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  • As you're watching this video, thousands of kilometers beneath your feet, edging on

  • the brink of alien and terrestrial, lies two vast structures with unknown origins, and

  • scientists call them...

  • Earth blobs?

  • Uhh wait what?

  • Did I read that correctly?

  • Yes, yes I did read that correctly.

  • These 'blobs' have been a big geologic mystery that researchers believe are having

  • an untold effect on our planet and it's baffled scientists for over 40 years.

  • So what do we know about them?

  • Well, Earth blobs have picked up this rather un-sciency name because they look sort of

  • blobby with round, soft edges.

  • No, not that type of blob.

  • Scientists call them Large Low Shear Velocity Provinces, because waves of energy slow down

  • through these zones, but boy, that's a mouthful so let's just stick to Earth blobs for now.

  • They're hidden underneath Earth's crust, like really, really deep - about 2,000 kilometers

  • deep.

  • These blobs are so massive that if we moved them to Earth's surface, the International

  • Space Station would need to navigate around them.

  • So to better understand these gigantic structures, we need to journey into the center of the

  • earth.

  • They begin where Earth's mantle meets the outer molten core.

  • In the 1970's, scientists discovered that one of the blobs sits under the Pacific ocean,

  • while the other one sits under Africa and part of the Atlantic ocean.

  • So we know their general location and we know that these regions are different from the

  • surrounding mantle material because seismic waves move through these massive regions slower

  • than their surroundings.

  • But there are still many unanswered questions.

  • No one knows for sure where they came from, how long they've been around, or even what

  • their role is on the planet.

  • But yah know, scientists love a good mystery hidden deep within the Earth's crust.

  • So it's been an ongoing debate ever since they were discovered 40 years ago with a whole

  • range of ideas trying to explain them.

  • One hypothesis has described them as plumes of hot upwelling rock that connect to surface

  • volcanoes to form island chains like Hawaii and Iceland.

  • Another has speculated that the blobs are disrupting Earth's magnetic field.

  • And others have suggested that the blobs are connected to super volcanoes that at one time

  • caused extinction events.

  • So yeah... the ideas run from the generally benign to the apocalyptic.

  • But these are just hypotheses.

  • Because it's impossible to reach these depths in one piecetemperature and pressure would

  • kill youscientists have to rely on a multitude of techniques to tell us what the interior

  • looks like, and maybe even explain how these mysterious regions affect our planet.

  • One way is with seismic tomography, a technique that helps us look below the crust by tracking

  • and calculating seismic waves.

  • This was how scientists actually discovered the blobs in the first place.

  • But while the method revealed where the blobs are and how large they are, it can't really

  • tell us much about their density.

  • So one researcher turned to a new technique called tidal tomography to peer under Earth's

  • crust.

  • It uses sensitive GPS measurements to track Earth's body tides and can give us a better

  • gauge of the blobs' density.

  • Preliminary results showed that the blobs were pretty dense and could be composed of

  • iron and have similarities to primordial material.

  • While geochemists are analyzing the chemical composition of lava samples to help determine

  • what role blobs could play on volcanoes.

  • One study, looking at underwater lava flows along Costa Rica, suggested that at least

  • one of the blobs may have been a source for an extinction level event millions of years

  • ago.

  • So evidently more research is needed to demystify the blobs before we make any conclusions.

  • What's important to keep in mind is that each of the earlier ideas may present a different

  • picture of Earth's inner workings and the role the blobs could play on our planet, which

  • is why these regions are so scientifically interesting.

  • They could tell us very different things about the planet, from its earliest beginnings to

  • the magnetic field to even super volcanoes.

  • But until Brendan Fraser figures out a way to journey back to the center of the Earth,

  • we'll use the techniques at our disposal to reveal the mysterious blobs wrapped around

  • the heart of our planet.

  • Come on Brendan, we're counting on you.

  • If you liked this episode, let us know if there are any other mysterious science phenomenons you'd like us to

  • cover down in the comments. Make sure to subscribe and thanks for watching.

As you're watching this video, thousands of kilometers beneath your feet, edging on

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隱藏在地球地幔中的神祕結構。 (The Mystifying Structures Hidden Within Earth’s Mantle)

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    林宜悉 發佈於 2021 年 01 月 14 日
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