A Highly Sensitive Extensometer and Observation of the Array of Crustal Deformations

Abstract

It is indispensable in the continuous observation of crustal deformations to estimate the volume of the deformed region. The author has been engaged in performing the observation of the array of linear strains by means of several highly sensitive extensometers and ones of some other types at Osakayama observatory since 1960.
By analyzing the result of this observation, he has been enabled to obtain the diameter of permanently deformed parts of the crust within the recent years, the total change of the elastic energy contained in the part and the expectant magnitude of the earthquake which may break out with in the limit of the straining. The author corraborates moreover that the strains caused by such as the tidal forces have almost world-wide effects, but the ones caused by pseudo-crustal movement have various minor regional effects.