South Atlas Research Articles

Relocation of the 8 September 2023 High Atlas, Morocco, Earthquake Aftershock Sequence

ABSTRACT The earthquake that occurred on 8 September 2023, with a magnitude of 6.8, was the most destructive earthquake event in Morocco in the past decade. This earthquake took place in the Al Haouz region, located in the western part of the High Atlas Mountain range. To better understand what caused and triggered this earthquake, the earthquake catalogs including P and S arrival times were collected from the Moroccan seismic network and combined with regional data from the International Seismological Centre. The mainshock and aftershocks were relocated by using iLoc, a state-of-the-art single-event location algorithm, and then by the multiple event location double-difference algorithm, hypoDD. The improved earthquake relocations using iLoc and the double-difference methods provide sharper lineation of seismicity and agree well with tomographic images of the earthquake zone. The seismicity distribution and the focal mechanism of the mainshock indicate that the earthquake sequence has occurred along the South Atlas fault system.

Fold-thrust belt in the southern front of the central High Atlas (Morocco): Analysis and implications for the tectonic inversion of the atlas system

Thrust folds have developed significantly in the meso-Cenozoic rock units of the Errachidia-Boudnib basin. The study areas correspond to the north part of the Pre-African Trough, which is located between the Anti-Atlas and the Atlas systems. It is characterized by faulted anticlines that are indicative of a foreland orogenic context.The Atlas system's structural evolution underwent several stages, starting with a Triassic extensional event followed by a period of fault reactivation during the Atlas compression. This research focuses on examining the thrust and detachment folds associated with both reverse and strike-slip components. For this purpose, we performed detailed geological mapping and interpretation of folding and fault slip data.As a result of shortening, field observations reveal that the study area exhibited well-developed thrusting geometry. Preexisting blind faults and multiple decollement levels within favorable formations such as Cenomanian evaporitic marls, Cenomanian-Turonian marls rich in organic matter, and Senonian argillites influence the folding patterns, which are not uniform. The findings demonstrate two key points. First, the most significant folds have formed along major blind thrusts. Subsequently, between these major faults, detachment folds were developed within the Jurassic-Cretaceous strata. Currently, due to erosion, certain thrusts have become visible, including the Ta'bbast thrust fault, Ait Atman (from the first stage), and the Timazguit fault zone (from the second stage). The South Atlas fault largely remains a blind fault. Additionally, the study emphasizes the presence of strike-slip components and en-echelon folding, indicating a transpressional regime during the uplift of the Atlas system.

Structural analysis, tectonic fracturing modeling, and kinematic evolution along the South Atlas Fault at the northern border of the Tinghir-Errachidia-Boudenib basin (Pre-African Trough, Morocco)

The structural evolution of the High Atlas orogenic belt is characterized by the formation of the thrust propagation folds. The exploration and understanding of the southern central-eastern High Atlas orogenic wedge system are still in their infancy. The significance of the growth of the Tinghir-Errachidia-Boudenib foreland basin (TEB) is underestimated due to limited constraints on surface structural styles and kinematics analysis, as well as insufficient surface data. This question is addressed by using several multi-sources and multi-scale data including a geological map constrained from fieldwork and kinematic analysis, combined with subsurface magnetic data. The integration and analysis of these data provided a comprehensive understanding tectonic fracturing model and reconstruct the kinematic evolution of the northern border of the TEB basin. Analysis of surface and subsurface data identify E−, ENE-to WNW- trending Jbel Tisdar and Jbel Rhouir anticlines interpreted as a fault-propagation fold. Magnetic investigations show a positive anomaly superposed on the hinge of the Jbel Tisdar and the Jbel Rhouir anticlines indicating a Triassic and/or Paleozoic uplifted magnetic materials. Along the southern Atlas margin, brittle tectonic is represented by E−to ENE-reverse faults with a small dextral strike-slip component and NNE-to NE-trending strike-slip faults with a reverse component and associated with NW- trending ones. Fracturing mechanism fault-propagation fold highlights three fracture sets: (i) syn-folding E−trending axial fractures; (ii) syn-folding NW- trending transverse fractures and (iii) late-folding NE-trending fractures. Fault kinematics analyses provide a transpressional tectonic regime, responsible for the structuring (folding, faulting, fracturing) of the Jbel Tisdar and the Jbel Rhouir fault-propagation fold, developed in response to Alpine compressional inversion of the central-eastern High Atlas belt.

