"In June 1983 a high resolution seismic survey was conducted at the DOE, LETC's underground coal gasification test site near Hanna, Wyoming. The objectives of the survey were to locate and characterize underground burn zones and to identify shallow geologic faults at the test site. Seismic data acquisition and processing parameters were based upon prior work in the area, and were specifically designed to emphasize reflections at the shallow. Data were obtained on two north-south lines along the test site boundary in addition to a three-dimensional grid over the Hanna IV experiment area. Processing included time varying filters, deconvolution, trace composition, and three-dimensional areal stacking of the data in order to identify burn zone anomalies. Anomalies were discernable resulting from the rubble-collapse void above the burn zones in the vicinity of the injection wells at the Hanna IV experiment area. The fault studies disclosed faults at the Hanna IV experiment rea which may be responsible for the unexpected problems experienced in the early in-site gasification tests. for the test site the fault system was found to be generally arcuate east-west trending graben complex with numerous antithetic faults."