Northern Afar Research Articles

Spatial distribution of inadequate meal frequency and its associated factors among children aged 6-23 months in Ethiopia: Multilevel and spatial analysis.

More than two-third of global child death is occurred due to inappropriate feeding practice that happened during early childhood period. Evidence on meal frequency status among infant and young children at national level can be used to design appropriate interventions to improve the recommended feeding frequency. Therefore, this study was aimed to explore the spatial distribution and identify associated factors of inadequate meal frequency among children aged 6-23 months in Ethiopia. Secondary data analysis was conducted using the 2019 mini Ethiopian Demographic and Health Survey data. A total weighted sample of 1,532 children aged 6-23 months were included. To identify significant factors associated with of inadequate meal frequency, multilevel binary logistic regression model was fitted. Variables with p-value < 0.25 from the bi-variable model were exported to multivariable analysis. In the multivariable model, variables with p-value < 0.05 were declared as significantly associated factors and adjusted odds ratio (AOR) with its 95% confidence interval were reported. Multilevel models were compared using deviance and log-likelihood. Spatial analysis tools were utilized to visualize the distribution of inadequate meal frequency. Bernoulli model was fitted using SaTScan V.9.6 to identify most likely clusters and ArcGIS V.10.8 was used to map the hotspot areas. Ordinary least square and geographic weighted regression models were used and compared using information criteria and adjusted-R2. Local coefficients of factors associated with hotspots of inadequate meal frequency were mapped. The prevalence of inadequate meal frequency was 47.03% (95% CI: 44.54%, 49.53%) in Ethiopia. Age of the child, sex of the household head, timely initiation of breastfeeding, current breastfeeding status, number of antenatal care visit, maternal education, and region were significantly associated with inadequate meal frequency. The spatial distribution of inadequate meal frequency was showed significant variation across Ethiopia (Global Moran's I = 0.164, p-value <0.001). A total of 38 significant clusters were detected through SaTScan analysis, from these the 22 primary clusters were located in Somali and Harari. The prevalence of inadequate meal frequency was high in Ethiopia and had significant clustering patter. Significant hotspot clusters were located in Somali, northern Afar, Harari, Amhara, Gambela, and eastern South nation nationalities and peoples' region. Therefore, public health interventions which enhance breastfeeding practice, optimal number of antenatal care visits, educational empowerments should target hotspot areas to decrease inadequate meal frequency practice.

The Dynamic Crust of Northern Afar and Adjacent Rift Margins: New Evidence From Receiver Function Analysis in Eritrea and Ethiopia

AbstractAfar is undergoing the final stages of continental rifting and hosts the triple junction between the Red Sea, Gulf of Aden, and Main Ethiopian rifts. To better understand the nature of the crust and continental breakup in the region, we calculate teleseismic receiver functions across northeastern Afar and the Danakil microplate, using new data from a regional deployment in Eritrea. We estimate the Moho depth and bulk crustal VP/VS ratio using the H‐κ stacking method. The heterogeneity of our crustal thickness estimates (∼19–35 km) indicates that the Danakil microplate has undergone stretching and crustal thinning. By investigating the relationship between crustal thickness and topographic elevation, we estimate the regional crustal bulk density as ρc ≈ 2,850 ± 20 kg m−3, which is higher than expected, given the crustal thickness of the region. We show that topography is 1.5 ± 0.4 km higher than would be expected due to crustal isostasy alone. We propose that this topography is supported by the same hot mantle upwelling suggested to be responsible for the onset of rifting in East Africa. Uplift is generated due to the presence of a hot thermal anomaly beneath the plate and by thinning of the lithospheric mantle. Our results are consistent with a number of independent constraints on the thermal structure of the asthenospheric and lithospheric mantle. Evidence of melt within the crust is provided by anomalously high VP/VS ratios of &gt;1.9, demonstrating that magma‐assisted extension continues to be important in the final stages of continental breakup.

