WEBVTT
Kind: captions
Language: en

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I'm at Wiechert's Earthquake Observatory
in Göttingen, Germany.

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This is the oldest working seismic station,
— earthquake detector — in the world.

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But there's also a more unusual bit
of scientific equipment here:

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a four-ton steel ball that can be raised up
14 metres above the ground

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and then dropped,

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because it's a lot easier to set up
and calibrate an earthquake detector

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if you can make the ground shake yourself.

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- The equipment we have here
started to work in 1903,

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and it's still working.

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Wiechert was the one who created
the first real working seismometer.

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These things record on smoked paper.

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This is ordinary white paper.

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We take the flame of a paraffin burner
to get soot onto that paper.

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We think we are the only ones in the world
who are doing that.

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Wiechert had a theory
that seismic waves allow you

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to look into the inside of our planet.

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His assistant, Mintrop, had to
prove Wiechert's theory.

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He started to calculate, and he found out
if he takes a ball of about four tonnes

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and drops it, then he is
creating a small earthquake,

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an earthquake big enough
to check the theory of Emil Wiechert.

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- The researchers here a century ago
could create a tiny artificial earthquake

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and then measure it.
So what?

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Well, earth tremors move
through the ground in two ways.

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The P-waves, or primary waves,
compress the ground back and forth

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in the direction that the wave is travelling,
squeezing it together.

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Travelling slightly slower are the S-waves,
the secondary waves,

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which shear the ground side-to-side.

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And those waves behave differently,
in duration, and wavelength, and intensity,

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depending on the ground
they're travelling through.

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So, if you're clever,
and Mintrop was clever,

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then you could set up seismic
detectors all round an area,

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create a small artificial earthquake
by, say, dropping a four-ton steel ball,

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and use the reflections
from within the earth

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to build up a picture of what was below
without having to dig.

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- This knowledge spread
all over the world.

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Mintrop got an invitation to Mexico
from an oil-drilling company.

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They had an oil field. They asked Mintrop
if he could measure the size of that oil field.

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He said, "I don't know. We don't
have oil fields in Göttingen,"

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but he accepted the invitation to Mexico,

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and of course he did not
take the ball with him,

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because in Mexico he was allowed
what he wasn't allowed here.

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He was allowed to use dynamite.

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And he measured the size of this oil field
with incredible accuracy.

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He had the not-so-nice nickname
The Crazy German.

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He was running around with bodyguards,
hiding his equipment in tents,

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because our American friends were very eager
to find out how that works,

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because that was the
licence to print money.

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- So, 100 years ago, with a
much older release mechanism,

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and probably a lot more effort,
that steel ball dropped for the first time

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onto what was then
pretty much flat ground.

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Nowadays there's much better equipment

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for figuring out what's under
the earth's surface but, uh,

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it's not quite as dramatic.

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- I told you your camera would fall...!
- [laughter]

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It's still rolling!