Seismic processing and imaging with a drill-bit source

Apparatus for determining while drilling in the earth with a drill bit the positions of seismic wave reflecting geologic formations in the earth, said drill bit serving to generate the seismic waves, which comprises at least one pair of seismic wave sensors positioned in the earth near the surface thereof, in at least one pair of known positions with respect to said borehole, said seismic waves generated by said drill bit which travel directly to said sensors and second seismic waves generated by said drill bit which are reflected by the geologic formations, at least one pair of adaptive filtering means each connected to receive sensed signals from one of said at least one pair of seismic wave sensors, means utilizing an adaptation algorithm to adapt said at least one pair of adaptive filtering means to optimize a crosscorrelation function between their outputs, impulse responses of said at least one pair of adaptive filtering means after convergence yielding arrival times and amplitudes of direct and reflected waves from said drill bit.