Capacitance Retrieval from Resistivity and P-wave Velocity Products and Ratios

A common methodology consists in comparing seismic refraction and ERT (Electrical Resistivity Tomography) sections for general interpretation. In this paper, the numerical values and seismic refraction and ERT sections have been multiplied and divided. Dimensional analysis showed these operations related to capacitance. This is unexpected as Vp (a mechanical property) does not seem to be related to electrical charge storage. Utility databases have been used to analyse Vp and resistivity sections recorded in Ireland. Ratios and products of these sections effectively delineated culverts, water pipes, and possibly water tables. Two possible explanations have been considered for these delineations: one based on electromagnetic models, and the other on the second order partial derivatives of the resistance. The latter, linked to Poisson’s ratio, seemed more promising due to a lack of correlation with electromagnetic models. Future research can investigate karst detection using this approach, and potentially a retrieval of subsurface Poisson’s ratio through inversion.