Stories
Slash Boxes
Comments

SoylentNews is people

posted by azrael on Tuesday September 09 2014, @07:15PM   Printer-friendly
from the when-in-doubt-make-things-up dept.

Caltech scientists believe that the textbook theory behind volcanoes is wrong (PDF article):

In the typical textbook picture, volcanoes, such as those that are forming the Hawaiian islands, erupt when magma gushes out as narrow jets from deep inside Earth. But that picture is wrong, according to a new study from researchers at Caltech and the University of Miami in Florida.

New seismology data are now confirming that such narrow jets don't actually exist, says Don Anderson, the Eleanor and John R. McMillian Professor of Geophysics, Emeritus, at Caltech. In fact, he adds, basic physics doesn't support the presence of these jets, called mantle plumes, and the new results corroborate those fundamental ideas.

According to current mantle-plume theory, Anderson explains, heat from Earth's core somehow generates narrow jets of hot magma that gush through the mantle and to the surface. The jets act as pipes that transfer heat from the core, and how exactly they're created isn't clear, he says. But they have been assumed to exist, originating near where the Earth's core meets the mantle, almost 3,000 kilometers underground—nearly halfway to the planet's center. The jets are theorized to be no more than about 300 kilometers wide, and when they reach the surface, they produce hot spots.

While the top of the mantle is a sort of fluid sludge, the uppermost layer is rigid rock, broken up into plates that float on the magma-bearing layers. Magma from the mantle beneath the plates bursts through the plate to create volcanoes. As the plates drift across the hot spots, a chain of volcanoes forms—such as the island chains of Hawaii and Samoa.

This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 5, Informative) by DrMag on Tuesday September 09 2014, @07:32PM

    by DrMag (1860) on Tuesday September 09 2014, @07:32PM (#91419)

    ...these scientists are saying the correct view is this:

    The new measurements suggest that what is really happening is just the opposite: Instead of narrow jets, there are broad upwellings, which are balanced by narrow channels of sinking material called slabs. What is driving this motion is not heat from the core, but cooling at Earth's surface. In fact, Anderson says, the behavior is the regular mantle convection first proposed more than a century ago by Lord Kelvin. When material in the planet's crust cools, it sinks, displacing material deeper in the mantle and forcing it upward.

    "What's new is incredibly simple: upwellings in the mantle are thousands of kilometers across," Anderson says. The formation of volcanoes then follows from plate tectonics—the theory of how Earth's plates move and behave. Magma, which is less dense than the surrounding mantle, rises until it reaches the bottom of the plates or fissures that run through them. Stresses in the plates, cracks, and other tectonic forces can squeeze the magma out, like how water is squeezed out of a sponge. That magma then erupts out of the surface as volcanoes. The magma comes from within the upper 200 kilometers of the mantle and not thousands of kilometers deep, as the mantle-plume theory suggests.

    As a scientist, I feel like their idea is sound, but it's being a bit over-sold. There are a number of claims made without support in the public article; but to be fair the journal article may have better details. I'd feel better if it was less "OMG; scientists have been wrong all this time!!" and more "The best idea we've had to date doesn't seem to be working out with better measurements; this may be a better approach."

    • (Score: 2) by opinionated_science on Tuesday September 09 2014, @07:34PM

      by opinionated_science (4031) on Tuesday September 09 2014, @07:34PM (#91422)

      Indeed. a 3000 km "fountain o' molten rock", probably requires better classification....!

    • (Score: 4, Interesting) by tangomargarine on Tuesday September 09 2014, @07:48PM

      by tangomargarine (667) on Tuesday September 09 2014, @07:48PM (#91428)

      It doesn't help that the headline says "May Be" Wrong. Not sure if it was mostly because of The Other Site, but whenever I see "may be" anything, I hear "probably still is, but we have this crazy new theory we based on a bunch of untestable assumptions and got these editors to fall for."

