地震P波及びS波の速度の比と其の應用に就いて

抄録

The velocity ratio of P and S waves is obtained by many authors to be nearly constant everywhere in the earth's crust. In the present investigatio_??_, is treated this problem by a method of t_p-T_p-s diagram which gives the relation between the arrival time of P and duration of (P-S). Examining in many cases of large earthquakes of both shallow and deep origins occurred in our country, the relation is obtained to be approximately linear as is expected, especially in the cases of deep-seated earthquakes. From these investigations, the velocity ratio of P and S waves is obtained as about 1.73 in the upper part, it may be probably the so-called Mohorovicic layer, but its value seems to differ in different localities; while, in the deeper part nearly a constant value of 1.79 is obtained. Thus, using the result we are able to obtain the depth of seismic focus by a simple method, especially in case of deep-seated earthquakes.