Dissertations / Theses on the topic 'Afar, Ethiopie'

Cette description grammaticale de l’afar s’appuie essentiellement sur des données recueillies sur le terrain auprès de très nombreux locuteurs afarophones, vivant à Djibouti, en Erythrée et en Ethiopie. La richesse des données a permis de prendre en compte les variantes dialectales tout au long de la description. Celle-ci s’organise autour de plusieurs parties : système phonologique et phonétique, système nominal, système verbal, et syntaxe de l’énoncé. Cette étude a permis de mieux évaluer l’originalité de certains traits connus mais aussi de mettre en valeur des traits peu connus voire ignorés jusqu’à présent. Citons entre autres : redéfinition du statut de la rétroflexe ; approfondissement des valeurs sémantiques et syntaxiques attachées aux différents procédés de dérivation nominale et verbale ; illustration du rôle primordial de la relative dans une langue où il n’y a pas de catégorie « adjectif » ; étude détaillée de la polarité de genre et de l’accord du verbe en genre non en nombre (accord au singulier avec un nom marqué comme pluriel) ; distinction entre noms adverbiaux et adverbes sur des critères syntaxiques; mise en valeur de la portée syntaxique et sémantique des quatre postpositions; meilleure définition de la catégorie des idéophones sur le plan morphophonologique, syntaxique et sémantique ; mise en lumière des procédés de topicalisation. En apportant un nouvel éclairage sur l’afar, à l’intérieur du couchitique et de la famille afro-asiatique, cette thèse se veut aussi une contribution à la typologie des langues
This grammatical description of Afar is mostly based on fieldwork data collected from a great number of Afar speakers living in Djibouti, Eritrea and Ethiopia. The wealth of data has allowed us to embrace dialectal variations in the description. This description has been built around several components: the phonological and phonetic system, the nominal system, the verbal system, and the syntax.This study leads us to better assess the originality of some features that are already known, and also to bring out other features that were not well known or unknown until now: redefinition of the status of retroflex consonants ; enhanced understanding of semantic and syntactic values of different processes of nominal and verbal derivation ; illustration of the crucial role of the relative clause in a language without adjectives ; detailed study of gender polarity and verb agreement in gender – and not in number – (agreement in the singular with a name marked in the plural) ; differentiation between adverbial names and adverbs on the basis of syntactic criteria ; highlight of the syntactic and semantic significance of four postpositions ; better definition of ideophones from the morphophonological, syntactic and semantic aspects ; highlight of topicalization processes. By shedding new light on Afar within the Cushitic and Afro-Asian family, this thesis aims also to contribute to language typolog*y

L'épisode de rifting en cours en Afar Ethiopien, initié en Septembre 2005, est étudié à l'aide de l'interférométrie radar (InSAR), et de la corrélation sub-pixel d'images optiques et radar. Un traitement en série temporelle de ces données géodésiques permet de séparer les événements discrets et les déformations transitoires lentes. Les intrusions magmatiques sont isolées, et le champ de déformation de surface est inversé pour déterminer les caractéristiques géométriques des dikes. L'interaction entre dikes est étudiée à l'aide d'un calcul des variations de contraintes normales statiques sur le plan vertical du dike. Des relations d'échelle sont déduites, et leurs implications mécaniques sont discutées. La présence d'un réservoir sub-crustal d'alimentation, situé au centre du segment magmatique, est mise en évidence. Des déformations transitoires, causées par des cycles de remplissage/vidage de ce réservoir, sont suivies au cours du temps. Un modèle synthétique permettant d'expliquer la cyclicité de l'activité magmato-tectonique sur différentes échelles de temps, de l'heure à la centaine d'années, est introduit. Ce modèle prend en compte la stratification rhéologique de la croûte, la dynamique de recharge du système magmatique central et de mise en place des dikes, et la variation d'épaisseur crustale le long de l'axe du rift. Il intègre aussi les informations issues d'observations effectuées lors de crises de rifting précédentes en Afar et en Islande

