All issues
Successor
Volume 4 (1956)
- Issue 3 Pages 85-
- Issue 2 Pages 31-
- Issue 1 Pages 1-
Volume 4, Issue 2
Displaying 1-9 of 9 articles from this issue
- |<
- <
- 1
- >
- >|
-
Sushil CHANDRA DAS GUPTA1956 Volume 4 Issue 2 Pages 31-40
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSSeveral attempts have been made to explain the microseisms, the latest being that of Longuet-HIGGINS based on the idea that they are produced by stationary waves. In this paper the author has attempted to show that in case of storms, microseisms are also likely to be generated by progressive waves. The character of microseisms has been proved to be of the RAYLEIGH type approximately. The average velocity and wave length of microseisms have been shown to agree approximately with the observational results referred to in this paper. The period-relation observed by BERNARD and DEACON viz, that the period of microseisms is half the period of sea-waves supposed to generate them, is also shown to agree. The ratio of horizontal and vertical maximum amplitudes has been found and has been shown to depend on the geological structure and not on the distance. In conclusion the possible reason for absence of microseisms on the approach of monsoons has been given as noted by GHERZI.View full abstractDownload PDF (740K) -
Yasuo SATO1956 Volume 4 Issue 2 Pages 41-42_2
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSNomographs for the phase- and group-velocity of Love-waves were made. Such nomographs were already made by the same author a few years ago, but the present ones are more convenient for the practical work of seismometry because of the range of parameters and the precision obtainable.View full abstractDownload PDF (576K) -
Yasuo SHIMAZU1956 Volume 4 Issue 2 Pages 43-47
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSChemical structure of a simplified model of the planet of which the components are Fe-Si-O is discussed. Chemical equilibrium and hydrostatic equilibrium are assumed and emphasis is placed on gravitational separation due to density differences and chemical interaction among components, which control the equilibrium arrangement of stable phases.It is concluded that the present gravitational field of the earth is too strong for reasonable arrangement of the components.
Models with probable gravitational field are discussed and the following conclusions are obtained; (a) in 2, 000°K isothermal model, Fe2SiO4 content shows a maximum at a certain depth and SiO2 and FeO which are at shallower and deeper depths respectively will disappear soon; (b) in 2, 000°K (surface)→6, 000°K (center) model, the radius of the Fecore is one-half of the earth's radius. The mantle is composed of Fe2SiO4, SiO2 and isolated O.View full abstractDownload PDF (413K) -
Michiyasu SHIMA1956 Volume 4 Issue 2 Pages 49-51
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSTemperature distributions within the mantle have been calculated by the modern theory of solid, on the assumptions that the thermal state is nearly stationary at present and there is only a conductive heat flow within the mantle. The main results obtained are as follows. Under the above assumptions, temperature distributions with γG less than 2.25 cannot be obtained in the B-layer (413-1000km). The ternperature gradient there is nearly constant and increases gradually with depth in the D-layer. (1000-2898 km).
Notations. ρ: density, ρ0: density at p=0 and T=0, p: pressure, T: temperature, r:distance from the earth's centre, g: acceleration of gravity, KT: isothermal bulk modulus, KS: adiabatic bulk modulus, α: coefficient of thermal expansion, γG: GRUNEISEN'S parameter, φ: KS/ρ, υp: velocity of P-wave, υs: velocity of 8-wave, A: mean atomic weight, N: LOSCHMIDT'S number, λ, μ, m, n, l: LAME'S constants, K: thermal conductivity, P: rate of generation of heat per unit volume, Cυ: specific heat at constant volume, Cp: specrfic heat at constant pressure, δ: constant relating to crystal structure.View full abstractDownload PDF (245K) -
Keiiti AKI1956 Volume 4 Issue 2 Pages 53-62
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSIn connection with the earthquake energy problem, the thermal processes which can result in the steady accumulation of necessary energy somewhere close to the bottom of the earth's crust has been investigated. With the aid of experimental and theoretical laws concerning thermal convections, some informations about the physical state at the place have been obtained.View full abstractDownload PDF (937K) -
Chuji TSUBOI1956 Volume 4 Issue 2 Pages 63-66
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSVarious facts appear to suggest that one continuous field of mechanical stress developed in the earth's crust has a certain upper limit for its voluminal extent. The ultimate mechanical stress energy that can be stored up in this whole volume until a break-down takes place in it may be identified with the energy of the largest possible earthquake. The energy deduced on this hypothesis agrees well with those of the actual largest earthquakes. The area A in which aftershocks occur in association with a major earthquake has been found by UTSU and SEKI regularly to increase with the magnitude M of that main shock. This relation, when combined with the magnitude-energy relation due to GUTENBERG and RICHTER, yields a formula
E=6×102×A1·5.
The numerical values of the coefficient and of the exponent of A in this formula can be well explained by the hypothesis stated above regarding the spatial distribution of the stress energy within the earth's crust.View full abstractDownload PDF (366K) -
Yoshibumi TOMODA1956 Volume 4 Issue 2 Pages 67-70
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSA simple approximate method for calculating the correlation coefficient ρ (x, y) between two probability variables x and y, say, is given in the present paper. The essential point of this method is to divide the whole range of each variable into two classes and denote the variable x (or y) by +1 or -1 according as it is larger or smaller than its mean value. If the correlation coefficient between these new series of x and y is r(x, y), we can prove the relation (3) in section §1. By using this relation, we can calculate the required coefficient ρ(x, y) with much less numerical labour than otherwise.View full abstractDownload PDF (214K) -
Keiiti AKI1956 Volume 4 Issue 2 Pages 71-79
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSAn automatic relay computer for calculating autocorrelation coefficients, based on the simplified method of its computation proposed by Y. TOMODA, has been built for the purpose of analysing seismograms. Seismograms of about one hundred near earthquakes recorded at the Central Meteorological Observatory in Tokyo and at the Mizusawa Latitude Observatory were used for the analyses. Each seismogram was divided into several portions, and within each portion, the dependence of the prodominant period of seismic waves upon the magnitude of the earthquakes and upon the crustal structure of the wave path were studied.View full abstractDownload PDF (1044K) -
Kei AKAMATU1956 Volume 4 Issue 2 Pages 81-83
Published: 1956
Released on J-STAGE: April 30, 2009
JOURNAL FREE ACCESSTOMODA'S method for calculating the correlation coefficients has been applied to microtremor analysis and it is shown that the method can safely be used for the purpose, if the sample size is larger than about 300.View full abstractDownload PDF (162K)
- |<
- <
- 1
- >
- >|