Role of Fracturing in the Organization of the Karst Features of Azrou Plateau (Middle Atlas,Morroco) Studied by Remote Sensing Imagery

Karst formation geometry can be controlled by fractures and faults, and by other lithologies. Here we show the organization of kastic collapse features related to structures and to extensive basaltic lava flows in the Middle Atlas of Morocco. A lineament map of major faults and fractures has been created for the Middle Atlas using Landsat 7 ETM⁺ satellite images. This shows a dominant NE–SW regional direction and less prominent NNW–SSE and ENE–WSE directions. All these directions coincide with the alignments of karstic depressions that have formed in the Liassic limestones. The basaltic flows covering these formations on the Middle Atlas limestone plateau, have allowed the generation of cryptokarst, geometrically organized a long these major lineament directions. Karst landforms probabaly existed before the eruption of the lavas, but there were partly invaded by intrusions and volcanism. The extensive basaltic flows allowed for increased infiltration, and subsurface water flow, increasing the rate of kast formation after eruptions. Some basins show evidence of increased subsidence after lava emplacement (Aguelmam Sidi Ali Lake) and some maar-like craters also have subsided after eruption, by karts formation. We lay out the structural and lithological controls on Karstic formation in an intraplate volcanic field based on limestones and evaporites.     

The impact of health financing and CO<Subscript>2</Subscript> emission on health outcomes in Sub-Saharan Africa: A cross-country analysis

The current paper examines the relationship between health financing (public and out-of-pocket health financing), CO₂ emission and health outcomes in 35 Sub-Saharan African countries for the period of 1995–2012. The panel unit root and cointegration tests are conducted as pre-tests, followed by the estimation of the parameters using the FM-OLS and DOLS techniques. The findings of the study show the importance of public health financing as one of the major factors that lead to better health outcomes, whereas the out-of-pocket expenditure is found to be harmful to population health since it leads to increase under-5 mortality rate. Although the results show a negative relationship between CO₂ and health outcomes, still these results remain inclusive. In addition, the findings reveal the importance of socioeconomic factors such as income and education as key determinants of health outcomes.     

The Djidjelli (Algeria) earthquakes of 21 and 22 August 1856 (I<Subscript>0</Subscript> VIII,IX) and related tsunami effects Revisited

New historical data from primary sources, allow us to revisit the Djidjelli earthquakes of 21 and 22 August 1856 (I₀ VIII, IX respectively). These two large seismic events are among the most significant events that have affected the North African coast. They have caused extensive damage and generated a tsunami that propagated at several harbours of the western Mediterranean Sea. The effects of each earthquake are analysed from all documentary source materials, emphasising the confrontation of observations and data for an accurate reconstruction of the macroseismic field of both events. The method used provides a more precise way to determine the characteristics of the Djidjelli earthquakes.     

InSAR analysis of a blind thrust rupture and related active folding: the 1999 Ain Temouchent earthquake (M w 5.7, Algeria) case study

We study the surface deformation associated with the 22 December 1999 earthquake, a moderate sized but damaging event at Ain Temouchent (northwestern Algeria) using Interferometric Satellite Aperture Radar images (InSAR). The mainshock focal mechanism solution indicates reverse faulting with a NE–SW trending rupture comparable to other major seismic events of this section of the Africa–Eurasia plate boundary. Previously, the earthquake fault parameters were, however, poorly known because no aftershocks were precisely determined and no coseismic surface ruptures were observed in the field. Using a pair of ERS data with small baseline and short temporal separation in the ascending orbit we obtained an interferogram that shows the coseismic surface displacement field despite poor coherence. The interferogram measures four fringes and displays an ellipse-shaped lobe with ∼11 cm peak line-of-sight displacement. The elastic modeling using a boundary element method (Poly3Dinv) indicate coseismic slip reaching up to 1 m at 5 km depth on the N 57° E trending, dipping 32° NW Tafna thrust fault. The geodetic estimate of seismic moment is 4.7 × 10¹⁷ N m. (Mw 5.7) in is good agreement with seismological results. The elliptical shape of the surface displacement field coincides with the NE–SW trending Berdani fault-related fold. The consistency between the geological observations and InSAR solution shed light on the precise earthquake location and related Tafna fault parameters.     

