Making Artificial Earthquakes with a Four-Tonne Steel Ball

In Gรถttingen, Germany, there's a four-tonne steel ball that can be raised up a 14-metre tower -- and then dropped in less than two seconds, crashing back to earth. It makes tiny, artificial earthquakes: here's why.
Thanks to all the team at Wiechert'sche Erdbebenwarte Gรถttingen! You can find out more about them here:
Three things I had to cut out of this video, because they didn't quite fit into the story or because I couldn't film them:
The reason the steel ball survived two world wars is because the university's records listed it by use as a "rock-ball", not by composition as a "steel ball" - so no-one melted it down for weaponry.
The observatory team refill that pit every year to make the ground flat, and the ball just digs a hole again. The rock's just being compressed underneath. They joke that, somewhere in Australia, there's a slowly growing hill...
And finally, the ground steams for a little while after the ball hits: it gets rather warm...
Edited by Michelle Martin (@mrsmmartin)
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I'm at viet earthquake observatory in . goating in germany this is the oldest . working seismic station earthquake . detector in the world but there's also a . more unusual bit of scientific equipment . here a four tons steel ball but can be . raised up 14 meters above the ground and . then dropped because it's a lot easier . to set up and calibrate no earthquake . detector if you can make the ground . shake yourself the equipment we have . here started to work 1903 and it's still . working we had was the one who created . the first real working seismometer these . things record on smoked paper this is . ordinary white paper we take the flame . of a paraffin burner to get soot on to. that paper we think we are the only ones . in the world who are doing that we had . had a theory that seismic waves allow . you to look into the inner of our planet . his assistant min trop had to prove . vhat's . theory he started to calculate and he . found out if he takes a ball of about. four tons and drops it then he is . creating a small earthquake an . earthquake big enough to check the . theory of mev hood the research is here . a century ago could create a tiny . artificial earthquake and then measure. it so what . well earth tremors moved through the. ground in two ways the p waves or . primary waves compress the ground back. and forth in the direction that the wave . is traveling squeezing it together . traveling slightly slower are the s . waves the secondary waves which shear . the ground side-to-side and those waves . behave differently in duration and . wavelength and intensity depending on . the ground they're traveling through so . if you're clever and minter up was . clever then you could set up seismic . detectors all round an area create a . small artificial earthquake by say . dropping a four-ton steel ball and use . the reflections from within the earth to . build up a picture of what was below . without having to dig this knowledge . spread all over the world min table got . an invitation to mexico from an oil . drilling company they had an oil field . they asked min table if he could measure . the size of that oil field he said i . don't know we don't have oil fields and . getting him but he accepted the . invitation to mexico and of course he . did not take the ball with him because . in mexico he was allowed was he wasn't . allowed here he was allowed to use . dynamite and he measured the size of . this oil field with an incredible . accuracy. he had the not-so-nice nicknamed the . crazy german who was running around with . bodyguards hiding his equipment intense . because our american friends were very. eager to find out how their works . because that was the license to print . money so a hundred years ago with a much . older release mechanism and probably a . lot more effort that steel ball dropped . for the first time onto what was then . pretty much flat ground nowadays there's . much better equipment for figuring out . what's under the earth's surface but. it's not quite as dramatic it's still . rolling. .

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