes.

        Either way, if something is about to erupt in Iceland, unless its Hekla or Grimsvotn, we’ll likely see a lot of green stars first, not entirely dissimilar from the Bardarbunga situation.

  4. Henrik – an absolutely fascinating post! Thank you! Oddly, I had recently being thinking over flank collapses and this article is perfectly timed.

  5. remembering Bob on his Island (forgot the name, brain is on holiday) of Landslides all over the place, the Canaries are really a point in case with the talk of a slide wit enormous repercussions

  6. Hello! I’ve been lurking around for probably over a year now, just reading and learning. This post was wonderful to read. The line about Cotopaxi stuck with me. This post, and the first scientific project post, got me thinking about volcanoes that have rebuilt their cones, say St. Helens pre-1980, Augustine, or Shishaldin. They would be theoretically harder to notice on a topographic map. We would have to look nearby, for example at Augustine’s asymmetrical coastline, for evidence or undertake other studies that many of us don’t have the capacity to do. It serves somewhat as a reminder that flank collapses on volcanoes like these may represent an unknown hazard to locals, the aviation community, etc. until targeted research is done.

  7. My first though after hearing of multiple flank collapses was that the ground level adjacent to the volcano would be altered by the first collapse, so presumably the subsequent collapses would be in different directions?

    Also flank collapse vs minor debris fall – I guess I think it needs vent exposed to a depth equal 50% of the original edifice to count as a ‘flank collapse’ (how does that sound as a fair criteria??)

  8. A few scattered quakes on the northern flank of Mauna Loa today, but really shallow.

  9. Well, I guess the answer to my original question, “Is this odd? Is this disproportionate to the rest of the major chains of volcanoes elsewhere?” is a resounding “Maybe.” LOL

    Thanks all for this work and post, your insight is unique and your drive to get to the truth is inspiring.


  10. a volcano blowing its top:
    being inactive for ‘a while’
    rapid intrusion,
    blogged at the top or not enough room, finds room further down,
    a biggish quake and KABOOM

  11. Alaska is having the shakes. A 6.9 yesterday in the Aleutian islands, a 6.3 today not too far from Redoubt. Holidays are a good time to release stress.

    • And that Redoubt quake, at 116 km depth, is right in the melt zone for the subducting slab…

      • No worries. No quakes in a melt. At the depth this will be tectonic. Of course a good shake can affect a volcano above but that is different.

      • My thinking is that as melt forms and percolates out, the stress on the plate shifts and adjusts for the new voids.

        I’m not sure how that would look on a beach ball. 🙁

        • How do you distinguish that though? The mechanism shows a fault plane not in alignment with the sub ducting slab’s overall trend, but still as a thrust fault. That might be what it looks like as the mass just tries to fill the space using whatever slip plane will get the job done with the least energy expenditure. (no, not a conscious decision, no “cosmic mind” at play here, just the stress vectors that fail first)

          For all: Albert is quite correct about no quakes in melted material. This is more akin to the subducting plate going through a stage of break-up and fragmentation. The hydrated minerals having a lowered melting point and the remainder of the plate adjusting to compensate for the loss of mass. supporting structure is a more accurate term than mass. Remember, the Benioff zone extends deeper than this region, and that is the rest of the plate still exerting a pull on the oceanic plate. Had it shown normal mode faulting, it might have been a signature of the lower section of the plate starting to detach… a process that is probably measured in millions of years.

          Caveat: I may have read the beachball wrong, if so, then the second option applies.

          Update: Double checked… I got it right. Reverse or Thrust fault.

        • Another thing to consider – as a plate slides beneath the melt zone, that provides fresh hydrated rock that will now be melted, which provides for more melt production than a dry depeleted slab would. Earthquakes serve to shuffle the plate further along, providing that somewhat constant influx of magma.

          With that said, even if this did produce new melt, it probably wouldn’t affect the volcanic system for a long time with it being 120 km deep.

          • True, but we don’t have a real clear indication of how long it takes for melt to percolate up into a chamber. Some indications are that systems can come back to life and erupt in short order… but the trip from down deep… no idea. It probably has a lot to do with viscosity and the presence (or not ) of established pathways.

          • Exactly – and I would assume it would at the very minimum take years for fresh magma to migrate that far upward.

