The effects of Seismic Air Guns on Marine Animals.

Although we are not seeing much of Bob, the off shore volcanic vent, south the smallest Canary island, El Hierro, we do have some idea of what the sea bed there looks like. Survey ships still monitor the area, testing the water properties as it is not certain if the area is safe for humans to enter the waters.The ideal way to see the sate of the ocean floor is of course by using an ROV, Remotely Operated Vehicle.

These are expensive pieces of equipment and conditions near a volcanic vent could damage them. So the usual way to study the topography of an area like this is to use seismic air guns as seen in the clip below.

To a biologist and anyone concerned with animal welfare this method of mapping raises the question of how the explosions affect the marine animals, not just the large dolphins, but also small creatures that are important in the ecosystem.

Effects of a seismic air gun from a German research ship.

The sea is not a silent place. Despite the human concept of a still, blue environment filled only with the sound of the escaping air bubbles of a diver’s breathing apparatus the sea is an incredibly noisy place. There are the sounds of the tides over reefs of rocks and corals. The sound of rain on the surface. The movements and sounds made by animals and seaweeds and of course in seas around volcanic islands like El Hierro there are geologic sounds.
These sounds are the background noise to marine animals as the noises of the countryside are background to a human’s auditory senses.
The importance of the auditory senses to marine animals.
Sound gives a marine inhabitant a 3D picture of it’s environment. Fish have incredibly sensitive hearing.Several studies have shown that fish can determine the range and direction of underwater sound at frequencies ranging from 0.1-1.0 kHz. Most fish have two “inner ears” composed of tightly packed hair cells. More about the construction of these can be found here.

http://www.me.gatech.edu/minami.yoda/FLOIDLab/fishhearing/fishhearing.htm
Marine mammals also have internal ears that are designed to pick up love density sound waves (infra sound)
More information here.
http://www.dosits.org/animals/soundreception/mammalshear/landmammals/
Sound is also used as communication, in mating behaviours and for finding food. We are all aware of the “songs” of whales and dolphins but many animals make sounds we humans can hear. The most amazing one is of the Pistol shrimp. This is an excellent video and explanation how this tiny creature creates and uses noise .

Just like humans any strange noises produce altered behaviour in fish from being startled to stress and even death. Man made noise and it’s effects.

Human activity on oceans and shores have introduced alien noise to the marine habitat. Fish and mammals have such sensitive hearing over long distances that they can move away in advance on the approach of a boat with it’s engine running. The sounds of a ships engine may be uncomfortable for some fish but for dolphins, boats often appear to be a source of entertainment and they will happily approach and swim alongside. Hence it can be seen that not all marine creature react to noise in the same way.

There is such a huge diversity of animal life in the oceans , the detailed study of their physiology and behaviour is still very much in it’s infancy.
Like any Biological study the sheer number of species, each with it’s complex behaviours and habitats makes accurate observations and experiments incredibly difficult. Laboratory experiments on the whole will not give accurate results as any natural marine environment is very difficult to replicate.
However some work has been carried out on the effects of seismic air guns.
Seismic air guns are used to do underwater geological surveys. These project sound down toward the water into the rocks below. The air guns are towed by a moving boat. Long strings of hydrophones pulled behind the air gun array detect the reflected signals. This data provides information about the geology below the sea bottom.

Fancy being shot at by your seafood sallad? Here is a candidate for that experience, the Pistol Shrimp.

The peak source level of a seismic air gun array can exceed 250 dB re 1 μPa, and
although the bulk of the energy is projected downward, there is considerable lateral energy as well. There has been quite a lot of work carried out on the effects of Air Guns. McCauley et al. (2003) demonstrate that shots from a single seismic air gun can cause some damage to the sensory hair cells of the saccule of the ear of the pink snapper (Pagrus auratus, Forster 1801).

It was not accurately found what physiological damage was incurred but the observed fish suffered no mortalities and continued feeding despite some sensory loss.
Skalski et al. (1992) showed a 52% decrease in rock fishhh (Sebastes sp.) catch when the area of catch was exposed to a single air gun emission resulting in a received level of sound at 186–191 dB re 1 μPa (mean peak level) (see also Pearson et al. 1987, 1992) These investigators also found that fishes would show a startle response to received sounds as low as 160 dB, but this level sound did not appear to elicit a decline in catch. The basis for the decrease in catch is not clear, and it should be noted that, for the most part, there was no actual visual observation of the behaviour of the fish during air gun exposure. It is known that, like humans, when exposed to explosive or frequent loud noise, fish suffer permanent hearing loss.
Although these behavioural studies suggest that there might be some changes in behaviour associated with seismic air gun activity, a study by Wardle et al. (2001) that actually observed behaviour on a reef off Scotland as an air gun was fired at a level that was measured to be 210 dB re 1 µPa at 16 m from the source and 195 dB re 1 µPa at 109 m from the source found results to the contrary. The investigators found that several species of fish showed virtually no response to the air gun emission other than perhaps a transient startle response that did not change in any way the pattern of movement of the fish.

The effect on marine mammals is a cause for concern. There have been suspicions that Air guns could possibly interfere with the navigation organs causing beaching. As a result more studies are being undertaken such as this four year study of Humpbacked whales.

http://www.brahss.org.au/

How does all this affect El Hierro marine inhabitants?
El Hierro has a very special and well protected Marine Conservation area that is a magnet for professional and amateur marine biologists.
The eruption has caused huge worry for all those whose livelihoods and studies are centred in the waters off La Restinga.
The good news is that the volcanic activity has increased the fertility of the habitats by introducing beneficial nutrients, so encouraging the growth of algae, plants and micro-organisms. This of course will provide food for animals. So once the emissions stop the area will return back to a thriving marine community in a relatively short period of time.
The use of air guns in the area has been minimal. Maybe some fish will have impaired hearing and so be more at risk of becoming prey and maybe less healthy if noise is the primary sense used in hunting.
However I am of the opinion that most fish will be avoiding the area affected by the emissions anyway. This will be because of chemical and gaseous changes in the water. Any animals that can move away will have done so and have set up new territories or feeding grounds away from the polluted area. As the air guns were being used for only a short time over the polluted area then it is probable that it has caused very little detrimental effect, if any at all.

