地震の発震時刻と月,太陽の位置の関係

(日本およびその近傍の地震について)

抄録

It is often said that the occurrence of earthquake is affected by the moon or the sun. Various researches have been made on this problem, their relation however remains doubtful. In this paper, statistical correlations between the earthquake frequency and positions of moon and the sun are treated by using 8176 earthquakes in and near Japan. The author considers nine variables about the position of the moon or the sun, namely hour angles, azimuths and zenith distances of the moon and the sun at the epicenter, moreover, distance, time derivative of distance and phase of the moon . These values are precisely computed for the occurrence time of earthquakes and the correlations to earthquakes are investigated. Characteristic results thus obtained are as follows . 1) About the relation to the phase of the moon. During the time around the first and the last quarters of the moon, earth quake frequency increased distinctly about 15% above on average level, which is far beyond the limit of statistical fluctuation. For earthquakes of magnitude over 6, the increase reaches to 30% or more. 2) About the relation to the hour angle of the moon . Earthquake frequency changes systematically according to the hour angle of the moon for earthquakes of magnitude over 6 . Its maximum occurs near the time of moon's hour angle 90° and 300°.……………… From these results descrived above, the author suspects that the moon has influence on the occurrence of earthquake if it is difficult to connect directly the tidal force of the moon with the occurrence of earthquake.