Extensional Earthquakes in the Absence of Magma in Northern Afar: Insights From InSAR

AbstractIn magma‐rich rifts, normal faulting is commonly thought to be induced by dike intrusions. However, whether fault slip occurs purely tectonically is unclear. An earthquake sequence starting with a Mw 5.5 earthquake occurred in December 2022 in northern Afar, a continental rift near breakup. InSAR measurements show that seismicity was caused by normal faulting alone, without involvement of magma movements. Our best‐fit InSAR models show that conjugate faults ruptured during the seismic sequence with mainly normal dip‐slip and total deformation corresponding to a Mw 5.7 event, in agreement with local seismic recordings. Our models show that tectonic faulting accommodates 26 cm of extension corresponding to ∼30 years of plate spreading without any link to magma. Our observations point toward significant along‐rift variation in the proportion of extension from faulting, potentially caused by along‐rift variations in rate of extension and/or from a spatially and temporally segmented supply of magma.

Strain Accommodation by Intrusion and Faulting in a Rift Linkage Zone: Evidences From High‐Resolution Topography Data of the Afrera Plain (Afar, East Africa)

AbstractAt mature magma‐rich continental rifts, extension focuses along discrete axial segments where magmatism and diking are important in accommodating plate divergence. However, the role of magma in influencing the deformation at rift–rift offsets is still unclear as direct observations are rare. Here, we exploited high‐resolution Pléiades‐1 tri‐stereo imagery to produce the first 1 m Digital Elevation Model of the Afrera Plain linkage zone between the Erta Ale and Tat Ali magmatic segments in Northern Afar. We carried out a detailed structural analysis of both tectonic and magmatic features in the area and observed different trends and kinematics of these features. Magmatic features at Afrera strike N160°E ± 5°E, similar to the Erta Ale segment and perpendicular to the extension direction. Conversely, tectonic features fall into two families of ∼NW‐SE‐ and ∼NS‐striking oblique faults with right‐lateral and left‐lateral components, respectively, as shown by Riedel shears. We interpret the extension direction of tectonic features using observed opening of fractures, previous seismic, and InSAR‐based fault models and from that expected for the mapped conjugate fault pattern. While the results show scatter in the range of N46°E–N68°E, it is similar within error to the regional extension direction. The simplest model that explains our data is that in the linkage zone there is both extensional and shear strain. The dikes accommodate only extension, while conjugate oblique faults accommodate extension and shear strain. Our study shows that both magmatism and faulting are important during rift segment interaction and linkage.

Across and along-strike crustal structure variations of the western Afar margin and adjacent plateau: Insights from receiver functions analysis

We used teleseismic receiver function analysis to image the crustal structure beneath 24 broadband seismic stations densely deployed along two profiles traversing different structural units across the western Afar margin. Our high-resolution receiver function results image pronounced spatial variations in the crustal structure along the profiles and provide improved insights to understand how strain is partitioned in the crust during rifting. Beneath the western plateau next to northern Afar, the crust is likely felsic-to-intermediate in composition (average Vp/Vs 1.74), with a step like thinning of the crust from an average of 38 km beneath the western plateau to an average of 22 km beneath the marginal graben. Consistently thicker crust is observed beneath the southern profile (central Afar), showing four distinct regions of uniform crustal thickness: 1) an average crustal thickness of 42 km beneath the western plateau; 2) 34 km beneath the foothills area; 3) 28 km beneath the marginal graben and the wide extensional basin and 4) 21 km beneath the central rift axis. We use crustal thickness results to estimate a stretching factor β of 2.2 and 2.7 for central Afar and northern Afar respectively. Our estimated values are lower than β > 3.0 predicted from plate reconstructions, and we interpret that the variations are best explained by 2–5 km magmatic addition into the crust. The crustal composition beneath the southern profile is more complex with elevated Vp/Vs ratios ranging between 1.79 and 1.85 beneath the western plateau and marginal graben. This is consistent with a greater mafic component and best explained by crust altered by intrusions due to significant pre and syn-rift magmatic activity. Abnormally high Vp/Vs ratios of more than 1.90 are observed beneath the axial rift zone of central Afar, which most likely suggests the localization of partial melt within the crust.