McCauley RD, Fewtrell J, Popper AN (2003). High-intensity anthropogenic sound damages fish ears.

http://www.wsdot.wa.gov/NR/rdonlyres/0B027B4A-F9FF-4C88-8DE0-39B165E4CD94/61426/BA_HumanSoundonFish.pdf

Journal of the Acoustical Society of America 113,

Popper AN, Fewtrell J, Smith ME, McCauley RD (2004). Anthropogenic sound: effects on the behavior andphysiology of fishes. Marine Technology Society
Journal 37 Song J, Mann DA, Cot, PA, Hanna BW, Popper AN (2008). The inner ears of northern Canadian freshwaterfishes following exposure to seismic air gun sounds.
Journal of the Acoustical Society of America 124,

http://www.wsdot.wa.gov/NR/rdonlyres/0B027B4A-F9FF-4C88-8DE0-39B165E4CD94/61426/BA_HumanSoundonFish.pdf

In these Blog Posts I am keeping the contents as non-technical and jargon free as possible. For most people biology study ended after high school so I am aiming to provide an article that is easy to understand and informative for everyone and one which will encourage the reader to question and seek more information. I am also aiming to demonstrate how the different sciences do not stand in isolation. Each science is interwoven and affects another……… The human lifespan is frustrating as it is far to short to get to grips with the vastness of knowledge.

Diana Barnes

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150 thoughts on “The effects of Seismic Air Guns on Marine Animals.

  1. Nice article Diana, well-written English which is always pleasurable to read and very informative! One question: You say that there is a concern that the use of air guns may damage the hearing of whales to the point where they accidentally beach, but hasn’t this always been the case, long before humans started to pollute the seas with their sonics?

    • Difference being that there is very few things that create that loud noises in nature…
      Only thing that I can come up with is actually Krakatoa and a couple of other very noisy eruptions.
      210dB is a lot, and since water is a better sound carrier it would most likely ruin the hearing of whales quite far away.

  2. For those who have not given up on Hekla just quite yet.
    There was a 0.6M 14.6 kilometers SSE of Hekla at 10.28.24. The quake is not reported due to the bad depth locationing.
    However, that quake happened not at Hekla, instead it was at Vatnafjöll.

    • Time-wise, that is close to the 10:28:14 mag 1.8 at Torfajökull (7.1 km NNE of Álftavatn), ten seconds. Could it have been a ghost?

  3. Thank you Diana! I have read some short articles on general news sites about the effect of noise on marine animals but this is much more in depth (no pun intended!) :-D

  4. couple of typos

    a minor one,
    fishhh (Sebastes sp.) catch
    should say
    fish (Sebastes sp.) caught

    and a fun one
    Marine mammals also have internal ears that are designed to pick up love density sound waves (infra sound)
    should I think say ‘low density’ but love density sounds more interesting, and I’m surprised Geoloco has made no comment :)

  5. Thanks Diana, well written and very informative, it is mostly used for trying to find oil/gas all over the planet, one can only hope they use it sparingly

  6. Has there been a study of the number of beachings in the 1940 to 1945 timeframe? 1950’s Pacific? (War at Sea and Nuke Tests)

    • Know USN Consolidated PBY-5A Catalinas likely did sink some “whales” with depth charges (instead of German U-boats) in the North-Atlantic 1942-45, likewise RAF Coastal Command did so too. *caution : WW2 is huge subject*

      • Indeed. And very controversial as with all instances when humans have exceeded the standards of behaviour agreed upon by the social contract or when a nation wants to paint a different picture of its history for present-day political reasons. From long experience I know that even if a discussion starts off with the intention of keeping to the facts, it is not long before you have the first “Yes, but…” that signals the outbreak of a verbal WW III.

  7. http://www.esa.int – Today, 3:33 PM

    ESA – Observing the Earth – Nea Kameni volcano movement captured by Envisat


    Archived data from the Envisat satellite show that the volcanic island of Santorini has recently displayed signs of unrest. Even after the end of its mission, Envisat information continues to be exploited for the long-term monitoring of volcanoes.”

    (…)

  8. Diana, thanks for a piece on this topic that lacks the usual anguished environmental alarmism and presents more of the science detail in it than the typical article in the popular press/blog.

    Do you have more information on seismic surveys under ice, and specifically the photo captioned “Effects of a seismic air gun from a German research ship”? What are the effects? The photo implies massive and immediate fracturing of the ice. I have a hard time believing that amount of fracturing and open leads (in non windy conditions) would be caused in what must be just minutes by the evenly distributed energy of the seismic survey pulses rather than by the shear forces exerted directly on the ice by the ship.

    • Excuse me, but what does “apenas nuvens” mean? I don’t even know what language it is in :(

  9. “The peak source level of a seismic air gun array can exceed 250 dB re 1 μPa”

    While 250 dB is highly impressive, it’s “re 1 μPa” (reference one micropascal), which is less than the commonly used dB SPL (threshold of human perception) at 0.02 mPA (millipascal) or 20 μPa, which means that the “250 dB re 1 μPa” corresponds to 237 dB SPL.

    Second, we do not know the distance from the source at which it was measured. Usually, this is at 1 meter, but if this was measured at a significantly shorter distance, say 1 cm, it drops by a factor of ten thousand (= 40 dB) to 197 dB SPL. Since we have a figure of “195 dB re 1 µPa at 109 m”, i.e. 182 dB SPL at 109 m or 223 dB SPL at 1m from the “Wardle et. al.” study, we find that the first figure most likely is at a distance much less than 1 meter.

