Eruptions at Tongariro & Whaakari (White Island) and 1 million viewers!

Image by IGNS Ltd.

As most of you know 2012 had up until a couple of days ago been rather free from significant eruptions, but that has now changed. As the ash and smoke starts to clear we now know that the explosions at both Whaakari and Tongariro was not the main events.

Tongariro

Image by Lurking showing ash column height and ash spread radius. This plot was also made at the same time as Lurking became the 1 millionth viewer. Quite fitting really.

The eruption that happened during last night was mainly driven by water pushed past the steam flash point. That in turn caused a large steam driven explosion that hurled incandescent stones out of no less than 3 new vents in the mountain close to the Te Mari craters. The steam also lofted ash and steam up to a height of 6 000 meters (20 000 feet, or FLA 200 as the VAAC terminology goes).

Photograph by Diana Booth. Rare image of an ash and steam cloud taken from below as it rises into the heavens after an explosive phase ends.

The steam explosion was caused by rising magma hitting the permanent water table, also, the magma from Tongariro contains a lot of water, and that most likely decompressed into a steam explosion.

The event was rather short in duration. According to the seismograph plots the actual explosion was about 1 minute long, and the main eruptive phase was about 20 minutes long. After that there was mainly steam being ejected. The steam phase lasted for about 20 hours when a second smaller steam driven ash explosion occurred.

Image by Geonet.

Risks at Tongariro

This is most likely not the main event, this is just a pre-cursor activity as magma rises. It is quite normal for andesitic subduction volcanoes to have an initial phase of steam driven ash explosions like this. This phase can last for a day or two up to a few weeks before the real eruption starts.

Quite often the size of the steam explosions are indicative of what will come during the main event, and a steam driven ash explosion that lofts up material to 6000 meters height is telling us that there can be something rather large in the making. My best guess is that this will be around a VEI-3 eruption.

Earlier today I read an interview with a local woman living close to the volcano. I was taken rather aback when I read that she felt safe where she was living. She was telling about seeing ash and steam rolling down the side of the volcano into the valley she lived in. Apparently she and other locals think this is as bad as it gets.  This is rather ignorant since the main dangers are lahars and the even worse pyroclastic flows running down the mountain into the valleys.

I hope that the valleys will be evacuated in time. One should though not forget that the eruption can change pace rapidly, and that it is better to be safe than sorry. Dead is a rather permanent position in life.

http://www.stuff.co.nz/national/7426862/First-Tongariro-eruption-in-over-100-years

Whaakari (White Island)

Image by Geonet. Moonlighting volcano at its best! Beginning of the nightly steam explosion at Whaakari (White Island) back lighted by the wonderful moonligh.

Whaakari is also a member of the TVZ (Taupo Volcanic Zone). It is a very large volcano built up by no less than 78 cubic kilometers of material. It is a complex volcano containing multiple vents and craters. A few days ago the Crater Lake went from being a small mud pool into being a sizeable lake as the water level rose 6 meters over night due to increase in hydrothermal pressure. A day later (also at night) a steam driven explosion hurled up ash and mud covering the new crater, the same area that killed eleven sulphur miners during the end of the mining epoch at Whaakari.

Image by Geonet. The man activity was on the fourth of August, but the level of tremor is still above normal, a probable sign of rising magma in the system causing steam explosions during its progress.

White Island is well known for its high rate of eruptions. It normally erupt very complex lavas pointing to either a mixed heritage of basaltic and andesitic feeder sources, or a complex magmatic system with high fractioning of the magmas. This produces the famous “clean” and “dirty” andesites. The volcano is at best highly unpredictable and can erupt without giving any untoward signs beyond the normal high background level of activity. To go there during an eruptive phase is to be considered very dangerous.

Image by Global Volcanism Program taken by Richard Waitt, 1986 (U.S. Geological Survey). The current active area, photograph is from 1986.

The same goes for Whaakari as for Tongariro; this is most likely only a pre-cursor phase before the real activity starts. Historically Whaakari has slightly stronger eruptions than Tongariro with the norm being VEI-2 eruptions, but with an upwards trend in strength of the eruptions during the last 170 years with the norm now being medium sized VEI-3s. The last eruption was in 2001 and rated as a VEI-2. But the year before there was a short and brutal VEI-3. And it is fairly indicative of the volcano that it has an upwards trend as the volcanic system evolves. What makes this volcano more prone for larger eruptions than Tongariro is the large (almost limitless) access to water to drive the hydro magmatic processes going on down in the volcano. The currently active crater floor is only 13 meters above sea level.

1 million viewers!

Image by Spica.

