1966 年 19 巻 2 号 p. 81-95
Observations and analyses were elaborately carried out to make a more precise interpretation of the seismic waves generated by explosions than before. Among the wave groups which were recorded, the first one is the initial motion of direct or refracted P-waves; the second one is most likely the bodily waves unlike the views hitherto accepted, so it is considered a group of waves including reflected and refracted P-waves and later direct phases which succeeded the first wave group. As for the third and the fourth wave groups by comparative study of the theoretical and observed characteristics of their phase and amplitude, a satisfactory conclusion, both qualitatively and quantitatively, has been reached by regarding the third group as M21 waves and the fourth group as M11 waves. It has been clarified also that the most superficial layer contributed to the generation of these M-waves.
The reciprocity was also discussed. In order to make a precise examination of reciprocity, various kinds of conditions, especially explosion condition and horizontally layered structure, etc., should be unified beforehand.