oa Imaging Conditions for Time-Reverse Modeling

Active seismic processing is concerned with two-way travel times, down and up, through the<br>subsurface. In contrast, passive seismic methods are predicated on 3+ travel paths in the case of<br>interferometry, and one-way travel path wave fields in the case of source location. Secondary sources<br>and diffractions maintain the same kinematics as primary sources and can also be imaged in the<br>context of source location. We present the chain of time-reverse modeling, image space wave-field<br>decomposition, and various imaging conditions as a migration-like algorithm to locate subsurface<br>sources in passive data and diffractors in active data. The presented imaging conditions respond<br>differently to source mechanism radiation patterns which interpreted in combination provide more<br>information than simply location. Passive data examples are developed with surface acquisition<br>geometry.