Seismic waves in a wedge

Abstract

abstract The equations for elastic-wave propagation caused by an explosive point source are solved, by a finite difference scheme, for the case of an elastic wedge, with free boundary. Varying the wedge angle shows that the amplitude of the motion, at the corner, increases as the wedge angle is decreased. The results indicate that for wedges with angles varying from 0° to 180°, the amplitude decreases with decreasing β/α (shear- to compressional-wave velocity). The corner of the wedge generates surface waves and the elliptical particle motion in the waves is analyzed. The particle motion is elliptic and the major axes of the ellipses are inclined at half the wedge angle to the free surface. The surface wave travels to the corner from where it is “transmitted” and reflected. Surface waves are shifted by 180° - θ after transmission. For the case of a quarter plane, we get the same result as Alterman and Loewenthal (1970).