    Third, even if water carries sound well, doesn’t the Law of the Inverse Square still apply? If we use the figure from the Wardle et al study, 195 dB re 1 µPa at 109 m or 223 dB at 1 meter, the distance from the air gun blast at which it drops below the critical 130 dB SPL that causes instant aural damage in humans provided it is continuous turns out to be 44.6 km.

    There is one final aspect, the length of the pulse and its frequency. Is it continuous or is it in short bursts, each but a fraction of a second long? Bursts lasting a few milliseconds are far less damaging. To judge from the responses of the fish reported in the Wardle study, it seems highly likely that it is a question of millisecond bursts, but at what frequencies?

    The salient question is how close would a whale or fish have to be experience a) discomfort, b) behaviour-affecting discomfort, and c) aural damage?

    • Dunno, but randomly firing the shipboard sonar while in port works as a deterrent against swimmer attack.

      The old SQS-26 AXR can be lethal if you are too close and in the water.

    • Hello Henrik, the text clearly stated that the measuring distance was 16 meters and that it was 210 dB(A).
      Normal measuring distance is 1 (Europe) or 1.2 (Americas) meters from the center-point of emitting source.

  10. Diana, Thank you for an interesting article. I was not aware of the impact of seismic air guns on marine life – but it makes sense when you think about it.

  11. Great job, Diana. The video of the pistol shrimp is amazing. Never saw one before. Anytime we humans alter an animals environment, there are effects. Unfortunately, It will probably be many years before we know if these seismic air guns cause temporary or permanent effects.

    • Permanent? Nothing is permanent, other than extinction. When that happens another species had a new niche to fill and then merrily takes up the task of doing so.

      Isolated from Australia, the Thylacine became the de-facto “dog like creature that Dingo
      occupies in Australia. And the Dingo mave have supplanted the Thylacine when humans first arrived in Australia several tens of thousands of years ago.

      In Africa, the Hyena occupies a similar role… though it is a cat.(Feliformia) The African Wild Dog. Lycaon pictus, (African Wild Dog) and the Jackal are the only true dog family members in Africa as far as I know.

    • Oops… missed the Ethiopian wolf. Though it looks more like an oversized fox, it’s a wolf.

      Occasionally separated species will develop similar beneficial traits though they are separated populations (and sometimes species)

      • Common, Side-stripped and Black-Backed Jackals and the Semien Fox (also called the Abyssinian (or Ethiopian) Wolf: Canis Simensis) are all Canis (dogs). Then the foxes – Red, Ruppell’s, Sand or Pale and Cape. Then there’s the Fennec, Bat-Eared Fox and Wild (or Hunting) Dog which are all dog-like. The Hunting Dogs are the only ones that behave like Wolves and hunt in packs. Hyaenas are not dogs or cats (their claws are not retractable) and there’s also the Aardwolf, which is like a small hyaena. There are ten true cats and loads of things like Genets and Civets that look like cats but are not. :-D

      • Geo, I wasn’t meaning something so far reaching! I was thinking of something like a permanent lower hearing ability or complete loss of hearing. Or maybe damage to some inner sonar abilities. Gotta love your responses, tho! :)

      • Thanks Diana for a very interesting post – I especially liked the pool shrimp video.
        @ Geo – I never knew that the African hyena was a cat! Having googled it, I found that Hyenas belong to the Hyaenidae family (suborder feliforms) – I still think it looks more like a dog though!

        • I had always found Hyenas to be the creepiest behaving dog I had ever heard of. When I found out that it’s form of cat it made sense. (from observing Marlin Perkins sending Steve into peril while he watches safely from the blind)

          On the odd convergence line of thinking… Cheetahs have a gait and muscle structure more doglike than cats, though they are cats. They just took it to the extreme with the high speed endurance. They also lack a sheath for their claws (which are only semi-retractable)

          • ahh,so what it all boils down to is…. the retractable claws, a bit like the tomato being a fruit not a vegatable in biological terms…there are a set of rules for everything, but sometimes nature manages to overlap leaving us with a greyish area…why do we have to put everything in boxes?

          • Hyaenas are feared across Africa for being weird. They have the spookiest call – not a laugh at all – a sort of rising whoop. The real ones have a fearsome bite, they can crush a skull in a single bite. In folk stories were-hyaenas are ridden by witches and some witches can turn into hyenas. They often live close to urban areas and I used to hear them at night, even the baby ones are ugly. We once came across an adult fast asleep when on a walking safari in the North Luangwa Valley – we thought it was dead at first and went up really close to look at it, but it suddenly woke up and I don’t know who was more scared: us or the hyena! :-D

          • DebbieZ says:
            …why do we have to put everything in boxes?

            Ooh, an easy one.

            Survival

            As the worlds most skilled species at adaptation (we make a “tool” to over come the difficulty) we have an enhanced ability to look for patterns. Being able to recognize patterns and scenarios allow us to quickly take up a pre-determined tactic to deal with whatever it is. It biases our response. (run like hell or poke at it / hit it)

            THAT is why why group everything. On the downside, sometime our categorization behavior is in error and we have mistakes. It’s all about building stereotypes so that we know how to interact with whatever it is.

            Where stereotypes come into disfavor, is when they cross social bounds that are dictated to us by someone else. When they are “bad” they are generally in conflict with cultural groupings.

            (Folkways, Mores, Laws)

            On the geological scale, this pattern recognition aspect of being human usually shows up in seeing patterns in quakes that are not necessarily there.