          • New magma may not have to reach the surface; all it has to do is give stuff higher up the system a nudge.

            On the other hand, does crystalline mush provide much resistance?

    • From Cotopaxi:
      Yesterday´s report from IGEPN:
      Sismicidad: En las últimas 24 horas se contabilizaron 11 eventos de largo periodo (LP), 1 evento volcano tectónico (VT), 5 eventos híbridos (HB) y 17 episodios de tremor (TR).
      Gases: Desde las 07h00 hasta las 17h00 del día de ayer se han registrado a través de los instrumentos DOAS 2570 t/d de SO2, valor promedio obtenido a partir de 55 medidas.
      From the helicorder:

  12. Silly website code, this was intended to reply to Albert and his link to article from USGS.

  13. In the link provided? hvo.wr.usgs.gov/volcanowatch Although I do now see that what my browser shows as the new ‘current issue’ is dated July 11, 2013 – there may be a bit of an ordering problem. Never mind, it discusses the subsidence shown by volcanoes as the shaking causes the magma chamber to push outward and to broaden.

    • Oddly enough… that makes sense when you think about it. It’s like rocking the whole edifice back and forth, making it settle into the unstable basement. Sort of like setting a brick in mortar.

    • Mass ejection rate is about 1,641.1 m³/s DRE. (using Mastin et al)

    • “[Manam], despite remarkably symmetrical lower flanks has four distinct valleys, locally known as “avalanche valleys” due to their ability to focus avalanches and particularly pyroclastic flows generated at the summit


      And a Google Earth view of one of those “distinct valleys” that lies directly under the plume as it is being pushed by the prevailing winds. Looks quite ripe for a repaving. (SW quadrant of the volcano looking NE.)

    • Fatantastic catch! There was an M7.0 earthquake a bit to the west a few days ago. Darwin first pointed out that a big earthquake can trigger a volcano (he sat through a monster quake in Chile which triggered several volcanoes there). Perhaps the same happened here?

    • Note the high altitude semicircular cloud rings which form towards the northeast, into the wind, immediately after the eruption, perhaps 50-100 km away. You can get the same effect from shockwaves from meteors. I once saw such a cloud ring which must have been over 100 km across and stayed visible for well over an hour.

    • Where did you read or hear about this so I can check it out?

    • The volcano is just showing off since it has all the investigators nearby checking out the debris that washed ashore.

      What makes me curious is how long it takes to bounce the part’s serial #BB670 against the parts manifest for the missing aircraft. How long does it take to check a number in a database?

      They can argue about whether or not it’s fake or planted at a later time. The delay in confirmation that it should or should not be from that airframe only adds to suspicion. For the record… I tend to trust no one. Especially bureaucrats. They have a long reputation of selling out anyone for anything. With used car salesmen, you at least go into the deal knowing they are crooked by nature.


      • Investigators were evacuated for Piton de la Fournaise’s eruption which may have delayed communication. Then you have the time difference between La Reunion, Malaysia and the US. Plus time to search databases and check results. It could add up.

        • Yep it does take time . Just got out of an
          aviation website that was hijacked by a
          “Truther.” saying the part was put there to throw off the scent by some sort of Bilderberger/zionist outfit that controls ALL of the autopilots of all the airline and
          light aircraft…

          • I guess it would theoretically be possible to plant the part but as that would be very, very expensive, my take is planting the part would be very unlikely.

  14. The 777 has been around a while -long enough for aircraft to be parted out. But even if this was a replacement part from another aircraft it should be evident. Depending on Malaysian Air’s record keeping…

    • Well, you know that industry better than anyone I know… all I can say is that it is quite ordinary for meticulous records to be kept of aircraft parts and maintenance. Two guys that I used to work with were called in to testify as to the maintenance procedures that were done on a helo that had an incident… even after they were retired from the Aviation Maintenance depot where some of its components had been worked on… back before that particular Maintenance depot had been taken out of service and all activity transfered to another facility. (BRAC closure).

      That facility was taken over by CNET and turned into a Naval aviation maintenance school. (formerly in Millington TN) Millington in turn, was turned into the center for all of the rating (specialty) managers. (aka The Detailers, the guys who determine what billet you get assigned for your tour of duty). Naval Support Activity Mid-South

  15. Have the happy holiday-makers returned?

    #5 might erupt before it makes publication, if it has not done o already 😉

    • I took an age to work out why a full disk would hire a satellite before I realised you meant HiRes. D’Oh! Nice link, thanks!

