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Internal structure of the Earth and it's composition

  1. Oct 30, 2016 #1
    I was wondering how they managed to know the internal structure of earth and it's composition while there is lava and it's very hot such that no any instruments can get there...............seriously I am confused
  2. jcsd
  3. Oct 30, 2016 #2

    Simon Bridge

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    The internal structure of the earth is revealed through earthquakes and mathematical models.
  4. Oct 30, 2016 #3
    When I was first interested in the internal structure and composition of the earth in 1968, all we had were seismic data, experimental work on silicate melts and the rocks on the earth's surface. The models were essential built on that data, throwing in some meteorite data and what we knew of astrophysical phenomena. By melting a basalt, we can approximate what the temperature of a basaltic magma could be. Nucleosynthesis, BBN and from supernovae gave insights into what the general composition of the earth is likely to be. Seismic, magnetic and gravity data refined the model. 15 years later Sunoco bought into seismic programs intended to study the core. I justified that expense because it also revealed crustal information. Today, geophysical techniques are defining the structure in greater detail. Diamond anvil cell studies have totally opened the possible scenarios for composition and structure of the inner earth. Data from those studies give us possible composition of rocks and minerals, as well as melting and cooling temperatures and pressures.
  5. Oct 30, 2016 #4
    some say they use seisimic wave particularly body waves to study the internal structure of the earth but for what I know the method tells us whether that particular place it's in solid state or liquid state......still I can't understand how they managed to know the temperature
  6. Oct 31, 2016 #5
    The Earth’s Centre is 1000 Degrees Hotter than Previously Thought

    This article also mentions the use of the diamond anvil cell. Nine years before this paper was published, a "new" determination of the core's temperature was published. In a nutshell, this describes the process by which the model is built up and modified. Models are built on the prevailing data only to be modified as new techniques are developed. It's all the better when the new model can explain other phenomena. In this case, the higher temperature calculation made for a more workable geodynamo model and opened more options for the composition of the core. This, in turn, may help explain the distribution of primary carbon in both the core and mantle. Stay tuned to your local science station for weekly updates.
  7. Nov 1, 2016 #6


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    There probably isn't an easy answer to this without getting into a technical book or something. I expect that our measurements through seismic waves reveals much more than just the phase of the rock, but I don't know what all that might be.
  8. Nov 1, 2016 #7
    The physical properties of the deeper part of the earth are controlled by volume, rather than pressure. That's one property that has been worked out in great detail utilizing seismic waves. We've now gone to studying electron spin in iron the minerals of the deep mantle to understand the volume changes. While seismic waves in their simplest form are still used to determine structure and other aspects of the inner earth, the processing of the data has evolved. Seismic tomography is an example of that. 3-D imaging is one of the current applications. An excellent book is New Theory of the Earth by Don Anderson. It's very readable.
  9. Nov 1, 2016 #8
  10. Nov 1, 2016 #9
    I had the early version and bought the New TOE when it came out. I never looked at the Caltech pdf before, but got stoked looking at it today. Thanks for posting that link.
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