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Volume 11, Issue 2
Displaying 1-8 of 8 articles from this issue
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Tatsuhiko WADA1958Volume 11Issue 2 Pages 55-67
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSAn equation of state of forsterite based upon an ionic model has been deduced theoretically and the following results have been obtained.
1) Calculated variations of the density and incompressibility with pressure agree well with those obtained by K. E. Bullen for the B-layer. (Table 1) (Fig. 2)
2) The calculated activation energy value 3.29 e. v. is compatible with the experimental value by Hughes.
3) Variation of the activation energy with pressure is fairly less than expected. (Table 2) Using the data of distribution of electrical conductivity within the B-layer, the temperature gradient within it has been found to be about 1°/km. (Fig. 5)
4) A possibility of the polymorphic transition of forsterite from an olivine structure to a spinel structure is discussed. Comparing the lattice energies for both structures, it is shown that the transition is impossible. (Table 4)View full abstractDownload PDF (1171K) -
Hitoshi TAKEUCHI1958Volume 11Issue 2 Pages 68-75
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSA method is given to calculate tortional frequencies of an elastic sphere of variable density and elasticity. By this method, the tortional frequencies are calculated of the earth, the internal constitution of which is inferred from the study of body wave propagations within it. The period of fundamental tortional oscillation of the earth is shown to be 43.4 minutes. The phase velocity of the corresponding surface wave has a maximum value 6.90km/sec for a wavelength of about 10000km. The decrease of phase velocity for longer wave lengths may be due to the existence of the earth core at the depth of 2900km.View full abstractDownload PDF (662K) -
Ryôsuke SATÔ1958Volume 11Issue 2 Pages 76-86
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDetermination of crustal structures in various regions from observations of the dispersion of Love and Rayleigh-waves has been attempted by many authors. But the methods of analysis of observed data do not seem to be always adequate for the purpose.
Some authors defined the group-velocity by Un=Δ/tn (Δ: epicentral distance, tn: travel time of a certain trough or crest of waves) and the corresponding period by Tn=2(tn+1-tn), and they compared Un-Tn curves with theoretical group-velocity curves constructed under various assumptions of crustal structures. Some other authors defined the wave-length by Ln= UnTn and obtained the phase-velocity cn from the familiar equation Un=cn-Ln(dcn/dLn). They constructed cn-Ln curves.
The present writer investigated the adequacy of these procedures for determining crustal structures.View full abstractDownload PDF (927K) -
Hitoshi TAKEUCHI, Naota KOBAYASHI1958Volume 11Issue 2 Pages 87-101
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSA method is proposed for making nomograms for phase and group velocities of Sezawa waves. In Fig. 2 and 3, are shown the nomograms constructed by using the method for the case when λ′=μ′, λ=μ and ρ=ρ′. As to the notations used, see Fig. 1 below.View full abstractDownload PDF (925K) -
Research Group for Explosion Seismolgy1958Volume 11Issue 2 Pages 102-113
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSAt 01h 05m, Nov. 14, 1954 and at 01h 05m, Aug. 15, 1955, large amounts of explosives were fired near the Lake Nozori, Gumma Prefecture. At 01h 05m, Dec. 5, 1956, 1 ton of explosives was fired near Hokota town, Ibaragi Prefecture. 18 temporary observation stations for the Nozori explosions and 15 stations for the Hokota explosion were set up along the line connecting the Nozori and Hokota shot points. Each station was equipped with high-sensitive electro-magnetic seismometers with amplifiers. By these explosion-experiments the most probable crustal structure of nearly east-west section in the northern part of Kwanto District was deduced. It is shown in Fig. 7a. The depth of the Mohorovicic discontinuity was determined to be 25-30km. The depth of earthquake foci near Mt. Tukuba is generally found to be greater than 30km. Consequently earthquakes near Tukuba evidently occur in the upper part of the mantle.View full abstractDownload PDF (1038K) -
Kyozi TAZIME1958Volume 11Issue 2 Pages 114-115
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (220K) -
Kyozi TAZIME1958Volume 11Issue 2 Pages 115-117
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (299K) -
Kyozi TAZIME1958Volume 11Issue 2 Pages 117-118
Published: June 30, 1958
Released on J-STAGE: March 11, 2010
JOURNAL FREE ACCESSDownload PDF (224K)
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