          • @GeoLurking and DebbieZ: We Westerners tend to think our classifications are the only ones that work (like cats and their claws). In Malawi animals are classed as edible or non-edible – this makes much more sense if you think about it. A friend of mine is a anthropolgist specialising in botany and its uses. He quickly realised that it was no use asking traditional healers what they called a plant by showing them the leaves and flowers: they recognised plant types by their roots. Also sensible if that is the part that is used to make medicine. They also see patterns, but they are culturally different from our westernised ones.

          • In protein poor forested Cameroon it was ALL classed as edible or “beef”. Monkeys, birds, you name it — it all went in to the pot. The non-arboreal edibles were of course “ground beef”.

          • Hyenas, BTW, go beyond creepy to downright dangerous when hungry and in numbers. They will band together and cooperate in packs as wolves and hunting dogs do. People were killed in broad daylight by hungry packs of hyena near our urban-outskirts school. I personally had a very very near thing of that sort–though not in daylight.

          • Hi mnsteve! Are you from Cameroon too? I was brought up there in the 1950’s – lived at Bota (the port for Victoria which is now called Limbe) and at Tiko – the up-river harbour. My father was Harbour Master. My memories are all very hazy but I loved it. We moved to Malawi when I was a teenager and then I flitted back and forth between UK and Malawi for a few years. Then lived in Malawi (at another place called Limbe!) until mid 1990’s when I came to live in UK.

          • if one takes away the outer of an animals/human/insect etc. body they are all very similar, I saw a fly under a microscope and it looks ‘human’ eyes, head,skeleton,arms legs, so I think some Aliens put some DNA on the planet and are watching to see what happens under what circumstances, a bit of an experiment in lab kind of thingy and sometimes things go haywire if you look at some of the unusual things around the world

          • @Talla, Hi! Your posts make me nostalgic for a different continent than my current one . I grew up in East Africa but had a best friend from Cameroon near Ebolowa. I spent a month with his family and did a trip via Bamenda, Bafut and Victoria where of course we climbed the local volcano. Also hiked to a crater lake not too far from Lake Nyos. I have great memories of Cameroon though Douala remains in my mind the absolute epitome of how-the-heck-do-people-live-here hot and humid.

          • @mnsteve: What a wonderful holiday to have. We used to visit friends at Bamenda. I was too small to climb the mountain – but it was the first thing I looked for when I got up in the morning! I love heat and humidity – it’s cold that wilts me! :-D

  12. Anyone got any thoughts about a possible link between the seismic activity in Northern Italy and a similar high activity focus in Bulgaria, just north-east of Greece? Which way is which plate moving?

    http://www.emsc-csem.org/#2

        • The Adriatic Plate is a microplate that is believed to have broken off the African Plate.

          • I wouldn’t be surprised by a large quake in Greece or southwest of Portugal, in the next months. The movements in the Mediterranean have been active, Italian earthquakes, Bulgarian earthquake, a Spanish earthquake last year, Santorini is restless, I supposed that only a few regions over the plate boundary need adjustement, those being Greece and southwest Portugal (Turkey already had a large quake in recent years).

            Yes tell me these things are not connected but I don’t believe it. Its a plate boundary, naturally the whole place is under stress, and often when a large earthquake occurs in one area, other areas nearby tend to suffer also large earthquakes in times following.

            This might be within the next years.

            Its like Iceland, stress hasn’t been released recently in some places like the dead zone, east of Hekla, north of Vatnajokull, north of Askja, Thingvellir area, Kverfjjoll…

  13. Interesting article Diana. I saw a story on BBC website about how whales may be able to adjust their hearing in anticipation of a loud noise. Maybe it is necessary to develop a universally accepted warning sound prior to the use of air guns !

    http://www.bbc.co.uk/nature/18085158

  14. I am SO angry. Damn it!!! My whole dang post got eaten and I wasn’t even done with it. I’m about to give up any comments at all. W.T.F.

        • Thanks. By the time I get back around to re-do my comment, I forgot my point. I know it was about the man-made racket in the oceans. Oh, I referred to the U.S. Federal Register and Alaskan Apaches taking marine mammals by harassment (noise). Here’s the summary:
          In accordance with the Marine Mammal Protection Act (MMPA) regulations, notification is hereby given that NMFS has issued an Incidental Harassment Authorization (IHA) to the Apache Alaska Corporation (Apache) to take marine mammals, by harassment, incidental to a proposed 3D seismic survey in Cook Inlet, Alaska, between April 2012 and April 2013.
          Here is the title: Takes of Marine Mammals Incidental to Specified Activities; Taking Marine Mammals Incidental to Seismic Survey in Cook Inlet, AK. And finally, here’s the link: https://www.federalregister.gov/articles/2012/05/11/2012-11296/takes-of-marine-mammals-incidental-to-specified-activities-taking-marine-mammals-incidental-to#p-3 OK, the above info is what I was griping about disappearing from my realm earlier.

          • Umm… they gathered them up then did the survey? Or did they take them and keep them?

            Inquiring fur traders want to know.

      • No, Lurking, it did not make it to the server. i checked an hour after Brenda grumbled she lost it, there were just quite a bunch of spam comments, Brenda probably lost her link or had other computer problems. If it was a problem with wordpress, please let us know Brenda.

        • It was probably just my stupidity. I would certainly let you know if it were a wordpress item. Thanks!