The Variscan belts of North-West Africa: An African legacy to the Wilson Cycle concept

The concept of cyclic closure and opening of oceans along the same crustal scar was introduced by J.T. Wilson (1966) based on the example of the Atlantic Ocean and its continental borders. At that time, the only Variscan orogen cited south of Europe along the Atlantic coast of Africa was the Mauritanides of Mauritania. Here we report on the recent achievements in the Mauritanides from Mauritania to Morocco, and on the Moroccan Meseta orogen, which also records the Variscan orogeny. The Southern and Central Mauritanides are a poly-orogenic, Pan-African and Variscan orogen characterized by a thin-skinned tectonic style that mirrors the structure of the southern Appalachians, but with a different tectonic history. The Northern Mauritanides crops out in the Moroccan Oulad Dlim massif, northwest of the Reguibat Rise. This part of the belt compares with the southern part, but additionally exhibits in the west a Silurian-Devonian sector that shows possible affinities with Gondwana-derived Appalachian terranes. The Western Meseta is only affected by Variscan events, which were mild in the westernmost Meseta Coastal Block, while the Eastern Meseta was also affected by Eo-Variscan events. The along-strike change from the Mauritanides to the Meseta orogen is interpreted as a transition from a head-on collision south of the South Meseta transform fault (SMF, precursor of the South Atlas Fault, SAF) to a dextral, transpressional collision north of the SMF. South of the SAF, the Anti-Atlas and the Dhlou-Zemmour expose the foreland foldbelts of the Meseta and northernmost Mauritanides. The Coastal Block was likely displaced from the south-westernmost Anti-Atlas during the Early Carboniferous.The Wilson Cycle concept mostly applied in that the Atlantic Ocean opened where the prior Rheic Ocean had closed. Possible exceptions are the Sehoul Block north of Western Meseta and the Silurian-Devonian Sector of the Oulad Dlim massif, which may have separated from NW-Africa and re-amalgamated to it during the Variscan orogeny. Likewise, a NW-African fragment from the Anti-Atlas may have stranded in offshore Massachusetts in eastern North America. An early Ediacaran-Cambrian Wilson cycle nested in the classic cycle introduced by Wilson (1966) occurred along the margin of NW-Africa, where Cadomian terranes rifted off Africa, and some were transferred to Europe and some accreted back to NW-Africa. This early cycle likely controlled the localization of the subsequent Rheic rift, and that of the Atlantic rift along the Mauritanides after the Variscan collision.

Crustal configuration of the Naama and El Bayadh region of northwest Algeria: Inferences from gravity and magnetic analysis

Northwestern Algeria is located where the Saharan Atlas borders the Saharan Platform along the South Atlas Front. The origin of the South Atlas Front is controversial, thus a detailed gravity and magnetic analysis constrained by seismic reflection profiles and well data were conducted to determine the structural configuration of this region. A residual gravity anomaly map created using upward continuation and a reduced to the pole magnetic anomaly map indicated a series of northwest-trending maxima anomalies parallel to the Atlassic orogeny folds and faults and east-trending maxima within the Benoud foreland basin. These maxima mostly coincide with Paleozoic basement uplifts based on seismic reflection profiles. Depth analyses based on upward continuation, and two-dimensional forward modeling of the gravity and magnetic data indicated that the source of the maxima are mainly 5 km in depth with the magnetic sources being approximately 0.5 km deeper than the gravity sources. The gravity and magnetic models indicate that the source bodies are steep-sided and coincide with interpreted faults from the seismic reflection profiles. The maxima anomalies are mainly caused by basement uplifts instead of variations in density and/or magnetic susceptibility in the Paleozoic or older basement lithologies. The South Atlas Front and the Saharan Atlas on the central and eastern portions of Algeria is governed by a thin-skinned tectonics style involving the Mesozoic-Cenozoic sedimentary cover. While the western part was probably controlled by a mixed thin- and thick-skinned tectonic style with the reactivation of deeply rooted Triassic and Jurassic faults during Tertiary compressive events in the interpreted Paleozoic basement.Our gravity and magnetic models illustrate a crustal architecture model of the Paleozoic basement which is consistent with a north-dipping basement normal fault between less deformed Saharan Platform than the more deformed Atlassic domain. Such a crustal model aids in determining the nature of the Atlassic orogeny as geological and geophysical studies have been determining the variations of structural styles along its entire length.