      • mea culpa. English is not my first language. Native Texan is the first 😉

        I also point out to folks that my typing speed increased 20% when hot key editing is allowed, 5wpm -> 6wpm.

        • No worries. I am a denizen of the deep south myself. Texas is out yonder towards the sunset. I even have a grandkid and great grandkid living near El Paso.

          Your statement was proper usage and I think Clive is just yankin yer chain. 😀

          Word of caution though. It’s quite easy for the readers here to miss on some colloquial expressions. We tend to have an international audience. That is pretty much the reason that the official language of the Blog is English (of sorts), in order to reach the widest audience. For the most part, grammar Nazi’s are berated here. We basically don’t care, as long as people can get their point across with little interference.

    • that area is peppered with vulcanism, there are quiet a few earthquakes now, news of course goes to the Tsunami threat, I have a page bookmarked in my old PC when I find it will have a look for more info

  16. The ongoing Lakeview quake sequence in NW Nevada seems to be quieting down. This activity has been ongoing in bursts of activity since late fall of last year. In particular, two sequences in late July which featured a mag. 4.6 jolt, showed a depth pattern that extended from ~ 14km all the way to the surface, with a cluster of quakes ~8km. The sequence is noteworthy since the seismic data is strongly hinting that a dyke intrusion(s) are involved. Here is a good set of graphs from the Nevada Seismo Lab. Select the Graphs tab and scroll down to see the suite of graphs. http://www.seismo.unr.edu/Events/main.php?evid=504554
    The area is in an extensional zone (typical for Nevada east of the Sierra) and not known for volcanic activity. Will be interesting to see if this pattern continues, and whether any surface expressions. Not a lot of data or authoritative commentary available, but I will continue to research.
    Check it out.

    • Been following that too. Felt that dike intrusion was the best explanation. However , there are volcanic features in the area. Information is hard to find for that region.

      • Here’s the drumplot from the July 16 sequence. Sure looks like some fluid movement is occurring at various times. Note the rapid sequence of shocks prior to the two major shocks. Curious pattern. http://pnsn.org/seismogram/2015/07/16/lkvw/ehz/uw
        Now, if this sequence were to be happening in Iceland, the world would be all atwitter about a major eruption. But being in poor-old Nevada, nobody seems to care.

        • Well it is mostly a few ranches, cows antelope, and lots of big high and lonesome.. Lakeview , Or. Alturas Ca.
          and a few little towns like Denio Junction,Nv. are there.. But I’d sure like say John Vidale’s or Erik Klemmenti’s
          take on this…

          • Well, it appears possible/probable dyke intrusions are not completely unknown in the general vicinity of the Lakeview/Vyla events. Still, given that recent faulting has occurred clear to the surface and activity is higher than in 2011 means the situation is worthy of some extra attention. Here’s an abstract I just found describing possible dyke intrusions in NE Calif., which was prompted by some mid 4’s eq’s and associated swarm around 2011 in NE Calif. http://adsabs.harvard.edu/abs/2013AGUFM.V11D..08S

  17. Saturday
    01.08.2015 22:25:50 63.437 -23.939 10.0 km 3.3 99.0 8.9 km SW of Eldeyjarboði

  18. Only just got back from a week-long holiday abroad. Thank you for the kind comments and apologies for the long delay with NDVP number five. The delay being this long, I shall see what I can do about it for Friday, but it will be tight as these articles do take much longer to write than the regular ones and we do not want the standard to slip!

  19. Call me crazy, but this looks like Harmonic tremor to me at Lakeview.

      • Its Lakeview Oregon, or at least where the station is. The target area is NW Nevada, where the swarm occurred not too long ago.

        Tho I am a bit sceptical about HT getting from NW Nevada to Lakeview station in that magnitude.

          • Very doubtful. This is probably tectonic in the first place, and in the event that this were magmatic or magmatectonic, there is still a pretty low likelihood of anything being seen at surface level here.

            Basin and range volcanism still exists, but it’s very isolated, rare, and has happened more to the south than in the north in recent geological time.

