Geophysical Abstracts 152 January-March 1953

SEISMOLOGY 37
waves were determined as follows : Pn, 8.19 krnps ; Pg, 5.46 krnps ; P*, 6.38 kmps ;
Bn 4.39 kmps; and Sg, 3.01 kmps. Two new waves of mixed character, denoted
as Px, and Pa* were discovered. These latter apparently start from the focus
in the granitic layer as transverse waves; at the boundary between basalt and
yranite, Px is transformed into a longitudinal wave and arrives as such at the
surface, while Pa* is transformed into longitudinal at the Mohorovic'ic discon­
tinuity. Another wave Rl Pg, (the reflected Pg wave), was also traced. This
is a longitudinal reflected from Mohorovieic discontinuity without change in
character. Two transverse waves and two transverse surface waves were also
discovered. S. T. V.
14302. Ergin, Kazirn. Amplitude of PcP, PcS, 808, and ScP in deep-focus earth­
quakes : Seismol. Soc. America Bull., v. 43, no. 1, p. 63-83,1953.
A systematic study has been made of the ratios of (displacement/period) of
PcP, PcS, 8c8, and ScP to that of the corresponding incident wave (for example,
(displacement/period) PCP/ (displacement/period) p), using intermediate and
deep-focus earthquake seismograms. The results indicate that the observed
ratios of the horizontal components of the waves that are reflected as P waves
(i. e., PcP/P and ScP/S) and that of the vertical component of the waves that
are reflected as 8 waves (i. e., ScS/8 and PcS/P) at the mantle-core boundary
are considerably larger than the theoretical ones, whereas the observed ratios
of the vertical component of the first group and that of the horizontal component
of the second group are in fairly good agreement with the theoretical values.
Theoretical computations were based on the assumption that in the case of a
longitudinal wave the vibration is in the direction of propagation and in the case
of a transverse wave the vibration is perpendicular to the direction of propaga­
tion. It is further found that the behavoir of the direct P and S waves is in
accord with the theory, but the vibration of the ground is not in the direction of
propagation for PcP and ScP and is not perpendicular to the direction of propa­
gation for PcS and ScS. Author's Abstract
14303. Bullen, K. E., and Burke-Gaffney, T. N. Detection of 8 waves in the
earth's inner core: Nature, v. 170, no. 4324, p. 455, 1952.
Examination of Riverview records since 1909 and International Seismological
Summary data has demonstrated chiefly the relatively small number of records
on which the existence of PKJKP is likely to be verified. Apparently unless
records on which microseisms are negligible are available, the amplitude of
PKI-KP must be at least 20 /* in order that PKJKP be observed. M. C. R.
14304. Kisslinger, Carl. The effect of variations in chemical composition on the
velocity of seismic waves in carbonate rocks: Geophysics, v. 18, no. 1,
p. 104-115,1953.
To study variations in velocity in carbonate rocks, field measurements were
made in dense, crystalline to lithographic, calcitic and dolomitic limestones in
the St. Louis formation. Twelve geophones were used at a spacing of 50 centi­
meters. Comparison of chemical and velocity data indicates dolomitization may
have an effect on velocity, but the effect apparently depends on the dolomitization
process. Volume for volume replacement of calcite by dolomite tends to increase
the velocity, but dolomitization giving rise to local porosity tends to decrease the
velocity. M. C. R.