The Region of Metlaoui Facing Seismic Hazards: Study and Cartographic Approach (South Atlas of Tunisia)

The region of Metlaoui (South Atlas of Tunisia) is listed as one of the major seismotectonic zones of the national territory. About 10 major seismic events with moderate magnitude have occurred from the beginning of last century. The event of 7/11/1989 (Ms = 4.4) was undoubtedly the most important. It caused very significant material damage estimated at 224,525,000 Tunisian Dinars. This study uses a mapping tool to define areas with relatively high degrees of hazard and vulnerability. It also seeks to understand the active fault of the seismic events recorded in this region.

Seismicity and active stress field derived from the inversion of focal mechanism data, South Atlas of Tunisia

Seismicity and active stress field derived from the inversion of focal mechanism data, South Atlas of Tunisia

Discussion on ‘From Pan-African transpression to Cadomian transtension at the West African margin: new U–Pb zircon ages from the Eastern Saghro Inlier (Anti-Atlas, Morocco)’ by Errami et al . 2020 ( SP 503, 209–233)

An important paper has recently been published in Geological Society, London, Special Publications by Errami et al . (2020). On the basis of new U–Pb zircon radiometric data on magmatic and sedimentary rocks in the Saghro Massif, the authors revised the history of magmatic and geodynamic evolution of the Pan-African belts of the Moroccan Anti-Atlas along the northern edge of the West African Craton. The authors focused on the two main accretionary stages widely recognized in the Anti-Atlas (Ennih and Liegeois 2008; Gasquet et al. 2008): (1) a Paleoproterozoic episode, known as the Eburnean Orogeny, characterized by the extensive emplacement of granitoids at c. 2.1 − 2.0 Ga; (2) Neoproterozoic (800–450 Ma) events corresponding to the Pan-African Orogeny. However, in their lithostratigraphic framework of Proterozoic units of the Anti-Atlas, the authors do not account for the magmatic event recently recognized in several inliers in the Anti-Atlas (Fig. 1): Ighrem (Ikenne et al. 2017), Kerdous (Youbi et al. 2019) and Zenaga (Ait Lahna et al. 2020). Sills intrusive into the mixed carbonate–siliciclastic series of the Taghddout and Lkest groups, previously considered as Cryogenian, have been dated at between 1.7 and 1.6 Ga (Fig. 2). These new ages are c . 1 Ga older than previously thought, and call into question the stratigraphic position of the Tagdoute and Lkest groups in the southwestern domain of the Anti-Atlas. These series are now interpreted to be deposited in an intracratonic basin that developed after the assembly of the Nuna–Columbia supercontinent and before the break-up of the Rodinia supercontinent. The previous Cryogenian age for these deposits and their geodynamic setting thus need to be revised. Fig. 1. Geological map of the Anti-Atlas with the locations of the dated sills in the Ighrem, Kerdous and Zenaga inliers shown. SAF, South Atlas Fault; WAC, West African Craton; AVFZ, Ameln Valley Fault Zone; TTFZ, …

South African raptors in urban landscapes: a review

Globally, but especially in Africa, increasing human populations and anthropogenic land-use change are generally affecting diversity negatively. Urban environments in southern Africa typically comprise a mosaic landscape of anthropogenic infrastructure with some green spaces. These urban cities have a range of fauna that have persisted or increased in population density compared with areas that are more natural. We analysed the occurrence of diurnal and nocturnal raptors using South African Bird Atlas Project (SABAP2) data and reviewed literature. We found 66 raptor species occurred in South African cities. Thirty species had reporting frequencies greater than 10% in at least one of the 11 cities assessed, revealing impressive diversity of the raptor clade in South African cities. Five species were both abundant and widespread, occurring >10% in five or more cities each, of which three belong to the scavenger guild: Black-winged Kite Elanus caeruleus, African Fish Eagle Haliaeetus vocifer, Common Buzzard Buteo buteo vulpinus, Yellow-billed Kite Milvus aegyptius and Black Sparrowhawk Accipiter melanoleucus. However, only a few of these 66 raptors had been extensively studied in urban areas: the Black Sparrowhawk, African Crowned Eagle Stephanoaetus coronatus, Lanner Falcon Falco biarmicus and Peregrine Falcon Falco peregrinus. This lack of research is specifically severe, given that Africa is hosting a unique and diverse range of raptor species and that numbers and diversity of raptors have declined dramatically over the past decades across the continent. In fact, these four extensively studied species occurred in higher densities in urban areas than rural areas, which indicates that urban areas might create valuable opportunities for urban conservation, not least through public engagement.

