Water-filled fractures stimulated by hydraulic fracturing will severely attenuate S-waves. By comparing the P- and S-wave amplitudes generated from perforation shots in the Marcellus gas shale, one can infer the existence and constrain the location of stimulated hydraulic fractures. The waveforms of the perforation shots in unstimulated gas shale are first analyzed to define the prestimulation radiation pattern. Then the change of perforation-shot S-wave waveform is examined for information about the development of hydraulic fractures. S-wave attenuation validates the existence of offstage hydraulic fractures and the invasion of treatment fluid from another neighbor stage. This method might have potential use in designing an active seismic survey to more effectively monitor hydraulic-fracture stimulation beyond the current microseismic mapping techniques.