New results of P- and S-wave velocity measurements on two Apollo 12 rocks, 12052 and 12065, under pressures up to 10 kbars are presented. These rocks are basalt-like crystalline rocks with a bulk density of about 3.26 g/cm^3 and a mean atomic weight of 24.5. Like the Apollo 11 rocks, the velocities and the wave transmission efficiency are surprisingly low at low pressures despite their

relatively tight texture; at pressures below 200 bars, Q is estimated to be less than 100. The velocities increase very rapidly with pressure and approach 7.0 km/sec (P wave) and 3.9 km/sec (S wave) towards 10 kbars. No evidence is found for an increase of Q at 1 MHz with a reduction of the ambient pressure to 3 x 10^(-3) torr

Hamano, Y.

Kanamori, H.

Mizutani, H.

Caltech Authors - Main

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Proceedings of the Second Lunar Science Conference, Vol. 3, pp. 2323-2326 
The M.l.T. Press, 1971. 
Elastic wave velocities of Apollo 12 rocks at high pressures 
H. KANAMORI 
Earthquake Research Institute, University of Tokyo, Tokyo, Japan 
and 
H. MIZUTANI and Y. HAMANO 
Geophysical Institute, University of Tokyo, Tokyo, Japan 
(Received 20 February 1971; accepted 24 March 1971) 
Abstract-New results of P- and S-wave velocity measurements on two Apollo 12 rocks, 12052 and 
12065, under pressures up to 10 kbars are presented. These rocks are basalt-like crystalline rocks with 
a bulk density of about 3.26 g/cm3 and a mean atomic weight of 24.5. Like the Apollo 11 rocks, the 
velocities and the wave transmission efficiency are surprisingly low at low pressures despite their 
relatively tight texture; at pressures below 200 bars, Q is estimated to be less than 100. The velocities 
increase very rapidly with pressure and approach 7.0 km/sec (P wave) and 3.9 km/sec (S wave) 
towards 10 kbars. No evidence is found for an increase of Q at I MHz with a reduction of the ambient 
pressure to 3 x 10-3 torr. 
THIS REPORT presents new results of P- and S-wave velocity measurements on two 
Apollo 12 crystalline rocks, 12052,35 and 12065,68 under pressures up to 10 kbars at 
room temperature. The chemical composition of these rocks has been given by 
LSPET (1970) and KusHIRO and HARAMURA (1971). These two rocks closely resemble 
one another in composition and are, on the whole, of basaltic composition. The 
mean atomic weight of these rocks as calculated from the data given by KusHIRO 
and HARAMURA is 24.5 and is significantly larger than that of ordinary terrestrial 
basalts. 
The measurement method described by MIZUTANI et al. (I 970) and the high-
pressure system used by KANAMORI and MIZUTANI (1965) are employed. Since the 
method of MIZUTANI et al. was originally devised for very small samples (several 
millimeters in dimension), it ensures a high accuracy when applied to samples the 
size of the Apollo 12 rocks; the approximate dimension of the samples is 1 x 1 x 2 
cm3 . At pressures above 1 kbar, the accuracy of the present measurement is probably 
better than 0.7 % for P waves, and 1.5 % for S waves. At pressures below 200 bars, 
however, the wave transmission efficiency is so poor (low Q) that the onset of the 
signal becomes blunt and the accuracy drops considerably. 
The results are summarized in Table 1 and Figs. I and 2; Figs. 1 and 2 give the 
original readings, and Table I lists the smoothed values. Because the samples have 
large compressibilities, the correction for the pressure shortening of the sample is 
estimated. This correction is made according to COOK (1957) but the difference 
between the isothermal and adiabatic bulk modulus is ignored. In such case the true 
P- and S-wave velocities cx.(P) and {J(P) at a pressure P can be obtained from the 
