The Causse of El Hajeb belongs to the Tabular Middle Atlas (TMA), in which thousands of karst landforms have been identified. Among them, collapse dolines and dissolution sinkholes have been highlighted as a source of environmental risks and geo-hazards. In particular, such sinkholes have been linked to the degradation of water quality in water springs located in the junction of the TMA and Saïss basin. Furthermore, the developments of collapse dolines in agricultural and inhabited areas enhance the risk of life loss, injury, and property damage. Here, the lack of research on newly formed cavities has exacerbated the situation. The limited studies using remote sensing or geophysical methods to determine the degree of karstification and vulnerability of this environment fail to provide the spatial extent and depth location of individual karst cavities. In order to contribute to the effort of sinkhole risk reduction in TMA, we employed remote sensing and geophysical surveys to integrate electrical resistivity tomography (ERT) and self-potential (SP) for subsurface characterization of four sinkholes identified in the Causse of El Hajeb. The results revealed the existence of sinkholes, both visible and non-accessible at the surface, in carbonate rocks. The sinkholes exhibited distinct morphologies, with depths reaching 35 m. Topography, geographic coordinates and land cover information extracted on remote sensing data demonstrated that these cavities were developed in depressions in which agricultural activities are regularly performed. The fusion of these methods benefits from remote sensing in geophysical surveys, particularly in acquisition, georeferencing, processing and interpretation of geophysical data. Furthermore, our proposed method allows identification of the protection perimeter required to minimize the risks posed by sinkholes.

The Volubilis piggy-back basin, located at the front of the Rif belt, northern Morocco, is a subsided area, as a continuation of the deformational orogenic ridges, related to the present-day African and Eurasian convergence. For the first time, by morphotectonic studies, we analyzed the topographic evolution and drainage systems response. Our results proved the influence of active tectonics in the drainage network and topography of the Volubilis basin. The young phase is indicated by a less dissected planation surface comparing to the ridges, as well as by the ε-shaped hypsometric curve of the khoumane river. This latter drains the continuation of the basin and the eastern arc, where the tectonic activity is mostly concentrated. Based on swath analysis, the general trend of tilting was characterized and was attributed to the recent tectonic movement combined with folds growth of the ridges.

La zona de estudio se ubica en el frente del Pre-Rif externo (norte de Marruecos), en el límite entre la cordillera del Rif y la cuenca neógena del Saiss, y se caracteriza por presentar diapiros triásicos dentro de las formaciones alóctonas Meso-cenozoicas. Para comprender su contexto geológico y su evolución durante el Meso-Cenozoico, realizamos un análisis estructural basado en medidas de fracturación en los materiales que rodean estos diapiros. Los resultados obtenidos se completan con trabajos geofísicos y sísmicos previos. El ascenso de material diapírico (halita, anhidrita y yeso Triásicos) fuo controlado por un sistema de fallas de dirección NW-SE y NE-SW desde el Mesozoico al Cuaternario. El análisis de los contactos entre el material del Triásico y las margas sedimentarias del Mioceno ha revelado que algunos de los contactos tectónicos cartografiados como fallas son en realidad límites estratigráficos caracterizados por conglomerados poligénicos. Este trabajo supone una revisión de la evolución de estos diapiros y un análisis de su geometría actual.

This study uses electrical resistivity tomography (ERT) to characterize the shallow subsurface of the Ribat El-Kheir plateau and assess structural features that may influence groundwater circulation in the Liassic limestone aquifer. Five ERT profiles were interpreted to map resistivity contrasts between the limestone, Triassic clay-rich units and deeper Triassic formations. The interpreted models show resistivities from approximately 3 to more than 5000 Ω·m. The limestone reaches about 40 m in thickness in the southern sector and thins to approximately 5–20 m toward the west and north. A resistivity discontinuity near the 370 m station on Profiles 2 and 3 is interpreted as a fault-related zone; a conductive interval about 10 m wide on Profile 3 may represent intense fracturing. These features identify a potential target for follow-up geological and hydrogeological investigation. ERT constrains subsurface structure but does not, by itself, demonstrate groundwater occurrence, hydraulic connectivity or well productivity.