Abstract
The usual study of seismic reflections is limited to those from sharply defined contrasts in acoustic impedance. For reflections from transition zones in which acoustic impedance is continuously variable (such as the zones encountered in permafrost), the frequency-selective nature of attenuation and phase distortion leads to characteristics which may be used in pattern recognition to identify such reflections. An rms velocity-analysis procedure can be used to estimate depths and velocity gradients in transition zones. Some simple approximations allow us to avoid solving a system of nonlinear equations in many cases, and the result is a practical technique which can be applied to many transition zone reflections at reasonable computational cost.--Modified journal abstract.
