Formulas for time-lapse seismic refraction data analysis

Kristopher A. H. Innanen

Formulas for the analysis of time lapse seismic refraction difference data are derived, motivated by indications that during the 2014 University of Calgary Geophysics Field School a significant rain event produced detectable changes in the depth of the water table. The formulas are extensions of Hagedoorn's plus-minus method, wherein forward- and reverse-shot baseline and monitoring refraction travel times are mixed in several ways to extract differential depth-to-interface and jump in subsurface velocity values.