Placeholder Image

字幕列表 影片播放

  • 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


單字即點即查 點擊單字可以查詢單字解釋

B2 中高級

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

  • 5 1
    林宜悉 發佈於 2021 年 01 月 14 日