Large earthquakes have repeatedly occurred from Hokkaido to the Kamchatka Peninsula along the Kuril Trench. First, we confirmed the successive occurrence of large earthquakes of similar magnitude in nearby regions and within a short time interval using earthquake catalogs issued by international organizations. The searching criteria was whether a succeeding earthquake (Mw ≥ 7.75) had occurred within 500 km and 3 years of a preceding earthquake (Mw ≥ 7.70) in the period between 1890 and 2014. The pairs of successively occurring earthquakes were the June 1893 and March 1894 earthquakes, the September and November 1918 earthquakes, the October 1963 earthquakes, the October 1994 and December 1995 earthquakes, and the November 2006 and January 2007 earthquakes. These 5 pairs among the 21 large earthquakes were identified the successively occurring large earthquakes. Next, we tried to relocate the epicenters of the 1918 earthquakes because their epicenters had been changed in the version of the earthquake catalog referenced. We re-read the arrival times of the P and S waves from the seismograms of Japan Meteorological Agency and estimated the epicenters for the 1918 earthquakes from S-P times. The epicenters were a relative offset of about 160 km and the September event was near the epicenter of the 2006 Kuril earthquake.

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