          • Not to mention that this region is in the vicinity of Walker Lane. Well, in the northern reaches of where it is believed to extend to.

            Walker Lane takes up 15 to 25 percent of the boundary motion between the Pacific Plate and the North American Plate,”

      • I know a tavern called that because of the lake behind it. Be a surprise if it were there. 😀

    • That station is more than 90km from the epicenter of the swarm.

      There is the spectogram of 10 minutes of the plot given above (01:00 – 01:10).

      The recordings are most >20Hz high, no HT for sure and most probably not tectonic/volcanic related.

      I do believe the LKVW is non filtered, and this can mislead, because some networks provide filtered helicorders and others dont..and most wont specify if its filtered or not. At least a 10Hz LP filter would remove most of the noise..

      Not an expert.

    • So the rift boundaries act as a sort of waveguide and direct the energy. Imagine that.

      I do suspect that the plutonic emplacements in the region act to enhance the local shaking, similar to was was observed at Christchurch.

      Based on that study, it is possible that Memphis will receive less shaking that other cities at similar distance from the epicenter.

      • Yeah, that graphic is pretty cool and nicely demonstrates the channelling of the waves. In relation to the map, where are those sand features that I remember you writing about before? Hope you know what I mean 🙂

        • I don’t have an active graphic representation of them, but rummaging around the available papers, it seems that the extent of sand-blow fields is much more widespread than the local New Madrid area. I don’t have any data on what specific level of shaking is needed to cause them, but if my hunch is correct, large seismic events have happened all down through that area of the Mississippi flood plain, and even up the Wabash SZ.

    • Thanks for the info. This is in my area. Always looking for the latest on it.

  20. Greeeat… Not far from here, there was a triple homicide. According to the update from the local news, the Sheriff’s department has a “person of interest” in custody, and that the murder was possibly connected to a witchcraft ceremony accompanying the recent “blue moon.”

    This town is truly going nuts. Evidently that vampire that I dropped from training several years ago had quite an odd subculture of friends that he was hanging out with here locally. (Note: he self identified as a vampire) Not that he is or was connected with whatever happened, but it illustrates that there is a stratum of people in this town that just aren’t quite there…mentally. I knew about the nine year run of decapitated goats arbitrarily showing up in different parts of Fort Walton Beach, but this is the first I have heard of this sort of thing here.

    This appears to match the photo from the news story 30.522298N° – 87.337981W°

    • The “news” went out and scared up some Wiccan guy who decried the incident as painting his religion in a bad light. Never believe that a “news” person will ever pass up the opportunity to shove a microphone up somebody’s arse. Poor dude was probably just trying to have a quiet day at home and this reporter twit comes banging on his door.

      One of the more tragic bits about this event is that it gives the “reporters” an excuse to go bother people and try to paint the world with their personal stereotypes. Wiccans aren’t bad people, just a little weird.

  21. Worth keeping a quarter eye on Sakurajima… as much because of what it’s *not* as what it *is* doing.

    It is steaming/degassing pretty heavily. But it isn’t erupting. I’ve had the webcam up quite a bit, and haven’t seen anything resembling an eruption in several days. That’s highly unusual. Maybe I’ve just been missing them, bad timing, but it seems to be to be down from background levels, and *way* down from what it was just a few weeks ago.

    I don’t know if magma supply has dropped, if magma has found a new route and is accumulating elsewhere, or if it’s just badly constipated and awaiting an exceptionally large bang. But its behavior has changed, and its interesting.

    • In spite of Sakurajima being in almost continuous eruption since 1953(?), there is still uplift measured elsewhere in the caldera, so a marked changed in behaviour *is* well worth taking notice of.

    • Definitely a bit odd, especially in light of how active its been recently. There was some degassing at one of the older craters not too long ago (karen posted a screencap up on this page a bit). But that’s not the first time it has happened in the last few years.

      I think the worry is if a stickier batch of magma would come up through the smaller chamber and clog the conduit leading out – this could lead to a lot of pressure being built up.

      As for the uplift mentioned by Leon, it’s not only “elsewhere” in the caldera, but also at Sakurajima proper. Sakurajima itself deflated quite a bit after the disastrous early 1900’s eruption, but has been re-inflating ever since. At this point, it’s very close to the level it was at during that early 1900’s eruption, many Japanese volcanologists anticipate another similar sized eruption in the next 10-50 years.

