  By analyzing the Japan Meteorological Agency (JMA) seismic catalog for
different tectonic settings, we have found that the probability distributions
of time intervals between successive earthquakes --interoccurrence times-- can
be described by the superposition of the Weibull distribution and the
log-Weibull distribution. In particular, the distribution of large earthquakes
obeys the Weibull distribution with the exponent $\alpha_1 <1$, indicating the
fact that the sequence of large earthquakes is not a Poisson process. It is
found that the ratio of the Weibull distribution to the probability
distribution of the interoccurrence time gradually increases with increase in
the threshold of magnitude. Our results infer that Weibull statistics and
log-Weibull statistics coexist in the interoccurrence time statistics, and that
the change of the distribution is considered as the change of the dominant
distribution. In this case, the dominant distribution changes from the
log-Weibull distribution to the Weibull distribution, allowing us to reinforce
the view that the interoccurrence time exhibits the transition from the Weibull
regime to the log-Weibull regime.