  15. Many thanks for all your comments.As usual here, the post raises more questions rather than supplying answers.
    The geophysicists can have a field day with the complexities of air gun functions. The problems of bubble power and ghosting are bad enough in water in temperate and warmer latitudes, Sea ice evidently, is most difficult to survey beneath because Ice is very noisy stuff..Whales and fish manage to cope with this natural noise better than our scientific equipment :D
    Wales and Porpoises have always “beached” . Nobody fully understands why. Some beachings in modern times have had possible links with military/Naval weapons exercises.
    Industrial Survey findings must also be carefully evaluated as the need to find fossil fuels becomes more desperate!
    @ Edward lane…..I apologise for any spelling mistakes (A reminder that in using English English “S” is used instead of “Z” in apologise :D ) and grammatical errors…..I blame this on lack of caffeine or dyslexic fingers. As for Love density sounds …We won’t go there! I have only had coffee #1 and as you noted GeoLoco already has quite enough ammunition without encouraging and more. :D:D:D
    My thanks to the VolcanoCafe team for editing and supplying additional visuals and my congratulations to the commentors and readers who are fast becoming biologically inclined Vulcanologists :)

      • Thanks Diana for that post, and it was Carl who added the images. And me who missed the typos. :oops:
        @All. Diana sent the post to me and i saved it as a draft here, so Carl would have a quick post ready in times of need, when he is ultrabusy. One more draft is waiting to be released on such an occasion, by our very own schteve.
        But Carls schedule will be full for quite some more time. So we need more drafts. A continuation of the Eyjafjalla ash will follow…. But i am asking you. Who wants to write an article? Maybe Ukviggen .. on another Kamchatka Volcano… Kizimen is smoking almost every day lately http://www.emsd.ru/video/
        Or would one of the islander write something about their favorite Islandic volcano.. or maybe introduce many of them, like Irpsit did in comments… You get the idea, we need stuff to feed the blog.
        Say you would like to join the fun, ill contact you via email, and…..

        • Hello Spica – I’m still here but I am in the middle of a silly season. Have hardly spent more than three nights in a row in my own country, let alone at home, and that continues for a few more weeks. As soon as I get the chance I will ‘do’ Shiveluch – oodles of material gathered already, just waiting for me…

        • Hello Spica!
          I have quite a few in my mailbox, but my days have been so long that I have not had even the time to put them in.
          Could I send them to you and you edit them in?

  16. Hey guys. What up with katla? Take a look at the sil stations around there.

  17. To judge by the tremor charts, there is something going on in the area north of Katla, most likely Torfajökull. It shows up best at Slysaalda north of Katla which is the closest SIL to Torfajökull, but also from Jökulsa north of Eyjafjallajökull via Godabunga and Austmannsbunga to Rjupnafell ESE of Katla, Mjoaskard (Vatnafell SSE Hekla) and Vatnsfell in the Dead Zone. From this, I’d say that there’s something going on at Torfajökull that might possibly be an intrusion.

    For the others, just type their designation in the place of sly or mjo – jok, god, aus, rju, vat – and hit enter.

    • A bit of sleuthing reveals that intrusions are not uncommon at Torfajökull but also that there is little cause for alarm even if the Veidivatn fissures does start just NE of Torfajökull and run all the way to Bardarbunga.

      In their 2002 study of the Hekla and Torfajökull magma systems using S-wave retardation of earthquakes as a sort of volcano tomography, Heidi Soosalo & Pall Einarsson found evidence of a very large but mostly solidified body of magma – i.e. non-eruptive and due to its size most likely past the stage where it can be remobilised unless there is a really huge influx (we’re talking about a volume of solidified magma on the order of 25 – 30 cubic cilometers here) – centered at a depth of 8 km under the western part of the caldera measuring 4 km in diameter, the largest body identified so far in Iceland. They found no evidence of any body of magma under the southern part of the caldera, the most likely area for an active body due to the intense geothermal activity there. However, the method used cannot identify bodies of magma smaller than 800 m in diameter so if if there is one or more active bodies there, they must be small, thus there is no risk of a “Torfatubo”, at least in the near geologic future.

      https://notendur.hi.is/heidi/Data/Article-richard/SoosaluEinarsson04.pdf

      • I noticed (and agree on) this seemingly originating from that general area, but (as always) it has catch in my mind, of high winds in same period (can there be “frequency shift” involved due wind noise affecting ground tremour and therefore show in 1-2 Hz band?)

        • I’m not an expert, but not only does very strong winds seem to affect the whole tremor spectrum; red, green and blue, the rise in tremor also never is instantaneous which is what makes me think it may be magmatic movement in this case. Of course there are other possibilities such as a rockslide similar to but smaller than the 1967 Steinholtsjökull landslide north of Eyjafjallajökull, a large hydrothermal event at the southern end of Torfajökull caldera or even a glacier calving.

          • I have seen many patterns of wind or storm noise, possibly there is both some “ground noise” from Torfajökull area (maybe partly hydrothermal ?) and possibly also suspected increase in meltwater in the “north-tongues” of Myrdalsjökull glacier. Anyways the “green” signal is clearest (strongest) at sly. Only when wind dies down and this continiues we can ruleout wind. http://hraun.vedur.is/ja/oroi/sly.gif

          • But could wind produce the pattern of sharp peaks as if there had been series of small earthquakes? In my opinion it is quite clear that what we see at Slysaalda and other SIL-stations is not caused by wind. Furthermore if it were wind-related, it would be spread over a much larger area – if you look at the webcams, the weather seems to have been much worse south of Myrdalsjökull all day and the phenomenon isn’t visible on the SIL-stations there as if it was blocked out by Myrdalsjökull.

          • Ah, I was more thinking to (Green band wave spikes) transmitted with the winds to mjo (carried over from Torfajökull / Vatnafjoll / sly area), more than created by them.

  18. Update 23/05 – 07:15 UTC : aftershocks
    – Even after the headlines disappear all over the world, the earthquake misery goes on for the Ferrara area people. We are still noticing a huge number of aftershocks. A lot of them can be felt by the people and are giving them a really bad feeling. Since midnight we have recorded 12 aftershocks above M2.0. 2 of them a 2.9 and a 3.6 will certainly have been felt in the epicenter area.

