## 6 Conclusions  
Oued-Fodda, an inter-mountain city, is located in the western part of the Middle Cheliff Basin, which is the largest one in Algeria. With a population of over 40,000, Oued-Fodda is a good example of a growing urban city located close to a major active fault. In the present study, we focused on this city, one of the more damaged urban areas during the El-Asnam 1980 earthquake. In order to contribute to its site effects estimation and a deeper underground characterization, we used the HVSR method and the RWE inversion technique. The main results and conclusions are as follows:  
Figure 9: (**a**) Two-dimensional N-S cross-section (CD profile in Figure 3). (**b**) Two-dimensional ENE-WSW cross-section (AB profile in Figure 3). Red diamonds show the ambient noise measurement points. * The analysis of the ambient vibrations recordings using the HVSR method shows the predominance of single frequency peak curves in the center of the city (f0 ranges between 2.5 and 15 Hz). In the area surrounding the city center, two frequency peak curves are observed. The fundamental frequency, f0, ranges between 1.8 and 3.5 Hz. The second frequency peak, f1, which varies between 6.5 and 15 Hz, could be caused by the impedance contrast between the Holocene and Pleistocene deposits at shallow depths (<10 m). * The fundamental frequencies range between 1.8 and 15 Hz, this large variation is due to the local geology. The high frequency peaks (12.5-15 Hz) obtained on the knoll situated in the center of the city, along with the flat H/V curves confirm the assumption made by the WCC report [7] that this knoll is a bedrock outcrop. * From the inversion of the Rayleigh wave ellipticity curves, we obtained a four-layer model. The topmost layer consists of Holocene alluviums (Vs varies from 280 to 330 m/s), with a thickness less than 10 m. The second layer is composed of Pleistocene clays and conglomerates (Vs from 615 to 710 m/s). The bottom layer of the sedimentary deposits is composed of blue marks of Miocene age (Vs from 950 to 1350 m/s). The ante-Neogene bedrock, most probably composed of Mesozoic limestones and schists (Vs from 2000 to 2600 m/s), is at very shallow depths in the central part of the city (0-25 m). In the rest of the study area, the depth of the bedrock varies between 80 m and 198 m.
* The results of the RWE inversion show clearly the existence of lateral variations of the shear-wave velocities and the sediments thickness in the Oued-Fodda city. * The obtained shear wave velocity models can be further used for strong ground motion simulation in the Middle Chellif Basin. * The largest amplification factor is about 6 and is mainly observed west and south of the city center. Fortunately, in the city center where the buildings are mainly single floor (building frequency close to the soil fundamental frequency), the amplification factor is very low (-2). * The city of Oued-Fodda is growing southward, where the largest thickness of the sedimentary cover is obtained. Site effects investigations should be taken into account, especially for growing cities located in high-level seismic hazard zones, in order to minimize potential building damages due to earthquakes. Since the north of Algeria is characterized by moderate to high seismicity, this study is a good example to follow for bigger Algerian cities. [PERSON] acquired and processed the data and wrote the paper; [PERSON] proposed the methodology, contributed on the interpretation of the results and reviewed the paper; [PERSON]-[PERSON] reviewed and supervised the paper; [PERSON]-[PERSON] reviewed and supervised the paper by improving and editing the final manuscript drafts; [PERSON] helped with the data analyses and made the first corrections. All authors have read and agreed to the published version of the manuscript. Research received no external funding. We would like to thank the authorities of Oued-Fodda city for putting to our disposal all the data and information they had.