Multi criteria assessing approach of the slow-moving urban landslide hazard, the case of Moulay Yacoub town (Morocco)

Since many decades, the town of Moulay Yacoub (MY) has undergone an intensification of its urbanization to meet the demands of rental housing for the visitors of the hydrothermal springs, which is considered as the only attraction of the town. Unfortunately, the majority of the buildings, both private and public, suffer from varying levels of damages where the lithological and geomorphic field features are to blame, without omitting the anthropogenic effects. In fact, the town is built on a marly hill conducive to slope movements, ranging from shallow solifluctions to large landslides, besides the swelling/shrinkage behaviour of these marls. The paper presents a multi-source approach to investigate the activity and the interactions of slow urbanized landslides and expansive soils within the urban perimeter of Moulay Yacoub. Indeed, the desiccation cracks of marly soils reveal their expansive behaviour, also attested by the swelling values. The other geotechnical parameters obtained from laboratory tests show that the shallow marls samples are severely weathered compared to those of the compacted deep ones. The Borehole data and seismic noise survey allows the detection of several impedance contrasts corresponding to the shallow weathered-deep marls interfaces which in some cases represent the rupture surfaces of gravitational processes. The very slow but perennial activities of the later are attested by the inclinometers, the PS-InSAR monitoring and building damages. The case study provides a good opportunity to highlight the complementarity of the multi-source tasks which stand as a further contribution to fostering this kind of integrated approaches at the slope scale.

Groundwater in the Perthus Tunnel: feedback after excavation

This work presents the experiences gained during the construction of the Perthus high-speed railway tunnel (8.4 km long), as regards water inflow management, analysis of the impact on surface-waters and groundwater, monitoring of piezometers and water quality control, soil injections. The excavation met granodiorites, schists, diorites, gneisses, black schists and coarse river deposits (pebbles and blocks) near the north portal. Some important tectonic structures, and associated groundwater flow, were also crossed. Finally, a geothermal study on the hydrothermal springs Le Boulou, which were not impacted, is presented.

Geothermal potential mapping of Northeast Morocco (Bekrane-Ahfir) using remote sensing data and GIS

Geothermal energy is part of the renewable energy mix. It is used for heating, air conditioning and sometimes even for the production of electricity. Prospecting for such a resource proves to be a difficult and capital-intensive task. To overcome this constraint, we have used remote sensing which is an adequate tool to guide the prospecting through the elaboration of hydrothermal resource potential maps at the level of zones that present a favorable potential for exploitation (hyper-tectonized sites, volcanic sites, faulted sites, sites with hot geological formations, seismic zones...). The objective of this work is to carry out a study on the North-East of Morocco (Berkane Province), in order to identify favorable sites for geothermal exploitation such as geologically and hydrogeologically active sites. The methodology adopted consists in processing the images of the OLI (Operational Land Imager) and TIRS (Thermal Infrared Sensor) sensors of the Landsat-8 satellite in order to extract spectral indices (Clay mineral Index and Ferrous mineral Index,) detecting a geothermal activity and the surface temperature map (LST) using muticriteria analysis method (MCA). ) in the north-eastern part of Morocco. The results obtained show an almost perfect concordance of the distribution of the above-mentioned indices, with the map of lineaments which are considered as heat drains from the depth to the surface. Moreover, a correct correlation was established during the validation of these results with the map of the inventory of hydrothermal springs identified in the study area.

Variability of Carbonate Isotope Signatures in a Hydrothermally Influenced System: Insights from the Pastos Grandes Caldera (Bolivia)

Laguna Pastos Grandes (Bolivia), nesting in a volcanic caldera, is a large, palustrine-to-lacustrine system fed by meteoric and hydrothermal calco–carbonic fluids. These different fluid inputs favor a complex mosaic of depositional environments, including hydrothermal springs, pools, and an ephemeral lake, producing abundant present-day carbonates developing over a Holocene carbonate crust dated by U–Th. Present-day carbonates (muds, concretions, and microbialites) recorded a large range of isotope variations, reaching 13.9‰ in δ13C and 11.1‰ in δ18O. Sedimentological and geochemical data indicated that the main processes influencing the isotope record were: (i) rapid CO2 degassing and temperature decreases along hydrothermal discharges; (ii) strong evaporation favored by the arid high-altitude Andean climate, locally enhanced by capillary water rise within microbial mats or by wind-induced spray falling on vadose concretions. Unlike past or present perennial lake systems in Central Andes, the short residence time of brine waters in the ephemeral central lake prevents enrichment of lacustrine carbonates in 13C and 18O. The very low fraction modern F14C in these present-day carbonates demonstrates that incorporation of fossil magmatic carbon related to the volcanic context also prevents any radiocarbon dating. The use of isotopes for the interpretation of ancient continental series should always be accompanied by a thorough characterization of the environmental setting.

Life at the Dallol geothermal area, Ethiopia- a Planetary Field Analog on Earth

<p><strong>Introduction</strong></p><p>Dallol volcano area, proposed as a Mars analog, is considered one of the most extreme environment on Earth. It is located in the Danakil depression, a tectonically and volcanically active region in Ethiopia. The hydrothermal springs that compose the system discharge hyperacidic hot Fe-rich brines, which results in halite deposition when they contact with the atmosphere. As a result, Dallol geothermal area shows extremely high temperature (90-108°C in the springs), pH from -1.7 to 4, and supersaturated salt deposits [1-3].</p><p>Still, <em>life finds a way</em>. Despite these extreme features, microorganisms inhabiting Dallol geothermal region, as members of the class Nanohaloarchaea, have been described [3,4]. The analysis of the biodiversity that are surviving and thriving in such polyextreme system, as well as the study of their metabolic potential, could be fundamental to establish the habitability conditions to search for life on other planets.</p><p><strong>Methods</strong></p><p>We applied Shotgun metagenomics and Fluorescence in situ Hybridizations (FISH) methods to analyze the biodiversity and metabolic potential of Dallol geothermal area microbiome.</p><p><strong>Results</strong></p><p>Our results show the presence of both bacteria and archaea in the Dallol geothermal area, being Bacteria the most abundant domain in this environment. The detected microorganisms are mostly halophiles. However, there is a lower percentage of microorganisms described in extremely hot or acidic environments. FISH experiments corroborated that both bacteria and archaea are alive and active in the system.</p><p>Metagenomics analysis shows a predominance of metabolisms based on photosynthesis, heterotrophy and fermentation. In addition, metabolisms that use hydrogen and reduced sulfur compounds as an energy source stand out.</p><p>Additionally, genes related to the response to oxidative stress, heat shock, osmotic stress and detoxification have been detected, which could be involved in the adaptation of these microorganisms to the extreme conditions of the Dallol volcano area.</p><p><strong>References</strong></p><p>[1] Cavalazzi, B., et al. (2019). The Dallol geothermal area, Northern Afar (Ethiopia)—An exceptional planetary field analog on Earth. Astrobiology, 19(4), 553-578.</p><p>[2] Kotopoulou, E., et al. (2018). A polyextreme hydrothermal system controlled by iron: the case of Dallol at the Afar Triangle. ACS Earth and Space Chemistry, 3(1), 90-99.</p><p>[3] Carrizo, D., et al. (2019). Lipid Biomarker and Carbon Stable Isotope Survey on the Dallol Hydrothermal System in Ethiopia. Astrobiology, 19(12), 1474-1489.</p><p>[4] Gómez, F., et al. (2019). Ultra-small microorganisms in the polyextreme conditions of the Dallol volcano, Northern Afar, Ethiopia. Scientific reports, 9(1), 1-9.</p>