中部地方北西部における地震の発震機構

Abstract

mechanism solutions in this paper, however, were re-determined by modified Fourier method from initial motions of P-waves for earthquakes with magnitude greater than 3 occurred during the periods 1978-1991.As it has been reported, major type of focal mechanisms in the district is strike-slip with N60-80°W azimuths of P-axes.However, reverse faults are found to be predominant in the southern part of the Hida mountains and in the northern part of Miboro fault.Normal fault type mechanisms are also found to occur in the Hida region and southern end of Toyama Plane.Thus, the different types of mechanisms seem to be closely related to the tectonic movements of the region.On the basis of the regional characteristics of mechanisms, temporal change in mechanisms of earthquakes can be deteced in the future for monitering the variation in stress fields.