Cette thèse revient sur les caractéristiques des conflits armés éthiopiens contemporains(nature et manifestations) à partir d'une réflexion sur la trajectoire historique de l'État,héritier de l'empire construit par Ménélik II à la fin du XIXe siècle et dont les frontièresn'ont que peu varié depuis (hormis l'indépendance de l'Érythrée en 1993). L'expérienceimpériale est également à l'origine d'une perception de l'espace politique éthiopien entermes de " centre " et de " périphérie ". Perception qui demeure dominante au sein desétudes éthiopiennes, notamment dans l'étude de conflits perçus comme opposant le" centre " (assimilé à l'" État moderne ") à ses " périphéries " conquises durant la périodeimpériale (assimilées aux " sociétés traditionnelles "). La réflexion est donc construite àpartir de l'articulation des trois grands thèmes suivants : la formation de l'empire et del'État éthiopien, les conflits armés, et le thème centre-périphérie. Le thème centrepériphériese situe en effet au coeur des interprétations de la formation des empires etdes États. Le rapport entre ce deux thèmes (formation de l'État et thème " centrepériphérie") est ici reformulé à partir des notions de " secteur politique central " et de" secteur politique périphérique " (Coulon 1972). L'État est alors défini comme unprocessus historique produit par la formation (formelle, symbolique et cognitive) de cesdeux secteurs politiques central et périphérique. Ces deux secteurs interdépendants, dontles caractéristiques évoluent en fonction des reconfigurations économiques, sociales etpolitiques, sont à comprendre au sein d'un même ensemble produisant l'État éthiopien etson identité, sa nation.Cette thèse analyse donc le rapport entre la formation de ces deux secteurs politiques etles conflits armés en vue d'en offrir une grille de lecture renouvelée et dépassant lalecture dominante opposant le " centre " à ses " périphéries ". L'étude de trois régionsconflictuelles (Érythrée, Gambella, Afar) et de leur rapport à l'État éthiopien font alorsapparaître non plus une, mais trois grandes tendances de conflit (toujoursinterdépendantes et parfois cumulatives), à savoir : le conflit entre les deux secteurspolitiques, le conflit à l'intérieur du secteur politique central, et le conflit à l'intérieur dusecteur politique périphérique. Enfin, ce travail défend l'idée selon laquelle ces conflitsémanent d'une double crise de l'État éthiopien : une crise " de " l'État (remise en cause del'État éthiopien lui-même), et une crise " dans " l'État (remise en cause du régime et dugouvernement éthiopien, mais pas de l'État en lui-même). De cette double crise, héritéede la période impériale et qui éclot lors du Second règne d'Hailé Sélassié (1941-1974),dérivent les conflits éthiopiens contemporains.

ABSTRACT The sedimentary deposits of the Hadar Formation at Dikika and the Mount Galili Formation at Galili preserve a wealth of paleoenvironmental and paleoclimatic records spanning the last 5.29 Ma. Stable carbon and oxygen isotopic compositions of herbivore tooth enamel were analyzed for more than 600 specimens of 15 different taxa from 10 stratigraphic intervals. The application of carbon and oxygen isotopes here aims principally at reconstructing shifts in the relative abundance of C4 grasses, and its implications for climate indicators including temperature, aridity, and seasonality. The full range of δ13Cenamel values throughout the Plio-Pleistocene signifies a wide range of foraging strategies by the fauna, which in turn reflects the mosaic of vegetation at Dikika and Galili. Estimates of ecosystem carbon isotope composition (δ13Cecosystem , which is given by average δ13Cenamel of each large vertebrate taxon weighted by the respective faunal abundance and the estimated daily biomass consumption) is used to asses shifts in the ecosystem-scale proportion of C3 and C4 vegetation. In the Plio-Pleistocene, the general paleoenvironmental conditions varied from wooded grassland to grasslands with the total amount of C4 grass cover on the landscape varying between 35% and 91%. Likewise, the paleohabitat reconstructions indicate the presence of grassland, wooded grassland, woodland habitats throughout the Pliocene and in Middle Pleistocene but the relative proportion of the habitats has changed substantially with time. Although this result agrees with the general trend towards more open grassland since the Late Miocene, a rebound of closed habitats and C3 resources from closed canopy woodlands or forests is evident in the middle Pliocene between 3.42 Ma and 3.24 Ma. These changes in the proportion of habitats could have affected the distribution and availability of preferred food resources and has an implication on the interaction of the animals on the paleolandscape and competition for resources. 18Oenamel values also show a wide range of variation within each stratigraphic member and through time. Temporal variation of δ13Cenamel values within a given taxon, as well as differences among sympatric taxa, document different aspects of the environment and climate, including changes in drinking water source, seasonality, and periods of strong evaporation. Estimated δ13Cmeteoric water based on the most 18O-depleted hippo tooth enamel, displays values of -1.94 / (VSMOW) and -5.24 / (VSMOW) in the Middle Pleistocene of Asbole and middle Pliocene of Galili, respectively. A major shift in the isotopic composition of water at ~ 3.0 Ma was accompanied by a 6.0 / increase from middle Pliocene to the present. While a +3.8 / shift from early to middle Pliocene was documented. The isotopic composition of meteoric water between 4.6 Ma and 4.38 Ma was most 18O-enriched compared to the rest of the Pliocene estimates. Likewise, an increase in the estimated δ13Cmeteoric water values was documented in the Awash Valley and elsewhere in East Africa, which indicate a regional climate change since the early Pliocene. An increase in the aridity, which is expressed as mean annual water deficit (i.e., the difference between potential evapotranspiration and mean annual precipitation) is also evident since the early Pliocene. These changes during the Pliocene in the region may in part be attributed to a regional decrease in the amount of precipitation and changes in the moisture source superimposed on global climate changes.

