Tuesday, March 6, 2012

Supervolcanoes And Why You Shouldn't Worry So Much

It's a pretty quiet week in volcano world (at least until I can get my paws onto the latest GVP report), so I thought I might dabble in the realm of supervolcanoes today, since they are such a hot topic, and very misunderstood.

There has been plenty of hype in the news media surrounding so-called supervolcanoes like Yellowstone, Toba, Rotorua, Uturuncu, and the like. Media outlets looking for a sensational and fascinating story seem to fixate on the apocalyptic scenarios of a Yellowstone eruption, or an eruption so devastating that it wipes out humanity as we know it. While there are supervolcanoes in our midst, and some like Yellowstone that are still seething and breathing, a true supervolcanic eruption has never occurred in the span of recent human history, and probably will not for a very long time.

Yellowstone had its last truly catastrophic eruption some 600,000+ years ago. Journalists and some researchers point out that Yellowstone has a major caldera type eruption around every 600,000 years, and some say the volcano is overdue. But this again assumes that volcanoes actually have a schedule, and conform to our time lines. This of course is absurd. Volcanoes erupt simply when the conditions are met for an eruption, and Yellowstone is a far ways away from anything major. At the very worst, we'd probably see a small phreatic (water explosion) eruption, or a minor cone building event, but even this is far fetched at this point in time.

The ONLY supervolcanic eruption in human history occurred approximately 75,000 years ago in Indonesia. A volcano named Toba erupted, punching a gigantic caldera into the earth's surface, creating a mini ice age, and reducing the population of humans worldwide to around 5,000 individuals. This has been proven from many angles like ice-core samples that show an immense amount of sulphur dioxide and tephra, as well as DNS analysis of humans pointing to a genetic bottleneck around that time.

The next largest eruptions in recorded human history were the eruptions of Tambora in the 19th century, the eruption of Krakatoa (now Anak Krakatau, 'child of Krakatoa), and the eruptions of Mt. St. Helens, and Pinatubo. These eruptions were all on a scale of VEI 6 to VEI 4. Far from the supervolcanic force of a VEI 7 eruption which is required to be classified as a supervolcanic event.

There are no supervolcanoes currently displaying the characteristics of an imminent eruption. The requirements for such an eruption are extremely rare, and complex. First, the magma chamber has to be massive, fully charged, and pressurized, and then it needs an injection of fresh magma from the mantle. Surface observations would include heightened fumerolic and geyser activity, ground uplift and swift deformation, accompanied by multiple explosive events, culminating in the emptying of the magma chamber, and subsequent collapse of a massive caldera. There are NO volcanoes that currently display any of these characteristics... not even Yellowstone or Uturuncu.

Events like these are extremely rare, and require all of the above conditions to occur. Given that the earth has already suffered so many volcanic eruptions, and several supervolcanic events, one might wonder if the Earth still has the magma required to make one happen. It does, and supervolcanic events will happen again... but the likelihood of one happening in your lifetime is so infinitesimally small, they're hardly worth the calculation. In fact, you have a much better chance of seeing a meteor strike the earth, or a supernova in space than you are to see a supervolcano erupt.

Supervolcanoes are terrifying, fascinating, and worrisome for governments to prepare for... but one has to ask... given that we've never had a super eruption in our living history, why would we lose sleep over something that is so unlikely to occur? Most of the worry and hype can be blamed on the "2012'ers", Hollywood, or just plain old Yellow Journalism. Some can be blamed on conspiracy theories, or doomsayers. But truly, it is human nature to be on guard about any threat to our existence, and while the threat exists, we will always pay attention. I however will never lose any sleep worrying about Yellowstone. 

9 comments:

  1. Hi. Good article, but you're missing a couple of relatively recent big eruptions. Taupo (NZ) has produced a VEI 7 as a big or bigger than Tambora in the last 2000 years - the so called "Hatepe" eruption around 180AD - 230AD. Taupo was also responsible for the most recent VEI 8 (more recent than Toba), the "Oruanui" eruption, around 26,500 years ago.

    References:
    http://www.volcano.si.edu/world/volcano.cfm?vnum=0401-07=

    http://en.wikipedia.org/wiki/Oruanui_eruption

    http://en.wikipedia.org/wiki/Hatepe_eruption

    I'm still not worrying 'though - far more likely to get hit by a bus!

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  2. This video claims the last supervolcanic eruption was 26,000 years ago at Lake Taupo in New Zealand, which erupted over 1,000 cubic kilometers of material. http://www.youtube.com/watch?v=xAMrY7ty0dc

    Don't forget that the fear will wear off over the coming decades but in the mean time we will learn a lot more about super volcanoes. Considering that a billion people could die from a major SV eruption, I think the fear might serve a useful purpose in this case. You are right though, there are more pressing concerns. We are more likely to die from disease or war, cancer or heart disease, etc...

    IMO, the biggest hurdle is identifying these super volcanoes and recognizing the threat. We have done some of that now and I think/hope that we are now more ready than ever to deal with one. I don't think we knew about them 50 or 100 years ago.

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  3. Very true, I did forget to toss Taupo in there, thanks for the heads up!

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  4. are you sure you want to call Mt. St. Helens one of the biggest eruptions in recorded history ?

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  5. Mt St Helens was one of the biggest eruptions in recent history. It is certainly the largest U.S. eruptions in recent history. Many other eruptions are compared to the St. Helens flank eruption, and ash fall was incredibly widespread.

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  6. Hi Matt. Helens was a big eruption especially in -how- it erupted (laterally). But it was not the largest recent US eruption. There was much larger (30 times larger) one in Alaska in 1912 at Novarupta (Katmai).

    "came in 1912, from the aptly-named Novarupta volcano on the Alaska Peninsula, about 290 miles southwest of Anchorage. It was the largest volcanic eruption of the 20th century, and one of the five largest eruptions in recorded history."

    http://www.alaskadispatch.com/article/alaskas-biggest-volcanic-eruptions

    1912 is reasonably 'recent' by universal volcano timescale, I suppose. :)

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  7. Yep I've apparently missed a few... guess this is what happens when I write half asleep! I'll have to step up my game!

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    1. Yes typing e-mails or blog entries or whatever when tired is a great recipe for making mistakes! Do an experiment -- type one up then read it the next morning. Glad to help and thanks for taking my corrections in stride. Hope they didn't come across as snarky.

      Oh, don't forget about the VEI8 last year in southern California. The Los Angeles crater/caldera is still fuming noxious gasses every day. People have been reporting smog in the area for decades.

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  8. Heck, we all make a mistake or oversight once in a while. I have no ego to bruise on this stuff and appreciate any comments! The purpose of this blog is for information and education, and if the conversation is candid, it benefits everyone.

    As far as LA is concerned, I'm quite sure the emissions come from human activity and pollution. Even a supervolcano isn't as polluting as my neighbor city hahaha.

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