Kenya Rift Research Articles

Transmission Dynamics of Crimean-Congo Haemorrhagic Fever Virus (CCHFV): Evidence of Circulation in Humans, Livestock, and Rodents in Diverse Ecologies in Kenya.

Crimean-Congo haemorrhagic fever virus (CCHFV) is the causative agent of CCHF, a fatal viral haemorrhagic fever disease in humans. The maintenance of CCHFV in the ecosystem remains poorly understood. Certain tick species are considered as vectors and reservoirs of the virus. Diverse animals are suspected as amplifiers, with only scarce knowledge regarding rodents in virus epidemiology. In this study, serum samples from febrile patients, asymptomatic livestock (cattle, donkeys, sheep, and goats), and peridomestic rodents from Baringo (Marigat) and Kajiado (Nguruman) counties within the Kenyan Rift Valley were screened for acute CCHFV infection by RT-PCR and for CCHFV exposure by ELISA. RT-PCR was performed on all livestock samples in pools (5-7/pool by species and site) and in humans and rodents individually. CCHFV seropositivity was significantly higher in livestock (11.9%, 113/951) compared to rodents (6.5%, 6/93) and humans (5.9%, 29/493) (p = 0.001). Among the livestock, seropositivity was the highest in donkeys (31.4%, 16/51), followed by cattle (14.1%, 44/310), sheep (9.8%, 29/295) and goats (8.1%, 24/295). The presence of IgM antibodies against CCHFV was found in febrile patients suggesting acute or recent infection. CCHFV RNA was detected in four pooled sera samples from sheep (1.4%, 4/280) and four rodent tissues (0.83%, 4/480) showing up to 99% pairwise nucleotide identities among each other. Phylogenetic analyses of partial S segment sequences generated from these samples revealed a close relationship of 96-98% nucleotide identity to strains in the CCHFV Africa 3 lineage. The findings of this study suggest active unnoticed circulation of CCHFV in the study area and the involvement of livestock, rodents, and humans in the circulation of CCHFV in Kenya. The detection of CCHF viral RNA and antibodies against CCHFV in rodents suggests that they may participate in the viral transmission cycle.

Quantifying production losses associated with foot and mouth disease outbreaks on large-scale dairy farms in Rift valley, Kenya.

Foot and Mouth Disease (FMD) is a contagious viral disease to which dairy cattle are highly susceptible. An outbreak of FMD in a dairy herds can cause a drop in milk yield, increase mastitis infections, and force culling. These production losses can be substantial, but farmers undervalue the magnitude of the loss that they incur. The study quantified the association of FMD outbreaks with milk yield, mastitis incidences, and culling rates. The data was from three large-scale dairy farms with a recent history (2008 to 2018) of FMD outbreaks in a region endemic for the prevalence of serotype C of the FMD virus since the mid-1980s in the Rift valley of Kenya. A total of 507 cows were monitored for three consecutive periods of six weeks before, during, and after FMD outbreaks. Relative to the period before and after the disease outbreak, production losses were marked during the outbreak. A disease outbreak was associated with up to 4.7% of the cows drying off (n = 24) and milk production dropped by 16.1%. The incidence of mastitis increased from 5.4% to 21.5% (OR = 3.31, CI = 2.27, 4.83) and culling rates increased from 0.59% to 3.8% (OR = 6.71, CI = 1.99, 22.58).

Hydroclimate reconstructions in the Suguta Valley, northern Kenya, during the Early-Middle Pleistocene Transition

The Early-Middle Pleistocene Transition (EMPT) between 1200 and 700 ka represents a major global climate transition from dominantly 41,000- to 100,000-year glacial cycles. The forces and mechanisms behind this transition and the response of African environments are not well understood. The active volcanism and tectonics of the East African Rift System add complexity to local environmental systems and can erase important proxy records, inhibiting studies of lacustrine dynamics. As a result, there is minimal understanding of how this transition impacted the region's lake systems. At Paleolake Suguta, in the northern Kenya Rift, however, flood basalts cap lacustrine EMPT-age deposits, preserving these strata and their valuable paleoenvironmental record. This research presents a high-resolution reconstruction of hydrological change from approximately 931 to 831 ka within the Suguta-Turkana Basin in the northern Kenya Rift. Paleolake dynamics are reconstructed from a 41 m sedimentary section using diatom morphology, sedimentology, and X-Ray Fluorescence elemental analysis. Results show that lake levels varied greatly during this part of the EMPT with two wetter phases and two drier phases developing over about 100 kyr. From ∼885–831 ka, especially, the Suguta-Turkana Basin exhibits rapid changes in paleohydrology, ranging between deep stratified lakes; shallow, well-mixed lakes; and complete desiccation, with some of these changes occurring on an order of hundreds of years. This EMPT Suguta-Turkana-Baringo record therefore provides valuable insight into hydroclimate variability at an overall resolution of several thousand years, allowing reconstruction of past environments during a period of poorly understood terrestrial environmental change.

Analyses of Mosquito Species Composition, Blood-Feeding Habits and Infection with Insect-Specific Flaviviruses in Two Arid, Pastoralist-Dominated Counties in Kenya.

