Source Localisation by Diffraction Stacking

We introduce a new target-oriented localisation technique which does not require picking of events in the individual seismograms. The method is best suited for large networks of surface and/or downhole receivers. The localisation is performed by a modified diffraction stack of the in-put seismograms. Due to the unknown source time, the stack is re-peated for all possible source times within a time window. The sum of the squared individual stacks results in the so-called image section. The source location is obtained from the maximum of the image section for the time window under consideration. Since the focusing analysis is performed only in this section, no optimised search procedures are re-quired. The source time is then determined in a second processing step when the source location is known. Since the maximum of the image section is distinct even very weak events and multiple events can be de-tected. Initial tests with 2-D homogeneous media confirm the high po-tential of the method. The results also indicate that the localisation can be performed even without precise knowledge of the velocity model