巻号一覧
3 巻 (1950 - 1951)
- 2 号 p. 44-
- 1 号 p. 7-
前身誌
3 巻, 2 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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本間 正作, 關 彰1951 年 3 巻 2 号 p. 44-48
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーIn our previous report (Jour. Seis. Soc. Japan, 2nd Series, Vol. 2, No. 2 (1949), it was stated that the area of aftershock region (Akm2) and the radius of sensibility circle (Rkm) of several earthquakes in Japan were closely related with each other. Recently, we were able to collect more examples (cf. Table 1 and Figs. 1-9) and investigated these data together with those already reported.
From 12 land shocks and 9 oceanic shocks, we obtained the following relations:
log10A=(1.50±0.07)+(3.16±0.10)R×10-3 for land shock,
log10A=(2.13±0.10)+(2.86±0.13)R×10-3 for oceanick shock, which well support our previous results. (cf. Fig. 10.)
If the radius R of the Great Kwanto Earthquake of September 1st, 1923 be assumed as 700km, instead of 900km., the former formula becomes
log10A=(0.87±0.13)+(4.67±0.19)R×10-3
According to Prof. H. Kawasumi the latter relation is more preferable.抄録全体を表示PDF形式でダウンロード (446K) -
一戸 時雄1951 年 3 巻 2 号 p. 49-56
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーBy modifying the usual bifilar gravimeter, we have constructed a highly sensitive gravimeter named as “Double Bifilar Gravimeter”. Its sensitivity reached 10-10g/mm under usual conditions of the instrument, and the gravity variations by the earth tides were able to be clearly observed.抄録全体を表示PDF形式でダウンロード (635K) -
西武 照雄1951 年 3 巻 2 号 p. 57-61
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーAccording to the quantum theory of solid, the ratio of bulk modulus of a crystal to its rigidity is approximately proportional to density. By computing the ratio from the observed velocity values in the earth's mantle, several discontinuities can be found.
If the density does not decrease in the mantle according to depth, the decrease of the ratio cannot be explained without assuming some change in composition or succesive occurrences of polymorphic transitions. The ratio decreasses from 500km to 800km in deph. It seems reasonable to assume that the layer from 500km to 800km is a transitional one from the viewpoint of crystal theory. No other discontinuous decrease of the ratio can be seen except this layer. 'There are two discontinuities at 1, 000km and 1, 800km. It seems probable that the mantle has one transitional layer and two transitional points and so five layers in all. These layers are
a) 33km-500km
b) 500km-800km
c) 800km-1000km
d) 1000km-1800km
e) 1800km-2800km抄録全体を表示PDF形式でダウンロード (332K) -
貞廣 太郎1951 年 3 巻 2 号 p. 62-65
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーRadioactivities were measured by a G. M. counter at various depths in the Ikuno Copper Mine. Local anomalies and prevalences of penetrating γ-rays were studied.抄録全体を表示PDF形式でダウンロード (466K) -
田治米 鏡二1951 年 3 巻 2 号 p. 66-70
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーThe natural period and voltage-sensitivity of a portable electro-magnetic transducer will change from time to time. In order to be able to discuss amplitudes on the record, it is desirable to check these constants immediately on the spot after the transducer is used in the field. For this purpose, we have devised a simple method and made several experiments. The results show that the voltage-sensitivity can be determined with an error of a few percent.抄録全体を表示PDF形式でダウンロード (413K) -
渡邊 健1951 年 3 巻 2 号 p. 71-76
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーThe fundamental principle of the dynamical method consists in the application of vibrations generated by an oscillator set up on the ground surface. The oscillator, designed by the writer, consists of three steel-plate wheels, each 20cm in diameter, to which are bolted lead plated in order to produce an unbalance force. The sinusoidal elastic waves are generated in the ground. The amplitudes and phase differences at various points in the field under investigation are measured with sensitive electro-magnetic seismographs. Investigating the dynamical amplitude-distance and time-distance curves, the writer determined dynamical qualities-i. e., phase velocity, natural frequency and bedding value of the soil. Method of measurments and analysis of the field data are explained in detail with respect to the actual examples carried out near the Tokyo Station in Aug. 1950.抄録全体を表示PDF形式でダウンロード (550K) -
爆破地震動研究グループ1951 年 3 巻 2 号 p. 77-82
発行日: 1951/03/30
公開日: 2010/06/30
ジャーナル フリーLe 25 Oct. 1950, devait avoir lieu à Isibuti, à 20km environ à l'ouest de Mizusawa, une explosion simultanée avec 57 tonnes d'explosifs. Nous y installâmes 8 observatoires provizoires à des distances convenables du lieu de l'explosion jusqu'à 121km. Pour les signaux de temps nous inscrivions directement sur les sismogrammes les signaux de seconde de l'observatoire astronomique de Tokio par radio JJY (4MC). Le commencement des secousses peut être défini tiès précisément partout sauf à Kogota. Les hodocnrones des débuts des premières ondes et quelque suivantes sont dessinées dans la figure 3.
Deux branches d'hodochrones P1 et P2 sont apparues respectivement dans les observatoires proches et éloignés. Nous avons calculé les vitesses de ces deux phases et avons obtenu: 5.26±0.007km/sec et 6.31±0.017km/sec respectivement. Comme les deux branches se coupent près de l'origine, nous pouvons supposer. qu'il existe une couche peu épaisse, horizontale, à la surface, où la vitesse des ondes longitudinales serait de 5.26km/sec et que repose sur un milieu où la vitesse serait 6.13km/sec. Mais la distance épicentrale du point de rencontre est 9.5±9.74km et l'épaisseur de la couche 1.3±2.7km. L'existence d'une telle couche ne nous parait pas très certaine. Nous avons comparé le resultat avec celui de Prof. T. Matuzawa.
Les phases corrspondant aux oxides S ont été observées seulnient à quelques observatoires. Leui vitesse est 2.37±0.005km/sec., De plus on trouve en quelque observatoires une seconde phase claire qui eat en retard de 1sec. sur les ondes S. Ces deuxièmes S sont peut-être dues à un éboulement au-dessue des chambres après l'explosion.
D'ailleurs le material n'est pas encore sufflsant pour de telles discussions et nous préparons d'autres observations pour les prochaines occasions.抄録全体を表示PDF形式でダウンロード (764K)
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