Insect-specific flaviviruses (ISFs), although not known to be pathogenic to humans and animals, can modulate the transmission of arboviruses by mosquitoes. In this study, we screened 6665 host-seeking, gravid and blood-fed mosquitoes for infection with flaviviruses and assessed the vertebrate hosts of the blood-fed mosquitoes sampled in Baringo and Kajiado counties; both dryland ecosystem counties in the Kenyan Rift Valley. Sequence fragments of two ISFs were detected. Cuacua virus (CuCuV) was found in three blood-fed Mansonia (Ma.) africana. The genome was sequenced by next-generation sequencing (NGS), confirming 95.8% nucleotide sequence identity to CuCuV detected in Mansonia sp. in Mozambique. Sequence fragments of a potential novel ISF showing nucleotide identity of 72% to Aedes flavivirus virus were detected in individual blood-fed Aedes aegypti, Anopheles gambiae s.l., Ma. africana and Culex (Cx.) univittatus, all having fed on human blood. Blood-meal analysis revealed that the collected mosquitoes fed on diverse hosts, primarily humans and livestock, with a minor representation of wild mammals, amphibians and birds. The potential impact of the detected ISFs on arbovirus transmission requires further research.

Sedimentary ancient DNA of rotifers reveals responses to 200 years of climate change in two Kenyan crater lakes

Abstract Sedimentary ancient DNA (sedaDNA) has proven to be a useful tool for palaeoenvironmental studies, but only a handful of studies exist so far for tropical regions. In this study we used sedaDNA to study the temporal succession of Brachionus spp. rotifer mitochondrial DNA haplotypes using two sediment cores from two climatically different alkaline‐saline crater lakes from the Kenyan Rift Valley. Data were retrieved from a sediment core (dating back to AD 1800) from Lake Kageinya, located in the remote, hot and hyper‐arid Suguta Valley. sedaDNA was used to study the temporal succession of mitochondrial DNA haplotypes of Brachionus spp. rotifers. The results were compared to previously published data from Lake Sonachi, a well‐studied lake in the humid and colder mountainous region of Kenya near the town of Naivasha, now supported by a 210Pb age chronology. Both records extend back before the onset of substantial anthropogenic impact in these regions. The results revealed that climate—rather than anthropogenic impact—was most strongly correlated with haplotype changes in both lakes. During prolonged dry periods (such as from AD 1910 to the late AD 1960s), certain haplotypes persisted. Sudden changes and the emergence of alter native haplotypes were observed when climate became more humid or during episodes of highly variable climate (before AD 1910 and from AD 1960s onwards). Progressive changes in prevailing haplotypes during periods with variable climate could reflect local adaptation and/or be the result of immigration of new haplotypes after the eradication of previous populations during extreme environmental conditions (high temperatures, UV irradiation, pH and salinity). The results indicate that, despite adverse chemical conditions, sedaDNA in tropical lake sediments is preserved for at least a few hundred years. Therefore, its analysis provides a useful complementary palaeoenvironmental proxy for palaeolimnological reconstructions and novel insights on changes in rotifer populations through time.

Divergent Hantavirus in Somali Shrews (Crocidura somalica) in the Semi-Arid North Rift, Kenya.

Hantaviruses are zoonotic rodent-borne viruses that are known to infect humans and cause various symptoms of disease, including hemorrhagic fever with renal and cardiopulmonary syndromes. They have a segmented single-stranded, enveloped, negative-sense RNA genome and are widely distributed. This study aimed to investigate the circulation of rodent-borne hantaviruses in peridomestic rodents and shrews in two semi-arid ecologies within the Kenyan Rift Valley. The small mammals were trapped using baited folding Sherman traps set within and around houses, then they were sedated and euthanatized through cervical dislocation before collecting blood and tissue samples (liver, kidney, spleen, and lungs). Tissue samples were screened with pan-hantavirus PCR primers, targeting the large genome segment (L) encoding the RNA-dependent RNA polymerase (RdRp). Eleven of the small mammals captured were shrews (11/489, 2.5%) and 478 (97.5%) were rodents. A cytochrome b gene-based genetic assay for shrew identification confirmed the eleven shrews sampled to be Crocidura somalica. Hantavirus RNA was detected in three (3/11, 27%) shrews from Baringo County. The sequences showed 93-97% nucleotide and 96-99% amino acid identities among each other, as well as 74-76% nucleotide and 79-83% amino acid identities to other shrew-borne hantaviruses, such as Tanganya virus (TNGV). The detected viruses formed a monophyletic clade with shrew-borne hantaviruses from other parts of Africa. To our knowledge, this constitutes the first report published on the circulation of hantaviruses in shrews in Kenya.

Checklist of the diatoms (Bacillariophyta) from Lake Naivasha, Kenya, with some historical notes.

