巻号一覧
18 巻 (1965)
- 4 号 p. 181-
- 3 号 p. 133-
- 2 号 p. 61-
- 1 号 p. 1-
前身誌
18 巻, 4 号
選択された号の論文の7件中1～7を表示しています
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田治米 鏡二1965 年 18 巻 4 号 p. 181-194
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーLovz waves in a layer overlying a half-space are considered. Not only the signal but also free oscillations are excited by a source of a finite duration, resulting in a very complicated wave form. The present investigation is an attempt on the translation of the electromagnetic wave theory after BRILLOUIN (1964) into elastic waves dispersive. The other aim of it is to see theoretically the experimental results which were obtained by the author (1963, 1964). An outline of the wave group is easily understood by the similar treatment to that of BRILLOUIN'S.抄録全体を表示PDF形式でダウンロード (981K) -
(第2報)久本 壮一1965 年 18 巻 4 号 p. 195-203
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーIn the first paper, it was found that the travel time of S wave usually shows remarkable anomaly in eastern Japan. In the present paper, it was assumed that the travel time of S wave shows anomaly only if the S wave passes through a special domain. A trial was made to seek this domain and it was revealed that such a domain exists contiguous to the bottom of the “nest of earthquake hypocenters” in eastern Japan.抄録全体を表示PDF形式でダウンロード (667K) -
岡田 広1965 年 18 巻 4 号 p. 204-218
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーThe relation between displacements and periods when the periodic source is considered has been quantitatively investigated for LOVE waves in stratified two layers, however that, for RAYLEIGH waves in those layers, has been obtained only qualitatively in a theoretical expression by TAZIHE (1957, 1965).
In the present paper, the horizontal and vertical surface displacement as a function of period was calculated for the first six modes of dispersive RAYLEIGH waves for various values of POISSON'S ratio in the superficial layer, the values of other elastic constants being unchanged as follows: μ2/μ1=4, υp1/υp2=0.625, σ2=0.25.
According to a theoretical expression of displacements by TAZIME (1965), the predominance of displacements would be expected at the period of a minimum value of the group-velocity, since the displacements are such expressed as they are proportional to the term (c/U-1), where c and U denote the phase- and group-velocity respectively. However, in the present calculation, a maximum value of the displacement is obtained not always at the period of a minimum value of the group-velocity, but at the period between the minimum and maximum group-velocity in a certain case.
The higher modes of LOVE waves are, in general, inferior in the displacement, regard-less of the values of elastic constants. However, the displacements for dispersive RAYLEIGH waves are predominant not always in the lower mode, but in the higher mode when the value of POISSON'S ratio in the superficial layer is larger than 0.35.
As a result, it was found that the quarter wave-length law always holds in the horizontal and vertical displacement for these predominant periods.抄録全体を表示PDF形式でダウンロード (1431K) -
勝又 護1965 年 18 巻 4 号 p. 219-234
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーThe b's in magnitude-frequency relation n(M)dM=const.×10-bM dM are obtained for various regions in Japan and discussed in some detail. For the above purpose, the magnitude of earthquakes of hypocenter deeper than 60km and earthquakes of smaller magnitude which are not in “The Seismological Bulletin” are obtained and added to the present data. The range of regions for which the parameter b's are obtained, are determined from spatial distribution of earthquakes. In other words, the so-called “nest of earthquakes” are taken as a unit region.
The values of b's are 1.0-1.1 for the magnitude 6 and larger off the Pacific coast of Tohoku-Kwanto districts which is the most active seismic region in Japan for corresponding magnitudes and the b values for the magnitude range of 4 to 5 in other smaller regions, that is, “smaller nests” are around 0.9-1.0.
This result shows that at least for the active seismic regions, there are no remarkable difference of the b values among seismically active regions, also there is no significant difference of values between crust and upper mantle.
Also, the relation of b, m and β are discussed, where m is the parameter in the amplitude-frequency relation n(a)da=const. a-m da and β is the parameter in the intensity-frequency relation n(I)dI=const, ×10-βI dI.抄録全体を表示PDF形式でダウンロード (1394K) -
田中 寅夫, 三雲 健1965 年 18 巻 4 号 p. 235-244
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーAn attempt has been made by the use of digital filters to detect anomalous changes of ground deformation from its tiltmetric record.
It was found that the band-pass filters designed on the basis of the results of Fourier analysis can be effectively used for this purpose, eliminating tidal and meteorological variations with known frequencies. A small change of tilt, which might be related to local earthquakes in Wakayama region, is seen on some of the filtered records, but more observations are needed for a firm conclusion to this point.
Further attempts are under way by the present technique to see longer periods crustal deformation on the tiltmetric and extensometric records.抄録全体を表示PDF形式でダウンロード (800K) -
脈動の到来方向と Orbital Motion との関係池上 良平1965 年 18 巻 4 号 p. 245-254
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーThe most popular means to obtain the direction from which microseismic waves approach are the tripartite method and the method based on the orbital motion of the ground particle. However, it has been clarified by the theoretical researches on the Rayleigh-type dispersive waves that even among the waves having apparently Rayleigh-type orbits, there can exist two kinds of waves, one undergoing retrograde motion and the other undergoing progressive motion.
In the present study, the writer examined the winter microseisms that were recorded during the period from November 1964 to February 1965. The directions of approach of these microseisms were determined by the tripartite method, and also the orbital motions of the ground surface particles were drawn on the basis of the three-component seismograms, so as to compare the results of the two different methods. In consequence, 221 waves were recognized to have typical Rayleigh-type orbits, about 40% of which have undergone retrograde motion and about 20% are of progressive motion. Thus, it has become clear that the directions from which microseismic waves approach should not be determined merely by their orbital motion, because it would involve a great danger.抄録全体を表示PDF形式でダウンロード (912K) -
田治米 鏡二1965 年 18 巻 4 号 p. 255-257
発行日: 1965/12/25
公開日: 2010/03/11
ジャーナル フリーPDF形式でダウンロード (394K)
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