Seismic Interferometry in Image Domain Based on Reverse Time Migration for Passive Seismic Monitoring

I propose a direct migration method for passive seismic data based on a reverse time migration combined with a concept of the seismic interferometry. The subsurface image is obtained by three steps in this method which is recognized as the seismic interferometry in the image domain; the first is model-based wavefield extrapolation of time-windowed passive seismic signals, the second is crosscorrelation of the forward and backward extrapolated wavefields in the image domain, and the third is summation of the correlated image for all seismic events or all time windows. As a result of the modified imaging condition, surface related multiple reflections in the passive seismic data are focused on the reflection points. This image domain interferometry has potential to be an efficient processing method of continuous recording data. The daily subsurface condition can be updated by accumulating new reflection images with the continuous monitoring. A numerical experiment simulating local earthquakes with SEG/EAGE overthrust model validates the imaging algorithm with the image domain interferometry. Another numerical simulation result shows that this method has applicability to detect time-lapse velocity changes, though difference by the source distribution change is not negligible.