Long‐Period Surface Wave Seismology: Love Wave Phase Velocity and Polar Phase Shift

Abstract

Due to continuing improvement in instrumentation and data processing techniques, increasingly longer periods are being obtained in seismic surface wave measurements. Three aspects of surface wave propagation on a sphere, which become important at long periods, are treated in some detail: (1) the dependence of the spherical phase velocity on the relative positions of epicentre and station, (2) the importance of the polar component of Love waves, relative to the azimuthal component, and (3) the accuracy of the common practice of treating surface wave data as though they represent a continuous‐frequency phenomenon. The original work on polar phase shift theory (Brune et al.) predated derivations of the response of a sphere to realistic models of the earthquake mechanism. We update the original theory by basing the development on these later derivations. Copyright © 1976, Wiley Blackwell. All rights reserved