Abstract
Parmanent changes in displacement due to the 1927 Tango earthquake (M=7.5) are analyzed by using the method of "geodetic data inversion" developed in a previous paper (Part I; MATSU'URA, 1977), and a set of optimal source parameters is obtained for a system of conjugate faults, the Gomura and the Yamada.
Deformation fields are modelled by a multiple-fault system composed of several dimensional faults in an elastic half-space, and the optimization of model parameters is accomplished through a process of successive iteration of inversions for 85 triangulation and 25 levelling data around the seismic faults.
The optimal fault parameters obtained are D (dislocation)=3.7m, δ(dipangle)=64°E, λ(slip direction)=-8°, L(length)=33km, W(width)=19km, d(depth)=0.4km and θ(strike of fault)=N24°W for the Gomura fault, and D=1.8m, δ=58°N, λ=120°, L=15km, W=9km, d=0.2km and θ=N77°E for the Yamada fault, where the slip direction is measured counterclockwise from horizon on the fault plane. These results indicate that the two seismic faults constitute a system of conjugate faults caused by a single stress system of NW-SE compression.
A computer program for the geodetic data inversion is completed, by which a set of optimal source parameters of seismic and aseismic events can be obtained from the observed static displacement data.
