Recently it was found by Messrs. K. Kadoya, S. Hidaka and M. Miyamoto that the
ScS wave appeared very conspicuously in the seismograms of deep-focus earthquakes recorded at various stations near the epicenter. In this paper, the author intends to get a table of travel time curves of this
ScS wave for earthquakes of various focal depths. For this purpose, first the depth of the Earth's core is obtained by using the arrival times of the
ScS waves observed in the case of the deep-focus earthquake (1932, XI 13) whose position of epicenter, focal depth and the time of occurrence can be accurately known. This depth was obtained to be 2900 km. or a little larger, and the depth of 2900 km. hitherto generally accepted by seismologists is reassured. Then using the values of velocities of the
S waves in the crust obtained by us (Geophysical Magazine. Vol. VII, No.1, No.2 and No.3), the travel times of the
ScS wave are fully calculated and the results obtained is given in Table 5.
When the phases of
P,
S and
ScS all appear distinctly in the seismograms taken at a station near the epicenter, the focal depth of this earthquake and the epicentral distance of that place can be determined by the differences of arrival times,
S-P and,
ScS-P. Table 6 shows the relation between
H, and
S-P,
ScS-P. Tables 5 and 6 may be conveniently used for the investigation of near earthquakes.
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