On the Local Structural Character of the Earth‘s Crust

Regional differences in the crustal structure in Japan were investigated, in detail especially around Kyoto, by a duration analysis of the refracted seismic waves of natural earthquakes propagated along the discontinuous surfaces in the crust. Generally speaking the thickness of the earth’s crust or, in other words, the depth of the Mohorovičić discontinuity was estimated in our country to be greatly diverse from place to place, its range being nearly 25 ∼ 50 km. It was also found that the depth of seismic focus of most frequent occurrence in any region is intimately related to the thickness of the crust in the region concerned.