The Weibull-log Weibull distribution for interoccurrence times of earthquakes

Tomohiro Hasumi*, Takuma Akimoto, Yoji Aizawa

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

39 Citations (Scopus)


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 α1 < 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.

Original languageEnglish
Pages (from-to)491-498
Number of pages8
JournalPhysica A: Statistical Mechanics and its Applications
Issue number4
Publication statusPublished - 2009 Feb 15


  • Interoccurrence time
  • Log-Weibull distribution
  • Seismicity
  • Weibull distribution
  • Weibull-log Weibull transition

ASJC Scopus subject areas

  • Condensed Matter Physics
  • Statistics and Probability


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