A conceptual framework of groundwater flowpath and recharge in Ziban aquifer: south of Algeria

The Zyban aquifers (southern Algeria) are an important source of groundwater and are mainly found in limestone and dolomite from the Senono-Eocene. To be able to assess the effects of overuse of the Zeban groundwater, it is necessary to understand the origin of the recharge and determine its path out of the recharge zones. This study aims to better understand the flow path and replenishment areas using hydrology. For this purpose, 145 water samples were collected and analyzed for the determination of major ions and isotopes (18O, 2H and 3H). The isotope analysis of hydrogen, oxygen and tritium allowed a certain distinction between the origin and the mixture of water. The study area is located in the fault corridor of the South Atlas, a network of migration and folding defects that leads to a complex structure characterized by the subdivision of the formations and the variety of facies. The regional flow pattern is mainly influenced by the topography, and this is through the distribution of supply and flow, which is produced by transport at many depths and levels of distribution (local or regional). The rocky nature and the severe fractures are responsible for the division of the hydrogeological units and play an important role in the dynamics and transport of the groundwater. The hydrodynamic analysis shows the dominance of regional hydrogeology in terms of geological nature and structure. This is supported by a hydrochemical signal showing the distribution and evolution of the elements according to the structural and geological scheme (evolution from calcium bicarbonate facies to calcium sulphate medium facies).

Structural styles, tectonic events, and deformation features along a surface–subsurface structural transect from the South Atlas Front (N–S axis) to the Eastern Sahel foreland basin of Tunisia

2D seismic cross-sections calibrated to exploration wells allow highlighting the structural styles along a structural transect from the N–S axis, west of the Bouthadi–Chorbane anticline to the foreland, with a major regional tectonic anomaly striking roughly E–W along the subsurface Atlas front of the foreland basin. The interpretation of structural data and seismic profiles allow deciphering clearly the occurrence of Late Cretaceous–Paleogene inversion structures, accounting for folds detached along the basal intra-Triassic salt decollement level. These contractional structures in part result from the Middle–Late Eocene compressional events, which induced the first strong positive inversion in both the Atlas domain and adjacent foreland. The growth of these positive structures is outlined by angular unconformities, sedimentary gaps, and differential subsidence within the Paleogene deposits. The foreland area is characterized by a thick-skinned tectonic inversion style, where the Pre-Triassic basement is decoupled from its Jurassic–Quaternary sedimentary cover by a general decollement level located at the Upper Triassic/Lower Jurassic interface. The deformation features imaged by seismic sections are in agreement with such thick-skinned style controlled by deep-seated faults presumably inherited from the Pan-African basement. A regional structural cross-section is presented and discussed, crossing the N–S axis and outcrops of the South Atlas Front in the west and, then, running through the major structural anomaly of Chorbane and the foreland basin to the east. This regional cross-section has been also balanced and restored to its initial and intermediate geometries, i.e., after the Tethyan and Cretaceous extensional events and Paleogene compressional events, thus documenting the major tectonic anomaly of Bouthadi–Chorbane in the foreland as well as the overall structural evolution of the Atlas fold and thrust belt.

Montane forest birds in winter: do they regularly move to lower altitudes? Observations from the Eastern Cape, South Africa

Seasonal altitudinal migration to lower altitudes including the coast has been ascribed to a number of forest birds, of which 14 species occur at Fort Fordyce Reserve in the Eastern Cape, South Africa. Based on our observations and ringing at this site (2007–2017), as well as concurrent data from the South African Bird Atlas Project (SABAP2), we suggest that in this region only three species, the African Dusky Flycatcher Muscicapa adusta, White-starred Robin Pogonocichla stellata and Barratt's Warbler Bradypterus barratti, are regular altitudinal migrants. For two other species, the Grey Cuckooshrike Coracina caesia and Yellow-throated Woodland Warbler Phylloscopus ruficapilla, local movements apparently occur, but these may take place within the coastal zone rather than between the coast and inland forests.

