- 著者
-
宇津 徳治
- 出版者
- 公益社団法人 日本地震学会
- 雑誌
- 地震 第2輯 (ISSN:00371114)
- 巻号頁・発行日
- vol.31, no.2, pp.129-135, 1978-07-31 (Released:2010-03-11)
- 参考文献数
- 7
- 被引用文献数
-
2
1
Discrimination of foreshock sequences from earthquake swarms is an important problem in earthquake prediction. In this paper, the magnitudes of the largest, the second largest, and the third largest shocks in an earthquake swarm or foreshock sequence are denoted by M1, M2, and M3, respectively, and Japanese shallow earthquake swarms and foreshock sequences (with M1-M2≤0.6 and M1≥5.0 for 1926-64 or M1≥4.5 for 1965-77) are classified according to the values of M1-M2 and M1-M3, and the time sequence of the shocks of M1 and M2. If we select the earthquake swarms and foreshock sequences satisfying the following conditions, the highest proportion of foreshock sequences to earthquake swarms is achieved. The conditions are: (1) 0.4≤M1-M2≤0.6, (2) M1-M3≥0.7 (or M3 is too small to be determined), and (3) the shock of M2 precedes the shock of M1. The numbers of foreshock sequences and earthquake swarms selected under these conditions are 10 and 17, respectively, while the total numbers of foreshock sequences and earthquake swarms are 13 and 232, respectively. It is confirmed that the above criterion is also effective, if it is used during the course of an earthquake sequence.