It is supposed that the spatial distribution of the shallow earthquakes will differ from that of the deep earthquakes. In this paper the earthquakes distance between the successive shocks is studied in the crust and upper mantle divided into every twenty kilometers. Data are the earthquakes which occurred during ten years 1961-1970 in and near Kanto district (by J. M. A.).
It was found that the deeper the depth of earthquakes becomes, the longer the distance of two successive shocks become. Namely, in the depth shallower than 20km the earthquakes distance around 8km occupies the highest percentage and in the depth 80-100km around 100km. The distance distribution of all the earthquakes is similar to the cumulative distribution as the sum of the distribution in each depth which was calculated independently. As to the mathematical expression of the distribution function, the exponential distribution function f(S)=(1/μ)-(1/μ)S (S: distance, μ: expectation) seemed to fit well. It is a remarkable fact that the erathquakes with the depth shallow than 60km are crowded between Japan Trench and the sea off the coast of Kashima, and near Miyake Island, but earthquakes with the depth more than 60km transfer toward the land of Kanto district and along Izu Islands.