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2324 H. KANAMORI, H. MIZUTANI, and Y. HAMANO 
Table 1. Bulk density and velocity (in km/sec) of samples 
Pressure (kb) 
Sample Wave ---------------------------
0.0 0.2 0.5 1.0 2.0 3.0 
12052 p 4.30 4.90 5.55 5.93 6.32 6.55 
p = 3.27 g/cm3* s 2.59 2.70 2.84 3.03 3.34 3.55 
12065 p 3.27 4.44 5.21 5.80 6.24 6.47 
p = 3.26 g/cm3* s 2.14 2.42 2.73 3.04 3.38 3.54 
* No correction is made for the porosity. 
7.0 
6.0 
u 
:: 5.0 
....... 
E 
-"' 
~4.0 
Q) 
> 
3.0 
12052, 35 
5 
Pressure, kb 
10 
5.0 7.0 
6.80 6.90 
3.74 3.82 
6.74 6.86 
3.72 3.82 
Fig. 1. The P- and S-wave velocities of sample 12052,35 as a function of pressure. 
uncorrected P- and S-wave velocities r:x.'(P) and {J'(P) by 
r:x.(P) {J(P) [ 1 (P dP J--1 
r:x.'(P) = (3'(P) = l + 3p0 Jo (r:x.'(P)2 - t/3'(P)2) 
10.0 
7.01 
3.88 
6.96 
3.86 
where p0 is the density at 0 pressure. Numerical integration of r:x.'(P) and {J'(P) listed in 
Table 1 leads to a correction of only 0.4 % at 10 kbars; this correction is therefore not 
meaningful in view of other experimental uncertainties. It may be argued that the 
static compressibility data are more appropriate for this correction than the ultrasonic 
data. The static compression data on the Apollo 12 rocks reported by STEPHENS 
and LILLEY (1971) lead to a correction of about 0.8 % (at 10 kbars) which is still 
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Elastic wave velocities of Apollo 12 rocks at high pressures 
6.0 
u 
Cl> 
en 
...... 
E 5.0 
..>i: 
u 
0 
Ci> 4.0 
> 
3.0 
12065, 68 
5 
Pressure, kb 
10 
Fig. 2. The P- and S-wave velocities of sample 12065,68 as a function of pressure. The 
solid circle at 0 pressure indicates the velocity obtained after the pressure run. 
2325 
insignificant. The densities are measured by the Archimedes method at 0 (atmos-
pheric) pressure, and no correction is made for the porosity. 
The overall elastic and anelastic behaviors of the Apollo 12 crystalline rocks are 
surprisingly similar to those of the Apollo 11 rocks reported by KANAMORI et al. 
(1970) and SCHREIBER et al. (1970). The rapid increase of the velocity for the initial 
2 kbar pressure increase found for the Apollo 11 rocks is also typical of the Apollo 12 
rocks. Although the velocity of the Apollo 12 rocks is slightly larger than that of the 
Apollo 11 rocks, it is still consistent with the travel times obtained by the Apollo 12 
seismic experiments (LATHAM et al., 1970), if the vertical velocity gradient beneath the 
lunar surface is caused by compaction alone. Thus the conclusion that the shallow 
part (to a depth of about 20 km) of the mare region consists of relatively homogeneous 
basalt-like material (KANAMORI et al., 1970; LATHAM et al., 1970) seems to be sub-
stantiated. 
The wave transmission efficiency, at low pressures, of the Apollo 12 samples is 
surprisingly poor; it is much poorer than would be expected from the apparently 
tight textures of these samples. The wave transmission efficiency is frequently specified 
by the quality factor Q, where 27T/ Q is the fractional loss of energy per cycle of osci11a-
tion of a vibrating system. Although the value of Q could not be measured accurately, 
a crude comparison of the amplitude of ultra-sonic waves transmitted through these 
lunar rocks with those through ordinary terrestrial rocks suggests that the value of Q 
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2326 H. KANAMORI, H. MIZUTANI, and Y. HAMANO 
cannot be larger than 100 at pressures below 200 bars. This value may be compared 
with the value Q ,......, 20 obtained by WANG et al. (1971) at a frequency of a few Hz, and 
