Abstract
In 1966, the artificial explosions off the Atsumi Peninsula were carried out by the Reserch Group for Explosion Seismology (R.G.E.S.). At the same time, many Matsushiro earthquakes were recorded at the temporary stations of the R.G.E.S. These stations and the Matsushiro earthquakes form ray paths like those in a fan shooting.
The travel times derived from these earthquakes were analyzed and the following conclusions were obtained. The observed appearent velocities are 6.1 km/sec and 7.7km/sec, respectively. However, the intermeditate appearent velocity has not been observed. These evidences agree with the results which are obtained by the R.G.E.S.
The lack of the intermeditate appearent velocity may suggest that the intermeditate crustal layer (the so called basaltic layer) does not exist, or it is masked in the Central Japan. These travel time curves are explained by the crustal structure obtained by the R.G.E.S..
