71 st EAGE Conference & Exhibition — Amsterdam, The Netherlands, 8 - 11 June 2009 X043 Active Seismic Imaging Using Microseismic Events A. Reshetnikov* (Free University Berlin), S. Buske (Free University Berlin) & S. Shapiro (Free University Berlin) SUMMARY We have developed a passive seismic imaging approach which consists of two steps. Firstly, the hypocenter of the microseismic event is precisely located. Secondly, this event is treated as a "pseudo- active" seismic source and we process the refections within the recorded wavefeld using a directional migration algorithm in order to construct a high-resolution image in the close vicinity of the located hypo- center. In this paper we describe this approach and demonstrate the application to several microseismic events recorded by a borehole array in the SAFOD (San-Andreas-Fault-Observatory-at-Depth) main hole. The results are high-resolution images of different fault branches related to the San-Andreas-Fault (SAF) system in the close vicinity of the borehole. The comparison of these fndings with existing surface seismic refection images as well as additional borehole information demonstrate some interesting features. In summary our results allow a spatial characterization of the complex internal structure of the SAF and can certainly be helpful for other studies which rely on this knowledge.