with the value on the order of 100 obtained by WARREN et al. (1971) over a frequency 
range of 40 to 13 kHz. These values are much smaller than that required to explain the 
seismic ringing in terms of a diffusive and a dispersion process (LATHAM et al., 1970). 
PANDIT and TOZER (1970) suggested on an experimental basis that, when the ambient 
pressure is reduced to 10- 2 torr, the value of Qin porous terrestrial rocks increases by 
a factor of 5 over the value measured at I atmosphere. In order to see whether the 
pressure effect on Q is significant or not, we bonded 1 MHz transducers directly on the 
sample 12065,68, suspended it by a thin wire in a vacuum chamber, and observed 
the change with pressure of the decay rate of the ultra-sonic reverberation. No signifi-
cant change of the decay rate, however, was observed over the range from 1 atmosphere 
to 3 x 10-3 torr. Since this experiment was made on a sample which had been sub-
jected to high confining pressures during the velocity measurements, it is possible that 
the lossless "welded" contact had been destroyed and that the frictional dissipation 
became significant. It is also possible that the scattering at the grain boundaries is so 
large at such a high frequency, 1 MHz, that any pressure effect on the attenuation is 
masked. In any case, the increase of Q with a reduction of ambient pressure could not 
be confirmed in our experiment. 
REFERENCES 
CooK R. K. (1957) Variation of elastic and static strains with hydrostatic pressure; A method for 
calculation from ultrasonic measurements. J. Acoust. Soc. Amer. 29, 445-449. 
KANAMORI H. and MIZUTANI H. (1965) Ultrasonic measurement of elastic constants of rocks under 
high pressures. Bull. Earthquake Res. Inst. Tokyo Univ. 43, 173-194. 
KANAMORI H., NuR A., CHUNG D. H., WoNES D., and SIMMONS G. (1970) Elastic wave velocities of 
lunar samples at high pressures and their geophysical implications. Science 167, 726-728. 
KusmRo I. and HARAMURA H. (1971) Major element variation and possible source materials of 
Apollo 12 crystalline rocks. Science 171, 1235-1237. 
LATHAM G., EWING M., DORMAN J., PRESS F., TOKSOZ N., SUTTON G., MEISSNER R., DUENNEBIER 
F., NAKAMURA Y., KovACH R., and YATES M. (1970) Seismic data from man-made impacts on the 
moon. Science 170, 620-626. 
LSPET (Lunar Sample Preliminary Examination Team) (1970) Preliminary examination of the 
lunar samples from Apollo 12. Science 167, 1325-1339. 
MIZUTANI H., HAMANO Y., foA Y., and AKIMOTO S. (1970) Compressional wave velocities of fayalite, 
Fe2Si04 spinel, and coesite. J. Geophys. Res. 75, 2741-2747. 
PANDIT B. I. and TOZER D. C. (1970) Anomalous propagation of elastic energy within the moon. 
Nature 226, 335. 
SCHREIBER E., ANDERSON 0. L., SOGA N., WARREN N., and SCHOLZ C. (1970) Sound velocity and 
compressibility for lunar rocks 17 and 46 and for glass spheres from the lunar soil. Science 167, 
732-734. 
STEPHENS D.R. and LILLEY E. M. (1971) Pressure-volume properties of two Apollo 12 basalts. Second 
Lunar Science Conference (unpublished proceedings). 
WANG H., TODD T., WEIDNER D., and SIMMONS G. (1971) Elastic properties of Apollo 12 rocks. 
Second Lunar Science Conference (unpublished proceedings). 
WARREN N., SCHREIBER E., SCHOLZ C., MORRISON J., KUMAZAWA M., and ANDERSON 0. L. (1971) 
Elastic and thermal properties of Apollo 12 and Apollo 11 rocks. Second Lunar Science Confer-
ence (unpublished proceedings). 
© Lunar and Planetary Institute • Provided by the NASA Astrophysics Data System 


Elastic wave velocities of Apollo 12 rocks at high pressures

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Elastic wave velocities of Apollo 12 rocks at high pressures

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