Foreshocks and Aftershocks of Kanto Earthquake, 1923

September 1, 1923, southern Kanto was devastated by a severe earthquake. The main shock of the events, which occurred at 11 h 58 m (JST), was felt all over Japan. The highest seismic intensity is 7 in JMA scale at the southern part of Kanagawa, Tokyo and Chiba prefectures. The epicenter is located on the Sagami-nada. Parameters of the main shock given by the Japan Meteorological Agency are as follows ;origin time : 11 h 58 m, September 1, 1923.epicenter : 35° 20' N, 139° 20' Emagnitude : 7.9The earthquake was accompanied by many fore- and after-shocks. The foreshocks occurred in Kashima-nada. It seems that the foreshock activities began in May 1923 and became vigorous in June 1923 before the occurrence of the main shock.The aftershocks occurred in Kanagawa, Yamanashi, Saitama, Chiba, Ibaraki prefectures and near seas, and the general trend in decrease of daily number of the aftershocks can be explained by Omori's generalized formula.