The Dabbahu-Manda Hararo rift segment is a ~25 x 60 km rift zone in Afar, Ethiopia, where a series of axial dyke intrusions has recently occurred. Basaltic eruptions associated with individual dyking events between 2007-2010 have been fed from fissures along the rift axis and been relatively short-lived events lasting less than 60 hours. The volume of melt delivered to the rift surface by these eruptions has been a minor component of the total melt volume supplied to the shallow crust since the onset of the active rifting phase in 2005 and the current intruded to erupted melt ratio for the 2005-2010 period is ~260:1. This is below typical values for magmatic rift zones and may suggest that further volcanism is likely to occur before this activity ceases. ⁴⁰Ar/³⁹Ar geochronology of basaltic lavas from the flank of the rift and from a region of off-axis volcanism to the west of the rift zone gives ages of 25 – 450 ka. These constrain the development of a prominent axial graben in the northern part of the rift to < 30 ka and based on the age-distribution of lavas across the rift flank suggests that volcanism has been focused to the present neo-volcanic zone for at least 200 ka. Geochemical and isotopic constraints on melt generation suggest ~4-6 % partial melting of fertile mantle beneath rift at depth of ~100-75 km. Lavas erupted at the rift axis and from off-axis volcanoes are derived from a common mantle source, however, axial lavas are shown to represent slightly greater extents of partial melting suggesting a focused mantle melting anomaly, such as those seen at ocean ridges, is forming beneath the rift zone.

The Afar region of Ethiopia is slowly being torn apart by the Red Sea, Gulf of Aden and Main Ethiopian rifts which all meet at this remote, barren corner of Africa. Prior to rifting, volcanism probably started here some 30 million years ago, marked by the arrival of the Afar mantle plume and subsequent eruption of kilometres thick flood basalts. To the north and east the Red Sea and Gulf of Aden rifts have already progressed to become sea-floor spreading centres where new oceanic crust is produced. Active spreading on the Red Sea rift takes a landward step west into Eritrean Afar at approximately 15oN, after which divergence between the Nubian and Arabian tectonic plates is localised into 60 km long, 20 km wide magmatic segments that undergo periodic rifting cycles. This part of Afar is a unique natural laboratory where the process of transition from continental rifting to sea floor spreading can be studied. In September 2005 a dramatic rifting episode began on one such segment of the Red Sea rift in Afar (the Dabbahu magmatic segment), whereby a 60 km long dyke containing an estimated 2.5 km3 magma was intruded in just two weeks, allowing opening of up to 8 m. Since then a further 13 smaller dykes have been intruded, some with fissural eruptions of basaltic lava. Subsidence observed via geodetic observations can only account for a small fraction of the magma supply required to in ate the dykes, suggesting a deep crustal or upper mantle source must exist. The magnetotelluric (MT) method is a passive geophysical technique, used to probe the Earth to reveal subsurface conductivity. The presence of fluids can dramatically increase conductivity by orders of magnitude making the MT method ideally suited to detecting them. MT data collected from 22 sites on profiles near to and crossing the active rift are analysed and interpreted in conjunction with seismic and petrological constraints. They reveal for the first time, the existence of both a mid to lower-crustal magma chamber directly below the rift, and an o -axis zone of partial melt well within the mantle. The volume of melt contained within the crust and upper mantle below the Dabbahu segment is estimated to be at least 350 km3; enough to supply the rift at current spreading rates for almost 30 thousand years, assuming that both melt containing regions supply the rift. Vast amounts of highly conductive material, suggesting the existence of pure melt in places, are also required in the shallow crust close to Dabbahu volcano which lies at the northern end of the segment. Further data collected on the currently inactive Hararo segment which is the next one to the south of Dabbahu, show a smaller zone of partial melt that appears to be pooling at the Moho, inferred seismically to be at about 22 km, but little or no melt is required within the mid-crust. The minimum amount of melt estimated to be contained here is just 21 km3; an order of magnitude less than on the Dabbahu segment, but similar to estimates for melt within the crust found below the rift axis in the continental Main Ethiopian rift. This, along with other morphological evidence, suggests that this rift segment is less mature than the Dabbahu segment to the north, rather than it simply being at a different stage of a rifting cycle. A wide spread layer of highly conductive sediments up to 2 km thick has been imaged at most locations. This was unexpected on the Dabbahu segment where the surface of the Earth is dominated by heavily faulted basalts erupted from fissures, which are seen as a resistive uppermost layer several hundred metres thick. The high conductivity of the sediments is attributed to high heat flow and the presence of brines.

The development of magmatism during the transition from continental rifting to sea-floor spreading remains poorly understood as most rifted margins are now inactive and buried beneath thick sediments. Dabbahu and the basaltic Erta Ale volcanoes situated within the actively rifting Afar region of northern Ethiopia, offer a unique opportunity to address this problem. The nature of rhyolitic volcanism, the sub-volcanic system, and their relationship to basaltic magmas involved in dyking events is investigated at Dabbahu volcano and forms the main subject of this study. The evolution of the volcano is constrained through 9 new 40Ar/39Ar dates and geochemical analysis of 93 samples, supplemented by a new geological map. Dabbahu has been active for over 65,000 years, erupting basalts through to evolved pantellerites. Modelling shows the evolved magmas were derived through protracted (>80%) fractional crystallisation. A shallow magma storage region (1-5 km) is confirmed through melt inclusion analysis, and further constrained with seismic and InSAR data. However, it is proposed that this region is a temporary site of pre-eruptive storage for evolved products and the site of differentiation lies at depth within the crust (14-20 km). Field evidence indicates that magmas were not erupted in fractionation sequence and mixing between cogenetic magmas is recorded on all scales. The input of new magma may have been a key eruption trigger at Dabbahu throughout its history, as was the case in the most recent 2005 eruption at the Da’Ure vent following dyke injection. Erta Ale is a basaltic shield within the most northerly magmatic segment of the same name, and contains one of the world’s longest lived lava lakes. An overview of the events of the November 2010 eruption in this remote area has been constructed through a combination of ground observation and remote sensing. Analysis of zero age lavas provides new insights into this unique volcano

