The present disclosure provides a system and method for estimating fracture density within a subsurface formation from S-wave seismic data. In one embodiment, the S-wave seismic data is separated into fast (“S1”) and slow (“S2”) data. A computer is used to compute local similarity of the S1 and S2 data and to compute a cumulative time-difference by which the S2 data lags the S1 data from the local similarity. Based on the computed cumulative time-difference, the fracture density of a subsurface formation is estimated.