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Featured Rethinking the Earth's core

  1. Mar 14, 2017 #21
    Because we make a model of the Earth that includes a solid core and predict when and where the energy from an earthquake would arrive. Then we look at seismic recordings of all the earthquakes that have ever got recorded and we see that our model fits the data (it predicts what we observe). Then some time in the future an earthquake happens and we can tell you exactly where to look to find that little squiggle that was caused by the wave that bounced off the core. You look at the seismic recordings for a station in Mozambique and sure enough at 12.45 on the 18th of January GMT there's that little squiggle in the recording which has a wavelet with exactly the size and shape we predicted.

    There are other, independent, observations of the so-called "PKJKP" phase --- a shear wave passing through the inner core --- that would necessitate that inner core is solid.

    You get this sort of info by looking at data from multiple recording stations. There are people who do this sort of thing for a full time job. See here for a database of loads of earthquakes: http://www.globalcmt.org/CMTsearch.html
     
    Last edited: Mar 14, 2017
  2. Mar 14, 2017 #22

    davenn

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  3. Mar 14, 2017 #23

    1oldman2

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    That says it all. :ok:
    Here are some abstract links to papers from the meeting I pulled the original post from. The BBC article I cited was a spin off from these. They are rather technical by my standards but they give an idea of how the concept was developed.
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/153611
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/146476
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/160185
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/146572
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/128201
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/136411
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/174036
    https://agu.confex.com/agu/fm16/meetingapp.cgi/Paper/196402
     
  4. Mar 15, 2017 #24
    In terms of the "light" element in the core. It is important to reiterate that we are talking about ~5%.

    Nobody doubts that 95% is made of iron and nickel.
     
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