A partir de l'identification de plusieurs frontières de l'espace djiboutien (auparavant Côte française des Somalis, puis Territoire français des Afars et des Issas), nous revisitons l'histoire coloniale de Djibouti sous l'angle de la fabrication des territoires. Nous étudions particulièrement cinq frontières que l'on peut tracer sur une carte : les limites ethniques, les limites internes, les frontières internationales terrestres, le corridor ferrovaire et les frontières maritimes. Nous étudions comment ces différentes frontières ont été découvertes ou inventées à Djibouti, dans le cadre général de la formation des espaces dans la Corne de l'Afrique au XIXe siècle, puis comment elles ont été réalisées. Nous analysons les évolutions - dont l'éventuelle consolidation - de ces frontières jusqu'à l'indépendance. Enfin nous en étudions les conséquences et répercussions, en particulier la coercition qu'elles exercent, directement ou indirectement, sur les habitants.

Parmi toute la diversité microbienne des trois domaines du vivant, une fraction des microorganismes (en particulier certaines Archées) s’est adaptée aux conditions les plus extrêmes. La plupart des environnements extrêmes se caractérisant par de multiples facteurs de stress, une partie des extrêmophiles sont en réalité polyextrêmophiles. Néanmoins, il n’y a pas de microorganismes connus adaptés simultanément à un pH très faible (<1.5) ainsi qu’une très forte salinité (et éventuellement une forte température). Soit il n'existe pas d'adaptations moléculaires capables de supporter certaines combinaisons de pH et de salinité, soit ces incertitudes sont liées au fait que les environnements hyperacides et hypersalés (et chauds) sont rares et inexplorés.Le désert de sel de la dépression de Danakil en Ethiopie se situe à la confluence de trois plaques tectoniques dans le rift Est Africain. Au milieu de cette zone géologiquement active, le dôme géothermal de Dallol et ses environs offrent une rare combinaison de paramètres physicochimiques, alliant forts taux de sels (20 à 78%, riches en Mg2+/Ca2+ ou en Na+(/Fe2+/3+)) et des pH neutres à négatifs (~6 à -1.5). Par conséquent, l'ensemble de ces sites constituent un bon modèle pour étudier les communautés microbiennes le long de ces gradients rares et uniques. Au cours des quatre dernières années, nous avons collecté 235 échantillons au niveau des différents sites de Dallol et ses alentours. Des mesures physicochimiques in situ et ex situ nous ont permis de caractériser chaque environnement et d’estimer son habitabilité théorique. Nous avons ensuite procédé à la purification d’ADN des échantillons amplifié et séquencé des gènes d'ARNr 16S/18S afin de caractériser la diversité microbienne que nous avons comparé à des bases de données et classées phylogénétiquement. Nous avons également complété notre étude par des analyses/observations au cytomètre de flux au microscope (optique, électronique à balayage et confocal).Les environnements hypersalés (~30% de NaCl) et légèrement acides (pH 4-6) ont montré une diversité de microorganismes très élevée, dominée par les Archées (80% du total des séquences) en particulier des phyla Halobacteria et Nanohaloarchaeota, fréquemment associés dans les milieux hypersalés. Nous avons pu constater que l’augmentation de l’acidité et la salinité s’accompagnait de l’augmentation de la proportion d’Archées (en particulier de Nanohaloarchaeota). Une meilleure adaptation des archées halophiles par rapport aux bactéries pourrait expliquer leur prévalence. Quant aux nanohaloarchées, leur augmentation pourrait être lié à leur rôle suspecté d’ectosymbiontes d’haloarchées : dans le cas d’une relation mutualiste, ils pourraient favoriser l’adaptation de leur hôte aux conditions plus extrêmes ; dans le cas d’une relation parasitaire, des conditions environnementales plus difficiles pour l’hôte pourrait favoriser le parasitisme. Aucune trace de vie microbienne n'a été trouvée dans les environnements les plus polyextrêmes (salinité 20-78%, pH -1 à 3). Pour certains sites, nous interprétons que les valeurs de chaotropicité, d'activité de l'eau et de force ionique liés à la composition et concentration de sels (minimum 50%, riches en Mg2+/Ca2+) sont limitantes pour la vie microbienne. Pour d'autres, comme le dôme de Dallol, il pourrait s'agir de la combinaison d'hypersalinité et d'hyperacidité (pH~0) qui le rendent inhospitalier, sans exclure d’éventuels composés chimiques stérilisateurs. Les environnements avec une biomasse faible ou absente étant sensibles à la biocontamination, nous avons tâché d’estimer l’impact de cette biocontamination sur l’étude des sites multi-extrême de Dallol et de ses environs. Nous proposons ainsi un protocole rigoureux, basé sur l’utilisation d’analyses croisées et de témoins positifs/négatifs dans toutes nos expériences afin de séparer l’ADN endogène et exogène, et de distinguer les cellules des biomorphes abiotiques dans nos échantillons