Neo-deterministic seismic hazard assessment in North Africa

North Africa is one of the most earthquake-prone areas of the Mediterranean. Many devastating earthquakes, some of them tsunami-triggering, inflicted heavy loss of life and considerable economic damage to the region. In order to mitigate the destructive impact of the earthquakes, the regional seismic hazard in North Africa is assessed using the neo-deterministic, multi-scenario methodology (NDSHA) based on the computation of synthetic seismograms, using the modal summation technique, at a regular grid of 0.2?×?0.2°. This is the first study aimed at producing NDSHA maps of North Africa including five countries: Morocco, Algeria, Tunisia, Libya, and Egypt. The key input data for the NDSHA algorithm are earthquake sources, seismotectonic zonation, and structural models. In the preparation of the input data, it has been really important to go beyond the national borders and to adopt a coherent strategy all over the area. Thanks to the collaborative efforts of the teams involved, it has been possible to properly merge the earthquake catalogues available for each country to define with homogeneous criteria the seismogenic zones, the characteristic focal mechanism associated with each of them, and the structural models used to model wave propagation from the sources to the sites. As a result, reliable seismic hazard maps are produced in terms of maximum displacement (D _max), maximum velocity (V _max), and design ground acceleration.     

A 48-kyr-long slip rate history for the Jordan Valley segment of the Dead Sea Fault

We investigate the late Quaternary active deformation along the Jordan Valley segment of the left-lateral Dead Sea Fault and provide new insights on the behaviour of major continental faults. The 110-km-long fault segment shows systematic offsets of drainage systems surveyed at three sites along its southern section. The isotopic dating of six paleoclimatic events yields a precise chronology for the onset of six generations of gully incisions at 47.5 ka BP, 37.5 ka BP, 13 ka BP, 9 ka BP, 7 ka BP, and 5 ka BP. Additionally, detailed mapping and reconstructions provide cumulative displacements for 20 dated incisions along the fault trace. The individual amounts of cumulative slip consistently fall into six distinct classes. This yields: i) an average constant slip rate of 4.7 to 5.1 mm/yr for the last 47.5 kyr and ii) a variable slip rate ranging from 3.5 mm/yr to 11 mm/yr over 2-kyr- to 24-kyr-long intervals. Taking into account that the last large earthquake occurred in AD 1033, we infer 3.5 to 5 m of present-day slip deficit which corresponds to a Mw  7.4 earthquake along the Jordan Valley fault segment. The timing of cumulative offsets reveals slip rate variations critical to our understanding of the slip deficit and seismic cycle along major continental faults.     

Structural analysis of tin-bearing mineralization in Bou El Jaj district (Hercynian Central Massif,Morocco)

The aim of this paper is to characterize the geological setting of tin-bearing mineralization at the Bou El Jaj (BLJ) sector, located in the NE termination of the Moroccan Central Massif, South of Meknes city, along the NE-SW-striking shear zone. The main tin mineralization corresponds to a NNE-SSW altered corridor of tourmaline, about 10 to 12 km long, from BLJ to Achmmach mount. The geological structures are affected by three ductile deformation phases D1, (E-W shortening), D2 (NW-SE shortening), and D3 (N-S shortening), overprinting folds, and one brittle deformation event D4 (NW-SE shortening), which was synchronous with alteration and mineralization. The tourmaline-altered sediments occur in two parallel veins, about 2.5 km long and 200 m wide for each one, and are controlled by structures such as bedding, main cleavage, thrusts, and joints. Tin mineralization as cassiterite is always associated with tourmaline alteration and is controlled by the different structures.