High resolution seismic investigation in salt mining context

The high resolution seismic (HRS) reflection survey was conducted on an experimental site in eastern France. Three profiles were designed in order to check the detectability of salt-mining cavities at depth range of 110-180 m. The detection and location of cavities on the HRS images are based on indirect symptoms corresponding to cavity-induced perturbations of lower markers. In most cases, the cavities were detected and the accuracy of estimation of horizontal extensions of the cavities was surprisingly good (of about 10 m). The accuracy of vertical positioning is difficult to establish when the detection is performed indirectly and the only information that could be derived is that a cavity is beyond the masked geological interface. The detection ability depends on the size of the cavity in regard to wavelength and depth. These factors are included in AN coefficient which was used in order to evaluate the detectability of a given cavity