L’espacement régulier des drains transversaux du front sud atlasique tunisien : implication morphotectonique

Les rivieres sont dans les chaines de montagnes, avec les glaciers pour les plus hautes, les principaux regulateurs de l’erosion. Leur puissance erosive est a la fois controlee par la pente locale, la pente regionale, le flux d’eau et l’erodabilite du substrat. Il a ete remarque que la plupart des chaines recentes lineaires presentaient un espacement regulier de leurs drains transversaux, quels que soient le climat sous lequel elles se developpent et le taux de soulevement auquel elles sont soumises. Dans le cas des chaines de montagnes recentes et lineaires, cet espacement rapporte a la largeur des flancs de celles-ci, defini sous le terme de rapport d’espacement (R), montre des valeurs proches de 2. Cette caracteristique traduit un certain etat d’equilibre entre le reseau de drainage et le soulevement tectonique a l’origine de la chaine sur lequel le reseau se developpe. L’analyse du reseau transverse dans les chaines nord et sud des Chotts le long du front sud-atlasique tunisien montre que ce rapport d’espacement R est compris entre 1,86 et 2,74. Il est comparable a celui du reseau transverse des chaines de montagnes recentes dont les dimensions sont un a deux ordres de grandeur superieures a celles des Chotts. Au vu de l’âge tres recent (plio-pleistocene) des plis du front sud-atlasique tunisien, notre etude suggere que cette caracteristique du systeme de drainage transverse dans les chaines lineaires est acquise des les stades precoces de leur developpement.

The three main steps of the Marrakech High Atlas building in Morocco: Structural evidences from the southern foreland, Imini area

The timing of Cenozoic deformation in the intraplate orogen of the High Atlas of Morocco is still a matter of debate. In this work, the deformation calendar has been studied in the southern foreland of the Marrakech High Atlas. Using a structural approach and the mapping of the Cenomanian–Turonian reference layer, we propose a coherent chronology of deformation that proceeded in three stages: (i) a Late Eocene event that set local and minor structures, barely visible nowadays, but important enough to trigger the record of a first detrital pulse; (ii) an Early(?)–Middle Miocene event that is not related to important shortening, setting gravity “sheets” that provoke cover deformation and feed a second detrital pulse; (iii) a Late Pliocene–Quaternary event that is mainly observed through the activity of basement features like the South Atlas Front of the Imini Fault in our studied area and reworks earlier structures. This calendar can partially fit to the geodynamic changes occurring in the western Mediterranean realm during the Cenozoic. Specifically, the Early(?)–Middle Miocene stage of deformation is suggested to be intrinsic to Morocco.

Transient fluvial incision as an indicator of active faulting and Plio-Quaternary uplift of the Moroccan High Atlas

One of the challenges facing Earth Scientists is to determine the extent to which geomorphic features can be used to extract tectonic signals from landscapes. Here, we quantitatively analyse the long profiles of rivers that drain southwards across the South Atlas Fault (SAF), a thrust fault that forms the southern margin of the High Atlas Mountains in Morocco, to derive new data on the Late Cenozoic activity of this fault system. River long profiles were extracted for 32 major rivers flowing southwards into the Ouarzazate Basin. Of these, eleven exhibit concave-up river profiles with a mean concavity of 0.64 and normalized steepness indices in the range 47.5–219.0m0.9. By contrast, 21 rivers exhibit at least one knickpoint upstream of the thrust front. Knickpoint height varies from 100 to 1300m, with calculated incision at the range bounding fault ranging from 80 to 900m, despite the drainage areas upstream of the knickpoint ranging over several orders of magnitude. In map view, knickpoint locations generally plot along sub-parallel lines and there are no obvious relationships with lithological units for knickpoints exhibiting slope-break morphology. Channel reaches below slope-break knickpoints have higher mean concavities (0.76) than above the knickpoint indicative. This observation combined with a lithological or river-capture origin for the knickpoints having been ruled out suggests that an increase in uplift rate along a planar fault zone during the Plio-Quaternary caused the initiation of the transient response (i.e., knickpoint formation) to a change in base-level observed in the river profiles. This uplift event can be correlated to the convective removal of the lithospheric root to the Atlas Mountains resulting in the anomalously high topography at the present day.