From the vast microbial diversity of the three domains of life, a fraction of microorganisms (in particular some Archaea) have adapted to the most extreme conditions. Since most extreme environments are characterised by multiple stress factors (e.g. hot and acidic hydrothermal springs, saline and alkaline lakes, etc.), some extremophiles are in fact polyextremophiles. Nevertheless, there is no microorganism known to be adapted simultaneously to a very low pH (<1) and high salinity (and possibly high temperature). Either there are no molecular adaptations capable of withstanding certain combinations of pH and salinity, or this absence is related to the rarity of hyperacidic and hypersaline (and hot) environments, leaving them unexplored.The salt desert of the Danakil Depression (Afar region) in Ethiopia lies at the confluence of three tectonic plates in the East African Rift. In the middle of this geologically active zone, the Dallol geothermal dome and its surroundings offer a rare combination of physicochemical parameters, with high salt levels (20 to 78%, rich in Mg2+/Ca2+ or Na+(/Fe2+/3+)) and neutral to negative pH values (~6 to -1.5). Therefore, these sites provide a good model for studying microbial communities along these rare and unique parameter gradients. Over the last four years, we have collected 235 samples (solids, liquids, plankton biomass) from the different sites in and around the Dallol dome. In situ and ex situ physicochemical measurements have enabled us to characterise each environment and estimate its theoretical habitability based on previously known life-limiting conditions. We then proceeded to DNA purification of the samples and amplified and sequenced 16S/18S rRNA genes in order to characterize the microbial diversity, which we compared with databases and classified phylogenetically. We also completed our study by using a flow cytometer (for multiparametric analysis), and microscope observations (optical, scanning electron and confocal laser scanning).Hypersaline (~30% salts, dominated by NaCl) and slightly acidic (pH 4-6) environments showed a very high diversity of microorganisms, dominated by Archaea (at least 80% of the total sequences) in particular Halobacteria and Nanohaloarchaeota, frequently associated in hypersaline environments. We observed that the increase in acidity and salinity was associated with an increase in the proportion of Archaea (especially Nanohaloarchaeota). A better adaptation of halophilic archaea compared to bacteria could explain their prevalence. Concerning nanohaloarchaea, their higher proportion could be linked to their suspected role as haloarchaea ectosymbionts: in the case of a mutualistic relationship, their association could favour the adaptation to more extreme conditions; in the case of a parasitic relationship, the rise of acidity and salinity may weaken the host and increase the parasite prevalence. No trace of microbial life has been found in the most polyextreme environments (salinity 20-78%, pH -1 to 3). For some sites, we interpret that the chaotropicity, water activity and ionic strength values related to the composition and concentration of salts (minimum 50%, rich in Mg2+/Ca2+) are limiting for microbial life. For others, such as the Dallol dome, it could be the combination of hypersalinity and hyperacidity (pH~0) that make it inhospitable, without excluding the possible presence of sterilising chemical compounds. As environments with low or absent biomass are sensitive to biocontamination (local or laboratory), we have also tried to estimate the impact of this biocontamination on the study of the multi-extreme sites of Dallol and its surroundings. We thus propose a rigorous protocol, based on the use of cross-analyses and positive/negative controls in all our experiments in order to separate endogenous and exogenous DNA, and to distinguish cells from abiotic mineral biomorphs in our samples

Dyke intrusions and normal faulting play an important role during continental break-up but little is known about how the normal faults develop. Direct evidence of dyke-induced faulting is limited by the lengthy repeat times between individual rifting episodes, the small amount of subaerial rift zones and until recently the technical ability to record small surface changes across large areas. The most recent (2005-2010) rifting episode at the Dabbahu rift segment, Afar, Ethiopia provided a unique opportunity to study dyke-induced fault growth. The combination of new high-resolution topographic LiDAR data and interferometric synthetic aperture radar (InSAR) data provides information of cumulative as well as incremental fault throw. In this thesis I use high-resolution LiDAR data of the Dabbahu rift segment to reveal a dense network of short fault segments (>3400) at various stages of fault linkage set in flood basalt plains. I develop and present a semi-automatic algorithm that extracts throw along surface fault traces from the high-resolution LiDAR DEM. The largest amount of throw (~80 m) is found on faults towards the east of the rift segment. At the central Ado’Ale volcanic edifice predominant bookshelf faulting is evident which might be an indication of a lateral shift of the dykes towards the east. I use the throw data to derive a strain field for the rift. Faults record ~140 m of extension, implying extensive resurfacing. I derived displacement data from two LiDAR surveys and InSAR data, for two separate dyke intrusions. Both data sets show that faults are re-activated in a broad, 3-4 km wide, asymmetric zone parallel to the dyke induced subsidence with the majority of the new throw being accumulated on 1-2 large west-dipping fault structures in the east. The incremental displacement-length, d − L, data presented here is the first quantitative study of accumulation of new fault throw across an entire rift segment. Incremental throw across linkage zones suggest two types of behaviour once fault linkage is complete. 1) Individual fault segments maintain the ability to slip independently. This was previously only observed during analogue modelling. 2) The connected faults act as one throughgoing fault with slip unaffected by the linkage zone. The combination of these two processes might be responsible for the commonly observed small-scale corrugation in d − L data. In contrast to published fault growth models, I present evidence that the remnant fault tip of a linkage zone does not necessarily become inactive once linkage is complete, and that linkage zones do not ‘catch up’ through accelerated throw once linkage is complete.

