Patent ID: 8395965

Claim:
A method of processing seismic signals recorded by seismic receivers in response to a seismic wavefield generated by a seismic source emission, comprising the steps of: using the seismic signals to determine a location of a turning point in a sub-surface of the earth, wherein the turning point comprises a location at a level z α where a seismic wave generated by the seismic source propagates parallel to the level z α at the turning point and on a first side of the turning point the seismic wave is downgoing and on a second side of the turning point the seismic wave is upgoing; determining properties of a total wavefield at level z α wherein the properties of the total wavefield are determined from the seismic wavefield and a structure of the earth above the level z α and wherein the total wavefield comprises the seismic wavefield and a vertical derivative of the seismic wavefield; using the properties of the total wavefield at level z α to process parameters characterizing properties of the earth or sub-sections of the earth in a vicinity of the turning point; and using the processed parameters to interpret the seismic signals to generate an image of the sub-surface of the earth.