Km In Thickness Research Articles

爆破地震動観測による本州中央部を南北に横断する測線上の地殼構造

From the observed data of seismic waves from Siunzi, Annaka and Kawazu explosions and a natural earthquake occurred near Miyake-jima listed in Part I of this paper, crustal structure was derived for the profile along the longitudinal line of 139°E. Although the available data obtained are not enough to draw precise picture on crustal structure, the following is proposed as a plausible one.The superficial layer varies from 0 to 3.5km in thickness and from 1.61 to 2.83km/sec in P wave velocity. The first layer with P wave velocity of 6.00km/sec has 12km thickess under the Siunzi shot point and its lower boundary has downward inclination towards south with an angle of 1°29′. The second layer has P wave velocity of 6.82km/sec, which is observed in Japan for the first time. The boundary surface of this and the third layer, so-called Mohorovicic discontinuity, was estimated for various values of P wave velocity in the upper mantle. The depth of this surface is about 40km near Siunzi shot point and becomes deeper towards south, reaches its maximum of about 50km at around 150km away from the shot point, and then becomes shallower to about 25km near Miyake-jima.

Theory of overhead nonblanketing sporadicE

We suggest a model for overhead nonblanketing sporadic E based upon scattering from a belt (1 or 2 km in thickness) of irregularities within a stratified E layer. Predicted h′f curves are compared with observed data and found to be in good agreement.

福井地震の走時曲線と地殻構造

Examining the seismological data for the Fukui Earthquake, June 28. 1948, the author obtained the travel-time curves of P, P* and Pn and determined the depth of the origin of P-wave of the earthquake together with the layered structure of the earth's crust in Japan. The latter result does not agree with those obtained previously by other authors. The layers corresponding to P and P* were respectively found to be 35km and 14km in thickness.