The ontogenetic pattern of Hippopotamus gorgops Dietrich, 1928 revealed by a juvenile cranium from the one-million-years-old paleoanthropological site of Buia (Eritrea)

An almost complete cranium of a juvenile individual from the late Early Pleistocene site of Buia, in the northern Afar (Danakil) Basin in Eritrea, reveals a different growth pattern of the extinct species Hippopotamus gorgops Dietrich, 1928 compared to the extant species Hippopotamus amphibius Linnaeus, 1758. The specimen shows important cranial features of Hip. gorgops (also visible in adult specimens), with a derived cranial anatomy that is related to the specialization to a more aquatic life style than other species of Hippopotamidae: elevated nuchal and sagittal crests, strongly elevated orbital cavities, short neurocranium and elongated palate. A geometric morphometrics analysis was performed in the lateral view on skulls of Hip. gorgops and Hip. amphibius, to investigate size-shape relationship and to compare ontogenetic growth trajectories between both taxa. The study revealed that, during growth (increase in size and age), variations in skull shape are prominent in Hip. amphibius; juvenile and adult individuals of Hip. gorgops display strong morphological similarities but size and shape are poorly correlated. The results support the hypothesis that in a relatively early ontogenetic stage, Hip. gorgops was more specialized in its aquatic adaptation than Hip. amphibius.

Plate‐Boundary Kinematics of the Afrera Linkage Zone (Afar) From InSAR and Seismicity

AbstractStudying the mechanisms of interaction between rift segments is key to understanding the kinematics of plate boundaries in continental rifts. However, the spatial and temporal evolution of deformation at rift linkage zones is rarely observed directly. Here, we combine InSAR data spanning 2005–2010 and 2014–2019 from ENVISAT and Sentinel‐1 satellites, respectively, with local seismicity from the Afar rift to investigate the plate‐boundary kinematics of the Afrera linkage zone, the junction between the Erta Ale and Tat Ali magmatic segments in Northern Afar (Ethiopia). We obtain time‐series of cumulative InSAR Line‐Of‐Sight (LOS) displacements that show deformation is accommodated by a series of active en‐echelon faults striking ∼NS and characterized by normal slip associated with a left‐lateral strike‐slip component. Additionally, we observe spatial variation in fault behavior with stick‐slip and creep. The faults in the center of the linkage zone behave primarily in a stick‐slip mode (with abrupt fault displacements up to ∼40 mm) and fault motions are associated with earthquakes of ML &gt; 5. Conversely, faults at the edge of the linkage zone, near the magmatic segments, show creep and some stick‐slip behavior (with cumulative LOS displacement up to ∼30–40 mm over a ∼5‐year period) accompanied by low‐level seismicity. Some of the creeping faults are also spatially associated with hydrothermal springs. We interpret that the temporal behavior of the faults in the linkage zone is controlled by the interplay between tectonic extension, high heat flows, and fluid circulation near the magmatic segments where creeping of some faults is favored.

Geochemistry of the Adwa – Yeha felsic plugs and domes, Tigray – Northern Ethiopia: Implications to their petrogenesis and tectonic setting

