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  • On April 25th, an earthquake with a magnitude of 7.8 struck Nepal, claiming the lives of

  • thousands of people and leveling buildings in and around the capital city of Kathmandu.

  • You may have heard scientists quoted in the news, saying that this quake wasinevitable,”

  • and in a sense, it was.

  • Nepal is home to the tallest mountain in the world, after all, and the movements of the

  • earth’s crust are what help form mountains in the first place.

  • But geologists with the U.S. Geological Survey say that strong earthquakes are actually pretty

  • rare in this part of Nepal.

  • In the past hundred years, only four earthquakes of magnitude six or higher have occurred within

  • 250 kilometers of the current quake.

  • Before last week, the most recent one happened in August of 1988, when a 6.9 quake struck,

  • causing about 1500 fatalities.

  • And a catastrophic quake occurred at almost the same spot in 1934, destroying a large

  • part of Kathmandu and killing nearly 11,000 people.

  • While rare, these quakes are reminders of Nepal’s precarious geological position:

  • It sits right on top of a subduction zone -- where one plate of the Earth’s crust

  • slides under another.

  • In this case, the Indian Plate is pushing itself to the north, under the rim of the

  • Eurasian Plate.

  • And Nepal’s southern border rests directly on the boundary between those two plates,

  • on a formation called a thrust fault.

  • As one giant plate slowly tries to slide under the other, stress gradually builds up in the

  • rock around the fault lines, until all that energy is released in the form of an earthquake.

  • Adding to the power of this latest quake was the fact that it was pretty shallow -- its

  • epicenter was just about 15 kilometers below the surface, while other quakes in the region

  • can happen as much as 200 kilometers down.

  • The closer to the surface that an earthquake strikes, the more severe its vibrations are,

  • and the more damage it can cause.

  • So, the forces that created the majesty of the Himalayas are also what caused the destruction

  • that were seeing now.

  • If you’d like to help victims of the Nepal earthquake, weve included a list of nonprofits

  • that are sending relief to the area, in the description below.

  • Now for some good news from underground.

  • One thing that the earth keeps giving us is fossils -- and last week a strange new addition

  • was made to the Dinosaur Family Tree.

  • Discovered in a 160-million-year-old fossil in China, it’s been named Yi qi -- and it

  • raises the question of whether some dinosaurs could actually fly.

  • Makes sense when you think about it, since birds are considered the modern descendants

  • of dinosaurs. Some ancient dinosaurs definitely had feathers, and a few -- like the lovely

  • Archaeopteryx -- even had wings.

  • But the general consensus among scientists is that, by definition, the extinct dinos

  • we know as non-avian dinosaurs couldn’t fly on their own -- though a few of the smaller

  • ones may have been able to glide.

  • But Yi qi might change that.

  • In this week’s issue of the journal Nature, paleontologists report that it’s the first

  • fossil dinosaur found to have some of the same bone structures as modern flying animals.

  • Specifically, they say, the bones in its wrist are just like those found in bats.

  • There were even the remains of an apparent membrane on the forelimb, kind of like a bat’s

  • wing. And part of the fossil included feathers -- although not the kind of feathers used

  • in flight.

  • Unfortunately, the fossil isn’t complete enough for scientists to tell whether this

  • dinosaur could actually fly by flapping its feathered wings, or whether it glided -- like

  • Archaeopteryx probably did.

  • Finally, one more thing to file underweird stuff weve found in the ground:”

  • Scientists working in Antarctica this week announced that theyve discovered a huge

  • network of subterranean saltwater lakes, stretching at least 12 kilometers long.

  • Geologists made the find while conducting electromagnetic surveys of Antarctica by helicopter,

  • when they picked up traces of brine, or salty water, up to 300 meters below the surface.

  • This isn’t the first time that water has been found trapped under Antarctica, though.

  • Our very first SciShow News update ever was about Lake Vostok, a subglacial Antarctic

  • lake which Russian scientists reached for the first time in 2012, after drilling through

  • 4 kilometers of ice.

  • Scientists are intrigued by these deposits of water, because theyve likely been there

  • for millions of years -- dating back to when the continents and the climate were different,

  • and Antarctica had liquid water on its surface.

  • With this water now trapped underground, it’s thought to be home to extreme forms of microbial

  • life -- including some forms that humans have probably never seen before.

  • So, there’s still much more about this planet, and the life on it, for us to learn about,

  • starting from the ground up.

  • Thank you for joining me for SciShow News. Which is brought to you by this episode’s

  • President of Space, Kevin Bealer who saysDon't forget to be awesome! And hi mom!”.

  • If you want to find out how you can support us visit Patreon.com/scishow where you can

  • find cool stuff like exclusive Fancy Facts every month. And if you want to keep getting

  • smarter with us, just go to youtube.com/scishow and subscribe.

On April 25th, an earthquake with a magnitude of 7.8 struck Nepal, claiming the lives of

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ネパール地震の内部 (Inside the Nepal Earthquake)

  • 202 11
    Shuchun Huang に公開 2021 年 01 月 14 日
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