SEISMIC MONITORING OF DIFFRACTION IMAGES FOR DETECTION OF LOCAL HETEROGENEITIES

Diffracted waves contain valuable information regarding both the struc ture and composition of the media they are in. In seismic data process ing, however, these waves are usually regarded as noise. In this paper , we present an attempt to use scattered/diffracted waves for the dete ction of local heterogeneities. The method is based on the detection o f diffracted waves by concentrating the signal amplitudes from diffrac ting points on the seismic section. This is done using a correlation p rocedure that enhances the amplitude of the seismic signal at the loca tion of the diffractors on the common-diffraction-point section (D-sec tion), The new local time correction for diffraction traveltime curve parameterization is based on the radius of curvature of the diffracted wavefront and near-surface velocity. We use the idea of seismic monit oring for detection and delineating local objects which may occur with in the subsurface resulting from human activity or fast geological pro cesses. The method consists of continuous repetition of seismic experi ments above an investigated area, constructing D-sections, and compari ng the images obtained.