      --
      "Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
      • (Score: 2) by Alfred on Tuesday September 09 2014, @09:15PM

        by Alfred (4006) on Tuesday September 09 2014, @09:15PM (#91486) Journal
        Because of these "untestable assumptions " much of science had the credibility of the Brothers Grimm. Maybe it happens this way, maybe it doesn't, you didn't see it. Fortunately, modern science sounds more plausible on a greater percentage of it stories than the Brothers Grimm on theirs ;-)
        • (Score: 3, Funny) by edIII on Tuesday September 09 2014, @10:43PM

          by edIII (791) on Tuesday September 09 2014, @10:43PM (#91513)

          Fortunately, modern science sounds more plausible on a greater percentage of it stories than the Brothers Grimm on theirs ;-)

          I dunno, man. Have you seen the fucking news lately? If I heard some crazy old lady was caught enticing children to her home that she painted pink and had glued hard candy too, only to cannibalize the little ones with her commercial oven, I would not be so quick to dismiss it as a tabloid story today...

          --
          Technically, lunchtime is at any moment. It's just a wave function.
          • (Score: 0) by Anonymous Coward on Wednesday September 10 2014, @07:18AM

            by Anonymous Coward on Wednesday September 10 2014, @07:18AM (#91593)

            Have you seen the fucking news lately?

            Wait, there's a news channel dedicated to fucking? ;-)

      • (Score: 2) by khallow on Wednesday September 10 2014, @02:22AM

        by khallow (3766) Subscriber Badge on Wednesday September 10 2014, @02:22AM (#91552) Journal

        What are these "untestable assumptions"? The theory makes straightforward assertions about the dynamics of the mantel and we have ways to check those assertions.

        • (Score: 2) by tangomargarine on Wednesday September 10 2014, @01:36PM

          by tangomargarine (667) on Wednesday September 10 2014, @01:36PM (#91662)

          and we have ways to pull a bunch of mathematical models out of our ass that support the hypothesis.

          FTFY.

          Well, at least instead of 3000km deep they're only saying 200km now. Not that, y'know, the deepest we've ever actually drilled down is only 15 [wikipedia.org]. Which was they estimated about a third of the way through the crust.

          --
          "Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
          • (Score: 2) by khallow on Friday September 12 2014, @12:07AM

            by khallow (3766) Subscriber Badge on Friday September 12 2014, @12:07AM (#92172) Journal

            We have a number of ways of determining what's down there aside from just digging. Vibration from earthquakes and deliberately induces shocks can both image the entire Earth and distinguish between liquids and solids. At some point, it might even become sensitive enough to detect even the slow motion of the mantle via the Doppler effect. Gravimetric methods can help determine upward and downward movement of the mantle. And xenolyths brought up from further underground can help us figure out the chemistry of the mantle and perhaps deeper underground.

            • (Score: 2) by tangomargarine on Friday September 12 2014, @03:42PM

              by tangomargarine (667) on Friday September 12 2014, @03:42PM (#92436)

              Hey, at least it's a damn sight more observable than all that string theory metaverse stuff :)

              Next week a group of scientists will prove the Great Green Arkleseizure. Beware the Coming of the Great White Handkerchief!

              --
              "Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
              • (Score: 2) by khallow on Friday September 12 2014, @06:19PM

                by khallow (3766) Subscriber Badge on Friday September 12 2014, @06:19PM (#92533) Journal

                Hey, at least it's a damn sight more observable than all that string theory metaverse stuff :)

                My point exactly. Let's cut them some slack.

  • (Score: 5, Interesting) by khallow on Tuesday September 09 2014, @08:45PM

    by khallow (3766) Subscriber Badge on Tuesday September 09 2014, @08:45PM (#91463) Journal

    That still doesn't explain things like the peculiar variability of volcanism in the interior of older continental plates (either you don't have much of it, or you end up with a hotspot which can have a considerable amount of volcanism associated with it). But that's more of a "last mile" problem with the structure of continental plates, I guess, than something that requires any interaction with deep heat sources.

