We have identified the seismic phase PKJKP, traveling through the inner cor
e of the Earth as a shear wave, in intermediate-period (2-10 s) records of
the deep 1996 Flores Sea earthquake at eight stations of the French seismic
network. This constitutes direct evidence of the solidity of the inner cor
e which, while generally recognized, was until now only inferred from indir
ect evidence. The arrival times on stacked seismograms require a shear-wave
velocity at the top of the inner core B-ICB = 3.65 km/s in agreement with
values suggested from normal mode observations. Julian et al.'s 1972 observ
ation of a lower velocity (2.95 km/s) is easily reconciled with our result
if interpreted as the surface reflection pPKJKP. The high Poisson ratio (v
= 0.44) can be reconciled with a normal crystalline structure without invok
ing partial melting on account of the overwhelming pressure at the center o
f the Earth. (C) 1998 Elsevier Science B.V. All rights reserved.