It is rather insane that it took us this short time to have 1 million viewers. From the beginning this has been a rather nutty experience. As I was convinced by a few others to create this place I expected a couple of hundred views per day, and a few comments. I never expected to start with 5000 viewers on the first day… And it just continued like that. As I have said many times, this is a group efforts and during the last half a year (slightly more) had a tremendous amount of posts published by many of our members. Keep those lovely posts coming and we will soon pass 2 million!

Little known fact, this is also Swedens largest blog… How about that?

CARL

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554 thoughts on “Eruptions at Tongariro & Whaakari (White Island) and 1 million viewers!

  1. Good morning everyone and G’day to our friends down under …I see what you mean Lurking. White Island is busy and Ruapehu has something causing those tremors. Interestingly Tongariro is relatively clear, no sign of anything untoward under there. However maybe it is a Kiwi Hekla… a couple of burps and up she goes.
    As I have nothing of great dramatic interest or deep thought yet this morning (Only on coffee # 1) I thought I would mention a little about the Icelandic tremor graphs and a hint for newcomers.
    As you travel round the Icelandic seismic monitoring sites (SILs) you will notice the blue high frequency line for many, often shows regular wavy patterns.
    If the SIL is by the sea then these lines coincide with tides and ocean waves. The pattern becomes very noticeable in windy weather as the waves break on the shore.
    SILs near towns or near main roads show daily activity. Vestmannaeyjar SIL shows the tremors caused by fishing industry activity as well as the ocean. The activity peaks early morning and again late afternoon with a significant drop at midday as the fleet goes out to sea and returns and it is less at weekends when the boats don’t go out.
    Those Sils on or very near rivers and glacial outlets during the winter has a fairly level appearance as the rivers may be frozen or most water locked within the glaciers. During late spring and early summer then these rivers and waterfalls become very active peaking from midday to evening as the sun warmth melts the ice.
    Now the glacial ice that is going to melt has melted and the river flow is steady.
    This river activity shows nicely this morning at Slysaalda. The recent glacial melts shows as waves that peak from late morning as the sun warms up the glaciers. yesterday and this morning the blue line is level indicating constant water flow and not a lot else.
    http://hraun.vedur.is/ja/oroi/sly.gif.
    Once you have watched these graphs for some time it is easier to pick out unusual activity it is either markedly Irregular for that SIL station or a pattern occurs that cannot be explained by human or natural cyclic activity. See Askja right now!

    • Yayyyy! Mila web cams are back. Just check out the beautiful winds at the base of Hekla this morning!
      http://eldgos.mila.is/hekla/
      Thank you so much to the Techies at Mila. I love watching Iceland’s many moods. When the cameras are down I feel something is missing in my life! It hurts being a Volcano addict!!!

  2. My Bulletin of World Volcanism (Issue 2) is out now. I need as many people to download it as possible. It documents all the previous months activity. It also includes an Interview a competition (Guess the volcano) and a ‘Volcano Analysis’

    Its free of charge and avaliable to anyone who wants it.

    To get the Bulletin. Simply send an e-mail to bulletinwv@hotmail.co.uk and enter ‘obtain bulletin’ and the code ‘M4RBVS2’ into the title box.

        • The results detected sulphur dioxide and carbon dioxide in the steam plume, which indicated that magma was closer to the surface than it usually was, Fournier said.

          It was unclear how high the magma was – it could be anything from metres to kilometres, Fournier said.

          If a magmatic eruption did occur then it wouldn’t necessarily be significant, he said. It could result in a lava flow or it could lead to a series of explosions.

          I think that the magma at the time of the steam event was somewhere below 2.2 km.

          Here is why.

          There was no tremor signal that would indicate transfer of heat to water which could then form steam. It went off instantly. The amount of energy coming about as one “pulse” means that the water went to a vapor stage all at once. If the stream had to develop pressure, that would have meant that there would likely have been a tremor run up on the siesmo, then a bang.

          Below 2.2 to 2.5 km, the water can be heated above the steam formation temperature with no stream showing up… that’s above the critical pressure.

          I think that the superheated water moved above this point and went immediately to vapor. That would explain the 6500 meter lofting of material with little to no precursor signal.

      • argh… I could kick myself. I didn’t think to ask him for that. It’s a 200km drive for him so I can’t really ask him again. Maybe one of the other kiwis popping their heads up here now could oblige? We must keep Tim in mind for the future, though, as he lives on the edge of Rotorua caldera very close to Okataina (where I actually thought the next activity was going to be… but there you go).

    • Certainly is, and very beautiful pictures too! Many thanks! Those widely spaced steam plumes makes you wonder if it’s a single point of magma with diverging steam channels, or if the magma is heating water at such widely spaced locations. If the latter, it’s quite a wad of magma pushing up there.

