Introduction

Abstract

In terms of its possible contribution to our understanding of the earth, few areas of seismological study have posed as many difficulties as that of seismic wave attenuation, or Q. Many surface-wave seismologists have measured amplitudes at two seismic stations along the same great-circle path from an earthquake and found, even after correcting for instrumental factors, that the amplitude of a particular phase is larger at the more distant station. Similarly, body-wave seismologists have long been aware of the severe effect that velocity gradients and low-velocity zones can have on wave amplitudes. Awareness that such effects can completely swamp those of anelasticity has, undoubtedly, deterred many investigators from pursuing research on seismic-wave attenuation.