Cette thèse revient sur les caractéristiques des conflits armés éthiopiens contemporains(nature et manifestations) à partir d’une réflexion sur la trajectoire historique de l’État,héritier de l’empire construit par Ménélik II à la fin du XIXe siècle et dont les frontièresn’ont que peu varié depuis (hormis l’indépendance de l’Érythrée en 1993). L’expérienceimpériale est également à l’origine d’une perception de l’espace politique éthiopien entermes de « centre » et de « périphérie ». Perception qui demeure dominante au sein desétudes éthiopiennes, notamment dans l’étude de conflits perçus comme opposant le« centre » (assimilé à l’« État moderne ») à ses « périphéries » conquises durant la périodeimpériale (assimilées aux « sociétés traditionnelles »). La réflexion est donc construite àpartir de l’articulation des trois grands thèmes suivants : la formation de l’empire et del’État éthiopien, les conflits armés, et le thème centre-périphérie. Le thème centrepériphériese situe en effet au coeur des interprétations de la formation des empires etdes États. Le rapport entre ce deux thèmes (formation de l’État et thème « centrepériphérie») est ici reformulé à partir des notions de « secteur politique central » et de« secteur politique périphérique » (Coulon 1972). L’État est alors défini comme unprocessus historique produit par la formation (formelle, symbolique et cognitive) de cesdeux secteurs politiques central et périphérique. Ces deux secteurs interdépendants, dontles caractéristiques évoluent en fonction des reconfigurations économiques, sociales etpolitiques, sont à comprendre au sein d’un même ensemble produisant l’État éthiopien etson identité, sa nation.Cette thèse analyse donc le rapport entre la formation de ces deux secteurs politiques etles conflits armés en vue d’en offrir une grille de lecture renouvelée et dépassant lalecture dominante opposant le « centre » à ses « périphéries ». L’étude de trois régionsconflictuelles (Érythrée, Gambella, Afar) et de leur rapport à l’État éthiopien font alorsapparaître non plus une, mais trois grandes tendances de conflit (toujoursinterdépendantes et parfois cumulatives), à savoir : le conflit entre les deux secteurspolitiques, le conflit à l’intérieur du secteur politique central, et le conflit à l’intérieur dusecteur politique périphérique. Enfin, ce travail défend l’idée selon laquelle ces conflitsémanent d’une double crise de l’État éthiopien : une crise « de » l’État (remise en cause del’État éthiopien lui-même), et une crise « dans » l’État (remise en cause du régime et dugouvernement éthiopien, mais pas de l’État en lui-même). De cette double crise, héritéede la période impériale et qui éclot lors du Second règne d’Hailé Sélassié (1941-1974),dérivent les conflits éthiopiens contemporains
This work deals with contemporary Ethiopian armed conflicts (nature and forms) out of areflexion on the state trajectory. The Ethiopian state is to be studied in the continuity ofthe empire built by Menelik II at the end of the XIXth century, whose borders haveremained almost unchanged since then (except the Eritrean independence in 1993). Theparticular perception of the Ethiopian political space studied in terms of “centre” and“periphery” is also embedded in this imperial period. A perception which remainscharacteristic of Ethiopian studies, considering the Ethiopian armed conflicts as opposinga “centre” (considered synonymous with “modern state”) to its “peripheries” inheritedfrom the imperial conquests (seen as “traditional societies”). The thesis is thus built outof these three following themes which represent the core of the reflexion: the Ethiopianempire- and state formation, armed conflicts, and the centre-periphery relation. In fact,the centre-periphery relation has been determinant in the theories dealing with empiresandstate-formation. Here, I aim at redefining the relationship between state-formationand the centre-periphery theories by using the notions of “central political sector” and“peripheral political sector” (Coulon 1972). The State shall then be considered as ahistorical process produced by the formation (formal, symbolical, and cognitive) of thesesectors. The sectors are dependent of each other and their characteristics derive fromconstant economic, social and political reconfigurations. They shall be considered in asame whole which produces the Ethiopian state and its identity, its nation.The thesis analyses the relationship between the formation of these two political sectorsand armed conflicts in order to rethink the dominant view considering conflicts as acentre conflicting against its peripheries. Illustrated by the study of three regions (whichhave been experiencing armed conflicts since the imperial period, i.e. Eritrea, Gambellaand Afar), and focusing on their constant and changing relations (formal or perceived)with the Ethiopian state, this work confirms the existence of three main conflict trends(interdependent and sometimes cumulative): the conflict between the two sectors, theconflict within the central sector, and the conflict within the peripheral sector. Finally, Iargue that the current Ethiopian conflicts derive from a dual state crisis: a crisis “of” theEthiopian state (the radical refusal of the state), and a crisis “within” the Ethiopian state(refusal of the regime or the government, but not the State itself). This dual crisisinherited from the imperial period took form during the second reign of Haile Selassie(1941-1974). The roots of contemporary armed conflicts in Ethiopia have to be situated insuch a crisis, and their continuation in its resilience

