MadSci Network: Earth Sciences
Query:

Re: Conditions at CENTER of Earth's Core

Date: Wed Aug 16 12:44:42 2000
Posted By: Eder Molina, Researcher PhD, Dept. of Geophysics, Institute of Astronomy and Geophysics - USP
Area of science: Earth Sciences
ID: 956813821.Es
Message:

The pressure at the center of the inner core is about 3.64 x 10^12 dynes 
per centimeter squared, and the temperature should be near 5000 degrees, 
according the measurements and adjustment to the high pressure physics 
models.
The comparison of the composition of the Earth with meteorites and
the behavior of seismic waves and the inertia moment of the Earth, as
well geomagnetic field models, suggests the inner core is composed by
Fe, Ni and S (more than 99% is Fe and Ni), with some little amounts of
O and Si. These Fe, Ni and S are present forming an alloy. For sure the
behavior of these materials are different than they are at surface,
because the great pressure and temperature conditions. This is a big
problem in using indirect data to try to determine the composition
and properties of this regions, because we have to obtain lab data
with great pressures and extrapolate the results in order to obtain
the best approximation.
The strength of the magnetic field and eletric current in this
region is unknown, and even the most elaborated magnetohydrodinamic
models have to make some assumptions and simplifications in order
to be feasible to calculate.
I suggest the book "Physics and Geology", from Jacobs, Russel & Wilson,
McGraw-Hill, second edition, 1974, where you can find many detailed 
information about these data and models.

Best regards

Eder C. Molina
eder@iag.usp.br
Dept. of Geophysics
University of Sao Paulo
BRASIL


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