The third Kurayosi explosion and the crustal structure in the western part of Japan.

Abstract

The third Kurayosi explosion was fired by the Research Group for Explosion Seismology on November 21, 1970 in order to detect the seismic waves reflected from deep crustal boundaries. Very clear reflected waves from the Conrad discontinuity were recorded by the instrument for seismic prospecting (E.T.L. recorder). There was also weak indication of the reflection from the Mohorovicic discontinuity in the records obtained at closely spaced temporary observation points equipped with FM data recorders at the shot distance of about 100km. On the basis of these results, a revision was made for the previous model. The crustal thickness obtained is about 35km and the Pn velocity, about 7.8km/sec.