The Adwa – Yeha felsic plugs and domes are chain of towering inverted cone-shaped isolated plugs and circular domes with wide basal diameters and steep-sided, narrow tops. They form contrasting prominent topography from the Trap basalt ridges of the Adwa – Axum - Tekeze volcanic ridge, located just west of the Northern Afar Depression. The felsic plugs and domes are concentrated in the Adwa – Yeha area, in a zone of about 20 km wide and 30 km long and generally aligned along NNE-SSW direction, parallel to the regional structural grain of the Precambrian basement and the Miocene - Pliocene rift margin faults. In this study, we investigated these felsic plugs and domes using petrological and major and trace element geochemical methods in order to constrain their petrogenetic evolution. Their possible tectonic link to the Western Afar Margin has also been investigated combining our geochemical data, with assessment of regional tectonic setting and geochronological data from previous studies. The results ascertain that the felsic plugs and domes are peralkaline trachytes and peralkaline to sub-alkaline rhyolites, formed by Assimilation Fractional Crystallization (AFC) of basaltic magma which involved removal of olivine, pyroxene, plagioclase, and Fe–Ti oxides, and moderate amount of crustal input. The eruption of the felsic plugs and domes occurred along reactivated Precambrian weakness zones during the formation of the western Afar boundary faults.

Observing Oblique Slip During Rift Linkage in Northern Afar

AbstractExtensional plate boundaries are segmented by offsets that transfer extension between the ends of adjacent portions of the rift by linkage zones ranging in width from a few tens of kilometers to several hundreds of kilometers. However, the kinematics of linkage zones is poorly constrained as direct observations are difficult to make. Here we combine InSAR, seismicity, and structural geology data from the Afar rift to show that an active linkage zone currently connects the two offset Erta Ale and Tat Ali segments. The overall right‐lateral shear between the segments is accommodated primarily by oblique left‐lateral slip along faults subparallel to the rift segments but an active conjugate fault system with right‐lateral slip is also present. Our results provide the first direct observational evidence that offset rift segments during continental breakup can be linked by a shear zone composed of a conjugate set of oblique slip faults.

Ultra-small microorganisms in the polyextreme conditions of the Dallol volcano, Northern Afar, Ethiopia

The Dallol geothermal area in the northern part of the Danakil Depression (up to 124–155 meter below sea level) is deemed one of the most extreme environments on Earth. The area is notable for being part of the Afar Depression, an incipient seafloor-spreading center located at the triple junction, between Nubian, Somali and Arabian plates, and for hosting environments at the very edge of natural physical-chemical extremities. The northern part of the Danakil Depression is dominated by the Assale salt plain (an accumulation of marine evaporite deposits) and hosts the Dallol volcano. Here, the interaction between the evaporitic deposit and the volcanisms have created the unique Dallol hot springs, which are highly acidic (pH ~ 0) and saline (saturation) with maximum temperatures ranging between 90 and 109 °C. Here we report for the first time evidence of life existing with these hot springs using a combination of morphological and molecular analyses. Ultra-small structures are shown to be entombed within mineral deposits, which are identified as members of the Order Nanohaloarchaea. The results from this study suggest the microorganisms can survive, and potential live, within this extreme environment, which has implications for understanding the limits of habitability on Earth and on (early) Mars.

Imaging Lithospheric Discontinuities Beneath the Northern East African Rift Using S-to-P Receiver Functions.

Imaging the lithosphere is key to understand mechanisms of extension as rifting progresses. Continental rifting results in a combination of mechanical stretching and thinning of the lithosphere, decompression upwelling, heating, sometimes partial melting of the asthenosphere, and potentially partial melting of the mantle lithosphere. The northern East African Rift system is an ideal locale to study these processes as it exposes the transition from tectonically active continental rifting to incipient seafloor spreading. Here we use S‐to‐P receiver functions to image the lithospheric structure beneath the northernmost East African Rift system where it forms a triple junction between the Main Ethiopian rift, the Red Sea rift, and the Gulf of Aden rift. We image the Moho at 31 ± 6 km beneath the Ethiopian plateau. The crust is 28 ± 3 km thick beneath the Main Ethiopian rift and thins to 23 ± 2 km in northern Afar. We identify a negative phase, a velocity decrease with depth, at 67 ± 3 km depth beneath the Ethiopian plateau, likely associated with the lithosphere‐asthenosphere boundary (LAB), and a lack of a LAB phase beneath the rift. Using observations and waveform modeling, we show that the LAB phase beneath the plateau is likely defined by a small amount of partial melt. The lack of a LAB phase beneath the rift suggests melt percolation through the base of the lithosphere beneath the northernmost East African Rift system.