Reactivated lithospheric-scale discontinuities localize dynamic uplift of the Moroccan Atlas Mountains: COMMENT

The Atlas Mountains of Morocco have received considerable attention in the past decade regarding the lithospheric structure and the uplift mechanisms of this structurally simple mountain belt. Miller and Becker (2014) have recently added to the discussion with new results from receiver functions and shear-wave splitting analysis. These results confirm the mantle upwelling hypothesis for the Atlas uplift that was postulated 10 years ago and we now see highlighted in several forums. The relationship between modest tectonic shortening and high topography in the Atlas was first addressed by Teixell et al. (2003). They concluded that crustal thickness is insufficient to account for the observed elevations, and proposed a mantle-driven (upwelling) component of uplift, supported by low seismic velocities in the Atlas mantle reported already by Seber et al. (1996). Subsequent efforts focused on modeling of gravity, the geoid, and topography that indicated a prominent lithospheric thinning, placing the lithosphere-asthenosphere boundary (LAB) at 70–90 km beneath the Atlas Mountains (e.g., Teixell et al., 2005; Zeyen et al., 2005; Missenard et al., 2006; Fullea et al., 2010). New contributions on the basis of active and passive seismology, partly under the Picasso project frame, are on their way (e.g., Bezada et al., 2013; Carbonell et al. 2013; Palomeras et al., 2013; Miller and Becker, 2014). Miller and Becker present a receiver functions profile that also shows a thinned crust and lithosphere beneath the Atlas Mountains. However, the thinned domain is bounded by abrupt steps coinciding with the location of the South Atlas thrust front; the authors propose offsets of 9 km of the Moho and 26 km of the LAB across the boundary thrust fault at Errachidia (Miller and Becker, 2014, their figure 2), arguing for the important role of lithosphericscale discontinuities in the Atlas mountain building. As for the crust, this is intriguing because early refraction studies by Wigger et al. (1992) and a more dense wide-angle survey by Carbonell et al. (2013) failed to detect a crustal step in this position, but especially because there is ample evidence that the South Atlas fault is a low-angle thrust zone (Saint Bezar et al. 1988; Teixell et al., 2003). Moreover, Miller and Becker imply that the same fault discontinuity goes down to offset the LAB, which means that the South Atlas thrust projects vertically to a depth of 90 km. This has doubtful geological sense even assuming that the present-day thrusts derive from the inversion of earlier extensional faults: those would also have a dip, and at a depth of 90 km they would be off the vertical projection of the fault surface exposure. Miller and Becker recognize that previous authors document shallowly dipping thrust faults from outcrop and seismic reflection studies, but they do not further discuss this issue. We are left questioning whether there is an enigmatic geological feature in the Atlas that escapes our understanding, or an issue of seismic data resolution. Miller and Becker compare the detected position of the LAB with a modeled position on the basis of the residual topography and on the assumption of isostasy, resulting in a large discrepancy, as the modeled LAB is even shallower than the actual base of the crust. This indicates a strong contribution of dynamic topography due to active mantle upwelling. We do not question the validity of dynamic topography for the Atlas, but we miss a discussion of the earlier potential field models which, on the basis of isostatic equilibrium, fitted the residual topography and the geoid with a greater lithospheric thickness, which would be in accord with the new receiver function results (see references above). Finally, we wish to conclude with a formal comment on the referencing to earlier work in the Atlas. Miller and Becker report a small orogenic shortening (15%–25%) inconsistent with Airy isostatic support and cite four papers, but none of them resulting in these small values of shortening nor do they address relationships between shortening and topography. Fullea et al. (2010) are not the primary reference for the distribution of Quaternary basalts, Frizon de Lamotte et al. (2009) do not provide cross sections to demonstrate shallowly dipping thrust faults, Sebrier et al. (2006) do not provide regional tomography models, and Beauchamp et al. (1999) do not suggest a mantle thermal anomaly as the source of volcanism in the Middle Atlas. Although these citations by Miller and Becker do not alter the main point of their paper, we wish to raise a word of caution for the persistence of incorrect citations.

The Risk and Vulnerability Assessment Centre at the University of Limpopo: Generating New Research Possibilities within Southern African-Nordic Centre

Multiple stresses such as poor service delivery; poverty; inadequate supply of infrastructure in water and energy; complex disease burden and food crises are rampant and prevalent in the rural poor areas making them to be vulnerable. The impact of climate change and variability is aggravating the already dicey situation. The Department of Science and Technology in South Africa, cognisant of this scientific prediction, responded by funding the establishment of Risk and Vulnerability Assessment Centres at rural universities in South Africa. The core mandate of the centres is to supply quality research data on rural areas on a number of critical indicators identified in the South African Risk and Vulnerability Assessment Atlas. In addition, these centres are expected to provide excellent tertiary education in spatial analysis and modelling applied to the environment, economic, social and health sectors. Data and information from the Atlas will be used by local authorities for improved planning, decision-making and appropriate intervention strategies at the target sites. This paper presents an overview of the centre at the University of Limpopo and explores some of the research areas in which the University of Limpopo can collaborate with other members in the Southern African-Nordic Centre Partnership DOI: 10.5901/mjss.2014.v5n3p684