    ——————————————————————————–

    Update 18:45 UTC :
    – PM Monti traveled to the Earthquake area today. He said that he wanted to see the damage with his own eyes.
    – The Italian government has declared the State of Emergency in the earthquake region. Calling the State of Emergency was needed to allow financial support from Rome.
    – PM Monti has also said that no taxes have to be paid this year as all money will be needed for the reconstruction.
    – The Prime Minister was confident that the damaged Industry and trade would recover very fast from this disaster

    http://earthquake-report.com/2012/05/20/very-strong-shallow-earthquake-kills-at-least-3-people-in-the-mantua-ferrara-and-modena-area-italy/

    • I love it when Prime Ministers or Presidents are “confident.”

      That means they don’t know and it scares the crap out of them.

  19. Hi

    thanks for this interesting article Diana. I also particularly like the (now famous) pistol shrimp !

    Here is an article on the El Hierro eruption dating from april 2012 and published by ULPGC.

    http://www.gi.ulpgc.es/geovol/El%20Hierro/Carracedo%20et%20al-Erupcion%20El%20Hierro-Geology%20Today-2012.pdf

    Thanks to todogeologia forum for giving the link.

    The article sums quite accurately the different events of the eruption and points out the very bad management of the crisis by the authorities (small wonder). It points also out the retention of information from some (guess who ?) scientists.

    • But was the management of the crisis very bad? Don’t forget that most of the activity prior to the eruption occurred to the north of the actual eruption site, and it was feasible that it could have occurred on land.

      Certainly there are lessons to be learned: one of which is the relationship between the crisis management team, the scientists and the politicians; and, the other is PR. The economy suffered short term but compensation has been paid and El Hierro is now on the map.

      If I lived on El Hierro, personally, I would be grateful that the civil protection measures taken were more disruptive than the volcano; I would not want the volcano, itself, to be more disruptive.

      • Hi KarenZ, I totally agree with you. After all the “excitement” of the Bob erruption vent taking the pressure off, I had almost forgotten that the earthquakes on El Hierro had presented a very real threat of landslides on the island that could have really threatened the human population…so maybe it is a bit too easy to criticise. I am 100% sure that the crisis team always acted in the best interests of the people of El Hierro…. I think it is the PR machine and politicians that could do with learning at bit more from this experience.

      • Sorry to disagree but I do think the management of the crisis was terrible. The Pr and political people did a really very bad job and did not react quick enough even when there was some scientific data to exploit. They were not enough reactive at the beginning and only achieved to scare people and tourist and to ruin the local economy. And they did not communicate clearly and hid information from the international scientific community. Do remember that this blog among other had to be remarked by its traffic fogures to gain some attention. Do remember also the reaction of certain official (N in particular) to the goodwilling presentation of results and graphs).
        personnaly I think the reaction of the scientific guy is appropriate as much data has been lost on this unique occasion.

        • The fact that I ommitted to mention the scientific people or Mr N in my reply above was entirely intentional …because words just fail me!

          • Mr N did take his holiday on Hierro so at least he put something into the local economy.

        • I am not getting involved in the politics but some of the criticism is harsh bearing in mind that it is very easy to be wise after the event. Overly harsh criticism may prevent lessons from being learned as it puts people on the defensive – lessons which may save lives in the future.

          • True, too harsh criticism is not productive, but we have to keep in mind that Bob happened on el Hierro, the question I am asking myself is: What if the Teide started rumbling? Tenerife is much more populated and the crisis management would be more complicated, if there were coordination problems in el Hierro, what would happen in an island with almost one million people living on it? and with a volcano with more explosive potential?

          • Teide, one of the two volcanoes on Tenerife, has been designated a decade volcano by the United Nations Committee for Disaster Mitigation so has a much higher profile. Tenerife also has a much higher profile, especially in terms of tourism.

            It is important that the right lessons are learned from El Hierro and that lives are not seen (“seen” in bold) to be put at risk to protect tourism.

          • KarenZ says:
            May 23, 2012 at 18:53

            “… Overly harsh criticism may prevent lessons from being learned as it puts people on the defensive…”

            True, but my criticism is only directed at pure idiocy (one guy) and a separate guy with what seems to me to be a self aggrandizing personality issue.

            As for the idiot, his own statements and positions are what roasted the chestnuts of his competency. But, being a politician what do you expect.

            As for Nemisio, I’m pretty sure he is quite competent in his field. His department may have issues with other Geologists, but thats not my problem. He wanted the plots pulled because he felt that it would adversely affect future research, I complied. No biggie for me. He has more shit to worry about that some person spitting out plots for the intellectual entertainment of it. I don’t have an issue with that.

          • Well at least this crisis was useful in pointing out that the emergency structure put in place by the authorities is not working as it should. From the point of vue of someone who followed the crisis since the beginning of October (ante tremor), there seems to be too many structures involved, each structure trying to find its place in a context of economic crisis. This surely did not help. Also there seems to have been a lot of rivalry between the different public structures instead of cooperation. Remember that a lot of data was not released even when it was available (bathymetries and the like).
            From my point of vue there were way too much political involvment in the whole thing.

          • Excuse me, but did Nemisio actually demand that plots you had made be withdrawn because they adversely affected the funding of the work of AVCAN? The only two reasons for such a demand I can think of are a) the employees of AVCAN are unable to do so themselves and funding might be withdrawn as a consequence once it was discovered, or b) as head of AVCAN he had been informed that if his office did anything that scared the tourists, funding would be terminated. If it’s the latter, I really do feel sorry for the poor wight.

    • It is interesting to see from the article that there was evidence of relatively recent submarine activity from research done in 1998 and 2001, especially as not much EQ activty has been recorded in the area prior to July 2011.

      And, anyone know what the status of the doming is?

