1916年8月6日の中央構造線断層帯の地震について

抄録

After the Russo-Japanese War, too little information about earthquakes was published by the Central Meteorological Observatory, and it has made us left in difficulty to examine earthquakes of the Taisho era precisely. Among such earthquakes, the M5.7 destructive earthquake on August 6th, 1916, in Ehime Prefecture was re-examined by the excavated same age documents. Irazu weather station and other stations, which were operated by the company of Besshi copper mine, reported the detail of this earthquake. Identification of reported places about cracks and falling rocks was done, in addition to the examination of the seismic intensity distribution left in newspapers and the Official Gazette. It is proposed to move the epicenter of this earthquake to (33.95°N, 133.4°E), where is six-km south from that in Utsu-catalogue, and closer to the Ishizuchi fault, which belongs to the Median Tectonic Line active fault zone. It is also found that this event has a felt foreshock a half day before, and a felt aftershock an hour later. This event is the first candidate of destructive earthquakes of the MTL active fault zone in the written history.