Quiescence period prior to strong earthquakes in the Kuril-Kamchatka zone

The characteristics of the distributions of the time differences occurrence of the consecutive earthquakes in the Kuril-Kamchatka zone, including the Hokkaido Island area, have been investigated in various magnitude ranges. For the purpose of the analysis, we used the data from the regional and world earthquake catalogs for the last 20 years. As a result of this analysis, a new intermediate-term precursor effect has been found: a quiescence period observed prior to the strongest earthquakes. This precursor manifests itself in the form of the long-term (2–6 months) absence of events with M ≥ 5.5 within the territory. For the predictive purposes, it was proposed to replace the quiescence period by such a more stable parameter as the sum of the three longest intervals between the earthquakes with M ≥ 5.0 in a sliding time window. The prognostic informativeness of this parameter has been assessed.