Seismicity During Continental Breakup in the Red Sea Rift of Northern Afar

AbstractContinental rifting is a fundamental component of plate tectonics. Recent studies have highlighted the importance of magmatic activity in accommodating extension during late‐stage rifting, yet the mechanisms by which crustal thinning occurs are less clear. The Red Sea rift in Northern Afar presents an opportunity to study the final stages of continental rifting as these active processes are exposed subaerially. Between February 2011 and February 2013 two seismic networks were installed in Ethiopia and Eritrea. We locate 4,951 earthquakes, classify them by frequency content, and calculate 31 focal mechanisms. Results show that seismicity is focused at the rift axis and the western marginal graben. Rift axis seismicity accounts for ∼64% of the seismic moment release and exhibits a swarm‐like behavior. In contrast, seismicity at the marginal graben is characterized by high‐frequency earthquakes that occur at a constant rate. Results suggest that the rift axis remains the primary locus of seismicity. Low‐frequency earthquakes, indicative of magmatic activity, highlight the presence of a magma complex ∼12 km beneath Alu‐Dalafilla at the rift axis. Seismicity at the marginal graben predominantly occurs on westward dipping, antithetic faults. Focal mechanisms show that this seismicity is accommodating E‐W extension. We suggest that the seismic activity at the marginal graben is either caused by upper crustal faulting accommodating enhanced crustal thinning beneath Northern Afar or as a result of flexural faulting between the rift and plateau. This seismicity is occurring in conjunction with magmatic extension at the rift axis, which accommodates the majority of long‐term extension.

Archaeological reconnaissance of the Late Pleistocene Red Sea coast in the Danakil

The paucity of archaeological evidence from the northern Afar Rift and Red Sea littoral remains a major hindrance to testing the hypothesised Out-of-Africa dispersal of early humans via the ‘Southern Route’—across the Bab al-Mandeb into Arabia and beyond. Encouraged by renewed geological studies (e.g. Atnafu et al. 2015), and recent archaeological discoveries (e.g. Walter et al. 2000; Beyin 2013), we initiated a pioneering exploration along the ancient Red Sea coast in the Danakil Depression (Figure 1a–c). The most conspicuous geomorphological features here constitute terraces of reef carbonates and associated marine deposits, formed when the depression was covered by the open Red Sea during the Middle to Late Pleistocene. Initial results of our exploration promise contexts in which the distribution and cultural/behavioural adaptation of early humans during the Out-of-Africa event can be closely investigated.

Archaeological reconnaissance of the Late Pleistocene Red Sea coast in the Danakil

The paucity of archaeological evidence from the northern Afar Rift and Red Sea littoral remains a major hindrance to testing the hypothesised Out-of-Africa dispersal of early humans via the ‘Southern Route’—across the Bab al-Mandeb into Arabia and beyond. Encouraged by renewed geological studies (e.g. Atnafu et al. 2015), and recent archaeological discoveries (e.g. Walter et al. 2000; Beyin 2013), we initiated a pioneering exploration along the ancient Red Sea coast in the Danakil Depression (Figure 1a–c). The most conspicuous geomorphological features here constitute terraces of reef carbonates and associated marine deposits, formed when the depression was covered by the open Red Sea during the Middle to Late Pleistocene. Initial results of our exploration promise contexts in which the distribution and cultural/behavioural adaptation of early humans during the Out-of-Africa event can be closely investigated.

