Journal of Physics of the Earth
Online ISSN : 1884-2305
Print ISSN : 0022-3743
ISSN-L : 0022-3743
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Volume 14, Issue 2
Displaying 1-4 of 4 articles from this issue
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  • A Statistical Significance Test of the Difference in b-value between Two Earthquake Groups
    Tokuji UTSU
    1966 Volume 14 Issue 2 Pages 37-40
    Published: 1966
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.14.37
    JOURNAL FREE ACCESS
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    The probability density function for the value of b in the formula logn(M)=a-bM estimated by the author's method has been obtained in an exact form. This function leads to a simple method to test the statistical significance of the difference between two b-values. Application of this method to SUYEHIRO'S data on foreshocks and aftershocks of the great Chilean earthquake of 1960 indicates a significant difference in b-value between the foreshocks and the aftershocks at the 98% confidence level.
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  • Time of Origination of Earthquakes in the Kuril-Adjoint-to-Kamchatka Region and the Local Time (Lunar, Solar)
    Gurgen P. TAMRAZYAN
    1966 Volume 14 Issue 2 Pages 41-48
    Published: 1966
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.14.41
    JOURNAL FREE ACCESS
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  • Differential Attenuation of P Waves as Derived from a Hindu-Kush Earthquake
    Tomowo HIRASAWA, Kei TAKANO
    1966 Volume 14 Issue 2 Pages 49-57
    Published: 1966
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.14.49
    JOURNAL FREE ACCESS
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    Fourier analysis is made of P and pP waves radiated from a Hindu-Kush earthquake (focal depth; 207km) to study attenuation of the seismic waves in the mantle. The long-period seismograms are supplied by the U.S. Coast and Geodetic Survey.
    In order to reduce random error in the observed spectra due mainly to incomplete correction for the effect of crustal layering, the P and pP wave observations are divided into three and two groups, respectively, according to their epicentral distances, and the average spectral structure is obtained for each of the groups. Assuming that the intrinsic Qα is independent of frequency in the period range involved (3-30sec for P and 3.75-15sec for pP), three independent values of the differential attenuation are derived from the spectral ratios of the average spectra. These observed values agree with the theoretical ones expected for the MM8-Qβ better than with those for the modified Qα-model by Teng (1966). This implies that Qα is roughly equal to Qβ in the MM8-model throughout the mantle. To obtain a better agreement with the observations the MM8-model is modified. For the trial Qα-model thus obtained, we have Qα=340, Q'α=140, and Q"α=2370, where Qα, Q'α, and Q"α are values of the average Qα throughout the whole mantle, for the upper mantle (h<0.14R), and for the lower mantle (h>0.14R), respectively.
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  • Frequency Dependence of the Reflection Coefficient for SH Waves at the Core-Mantle Boundary
    Ryosuke SATO, A.F. ESPINOSA
    1966 Volume 14 Issue 2 Pages 59-63
    Published: 1966
    Released on J-STAGE: April 30, 2009
    DOIhttps://doi.org/10.4294/jpe1952.14.59
    JOURNAL FREE ACCESS
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    The reflection coefficient for SH waves is derived in terms of ray and wave theory. A numerical computation is presented which treats the mantle as a homogeneous body. The objectives of this investigation are to compare the reflection coefficient from the ray theory with the reflection coefficient from the wave solutions, and to ascertain the validity of their application to core-mantle studies which use long-period shear wave observations. Also, the evaluation of the reflection coefficient is performed as a function of angle of incidence on the boundary, and as a function of the spectral component.
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