A METHOD OF PROCESSING MARINE SEISMIC DATA AND A METHOD OF SEISMIC SURVEYING

摘要

A method of determining seismic properties of a layer of the seabed, in particular a surface or near-surface layer (5), comprises directing seismic energy propagating in a first mode at a boundary face of the layer so as to cause partial mode conversion of the seismic energy at the boundary face. Fo r example partial mode conversion may occur when seismic energy propagates upwards through the interface between a surface or near-surface layer (5) an d the basement (6), owing to the difference in seismic properties between the surface or near-surface layer (5) and the basement (6).In the invention, the two modes of seismic energy - that is the initial mode and the mode generate d by mode conversions at the interface - are received at a receiver. The difference in travel time of the two modes between the interface and the receiver is determined from the seismic data acquired by the receiver.