Zisin (Journal of the Seismological Society of Japan. 2nd ser.)
Online ISSN : 1883-9029
Print ISSN : 0037-1114
ISSN-L : 0037-1114
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Volume 12, Issue 1
Displaying 1-7 of 7 articles from this issue
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  • A Statistical Study of Some Aftershock Problems
    Hiroshi KURIMOTO
    1959 Volume 12 Issue 1 Pages 1-10
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_1
    JOURNAL FREE ACCESS
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    According to T. Utsu, the largest shock in an aftershock sequence is by about 1.4 smaller than its main shock on magnitude scale. On the other hand, M. Båth has independently given 1.2 for the value. It is one of the main aims of this paper to deduce the above mentioned experiential results by the theory of probability.
    Now, the number of aftershocks is written by the equation,
    n(t)dt=A/t+Bdt, (1)
    where n(t) is the number of aftershocks occurring in a time interval between t and (t+dt). The relation between M (Magnitude) of main shock and A has been found to be expressed by the equation,
    logA=0.79M-3.8, (2)
    whereas B is independent of the magnitude of main shock.
    On the other hand, the frequency distribution of M of aftershocks is written in the form,
    n(M)dM=const.10-dMbM. (3)
    The relations (2) and (3) are assumed in deriving a POPULATION for a sequence of aftershocks. Then, using the theory of distribution of extreme values, we can find the most probable value of M of the largest aftershock. The result shows that the most probable value of the magnitude of the largest aftershock is about 1 to 1.4 smaller than that of the main shock.
    Another thing treated in this paper is to explain the statistical fact that the percentage of earthquakes accompanied by aftershocks decreases as their magnitueds become smaller. The percentages are calculated according to the extreme value theory. Good agreement is found between the calculated and the actual percentages.
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  • Measurements of Elastic Wave Velocities in Rocks at High Temperatures. I
    Kumizi IIDA, Mineo KUMAZAWA
    1959 Volume 12 Issue 1 Pages 11-18
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_11
    JOURNAL FREE ACCESS
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    A new method of measurement of elastic wave velocity in rocks at high temperatures by means of ultrasonic impulse transmission is presented. This method consists in directly measuring the wave velocity by making use of piezoelectricity of β-quartz crystal. It is shown that pieces of this crystal cut in several orientations can be used as transducers which receive and send out the longitudinal, transversal, or both types of waves. In our experimental conditions, β-quartz did not change in phase to α-tridymite at 870°C, presumably due to the inversion being of a sluggish type. The efficiencies of transducers were not reduced at 870°C and the measurement could be made up to about 1000°C or higher. From this fact, the possibility of the direct measurements up to several hundreds degrees above 1000°C is suggested.
    Rock specimens were cut out from volcanic rocks which were collected from several locations; Mihara Volcano, Ooshima Island; Usu Volcano and Showa-shinzan, Hokkaido; Hakone, Kanagawa Prefecture; Shidara, Aichi Prefecture.
    Some of the results obtained by this method are described; (1) the variation of longitudinal and transversal wave velocity with temperature; the increase of wave velocity with the rise in temperature; (2) the new volcanic rocks recently erupted showing the tendency of this increase of elasticity; (3) the increase of Poisson's ratio with the rise in temperature.
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  • A Method of Determining of the Underground Structure by Means of SH Waves
    Naota KOBAYASHI
    1959 Volume 12 Issue 1 Pages 19-24
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_19
    JOURNAL FREE ACCESS
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    SH wave can advantageously used for determining the underground structure, since it is known theoretically that if one superficial layer exists on a semi-infinite elastic medium, the SH wave critically reflected at the interface shows a very large amplitude at the surface.
    A new method of structure determination is attempted using the above mentioned theory and basic experiments concerning the production of SH wave were carried out in a prospecting field.
    The results obtained by this method in the field were almost the same with those by P wave prospecting.
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  • An Application of the Ray Theory to Stratified Layers (10)
    Kyozi TAZIME
    1959 Volume 12 Issue 1 Pages 25-26
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_25
    JOURNAL FREE ACCESS
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  • An Application of the Ray Theory to Stratified Layers (11)
    Kyozi TAZIME
    1959 Volume 12 Issue 1 Pages 27-28
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_27
    JOURNAL FREE ACCESS
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  • An Application of the Ray Theory to Stratified Layers (12)
    Kyozi TAZIME
    1959 Volume 12 Issue 1 Pages 28-31
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_28
    JOURNAL FREE ACCESS
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  • An Application of the Ray Theory to Stratified Layers (13)
    Kyozi TAZIME
    1959 Volume 12 Issue 1 Pages 32-33
    Published: March 30, 1959
    Released on J-STAGE: March 11, 2010
    DOIhttps://doi.org/10.4294/zisin1948.12.1_32
    JOURNAL FREE ACCESS
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