Inversion of source-generated noise in high-resolution seismic data

The immediate subsurface is often characterized by a layer of weathered bedrock or unconsolidated sediments. Typically, this surficial layer has a very high Poisson’s ratio and an unusually strong impedance contrast at its lower boundary, comparable, for example, to that observed at a “hard” seafloor. Within the offset range of high-resolution seismic surveys, the layer can be regarded as horizontal and seismic energy trapped within the layer generates horizontally propagating guided-wave trains. Together with Rayleigh waves, guided waves pose serious problems to high-resolution seismic imaging and are commonly referred to as “source-generated noise.” In a typical seismic shot gather, Rayleigh and guided waves define two cone-shaped time-offset windows that bound the optimum time-offset window in which primary reflections can be observed.