根尾谷近傍に発生する微小地震の2, 3の性質

抄録

Using the data obtained from co-operative observations of microearthquakes in 1963 and 1964, some properties of microearthquakes in the vicinity of the Neo Valley Fault were investigated in comparison with large earthquakes occurring within the past 70 years in the area concerned.
As the result, we could find that the seismic activity of the microearthquakes was closely related to the earthquake fault on a large scale, though the microearthquakes were not always distributed uniformly over the fault zone. Many shocks were occurring on the southwest side of the fault and they decreased monotonously with distance from the fault. In the northeast side of the fault, however, there was an aseismic area where no shock was occurring. Moreover, it is noteworthy that large earthquakes which occurred since the outbreak of the Mino-Owari Earthquake in 1891 were also distributed in exactly the same manner.
According to these facts, it has become apparent that the seismic activity of microearthquakes may well represent the seismicity in the past on a somewhat great scale. From this point of view, the generation mechanism of the earthquake fault was considered briefly in connection with the manner of seismic activity in the vicinity of the Neo Valley Fault, though it was too early to discuss such a problem in more detail.