Geoloists? The End of the world, or at least North America

Factual Questions
1

When it comes to end of the world scenario’s, the one that freaks me out the most is one we seem to hear about the least. Killer Asteroids, Nuclear holocaust, untreatable diseases, heck, even alien invasions get pretty much constant press (constant, in this instance meant to infer at least once a year).

The eruption of the Yellowstone Caldera on the other hand is something I heard about for the very first time when the Discovery channel did a special on it.

Now I do not profess perfect understanding about this, but I do remember this. If this puppy blows, North America can kiss itself goodbye, the pyroclastic current are likely to wipe out a three state area and the entire continent is likely to get a good covering of volcanic dust. Agriculture, gone, vehicles rendered useless, life as we know it, gone.

I can’t find a link to the show on the discover channel site, but here is a webquest page on the topic with lots of links.

The caldera is supposed to be on something like a 600,000 year cycle, with the last eruption some 600,000 years ago.

Now I understand that as far as geology goes, this could happen five minutes from how, or 100,000 years from now without the cycle being too far out of whack.

What i want to know is if there have been any further developments on this lately, and why it’s not something we all talk about at least as regularly as a big chunk of rock hitting the planet from space.

After all, this will happen. There is no doubt in the minds of any of the scientists I’ve ever heard on the topic, the question is when.

Any geology geeks on the board have new information?

-Doug

2

It is probably going to blow again. If the anticipated damage you cite is from the Discovery channel, they are far more confident in their predictive capabilities than the U.S.G.S., who are actively monitoring it and will make much noise if an event appears imminent.

You don’t hear more about it because nothing unusual is happening and (if and) when it blows again, there’s nothing to be done about it except try to be as far away as possible. If you’re concerned, live on the East Coast. It might not do anything for another 250,000 years (hmm, wonder where California will be then?). And I sincerely doubt it would end life as we know it.

From VOLCANO HAZARDS FACT SHEET:
Yellowstone: Restless Volcanic Giant

3

Thanks, beatle, that’s my suspicion as well, which I’m hoping for confirmation of.

I’m guessing that “In all likelyhood, nothing’s going to happen for the forseeable future” just wouldn’t have made for as impressive TV I guess.

-Doug

4

But you are right, that the odds of that happening seem to be stronger than for some of those other hazards. I grew up in Cody, WY, fifty miles from the East gate of Yellowstone, but it wasn’t until I studied geology out here in North Carolina did I fully understand the immensity of what had happened at Yellowstone. I slept through the earthquake of 1959–it was on the other side of the park.

The Mount St. Helens blast in 1980 was about a cubic kilometer of ash, I believe, the famous Krakatoa in 1883 was somewhere around twenty cubic kilometers, and Tambora in 1815 was about fifty cubic kilometers. It is said that the Krakatoa ash caused worldwide temperature changes for five or six years. The blasts in Yellowstone were thousands of cubic kilometers.

I believe the standard dating (verified by one of those links, USGS page about Yellowstone) is that the big explosions occurred 2.0 million, 1.3 million, and .6 million years ago. So, that looks like 700,000 years between blasts, and we’re only 600,000 years since the last one.

These things are inexact of course, and one of those links says its been 650,000 years since the last one. Wait and see?

Most explosive eruptions do give some warning, but I don’t think we have any idea of the time scale for something like this.

5

my advice is hide. If you can’t make it to that a terraformed Mars, Argentina or Australia might be good places to hang out for a few thousand years. If Yellowstone really goes for it, we could see a new Ice Age.

6

I spend quite a bit of time with calderas, albeit from a mostly geochemical perspective.

Calderas (or “supervolcanoes” as the Discovery Channel, TLC, BBC, et al., like to call 'em) are very, very large, very, very long-lived volcanoes that, very, very luckily, don’t go off very often.

The first stage of the caldera cycle (of course, the caldera cycle is a generalization) is regional tumescence with small-scale volcanism occurring along the caldera’s margin (ring-fracture). This stage may last several hundred to thousand years (<4 x 10[sup]5[/sup] years for the last eruption of the Valles Caldera, Jemez Mtns., NM) before the big’un, which could erupt up to 3000 km[sup]3[/sup] of ash, certainly enough to make everyone’s life miserable, no matter where they live.

So, I wouldn’t worry about Yellowstone until the ground starts rising (and they watch this closely) and small volcanic episodes (probably mostly lava domes and flows) start poppin’ off along and near the margins of the caldera wall. When I visit Yellowstone, I’m much more worried about traffic and crime.

Details of the Caldera Cycle can be found in “Resurgent Cauldrons” in Geological Society Memoir 116, by Robert L. Smith and Roy A. Bailey (pages 613-659). Most university libraries will have this volume.