Combined Seismic Electrical Investigations of an Artesian Acquifer below a Damsite in Costa Rica

This study reports preliminary results from a shallow damsite survey in Angostura, Costa Rica, combining reflection seismic and electrical techniques. There, an artesian aquifer presents the risk of a blow-out and needed to be mapped in 3-D for siting relief wells. Coincident deployment of both methods was somewhat hindered by surface geology and dependency of depth of investigation upon configuration. Electrical profiling data (pole-pole) have been inverted and are being checked by modelling. Seismic data have been brute stacked and a detailed velocity analysis is under way. The results presented here show that the presence or absence of the aquifer can be determined by the electrical method, whereas the seismic permits the delineation of the marker boundaries that in turn can constrain the modelling and inversion of electrical data.