      • Evenin’ All,
        “the status of the doming” That is the million dollar question… The last video that was released appeared to omit the depth reading just as it was getting interesting… (sorry I don’t have the link, but Earthquake-report.com had the video posted.)
        To be fair, the civil protection measures did work; in that nobody was hurt (except for one person doing gas measurements, if I remember correctly.) However, Carracedo most likely has some knowledge of “behind the scenes” events, and I would not be at all surprised if he was one of the scientists whose offers of assistance were turned down… Just my two cents worth :)

        • The doming in Carracedo’s paper appeared to be near Orchilla (may be Tanganasoga or somewhere nearby – it was not clear).

          • Whoops!!!
            goes back to re- look at the article again :) In the diagram, I think that although only one of the blue arrows is labelled “doming”, it refers to all three blue arrows… I may be wrong.
            I sure would like to see that diagram (Fig 2) in glorious 3Dotronic Lurking vision :D

          • So would I, especially if GeoLurking can get the whole sequence from 01/01/2011 (from memory fo one of Prof Sagiya’s plot for AVCAN, there was inflation before July 2011).

  20. A deep quake near Langjokull.

    Wednesday
    23.05.2012 13:16:03 64.589 -20.675 7.8 km 1.4 87.27 15.2 km SE of Húsafell

    • Once it was checked by a seismologist (you can see that because the initial grey outline of the coloured dot has changed to black and the “quality” is given as 99.0), the depth was adjusted to 11.6 km which is still deep relatively speaking but so high that most likely it is tectonic in nature.

          • Downgraded to 6.0 but still a quake strong enough to have the potential to do material damage had it occurred in an underdeveloped HRR part of the world with poorly constructed buildings such as the boondocks of Afghanistan, the interior of Algeria or Italy.

          • Don’t forget villages like Horred (Honest Whore), Dingle (Dangling), Mensträsk (Menstruation Swamp), Kräkångersnoret (Vomit Regret Snot) and Köttsjön (Meat Lake) in Sweden. I doubt the old houses would fare well with a quake of that magnitude.

          • My father told me that when he went through Medical College in the 1950s, it was the “done thing” to change one’s surname if it was a plebeijan -son as in Andersson or Gustafsson. Two of his classmates went through that process and only in the nick of time realised how close they had come to utter disaster:

            Dr Brunstig (Brownpath or alternately “In heat”)
            Dr Horsäng (“Meadow of Hor”, alternately “Hooker’s Bed”)

            Alas, there was no reprieve for the poor GP of Årjäng who in the 1930s, long before the Swedish “Curious-yellow” movies, had changed his name to Porrvik but regrettably opted for the alternate and more ancient-seeming spelling of Porrvig. Thus Dr “Pornographically Acrobatic” had to endure a career of ridicule and glee.

          • …continuation on Henrik…
            This is a tradition nowadays taken up by swedish police officers. Often to hilarious effect. The worst I have heard is Komissarie Fjuke. Translated that would be Lieutenant Small Vomit… (Fjuk = Small Vomit, also; weak-stomached, faint of heart, cowardice)
            However you turn it, it is not a name that behoves somebody with a gun…

    • Didn’t know that the Moon has a decidedly green tint to it over South America as shown on the Tungurahua webcam. It’s more of a Peridot green, yellowish green, than an Emerald green.

      • Did you get a screen shot? When I looked (time of posting above), it was still daylight.

        The green tint may be from volcanic ash. After Eyjafjallajokull, we had slightly greener skies here in London for a few days. Must have been spectacular further north.

        • No, no “screenie”. It was just an artefact of the lltv camera and me being facetious.

          (“Few things are more distressing to a well-regulated mind than seeing a boy, who ought know better, disporting himself at improper moments.”)

  21. Hi Spica, in the next few days I will be full of work or busy doing something almost entire day, including weekend. But next week I should be a bit more relaxed to write something about some less known Icelandic volcano. I was thinking Langjokull volcanoes, Bardarbunga or Oraefajokull, or Torfajokull or even the obscure Grimsnes, which is right around me. One of these.

    I will write to Carl, and he will forward to you..

    • *correction 7,500 units, but is largest “Hekla” drop for weeks. Other strain meters shows no real change.

    • *now about 10,000 units (from 22:40 UTC) Other strain meters shows no real change.

    • I was beginning to wonder how much further Hekla strain could go up without any drop – even with this small drop the strain must still be very high?

    • So far we heard very little about the Offshore Sumatran earthquakes. I was expecting more from two strong earthquakes which were, by then, considered somehow “anomalous”,,,

      • These quakes are south of Tasmania. As far as I know there is still a lot of activity off Sumatra but have not updated any plots.

        • Since they also involved the Australian plate, I thought they could be somehow linked… :)

    • A 3.8. I’m sorry Tyler, but I cannot see what you find “Interesting….” enough to call our attention to it? That there are earthquakes about 120 km WSW of Hawaii? That it is registered as being at a depth of 23.3 km when the maximum crustal thickness of Hawaii beneath Kilauea is given as 13 – 14 km ( http://bssa.geoscienceworld.org/content/80/3/675.abstract ) which means that it took place in the Moho? Is it that the uncertainty of depth at +/- 4.8 km is greater than the horizontal uncertainty of +/- 1.6 km?

      • Hello Henrik!

        Here is something for you, general rules of hydrostatics forbid the MOHO to be at that depth under Hawaii. Why is that now?
        Well, Hawaii is the highest mountain on the planet counted from the sea-floor. And a rule of thumb is that a mountain range pushes the crust to a minimum of twice the depth of the mountains height.
        If we take that into account we do not even have to look for any odd microplate that has sunk to explain that quake, it is just a normal crustal quake.

        • Why do I all of a sudden get a sudden notion of becoming a bearded greek running naked from the bath down the streets shouting evereka? :mrgreen:

        • I’m missing something here. Would you explain that rule of thumb. Twice the depth of the mountain’s height would put it underwater if datum is MSL. Also, oceanic crust vs continental vs rule of thumb?

