## 4 Results and Discussion
### Time-Domain Electromagnetic
With the central-loop device, three units are differentiated in depth: the shallowest (around 100 m depth) is characterized by a drop in resistivity values, although the local rises appearance would be associated to Messinian marks with sandstones interbedded. Between 100 and 300 m, conductive facies appear associated to Late Tortonian marks. Under these facies, the increase in resistivity values is associated to Jurassic dolomite aquifer. This interpretation also agrees with the information from direct data obtained in nearby outcrops (Figure 2B) and with the information provided by the seismic profile of Figure 3B. In the case of the central-loop device, the potential curve reaches approximately a depth of 510 m with stable values (at approximately 150 m, the voltages are approximately 10 \(\upmu\)V). In contrast, using the single-loop device, it offers values above 10 \(\upmu\)V only up to 65 m, and the curve is no longer stable at a depth of 250. Therefore, at this station, the Jurassic aquifer is not reached with this configuration. From all this, it can be deduced that the central-loop device performs better than the single-loop device for deep aquifer research (Figures 5 and 6). For the rest of the stations (S2 to S9), measurements with both configurations were made. For brevity, only the curves obtained by the central loop are shown (Figure 6). In all of them, the position of the Jurassic aquifer is detected at variable depths. In Figure 3A, the position of each of the TDEM stations on the seismic profile is shown. This allows us to compare the depth of Jurassic dolomites obtained by seismic (Figure 3) and electromagnetic methods (Figures 5 and 6). Figure 7A shows the resistivity section obtained with the electromagnetic method, resulting from the joint inversion of data from the ten measurement stations through the ZondTem2D software. At the northern end of the section, the method is able to detect both the Jurassic dolomites and the contact with the underlying Paleozoic basement. In the southern sector, the Jurassic unit is also detected by a change in the trend of conductive to resistive materials. The method fits poorly in the central sector of the profile, where is unable to detect the decrease in resistivity values associated to the Triassic facies at deeper levels. The seismic reflection profile and the resistivity profile obtained by the TDEM method are represented together in Figure 7B. A good correlation can be observed between the two techniques for modeling the Jurassic unit. For the upper 200 m, at the northern end of the section, the TDEM resistivity profile and the profile obtained by the electrical resistivity tomography (ERT) method are also compared (Figure 7C). The superposition of the ERT and TDEM profiles allows deducing a good correlation in the lateral and vertical variations of the resistivity values obtained in both techniques. Figure 6: Representation of the induced voltage curves (blue line) and apparent resistivity (red line) as a function of time at stations S2 (**A**), S3 (**B**), S4 (**C**), S5 (**D**), S6 (**E**), S7 (**F**), S8 (**G**), and S9 (**H**) using a central-loop device. For each of them, the fit between the field line and the line of the ZONDTEM1D software model has been represented. The straight red lines represent the resistivity as a function of the depth, interpreted after data inversion. A good fit is deduced, with RMS error value ranges between 1.7% and 5.6%.