1. A method to identify fractures in a hydrocarbon reservoir comprising: transmitting one or more seismic source signals into the earth; receiving one or more seismic signals at two or more geophones; recording source-receiver records to a computer processor comprising a user interface and a storage medium; pre-processing each pair of source-receiver records for each azimuth around one or more common source signals, including: applying linear move-out, removing dipping signals, extracting refraction travel time, and removing linear move-out; deriving anisotropic parameters from refraction travel time; and correlating changes in anisotropic parameters to one or more reservoir models.