Introduction

Inherent in the passive seismic imaging experiment is the troublesome coexistence of the direct source phase and its excited ghost reflections that image the subsurface. Akin to the multiple problem in conventional seismic, I propose to attack the direct waves as noise in the framework outlined by Guitton et al. (2001). Whereas his methodology is effective at separation of signal and noise models, building an appropriate noise model is often the most limiting aspect of the technique. I propose a method to reconstruct the parameters of the impinging direct wave that is responsible for the image point in the reflection in order to build the noise model. Alternatively, it is possible to separate the recorded wave field into its up-going and down-going constituents if one has all three components of the displacement recorded at the surface. Both of these methodologies will be discussed herein. The concepts are not mutually exclusive.