The use of passive seismic techniques to monitor oil- field completion and production processes is on the rise. Stress changes induced by such reservoir activities as hydraulic fracturing, water injection, or fluid extraction will often result in failure of the rocks with a concurrent release of seismic energy in the form of compressional (P) and shear (S) waves. Passive seismic monitoring is based on recording these emitted waves and then using their arrival times to estimate the location of the failure events.