Extension and stress during continental breakup: Seismic anisotropy of the crust in Northern Afar

Studies that attempt to simulate continental rifting and subsequent breakup require detailed knowledge of crustal stresses, however observational constraints from continental rifts are lacking. In addition, a knowledge of the stress field around active volcanoes can be used to detect sub-surface changes to the volcanic system. Here we use shear wave splitting to measure the seismic anisotropy of the crust in Northern Afar, a region of active, magma-rich continental breakup. We combine shear wave splitting tomography with modelling of gravitational and magmatic induced stresses to propose a model for crustal stress and strain across the rift. Results show that at the Ethiopian Plateau, seismic anisotropy is consistently oriented N–S. Seismic anisotropy within the rift is generally oriented NNW–SSE, with the exception of regions north and south of the Danakil Depression where seismic anisotropy is rift-perpendicular. These results suggest that the crust at the rift axis is characterized by rift-aligned structures and melt inclusions, consistent with a focusing of tectonic extension at the rift axis. In contrast, we show that at regions within the rift where extension rate is minimal the seismic anisotropy is best explained by the gravitationally induced stress field originating from variations in crustal thickness. Seismic anisotropy away from the rift is controlled by a combination of inherited crustal structures and gravitationally induced extension whereas at the Dabbahu region we show that the stress field changes orientation in response to magmatic intrusions. Our proposed model provides a benchmark of crustal stress in Northern Afar which will aid the monitoring of volcanic hazard. In addition we show that gravitational forces play a key role in measurements of seismic anisotropy, and must be considered in future studies. We demonstrate that during the final stages of continental rifting the stress field at the rift axis is primarily controlled by tectonic extension, but that gravitational forces and magmatic intrusions can play a key role in the orientation of the stress field.

Lake Afrera, a structural depression in the Northern Afar Rift (Red Sea).

The boundary between the African and Arabian plates in the Southern Red Sea region is displaced inland in the northern Afar rift, where it is marked by the Red Sea-parallel Erta Ale, Alaita, and Tat Ali volcanic ridges. The Erta Ale is offset by about 20 and 40 km from the two en echelon ridges to the south. The offset area is highly seismic and marked by a depression filled by lake Afrera, a saline body of water fed by hydrothermal springs. Acoustic bathymetric profiles show ≈80 m deep canyons parallel to the NNW shore of the lake, part of a system of extensional normal faults striking parallel to the Red Sea. This system is intersected by oblique structures, some with strike-slip earthquakes, in what might evolve into a transform boundary. Given that the lake’s surface lies today about 112 m below sea level, the depressed (minus ≈190 m below sea level) lake’s bottom area may be considered the equivalent of the “nodal deep” in slow-slip oceanic transforms. The chemistry of the lake is compatible with the water having originated from hydrothermal liquids that had reacted with evaporites and basalts, rather than residual from evaporation of sea water. Bottom sediments include calcitic grains, halite and gypsum, as well as ostracod and diatom tests. The lake’s level appears to have dropped by over 10 m during the last ≈50 years, continuing a drying up trend of the last few thousand years, after a “wet” stage 9,800 and 7,800 years before present when according to Gasse (1973) Lake Afrera covered an area several times larger than at present. This “wet” stage corresponds to an early Holocene warm-humid climate that prevailed in Saharan and Sub Saharan Africa. Lake Abhé, located roughly 250 km south of Afrera, shows similar climate-driven oscillations of its level.

Local Earthquake Magnitude Scale andb‐Value for the Danakil Region of Northern Afar