      • Hi Hendrik, (it is you isn’t it? You guys keep on changing your names all the time.. why can’t you just all be called bruce? Makes life much easier 😀 …

        as mentioned below, the steam plumes on the right are Ketetahi and not a new feature. Mind you, it would be interesting to know if they have become hotter or more active, not that anybody should go and look – they might just end up fried or parboiled (Ketetahi springs are out of bounds anyway at the moment).

    • Very nice work! Where exactly did he shoot from, and is it a location open to the public?

      I’ll be going to NZ soon, with the Mother of All Cameras and a long lens; that would be a good spot to shoot from if and when Tongariro serves up the main course – unless everything is socked-in with cloud of course…

        • Naw, that’s a lousy lens and not big enough or fast enough. THIS is me with a *proper* lens:

          (mods: how do I insert an image so it appears inline in the blog, not just as a link?)

          Mike

          GL Edit: I was wandering around and noticed the request.

      • Hi Mike, looks like activity is returning to New Zealand after a bit of a quiet spell (disregarding Ruapheu). With luck you might time it well!
        As for the shots, I’ll get Tim to reply but I imagine they were all taken from the road or near it. You can work out the position by pretty simply triangulation. Lower Te Mari crater is well visible in the foreground. The steam to the right is Ketetahi hot springs and is NOT a new feature. The new craters are all close to upper Te Mari crater.

        • Hmmm.

          I do know that area a bit – was there a couple of years ago. They look like they were taken from quite different places.

          The first shot looks like from near Rt 46, wider angle lens, maybe not far from Otukou.

          The other shots were taken from a much higher elevation, much further back – maybe even from Rt 47, a viewpoint where it comes down past Lake Rotopounamu, before the little boat dock and big hydro tunnel intake on Lake Rotoaira? That’s probably where I would park myself. Maybe even climb Mt. Pihanga and camp out there… grandstand view, and put a lake or two between me and the eruption!

          Mike

  3. I don’t believe it is Monowai.

    I went back a few more days on the Aqua/MODIS images, found an image of the raft whilst it was still fairlly clumped together. Then useing the cloud pattens as a guide zoomed the image out so that the longtitude and latitude lines showed.

    With those showing it looks as if it’s either come from the Macauley Island Caldera, or Giggenbach just to the NorthWest

    • Good thinking! However, as GVP lists Giggenbach as a mere 65 m below the surface (compare with the miniscule El Hierro which was deeper), I’d assume that something as large as the eruption responsible for this raft would certainly have been caught by either ship, plane or satellite?

      • Hmmm… Seems as if theres another one near by, not marked on google earth but is mentiond in the write-up for Macauley

        “Brimstone Island, 45 km west of Macauley at a location with a depth of about 2000 m and SW of Giggenbach submarine volcano”

        Seams a rather apt name, what with the large pumice raft floating around nearby 😛

  4. We just got a new Gallery -> Gems -> Microscopic images -> Mount Hood.
    Those images have never been published before and belong to our Volcanocafe-project… lets create our very own SEM Gallery of volcanic ashes/rocks.
    This time you can check out Andesit images.

    • Stupendous compared to El Hierro, and about normal for an awake volcano. In Hierro’s defense, I think most of it went straight into the seawater and was never airborne.

  5. Well, I think that sort of nails it.

    This spat of gorgeous weather (the Holocene) is making us stupid.

    The decline in body mass in human populations during the last 10,000 years has been estimated as less than 5 kg, or less than a 10 percent reduction in mass from a Late Upper Paleolithic mean of some 63 kg [1]. A decline of 5 kg would predict a decrease in endocranial volume only around 22 ml. The observed decline in several regions (including Europe, China, Southern Africa, and Australia) is between 100 and 150 ml during the past 10,000 years. Therefore, the reduction in body mass would be expected to have decreased brain size by only one-fifth to one-seventh the observed decline.

    http://arxiv.org/abs/1102.5604

    The gist of it… as I interpret it, is that moderate environments require less gray matter. Brain tissue is one hell of an energy hog and it makes sense that if you don’t need it, eventually you get less of it.

    It also sort of supports the idea that people in Northern countries have contributed to most of the profound achievements. Not that tropical and equatorial populaces are deficient, the Inca and Maya did some kick arse stuff… and I’m sure there a more that a few from the Indian subcontinent that can kick as in the accomplishment realm, just look at Mohenjo-daro…

    Okay… so I shot my own theory in the ass. Not the first time. 😀

  6. Renato cleaned his windowsill once to try to gather puehue ash, unfortunately he lives close to Copacabana and so all he got off with an adhesive next day was sand and odd bits of ash from a heavy smoker upstairs.

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