Climate and the Evolution of Group-Living Behaviour in the Armadillo Lizard (Ouroborus cataphractus)

We evaluated the hypothesis that the regular use of the southern harvester termite, Microhodotermes viator, as food source by the armadillo lizard, Ouroborus cataphractus, originated as an adaptation to survive the summer dry season in a climatic regime where rainfall is highly seasonal. To do so, we determined the most important climatic predictors of the geographical range of this species. Climatic data were obtained for 130 localities where O. cataphractus is known to occur and 168 adjacent localities where it is known to be absent. For each locality, data for 10 climatic variables were extracted from the South African Atlas of Agrohydrology and Climatology database. We constructed a forward stepwise logistic regression model of the probability of O. cataphractus occurrence, based on the set of 10 climatic variables. The best model included, in order of importance, average monthly summer rainfall, mean annual precipitation, average monthly solar radiation, and the ratio of winter rainfall over summer r...

Climate and the evolution of group-living behaviour in the armadillo lizard (Ouroborus cataphractus)

We evaluated the hypothesis that the regular use of the southern harvester termite, Microhodotermes viator, as food source by the armadillo lizard, Ouroborus cataphractus, originated as an adaptation to survive the summer dry season in a climatic regime where rainfall is highly seasonal. To do so, we determined the most important climatic predictors of the geographical range of this species. Climatic data were obtained for 130 localities where O. cataphractus is known to occur and 168 adjacent localities where it is known to be absent. For each locality, data for 10 climatic variables were extracted from the South African Atlas of Agrohydrology and Climatology database. We constructed a forward stepwise logistic regression model of the probability of O. cataphractus occurrence, based on the set of 10 climatic variables. The best model included, in order of importance, average monthly summer rainfall, mean annual precipitation, average monthly solar radiation, and the ratio of winter rainfall over summer rainfall as most significant predictors. The selected model predicted 88.80% of the presences correctly and 85.52% of the absences. In essence, O. cataphractus is restricted to the winter rainfall zone of South Africa, excluding the high-rainfall southwestern section. We postulate that the highly predictable seasonal rainfall and the ameliorating effect of the Atlantic Ocean on climates in the Namaqualand region, in particular, have provided a unique selective regime for the origin of group-living in O. cataphractus. Dependence on M. viator as food source developed to survive the summer-autumn period of low food availability and resulted in the evolution of heavy armour and group-living behaviour. The moderate winters and early spring temperatures allowed full capitalization on high arthropod abundance during winter–spring, thereby overriding the negative impacts of armour and group-living on foraging efficiency at the home crevice.

3-D crustal structure in the Agadir region (SW High Atlas, Morocco)

The 1960 Agadir earthquake (Mw 6.0) constitutes the most damaging earthquake event in Morocco. With the expansion of seismic networks during the last decade in Morocco, new seismic data have been collected in this region. The P and S arrivals at 19 stations located in Southern Morocco are used to investigate the lithosphere in the Agadir region. In this study, we use a linearized inversion procedure comprising two steps: (1) finding the minimal 1-D model and simultaneous relocation of hypocentres and (2) determination of local velocity structure using linearized inversion. The model parameterization in this method assumes a continuous velocity field. The resolution tests indicate that the calculated images give near true structure for the studied region from 0- to 45-km depth. The results show that the total crust thickness varies from 30 to 40 km in SW High Atlas and confirm the modest crustal tectonic shortening and thickening in the Atlas Mountains of Morocco. The inferred geological structure reconstructed from the calculated image illustrates the existence of fault-related folding. The evidence for coseismic ruptures in 1960 on the Kasbah anticline combined with the 1960 earthquake hypocentre located in the tomographic image determines the seismic potential of the active fault and related fold. The resulting tomographic image shows a high-velocity anomalies that could be associated with the location of deep active fault (10–30 km) associated with the fold structure. In the South Atlas, theses anomalies could be associated with the South atlas thrust front structure.