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 was “inevitable,”
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 we’re seeing now.
If you’d like to help victims of the Nepal earthquake, we’ve 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 under “weird stuff we’ve found in the ground:”
Scientists working in Antarctica this week announced that they’ve 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 they’ve 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.
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