abstract: Sedimentary basins in the Afar Depression, Ethiopia archive the progression of continental breakup, record regional changes in east African climate and volcanism, and host what are arguably the most important fossiliferous strata for studying early human evolution and innovation. Significant changes in rift tectonics, climate, and faunal assemblages occur between 3-2.5 million years ago (Ma), but sediments spanning this time period are sparse. In this dissertation, I present the results of a geologic investigation targeting sediments between 3-2.5 Ma in the central and eastern Ledi Geraru (CLG and ELG) field areas in the lower Awash Valley, using a combination of geologic mapping, stratigraphy, and tephra chemistry and dating. At Gulfaytu in CLG, I mapped the northern-most outcrops of the hominin-bearing Hadar Formation (3.8-2.9 Ma), a 20 m-thick section of flat-lying lacustrine sediments containing 8 new tephras that directly overlie the widespread BKT-2 marker beds (2.95 Ma). Paleolake Hadar persisted after 2.95 Ma, and the presence and characteristics of the Busidima Formation (2.7-0.016 Ma) indicates Gulfaytu was affected by a reversal in depositional basin polarity. Combined with regional and geophysical data, I show the Hadar Formation underlying CLG is >300 m thick, supporting the hypothesis that it was the lower Awash Pliocene depocenter. At ELG, I mapped >300 m of sediments spanning 3.0-2.45 Ma. These sediments coarsen upward and show a progression from fluctuating lake conditions to fluvial landscapes and widespread soil development. This is consistent with the temporal change in depositional environments observed elsewhere in the lower Awash Valley, and suggests that these strata are correlative with the Hadar Formation. Furthermore, the strata and basalts at ELG are highly faulted, and overprinted by shifting extension directions attributed to the northern migration of the Afar triple junction. The presence of fossiliferous beds and stone tools makes ELG a high-priority target for anthropological and archaeological research. This study provides a new temporally-calibrated and high-resolution record of deposition, volcanism, and faulting patterns during a period of significant change in the Afar.
Dissertation/Thesis
Ph.D. Geological Sciences 2013

abstract: Providing an environmental context to early hominins is as important as describing the hominin fossils themselves, because evolutionary processes are tightly linked to everchanging ecosystems that vary across space and through time. An optimal understanding of ecosystems changes is critical to formulate and test hypotheses regarding human evolution and adaptation. Fortunately, the fossil record has yielded abundant remains of mammals which can be used to explore the possible causal relationships between environmental change and mammal – including hominin –evolution. Although many studies have already been conducted on this topic, most of them are framed at large spatial and temporal scales. Instead, this dissertation focuses on the evolution and paleoecology of only one group of mammals (the Suidae) in a specific geographical area (lower Awash Valley in Ethiopia) and within a constrained time frame (3.8–2.6 Ma). Three dissertation papers address: 1) changes in suid taxonomic composition in relation to Late Pliocene faunal turnover ~2.8 Ma in the Lee-Adoyta basin, Ledi-Geraru; 2) comparisons of suid diets from Hadar (~3.45–2.95 Ma) with respect to those of Kanapoi (~4.1 Ma, West Turkana, Kenya); 3) the dietary ecology of the suids from Woranso-Mille (~3.8–3.2 Ma). Results of these papers show that 1) after ~2.8 Ma there is a replacement of suid species that is coupled with low relative abundance of suids. This is compatible with more open and/or arid environments at this time; 2) suid dietary breadth was broader in Hadar than in Kanapoi, but this is mostly driven by the dietary niche space occupied by Kolpochoerus in Hadar, a suid genus absent from Kanapoi; 3) suid diets vary both temporally and geographically within the lower Awash Valley. Kolpochoerus incorporates more C4 resources (e.g., grasses) in its diet after ~3.5 Ma and in general, suids after ~3.5 Ma in Woranso-Mille had C4-enriched diets in comparison with those from nearby Hadar and Dikika. Presumably, the changes in suid communities (relative abundance and taxonomic composition) and dietary shifts observed in suids were triggered by climatic and habitat changes that also contributed to shape the behavioural and morphological evolution of early hominins.
Dissertation/Thesis
Doctoral Dissertation Anthropology 2018