  • (Score: 4, Funny) by present_arms on Tuesday September 09 2014, @10:38PM

    by present_arms (4392) on Tuesday September 09 2014, @10:38PM (#91510) Homepage Journal

    one hot topic

    well someone had to say it

    --
    http://trinity.mypclinuxos.com/
    • (Score: 0) by Anonymous Coward on Wednesday September 10 2014, @01:13AM

      by Anonymous Coward on Wednesday September 10 2014, @01:13AM (#91541)

      In a similar vein, I suppose the physics of a volcano are similar to the physics of a fart or the popping of a zit.

      Pressures build up until something gives.

      I know this is a crap post, so I'll duck out now...

    • (Score: 2) by Rivenaleem on Wednesday September 10 2014, @09:11AM

      by Rivenaleem (3400) on Wednesday September 10 2014, @09:11AM (#91607)

      It's sure to spark some heated debate.

  • (Score: 1) by Plazmi on Tuesday September 09 2014, @11:42PM

    by Plazmi (4498) on Tuesday September 09 2014, @11:42PM (#91528)

    Well I've been waiting for science to catch up to my crazy idea. This may be my one and only post to Soylent as I may be dragged off to the funny farm after, but here goes.... Some time around 2005 while doing some reading about asteroid orbits, I had an odd thought. Skipping the details, that thought lead me to the conclusion that the Earth (and every large body) has "gravity hallow". We don't have a magma core but instead a magma sphere somewhere between center and the surface. Here's the short of it....at the center of any large body, the resulting gravitation forces are null, zero, canceled by each other on all sides/directions. Unlike the surface where mass/gravity is pulling beneath you, at the center gravitational forces are pulling outward in all directions. A "gravity hallow". The nearer the center, the smaller the resultant forces. Nothing there to crush a molten core. So... where's the lava? Located where the opposing forces of the mass below verses the mass above would cause the most pressure. Someone probably already has a nice app to work that out, but I envision an inner sphere of lava instead of a ball at the center. Well that's it, I'm off to hide in a bunker. I figure I'll be branded a loon or someday read about some super brain dude/dudette that figured it out. (never mind I'm already a loon)

    • (Score: 2) by khallow on Wednesday September 10 2014, @02:24AM

      by khallow (3766) Subscriber Badge on Wednesday September 10 2014, @02:24AM (#91553) Journal

      You still have to account for the thousands of kilometers of rock pushing down on the center. Just because it's not experiencing much in the way of gravity, doesn't mean that it isn't experiencing huge forces.

    • (Score: 0) by Anonymous Coward on Wednesday September 10 2014, @06:29AM

      by Anonymous Coward on Wednesday September 10 2014, @06:29AM (#91584)

      You are not crazy, just incorrect. Crazy would be insisting that your theory is correct despite clear proof to the contrary (which does exist if you want to look for it).

      • (Score: 0) by Anonymous Coward on Wednesday September 10 2014, @07:15AM

        by Anonymous Coward on Wednesday September 10 2014, @07:15AM (#91590)

        I suppose the proof would be "because pressure", no?

  • (Score: 4, Funny) by jelizondo on Wednesday September 10 2014, @05:00AM

    by jelizondo (653) Subscriber Badge on Wednesday September 10 2014, @05:00AM (#91577) Journal

    Well, I'll be darned! Those folks in Miami have studied all the volcanoes around and are soooo qualified!

    Wait, no volcanoes near Miami? Well, at least they should know all about sinkholes!

    Sorry, I used to live in Ft. Lauderdale and I find it very funny that there are be vulcanologists in Florida when there isn't a fscking volcano anywhere near! It sort of reminds me of the Jamaican ice hockey team. Yes, they are real but is funny.

    • (Score: 0) by Anonymous Coward on Wednesday September 10 2014, @07:46AM

      by Anonymous Coward on Wednesday September 10 2014, @07:46AM (#91598)

      It's nowhere near that funny.