The Danakil region of northern Afar is an area of ongoing seismic and volcanic activity caused by the final stages of continental breakup. To improve the quantification of seismicity, we developed a calibrated local earthquake magnitude scale. The accurate calculation of earthquake magnitudes allows the estimation of b ‐values and maximum magnitudes, both of which are essential for seismic‐hazard analysis. Earthquake data collected between February 2011 and February 2013 on 11 three‐component broadband seismometers were analyzed. A total of 4275 earthquakes were recorded over hypocentral distances ranging from 0 to 400 km. A total of 32,904 zero‐to‐peak amplitude measurements ( A ) were measured on the seismometer’s horizontal components and were incorporated into a direct linear inversion that solved for all individual local earthquake magnitudes ( M L), 22 station correction factors ( C ), and 2 distance‐dependent factors ( n , K ) in the equation M L=log( A )−log( A )+ C . The resultant distance correction term is given by −log( A )=1.274336log( r /17)−0.000273( r −17)+2. This distance correction term suggests that attenuation in the upper and mid‐crust of northern Afar is relatively high, consistent with the presence of magmatic intrusions and partial melt. In contrast, attenuation in the lower crust and uppermost mantle is anomalously low, interpreted to be caused by a high melt fraction causing attenuation to occur outside the seismic frequency band. The calculated station corrections serve to reduce the M L residuals significantly but do not show a correlation with regional geology. The cumulative seismicity rate produces a b ‐value of 0.9±0.06, which is higher than most regions of continental rifting yet lower than values recorded at midocean ridges, further supporting the hypothesis that northern Afar is transitioning to seafloor spreading. [Electronic Supplement:][1] List of all local earthquakes used in the study with calculated local magnitudes and associated magnitude error. [1]: http://www.bssaonline.org/lookup/suppl/doi:10.1785/0120150253/-/DC1

Geochemistry of metavolcanics and granitic intrusive from western margin of northern afar depression, Dallol, Northern Ethiopia

The western margin of northern Afar Depression constitutes various rock units of Neoproterozoic basement complex. Major oxide data of metavolcanic and granitoid rock samples from basement complex indicate significant variation in the concentration of major oxides (e.g. Fe 2 O 3 , TiO 2 , CaO, MgO). Metavolcanic rocks of Dallol demonstrate heterogeneous nature of magma source. The mafic metavolcanics indicate two distinct groups, (i) CaO-enriched and (ii) tholeiitic composition. Another group of magmatic series, the felsic metavolcanic group, shows a co-genetic relationship with the tholeiitic metavolcanics. Granitoids on the other hand have a wider range of SiO 2 (61.5 – 76.65 wt %) and are peraluminous to metaluminous in nature. Keywords : Geochemistry, Metavolcanics, Granitioids, Dallol, Northern Afar Depression, Ethiopia.

A preliminary Geological and Generalized Stratigraphy of Western Margin of Northern Afar Depression, Dallol Area, Northern Ethiopia

The western margin of northern Afar Depression constitutes various rock units of Neoproterozoic basement complex, Paleozoic to Mesozoic sedimentary successions and the Oligocene to present volcano-sedimentary sequences. As part of a reconnaissance survey for mineral resources in selected districts of Afar region, a geological and structural map of Dallol area has been produced with the help of the Landsat Thematic Mapper Plus imagery at a scale of 1:100,000 and a simplified stratigraphy is constructed for the western rift margin, Dallol area.Keywords: Geology, Stratigraphy, Western Rift Margin, Dallol, Northern Afar Depression, Ethiopia.

Gaet’ale- a reactivated thermal spring and potential tourist hazard in the Asale salt flats, Danakil Depression, Ethiopia

This paper serves to document a thermal spring, called Gaet’ale, that was reactivated in 2005, during the majorseismo-volcanic crisis in the Danakil Depression of the Afar region of northern Ethiopia. Many dead birds surrounding the spring attest to deadly gas emanations (almost certainly CO2) coming from this spring, reminiscent of those from other volcanic lakes, and the Pamukkale springs in Turkey. Gae’tale currently features among the tourist attractions of the Dallol region of the northern Afar, but it may pose a potentially dangerous, and even deadly, hazard for tourists and their guides. Some suggestions are made to help mitigate the risks, and to allow for sustainable geotourism in this environmentally sensitive region. These include ensuring that tour operators in the area are made aware of the hazards, and are communicating these to their tourist clients (who should also be aware of these hazards through websites, tour guidebooks and open-access scientific journals), and avoiding the areas closest to the lake, and periodic testing, with lit flames, for the presence of excess CO2 in the area, with plans for quick and safe evacuation if needed. Guidelines for proper conduct are given for geotourists who are planning to visit the region, to ensure their health and safety in the vicinity of the thermal springs.