abstract: Two of the defining behaviors associated with the hominin lineage are an increased reliance on tool use and the routine incorporation of animal tissue in the diet. These adaptations have been linked to numerous downstream consequences including key physiological adaptations as well as social and cognitive effects associated with modern humans. Thus, a critical issue in human evolution is how to determine when hominins began incorporating significant amounts of meat into their diets. Bone surface modifications (BSM) have long been recognized as a powerful inferential tool in identifying the differential involvement of actors responsible for altering assemblages of bone recovered from both archaeological and paleontological contexts and remain a primary source of direct evidence for butchery activities. Thus, determining the spatiotemporal context of increased carnivory in the hominin lineage relies on the accurate identification of fossil BSM. Multidecade-long debates over the agents responsible for individual BSM indicate systemic flaws in historical approaches to identification. These debates are in part due to the extreme morphological overlap between BSM produced by certain agents of modification. The primary goal of this dissertation project therefore, is to construct probability models of BSM capable of identifying individual marks with an associated probability of assignment. Using a multivariate Bayesian approach to analyze experimentally-generated BSM data, this dissertation uses two different models, one incorporating both two and three-dimensional (3D) metric and attribute data associated with individual BSM and a second model comparing 3D geometric morphometric (GM) shape data associated with BSM. The 2D/3D attribute model of BSM is used evaluate an assemblage of fossil BSM recovered from the Ledi-Geraru research area, Ethiopia (2.82 Ma) in spatiotemporal association with early Homo. The results of the analysis reveal compelling evidence for early butchery activities, suggesting hominins may have been using both modified and unmodified stone implements to process carcasses. The second model, based upon 3D GM data, was used to evaluate the earliest purported evidence for stone-mediated butchery at Dikika, Ethiopia (3.39 Ma). The Dikika marks have been argued to be the result of crocodile feeding, trampling, and butchery by three different research groups. The 3D GM model evaluates the likelihood of each of these actors in the production of the controversial Dikika marks.
Dissertation/Thesis
Doctoral Dissertation Anthropology 2019

The study was aimed at investigating challenges hampering mother-tongue education with special reference to Afan Oromo in the Eastern Hararge Zone, the Oromia Regional State, Ethiopia. The study mainly explored the available learning materials and the skilled teachers in mother-tongue education, attitudinal factors, the extent of stakeholders’ support for mother-tongue education, parents’ education and their awareness about education through mother tongue and parent school involvements. In the study, the researcher used a mixed method approach in which both quantitative and qualitative research designs were employed to corroborate the data obtained through one method by using other methods to minimise limitations observed in a single design. In the quantitative design, survey questionnaires were employed. Accordingly, 634 primary school teachers and 134 students were randomly selected and asked to fill the questionnaires. These quantitative data were analysed through the SPSS software and responses were analysed using the percentages and the chi-square. Qualitative data obtained through in-depth interviews and observations were analysed using thematic approaches. Documents on education policy, constitutions of the country and reports of the Ministry of Education of Ethiopia were also consulted and integrated with the analyses of the data. The study generally suggests unless strong political and administrative supports are given and public awareness about the mother tongue use in education and development is created, the effort to make Afan Oromo the language of education, intellectuals and development may remain fruitless. In this respect, all the stakeholders, intellectuals and leaders must work together to overcome challenges and dilemmas that impede the implementation of mother-tongue education. The practical works on the ground should match with the language policy of the country. Popular awareness raising activities and mobilization of the communities should be carried out carefully to involve all the communities
African Languages

The study was aimed at investigating challenges hampering mother-tongue education with special reference to Afan Oromo in the Eastern Hararge Zone, the Oromia Regional State, Ethiopia. The study mainly explored the available learning materials and the skilled teachers in mother-tongue education, attitudinal factors, the extent of stakeholders’ support for mother-tongue education, parents’ education and their awareness about education through mother tongue and parent school involvements. In the study, the researcher used a mixed method approach in which both quantitative and qualitative research designs were employed to corroborate the data obtained through one method by using other methods to minimise limitations observed in a single design. In the quantitative design, survey questionnaires were employed. Accordingly, 634 primary school teachers and 134 students were randomly selected and asked to fill the questionnaires. These quantitative data were analysed through the SPSS software and responses were analysed using the percentages and the chi-square. Qualitative data obtained through in-depth interviews and observations were analysed using thematic approaches. Documents on education policy, constitutions of the country and reports of the Ministry of Education of Ethiopia were also consulted and integrated with the analyses of the data. The study generally suggests unless strong political and administrative supports are given and public awareness about the mother tongue use in education and development is created, the effort to make Afan Oromo the language of education, intellectuals and development may remain fruitless. In this respect, all the stakeholders, intellectuals and leaders must work together to overcome challenges and dilemmas that impede the implementation of mother-tongue education. The practical works on the ground should match with the language policy of the country. Popular awareness raising activities and mobilization of the communities should be carried out carefully to involve all the communities
African Languages