犬山地方の地震活動
1971 年 24 巻 1 号 p. 54-66
詳細
1971 年 24 巻 1 号 p. 54-66
Seismicity of Inuyama area were investigated during the period from April 1968 to March 1969. Total number of observed earthquakes were 9000. Among these shocks there were about 1100 shocks with the P-S time interval TP-S less than 4.0sec and about 850 shocks with 4.0sec≤TP-S≤10.0sec. There were maximum peaks in the frequency distribution of shocks at the P-S time intervals such as 0-4.0sec, 4.0-10.0sec and 17.0-21.0sec.
The relation between earthquake magnitude and P-F time at Inuyama station (INU) was obtained as
M=4.06·log (P-F)-5.15.
When released energy of earthquakes is very large during a certain short period, it is very small in the following certain period, but the increasing rate of released energy in a certain magnitude range is nearly constant for a long period and the larger the magnitude, the longer the period becomes.
Ishimoto-Iida's coefficient m seems to change more or less with time.
Two small earthquakes accompanied by aftershocks were observed in May and November 1968. Each magnitude of these main shocks was about 3.0 and in about ten hours after the first main shock, secondary main shock was observed. Some characteristics of these shocks were also discussed.
