HIGH Q-FACTOR EXTREMA OF SEISMICITY SPECTRA IN DIFFERENT REGIONS OF THE WORLD

Abstract

n this paper, we demonstrate high Q-factor extrema of seismicity spectra at periods of 24, 12, and 8 h, revealed by the Fourier analysis of earthquake catalogs in different regions of the world. This effect is mainly manifested for weak earthquakes and becomes insignificant with the increase of the earthquake energy. The diurnal periodicity usually has a maximum during night time, but this phenomenon is absent in some regions. Periods of 12 and 8 h are usually independent harmonics. Increases in the spectral components at periods of lunar–solar tide other than 24 and 12 h were not found.