Caracterización de un acuífero kárstico por sísmica de reflexión de alta resolución

the present study was carried out in the pyrenean foothills (southwest of france) and shows a good application of high resolution seismic reflection to the knowledge of the first hundred meters of the subsurface. we have clearly characterized a karstic aquifer localized in the old glacial valley of ossau. all measurements were registered with a 24 channels seismograph, a sledgehammer stroked on a metallic plate or a shotgun and 24 vertical geophones. the processing of the seismic reflection data follows a traditional sequence: the signals were initially processed with frequency filters, fk filters and deconvolution; finally, a depth seismic migrated section was created. the subsurface coverage of the acquisition scheme and the complete processing sequence allowed us to produce seismic sections of high quality which show reflexions down to 200m depth. the geometric and geological context where the oasis springs emerge is now clearly defined. the springs are encountered in this part of the ossau valley because of the near outcrop of the upper aptien limestones. additionally, the lock of the glacial formed by the north pyrenean fault, represents an insuperable border that allow the oasis springs to emerge.