Riley: Bill, this is Riley.
How does the Earth have earthquakes?
Bill Nye: Riley.
This is a fabulous question.
How does the Earth have earthquakes?
Well nominally, or just thinking about it
the first way, the Earth is made of these
big slabs of land that move around on the
lava or “magma,” which is what geologists
call that molten rock when it’s underground—magma.
And they move around and they just bump into
each other.
Four and a half billion years ago, when these
objects formed out of dust—it is interesting
to notice, Riley, that not only is the dust
on a bookshelf being pulled down by the Earth,
but the dust is ever so slightly pulling the
Earth up.
They are attracting each other.
It’s quite a thing to get your head around,
as we say.
So the Earth was formed from dust.
It came like this and it started spinning.
Then that compressing it, it got hot, and
now these pieces of land are bouncing off
each other.
So the ocean sits on top of plates of land.
The ocean is on top of solid stuff.
You may not have thought about that but the
ocean is relatively shallow compared to how
deep the Earth is, how big the Earth is.
So along this line, that’s one way we get
earthquakes.
Right now humans are causing earthquakes in
the North American Midwest.
A friend of mine lives in Oklahoma and what
we’ve done is drilled so many holes into
the crust, into the Earth, to get to oil and
gas that we’re actually allowing these much
smaller pieces of the Earth’s crust, the
outer layer, to shift around a little bit.
And that’s also causing what are just like
earthquakes.
It’s really a remarkable thing.
And I remind you, Riley: earthquakes don’t
kill people.
Buildings kill people.
So what we do now is we design buildings that
can stand an earthquake.
And if you’re in an earthquake—I’ve
been in several earthquakes.
I’m fine.
If you’re in a building and there’s a
big earthquake, try to get outside.
This is what we recommend.
And so I hope that in your lifetime here,
for example, in the United States, all our
buildings are made strong enough for earthquakes.
All our bridges.
Everything.
I hope we can pull that off because we understand
it now.
When I was a kid, Riley, when I was your age
this idea of tectonic plates—'tectonic'
is a Greek word for builder, for build.
The Earth is built of these tectonic plates.
That was still controversial.
The people didn’t altogether agree on it.
And it started in the 1800s with Alfred Wegener,
who saw where South America seemed to fit
into Africa, and it sort of does.
And there's really compelling evidence: he
found the same fossils in South America that
you find in Africa at the same level, the
same layers, of rock exist on both continents.
And he went, “Hey man, check it out.”
I paraphrase because it was German.
But that led to a whole bunch of discoveries
that proved that the main idea in all geology
is tectonic plates.
And some of them, by the way, some of the
evidence I mean, was done by submarines in
World War II, trying to sneak across the North
Atlantic like between the underwater mountains.
It’s very cool.
So tectonic plates allow the shifting of the
Earth’s surface which causes earthquakes.
On a much shallower level if you drill enough
holes in the ground and set off and pressurize
enough places you can also get earthquakes.
They’re just part of life, Riley.
It’s part of living on the Earth.
It’s cool.
