Abstract
A large earthquake, magnitude 7.5, occurred at the western end of the Ryukyu Trench on March 12, 1966. The focal process of this earthquake is discussed in detail here on the basis of the moving lithosphere model. Its focal process and the features of the lithosphere in the Taiwan region are explained by means of a simple picture.
The seismic parameters of this earthquake, which were obtained by analyzing two distinct phases in the initial P-wave group and by analyzing G waves, are as follows. Dip angle and dip direction of the fault plane are 82° and 215°, and the type of this fault is unilateral. The earthquake moment is 1.6×1027 dyne-cm; the average dislocation is 2.1×102cm; stress and strain drop are 6.6×10 bars and 1.8×10-4; strain energy is 1.4×1023 ergs; fault length in the strike direction is 2.7×10km; fault width is 2.8×10km; and rupture velocity is 1.9km·sec-1.
