On the Presence of Liquid in Earth's Inner Core
S. C. Singh,
12*
M.
A. J. Taylor,
2
J. P. Montagner
1
Seismological studies indicate that the inner core of
Earth is anisotropic for compressional waves (P waves), and
has low shear wave (S wave) velocity, and high seismic
attenuation. Using an effective medium theory for composite materials,
we show that the presence of a volume fraction of 3 to 10% liquid in
the form of oblate spheroidal inclusions aligned in the equatorial
plane between iron crystals is sufficient to explain the aforementioned seismic phenomena. Variation of S-wave velocity between the
polar axis and equatorial plane is more sensitive to the addition of liquid than that of P waves. The liquid could arise from the
presence of dendrites or a mixture of elements other than iron that
exist in liquid form under inner-core conditions.
1 Départment de Sismologie, Institut de
Physique du Globe de Paris, 4 Place Jussieu-75252, Paris Cédex
05, France.
2 Bullard Laboratories, University of
Cambridge, Cambridge, CB3 0EZ, UK.
*
To whom correspondence should be addressed. E-mail:
singh{at}ipgp.jussieu.fr
