The crustal structure in Wakayama District was derived from close observations of local and near earthquakes at network stations spread over the area. Laboratory experiment on bed rocks was also made to get reference data on seismic velocities.
The propagation velocities of the P- and S-waves and the layer thickness obtained, are: V_p=4.3km/sec, V_s=2.4km/sec, h₁=4km for the sedimentary layer, V_p=5.5km/sec, V_s=3.2km/sec, h₂=7km for the granitic layer, V_p=6.1km/sec, V_s=3.5km/sec, h₃=15km for the basaltic layer, and V_p=8.0km/sec, V_s=4.5km/sec for the mantle surface, respectively. The crustal depth to the Mohorovicic discontinuity in this region is estimated to be about 26km.
The spatial distribution of foci of micro-earthquakes in the northern part of the district, is confined above the granitic layer.

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The seismic waves due to the great nuclear explosions in the central Pacific Ocean (Bikini Atoll) in June and July 1958 were recorded by routine seismographs at the Abuyama Seismological Observatory of Kyoto University.
The remarkable result was that we found a new kind of wave-group which has the following properties on the records of long-period seismograph. The wave in this group is of a period 9 to 1 minute and its propagation velocity is about 300m/s. The arrival time is about 3 hours later than that of seismic P-wave. These properties are similar to those of the microbarographic oscillations produced by the nuclear explosions, and the phenomena can hence be attributed to the effect of atmospheric pressure fluctuations upon the inertia mass of the seismograph.

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This is a note on the program for Bendix G-15D computer prepared by F. Press and H. Takeuchi to calculate Love wave dispersion using Haskell's matrix iteration method. By this program the phase and group velocities are obtained corresponding to a specified wave length of Love wave on up to 39 homogeneous solid layers lying on a homogeneous solid half-space.

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By means of the program presented in this note, phase and group velocities of Rayleigh wave can be obtained on Bendix G-15D for a specified wave length on up to 20 homogeneous solid layers. If necessary, a liquid layer lying on the solid layers may be taken into account in the program.

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Using the variational calculus method developed in previous papers, we attack the mantle Love wave problem for the model earths by Jeffreys and Gutenberg. Contrary to the conclusion from the corresponding mantle Rayleigh wave problem, the Jeffreys model gives better agreement with observations of mantle Love waves than the Gutenberg model, in which there is a low velocity layer at a depth of about 150km.

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In the previous paper, the writer reported results of systematic calculations of the vertical distribution of amplitudes and particle orbits to clearify the general properties of M₁₁ waves which are propagated along the surface of a superficial layer overlying a semi-infinite elastic medium.
It is commonly believed that the particle orbit for M₁₁ waves at the surface is of a retrograde rotation to the direction of wave propagation. By the writer's investigation, nevertheless, it is found that the particle orbit for waves of which the wavelengths are longer than about 4.6H (H: thickness of the superficial layer), changes its rotational direction, if the substratum is rigid.
Though M₁₁ waves are of one type of branch waves, they are classified into two groups of different types of particle orbit depending upon the structure and the wavelength as above mentioned. This shows that the particle orbit does not indicate the general properties of M₁₁ waves. In other words, it is unreasonable to decide the type of M₁₁ waves only by the rotational direction of the particle orbit, on the basis above mentioned.
In order to see whether this complexity also occurs for M₂₁ waves or not, the writer studied vertical distribution of amplitudes and particle orbits for M₂₁ waves which are of another type of dispersive Rayleigh wave.
In general, the rotational direction of the particle orbit is an anti-retrograde one to the direction of wave propagation, but if the wavelengths are longer than about 4.6H, the particle orbit changes its rotational direction with the increase of the phase velocity, even for the same wavelength. Consequently, a line which divides the existence domain in two parts regarding the phase velocity can be obtained. In the lower velocity part, the rotational direction of the particle orbit is an anti-retrograde one, while on the other hand in the higher velocity part, it is a retrograde one. This complexity for M₂₁ waves is comparable with that for M₁₁ waves.
In accordance with the fact that the particle orbit for M₁₁ waves changes its rotational direction in the existence domain. There must be a line which devides the domain into two parts with respect to the rotational direction of the particle orbit for M₁₁ waves. In the previous paper, the writer could not get such a line. The reason seems to be that the line for M₁₁ waves is so close to the μ=∞ dispersion curve that it could not be distinguished.
These complexities for both M₁₁ and M₂₁ waves occur only at and near the surface, and the rotational direction of the particle orbit at a point of some depth in the superficial layer is similar to what is usually believed.

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