## 6 Results and Discussions
### Shear-Wave 2D Velocity Profiles
The surface trace coordinates of the fault, along with its dipping angle calculated in Yielding [8] and Ouyed [11], were taken into consideration for the inversion process. In the profile, Pr 7, we can observe normal faults at the top of the anticline. The surface trace of these faults was observed during the HVSR measurement campaign. The important variations in the thickness of the layers between the measurement points, P54, P55, P56, and P57 (Profile Pr7 in Figure 12), allowed us to obtain an approximate idea on the fault position under the surface. The presence of normal faults at the top of the Sara-El-Maarouf anticline was highlighted before by [PERSON] and [PERSON] [19]. This normal faulting comes as a result of the extension of the surface layers of the anticline due to the vertical slip on the El-Asnam fault [11,19]. The eight 2D velocity profiles in the Carnot Plain are mapped in Figure 14. Unlike the first zone, the synclinal shape of the basin is clearly visible in this zone. The depocenters are located north of the Chelif River, as attested by the CGG study [7]. The highest depths of the basin are observed around the city of El-Abadia, with a maximum depth of 760 m (P120 in Profile Pr14, Figure 14). Compared to the first zone, the lithost stratigraphic column contains two additional layers of the Miocene age; the Messinian marks and the Serravallian poudingues. The Holocene alluviums have a Vs value between 220 and 370 m/s and reach a maximum thickness of 21 m in the middle of the plain. The Pleistocene alluviums reach a maximum thickness of 86 m, and the Vs value for this layer varies between 330 and 680 m/s. The Upper and Lower Pliocene layers that outcrop on a narrow band north of the plain, dip south under the Quaternary layers and disappear in the middle of the plain. The absence of Pliocene deposits in the south is due to marine regression during the late-Miccene early-Pliocene period, where the shorelines were located in the middle of the plain [2]. These formations are therefore thicker in the north and reach thicknesses of 145 m (P92 in Profile Pr11, Figure 14). The Vs value for the Upper Pliocene sands and conglomerates varies between 390 and 750 m/s, and between 510 and 900 m/s for the Lower Pliocene sandstones. The Pliocene deposits lie over the Messinian blue marks, the uppermost layer of the Miocene. The Miocene deposits occupy most of the sedimentary column of the Middle-Chelif Basin, reaching thicknesses of 550 m. However, there is no impedance contrast between the four Miocene layers in the area. The Vs values for the blue marks stands between 640 and 1190 m/s. For the Tortonian sandstones, they vary between 830 and 1280 m/s, and between 890 and 1380 m/s for the Serravallion-Tortonian clays and marks. For the Serravallian poudingues and conglomerates, the shear-wave velocities vary between 1190 and 1400 m/s. For the Cretaceous bedrock, the Vs varies between 1650 and 2270 m/s. This variation is due to the lateral change of formations from Senonian clays and marks to Albian marks and limestones. In the southwestern part of the plain (Profiles Pr 9, Pr 10, and Pr 11, Figure 14), the Jurassic limestones that compose the Temoulga Massif dip vertically under the Neogene sediments, with a faulted contact between the limestones and the Cretaceous marks [35]. The calculated shear-wave velocities for the Jurassic limestones vary between 2300 and 2670 m/s. The third zone, which covers the Rouina-Ain-Defla region, has a different local geological context. The vast Quaternary plain gives way to hills and plateaus. The four 2D velocity profiles realized for this zone are mapped in Figure 15. The lithost stratigraphic column is dominated by the Tortonian sandstones and Serravallo-Tortonian clays and marks. The Vs values for sediments are in the same range as for the second zone. In the profile, Pr20 (Figure 15), we can see all the structural complexity that exists in this zone of closure. Figure 14: Shear-wave velocity profiles for Zone 2. Qt: Quaternary. Pl: Pliocene. Mi: Miocene. Cr: Cretaceous.