日本付近の地震 (1901年-1925年) のマグニチュード
1979 年 32 巻 3 号 p. 341-353
詳細
1979 年 32 巻 3 号 p. 341-353
Records of undamped Omori seismographs are found to permit fairly accurate calculation of magnitudes of earthquakes which occurred in the early years of modern seismology. Station bulletins, reports and reproduced seismograms are collected to obtain maximum amplitudes and periods. The data at Osaka Meteorological Observatory and Imperial University of Tokyo are found most useful. The Moscow-Prague formula is employed. The method is examined for 130 earthquakes fór which records of modern, damped seismographs are available. This examination is made all on the basis of Gutenberg-Richter's original worksheets to conform the present scale to the original definition of surface-wave magnitude. Station corrections are calculated. The results are successfully applied to major damaging earthquakes which occurred in Japan for 1901 to 1925, because no instrumental magnitudes were heretofore given and the epicenters are considered to be fairly accurate. The seismic activity during this period is not significantly different from the recent activity.
