- 公益社団法人 日本地震学会
- 地震 第2輯 (ISSN:00371114)
- vol.28, no.3, pp.303-311, 1975-10-10 (Released:2010-03-11)
A correlation has been found between intermediate earthquakes in Hida (the region around the city of Takayama) and shallower earthquakes in central Kwanto (the region around the city of Tokyo). Among 61 earthquakes of M≥5.5 in central Kwanto during the 51 years from 1924 through 1974, 37 earthquakes occurred in the one-year periods centered by the times of 16 earthquakes of M≥5.0 in Hida. The probability that 37 or more earthquakes in central Kwanto occur during those periods (total length=14.46 years) is 1.5×10-7, if the Kwanto earthquakes are distributed randomly in time. It seems impossible that the smallness of this probability is wholly attributed to some effects other than the true correlation, such as the selection of data, the clustering of earthquakes, etc. The correlation suggests the mechanical connection between the two seismic regions, which belong to the same segment of the Pacific plate underthrusting at the northeastern Japan arc.