back to article Machine learning helps geoboffins spot huge beds of hot rocks 1,000km across deep below Earth's surface

Geophysicists have uncovered large swathes of hot, dense rock lying nearly 3,000 kilometers beneath Earth's surface, hidden below the Pacific Ocean, thanks to an unsupervised learning algorithm. These structures, described as "ultralow-velocity zones" (ULVZs) in a study published in Science on Friday, were detected by …

  1. Christopher Reeve's Horse

    My guess is..

    It's something to do with remnants of subducted oceanic crust. Once subduction begins, oceanic slabs become very dense, stripped of lighter material through partial melting. They also have a surprisingly large amount of momentum, and may sink all the way to the mantle/core boundary.

    This site has details of lots of named and identified slab remnants around the world, and the Hades Underworld Explorer even lets you produce a cross section of the mantle from tomography data, simply by drawing a line on the surface map.

    1. Blank Reg Silver badge

      Re: My guess is..

      Maybe if this were any other year, in 2020 it's probably Godzilla.

    2. PaulVD

      Re: My guess is..

      Not that much momentum. A large slab of rock 1000km x 1000km x 10km deep, being subducted at say 1cm a year, has about the same momentum as a 100-ton jumbo jet travelling at speed. And when planes crash, their momentum does not carry them very far down into the earth.

      It is gravity, not momentum, that moves stuff around in the mantle, working on thermally-induced density variations. And ocean crust is largely solidified mantle material, so when it is subducted and melts again its density will not be terribly different from the mantle material that surrounds it.

      But the discovery of vast hot spots down at the edge of our planet's core has got to be the coolest science of the year. (I'll get my coat.)

      1. Christopher Reeve's Horse

        Re: My guess is..

        Your right, it's dominated by gravity and the sheer mass. Momentum isn't the right expression.


        3.00E+19 kg of oceanic crust travelling at 3.17E-10 m/s has a momentum of 9,512,940,000 kg m/s

        100,000 kg of jumbo travelling at 500mph (223.52 m/s) has a momentum of only 22,352,000 kg m/s

        If you'd have said 425 jumbo jets travelling at speed, I may have believed you.

        1. PaulVD

          Re: My guess is..

          My bad - thanks for checking my arithmetic. I think I must have used a 10m thick crust rather than 10km.

  2. Paul Kinsler

    "thanks to an unsupervised learning algorithm"

    Or "graduate student", as they are more usually known. :-)

    1. Anonymous Coward
      Anonymous Coward

      Re: "thanks to an unsupervised learning algorithm"

      or ULA for short. As such, it can also stand for "Uncommitted Logic Array" (for the overly mathematical), "Unrequested Leave of Absence" (you know who you are/were, even if no one else could ever be sure), or even "ULAaaa..." for the one-in-a-million kind.

    2. RM Myers

      Re: "thanks to an unsupervised learning algorithm"

      Wouldn't a graduate student be an "unpaid and unsupervised" learning algorithm? Or have things changed since I was among the cursed?

      1. NetBlackOps

        Re: "thanks to an unsupervised learning algorithm"

        You think they paid the algorithm? Not on your life.

  3. TeeCee Gold badge
    Black Helicopters

    ...anomalies in seismic waves...

    Hmm, I guess that would qualify as a "seismic anomaly" then? Probably just a fleet of Russian magnetohydrodynamic drive nuclear submarines deploying to strategic strike positions and nothing to worry about.

    1. lglethal Silver badge

      I'm not sure the Marquesus Islands count as a strategic strike position considering they are about as far away from ANYWHERE as you can get on our planet.

      But maybe they've got a cunning plan!

      1. Qumefox

        As far away from anywhere as you can get? How are real estate prices there? Because in the current socio-political climate, being as far away from anywhere as possible is looking better and better every day.

      2. Anonymous Coward

        It's not the Russians, Elon's Boring machine just got lost.

        1. Anonymous Coward
          Anonymous Coward

          Much Autopilot?

        2. jake Silver badge

          He has a machine for that? I thought being boring came natural to him ...

  4. Vulch

    Deep structures?

    Just hope they haven't found Callastheon.

    (Arthur C Clarke - The Fires Within)

  5. John Brown (no body) Silver badge

    And the Earth is the only terrestrial planet in our solar system

    See icon --------------->

  6. Sanguma

    Oh Noes!!!

    They've discovered a meeting of out-of-work politicos and police commissioners. What else could be so dense?

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