A plausible universal behaviour of earthquakes in the natural time-domain

In previous papers, we showed that in the new time-domain, called natural time: 1) the power spectrum of an SES-activity exhibits properties of critical phenomena and the power spectra of the local seismicity subsequent to an SES-activity become the same as that of the latter just before the main shock, 2) the power spectra of regional and long-term seismicity in both Greece and San Andreas fault system also exhibits features of critical phenomena. Here we show that the same can be found for the earthquakes in Japan. The "power spectra" in natural time of the seismicities in all the three areas fall on a universal curve. (Communicated by Seiya UYEDA, M.J.A.)