      The Aira caldera may not be a supervolcano the size of Yellowstone, but its still huge, and has many similar traits to other extremely large caldera systems around the world (along with its neighbors as well).

      With that said, I need to add an anecdote that the less-known Ata caldera to the south may be even more dangerous. Ata has had a higher volume of large explosive eruptions in the last 10,000 years, all in somewhat populated areas on the southern tip of Japan.

      • The Kikai caldera even further south has done more than Ata IIRC? And the last big one was big enough that the distance from the mainland didn’t prevent it getting thoroughly trashed.

        • Kikai has had 2 large caldera events, the last of which was the enormous VEI-7 6000 years ago. But ever since then, it’s been fairly benign with smaller rebuilding eruptions. Kikai is also far out at sea, so there isn’t the same volume of population nearby as there is for Ata, and even in the vent of a larger eruption, nothing that bad would happen since it would be either underwater, or on a remote island.

          Ata has had one major caldera event that was probably similar size as Aira’s VEI-7, and then has had multiple smaller caldera eruptions. I mention Ata as a specific risk because it has been highly active in the holocene, but has been extremely quite in the last 400-500 years or so. That could mean that either the magma supply has slowed down, or on the other hand, pressure could be building there.

          There also seems to be a significant risk of large phreatomagmatic explosions in populated areas near the Ata caldera based on the numerous maars. Obviously that poses a significant risk if it were to happen.

  22. In case someone is interested, besides plotting tomography, I also plot weather related stuff, since its my main hobby. Lately I am testing making 3D plots of hurricanes. This is an example of Soudelor typhoon in Pacific. Data is from the 2km HWRF model.




    • major cool. this is amazing.

      wow. saw them for a bit, and then the images went poof.

      • Not just “major cool” but super major cool. Since I think i heard that Soudelor was once the strongest cyclone ever measured(?) the graphic holds even more relevance. Thanks for sharing the fruits of some obviously serious labor. That an amateur can create this type of image from public data sources is in itself amazing. Maybe sometime you can give a layman’s description of how you are doing it?

        • Craig,

          as far as the strength of Soudelor, it’s not much more than a garden variety WPac typhoon. It is a rather large one, and did go super for a about a day, but is down to < 95kts recently. It may strengthen again getting closer to Taiwan due to the water being very warm close in.

          If you want the latest info, give Dr. @ryanmaue a follow on twitter. His dissertation was in tropical storms and climate, his info is sensationalism free.

    • Very nice. I occasionally develop a wind field vs range from core model and use that to evaluate the threat potential wind speeds for landfalling systems. Nothing as fine grained as this through.

    • How long does it take to do this ? What program did you use ? I am totally clueless as to how something like this is made ?

  23. Well Sakurajima just broke its duck with a typical, unremarkable small eruption from the usual (Showa crater) source, at 19.00 local time this evening. So it’s not entirely asleep, or entirely blocked.

  24. Does anyone notice the 4/5 quakes at Grimsvotn? I know that they are more than 10km sse from the volcano but think they may indicate a slight rise in activity.

  25. Pingback: Pictures, not necessarily pretty | Zoopraxiscope Too

  26. Can anyone see anything on the Hakone webcams? It should be daylight now so is it ash or just the webcam playing up?

    • The pictures got a bit clearer now, think it’s fog, sorry!

      • No… I want to see a volcano erupt IN a parking lot. I’m not overly fond of parking lots. You spend a six month assignment of sitting in one for 8 hours a day watching it with binoculars and you become a bit tired of them.

        • You don’t want it too close to the webcam, though, or you won’t see it. It would have to be a small one too so as not to take out the webcam. Does Hakone do small? 😉

  27. Re NDVP #5

    With the short time at my disposal since taking over this, I’m afraid I have not been able to complete it just yet. While it is more or less finished, it won’t be ready to publish until tomorrow, Saturday at the earliest. I apologise for the delay.

    • Looks to be a very interesting read even if the introductory “In the past four centuries nearly 280,000 people have died as a result of volcanic activity and millions more are thought to be at risk” seems to be a somewhat conservative estimate.

  28. Interesting little kick, is it tremoring or weather? Drumplots look normal although I haven’t looked too far afield yet but it does seem to be showing on hau.

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