The paired earthquakes within the Kamchatka Peninsula subduction zone

Abstract

During 1962 to 1993 three earthquakes were recorded of seismic moments greater than 1019 N m (Mw = 6.9 to 7.0) at depths from 0 km to 99 km within the Kuril-Kamchatka subduction zone near Kamchatka Peninsula. These earthquakes have occurred along the coast of the Peninsula under the dominating compressive stresses and thrust-faulting. These three earthquakes occurred in pairs; they were preceded by moderate-size (seismic moments from 1018 N m to 1019 N m) earthquakes located at distances from 10 km to 41 km from the epicentre of the large earthquake one to four years before the large event. Each time the moderate-size event was the first one, accompanied by aftershocks after a long-term sequence of single events in this area. This regularity in appearance of paired earthquakes can be used as an additional criterion to intermediate-term precursors to large earthquakes in the Kamchatka subduction zone.