          • I will one of these days write a post about hydrostatic effect on crust…

        • And add to that a hotspot to confuse things and possibly upset rules of thumbs. Be that as it may, can’t help if that paper says that they’ve found evidence that the crust is only 13-14 km below Kilauea against the rule-of-thumb implied 2 x 9.5 km. Counting from the summit or seafloor? If the former, rot gives a MOHO-depth relative zero or sea-level of 14½ km, if the latter 23.5 km.

          Anyhoo, that quake was far enough away from Hawaii to be only marginally affected by rot if at all.
          :)

  22. Good morning/evening from a warm Northern UK. yesterday was HOT! Wall to wall sunshine….. and yes! My fridge has packed in. Kaput!
    Yesterday also i was working with a program that sent me doolally! You know the sort of thing… You wish to make an important upload. It doesn’t work! Look up trouble shooting it say go to “B ” and so you do . At “B” it says information can be found at “A”…You hopefully go back to “A” (Where you had the problem in the first place) where it tells you to go to “B”…..Ad Nauseum. :cry:
    I missed a whole day of Volcanocafe. My temper was failing.
    This morning with milk going as sour as my mood I find local Pussy cats got into my veg beds and have scratched up my seed bed as, presumably, it i was better than their Cat litter.
    Today, said Pussy cats will get hot pepper powder up their backsides if they get into the veg beds again. Beds have been liberally dosed with Chilli Powder and white pepper. and I have been stimulated to make chilli con carne this evening.t!!!
    I need some good Icelandic Volcano watching to soothe my savage breast

    • Good morning! What you need is a Perfect Remedy – ½ home-made lemonade, ½ of what the French, curse them, implacably refuse to recognise as champagne because it isn’t made in France, hence reasonably priced unlike the highway robbery of the “real” product, topped by large strawberry and possibly a sprig of mint. Once the fridge is fixed, make yourself one with a bit of ice to keep it chilled and sit back to enjoy it in the sunshine accompanied by the sneezing of the outraged local feline population.

      • I would go for a gin and tonic, and to that a side-order of a trebouchet for the felinistic pests.

      • Running the risk of being called a chauvinist I would say that if Champagne is so expensive there must be a reason.
        There are plenty of other bubbly wines in France (Clairette de Dié, Crémant d’alsace and the like).
        Do not confuse caviar with lumps eggs! Foie gras is not liver paté ! Cava is pretty good of course but it is far from the mark and cannot compete with a true Champagne. My word on it ! :grin:

        • Ever try the Russian or Czech (Bohemian) varieties? While Champagne is nice, it’s a million miles from what the price tag suggests, in my estimation.

          • Do not get me started on Armenian Cognac… It is better than the modern “original” from France. The Armenian variant is only a thousand years older, but it is still deemed as being non-original. Hum… :)

      • <<<<< Smiles sweetly :D
        9.10 am saw me in the local electrical appliance shop… 10.50 saw my new larder fridge in place complete with door opening changed and old fridge removed…..and all for less than any other comparative service on line. My mood is lightening… last week the microwave , this week the fridge…. I am talking gently to the washing machine etc…..They say things happen in 3s!!! @Henri…..note taken and will do :D @ Carl I find super soaker water guns quite effective and can easily be stored in the greenhouse :D
        @Sissel..I love my wildlife.. even the marauding squirrels. I love dogs and all small furry things… Cats love me…..they wrap themselves round me…..They darn well KNOW I am seriously allergic to their fur and so they take revenge :D

        • @ Diana: Cats are weird like that – they always go for the people that are allergic or frightened of them. We once had a cat who hated people so very few knew we even owned one – then one evening the cat marched into a room full of people we had round for dinner and straight toward one poor girl who was seriously phobic about cats! I had to scoop up the cat and lock her in a bedroom (which is where she normally hid when people were around) to stop her stalking the girl – who was terrified!

          • sounds about right. Cats have amazing character and manipulate humans without most realising!

        • Diana, cats do not take revenge. Human brains are the masters in in this – as in all kinds of cruelty. Cats have more important / intelligent things to do. And they may love you, but not because they want to tease you!

          When I lived in Norway I felt sick about all the Norwegians who demanded the killing of wild animals because they were a threat to their domestic animals (mostly sheep). A few people found that the owners should do something to protect their animals (like having a shepherd in the mountains who accompanied the flock of sheep), but no, the sheep owners always won and the wildlife was killed. Bears, wolves, lynxes and eagles were of course “bad” animals (primary school knowledge) and it was a good thing to kill them. They had no rights.

          My points are:
          1) Animals, wild or domesticated, are not “good” or “bad”.
          2) If you do not want to be visited by special kinds of animals, put some effort in protecting yourself, with all respect for and without hurting the animal in question.
          A good fence often gives a good protection.

          • Good points, Sissel! Alas, there are 7,000,000,000 individuals of Homo Sapiens, each of whom has greater “rights” than even the most endangered of species. When wildlife endangers our habitat, we cull or demand culling. When humans endanger wildlife habitats we send aid in various shapes such as cultural aid to ethnic minority groups (Lapplanders who keep reindeer) or medical aid and food to those who have overexpoited their habitat so they can continue to displace wildlife. Go figure… ;)

        • @Sissel: As Diana states she loves wildlife, even squirrels! Her problem is with domestic cats. Obviously it’s not the cats’ fault that humans have introduced them into Europe and bred far too many of them but I know from personal experience how difficult it is to keep them away from a garden. I do have high fences but the cats scale them with ease. Luckily I have a dog who chases them out but this option is not open to everyone.
          I totally agree that wildlife should be given far more protection worldwide than it is now. :-)

  23. Carl… VC Mail. Sort of time sensitive in that it covers current ongoing events. Edit or elaborate as needed.

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