Lake Naivasha is one of only two large freshwater lakes in the Eastern Rift Valley of Kenya, East Africa. Together with its satellite lakes Crescent Island Crater, Oloidien and Sonachi, it comprises a great variety of pelagic and benthic habitats for aquatic biota, and its sediment record represents a unique archive of past climate change and long-term ecosystem dynamics in equatorial East Africa. This is particularly so because local paleoenvironmental reconstructions can be checked against historical data on the composition of aquatic fauna and flora collected in Lake Naivasha since the early 20th century. Some of the most prominent biological proxies for reconstructing past changes in lakes are diatoms (Bacillariophyta), a group of unicellular autotrophic eukaryotes of which the siliceous skeletons (valves) preserve well in lake sediments and are good indicators for, among others, climate-driven changes in salinity. However, diatom taxonomy and species concepts have changed a lot in recent decades, making it sometimes difficult for non-taxonomists to know which species are concerned in different published studies. This paper provides the currently accepted taxonomic names of the 310 specific and infraspecific diatom taxa reported from Lake Naivasha and its satellite lakes to date, together with their synonyms used in literature concerning these lakes as well as other, commonly used synonyms. Further, a short overview is given of the history of diatom research conducted on materials from Lake Naivasha and its satellite lakes. The present checklist may facilitate the identification and interpretation aspects of future diatom studies on the wider Lake Naivasha ecosystem and on other East African lakes that are less well studied.

The deep origin of ground fissures in the Kenya Rift Valley

Intense volcanic and geothermal activities characterize the Great Rift Valley of East Africa. Ground fissure disasters of the Great Rift Valley have garnered increasing attention in recent years. Through field investigations, trenching, geophysical exploration, gas sampling and analysis, we determined the distribution and origin of 22 ground fissures within the Kedong Basin of the Central Kenya Rift. These ground fissures caused varying degrees of damage to roads, culverts, railways, and communities. Trenching and geophysical exploration have shown that ground fissures in sediments are connected to rock fractures with gas escaping. The gases expelled from the rock fractures contained methane and SO2, which were absent in the normal atmosphere, and 3He/4He ratios in gases measured further indicated that the volatiles were derived from the mantle, suggesting that these rock fractures extended deep into the underlying bedrock. Spatial correlations with rock fractures demonstrate the deep origin of these ground fissures, which are associated with active rifting, plate separation, and volcanism. The ground fissures are formed due to movement on the deeper rock fractures, and then the gas escapes through the fissures. Determining the unusual origin of these ground fissures can not only guide infrastructure development and urban planning but also contribute to the safety of local communities.

GIS-based multi-criteria decision making under Silica Saturation Index (SSI) for selecting the best direct use scenarios for geothermal resources in Central and Southern Rift Valley, Kenya

Direct use (DU) of geothermal energy is site-specific and majorly dictated by economics. Even with the availability of high enthalpy geothermal fluids, DU could still be curtailed by fluid pH, salinity, and silica content. Selecting economically viable best direct use (DU) scenarios for a given geothermal resource needs meticulous matching of geothermal resource characteristics to the nearby economic activities and local infrastructure. Silica saturation index (SSI) analysis should also be factored in to avoid silica scaling of DU facilities and reinjection well. There is a lack of a visual framework for incorporating all the necessary criteria for selecting the best DU scenarios, hence the motivation of this research. The current study employed a GIS-based multi-criteria decision making (MCDM) method: a hybrid of the analytical hierarchy process (AHP) method with the weighted aggregated sum product assessment (WASPAS) method. The model analyzed nine utilization scenarios against eleven criteria to select the best DU scenarios for six high-enthalpy quaternary volcanoes in the central and southern Kenyan rift: Menengai, Elementaita, Eburru, Olkaria, Longonot, and Suswa. The best typical DU schemes identified were horticultural greenhouse warming, spa, and crop drying. The model was validated with existing DU case studies to gauge its ability to predict suitable utilization methods. There was a good matching between the model's selection and existing case studies implicating the synergistic merger of GIS-based MCDM methods and SSI as a robust tool for planning and carrying out the feasibility study for DU of geothermal energy.

Re-emergence of Rift Valley fever: an update and preventive measures.

Re-emergence of Rift Valley fever: an update and preventive measures.

Developmental Mechanism of Rainfall-Induced Ground Fissures in the Kenya Rift Valley

Active tectonic movement and frequent ground fissure disasters occur in the Kenya Rift Valley. Ground fissures are often exposed to the ground surface after rainfall, resulting in disasters and huge economic losses. We conducted a field geological survey and exploratory trenching in order to identify the developmental characteristics of ground fissures in the Kenya Rift Valley. The ground fissures were found to be connected with concealed bedrock fissures, which is a typical characteristic of tectonic ground fissures. From the perspective of regional tectonic stress and plate movement, we investigated the causes of hidden bedrock cracks and conducted a finite element numerical simulation to study the rainfall infiltration process in the presence of hidden bedrock fractures. The results showed that the fractures in the concealed bedrock are controlled by regional tectonic stress and a northwest-trending basement tectonic shear zone. The most intense rainfall infiltration erosion occurs in concealed cracks, where the settlement induced by rainfall is also greatest. Therefore, rainfall erosion is an important factor driving the expansion of ground fissures towards surface fractures. The results of this study provide a theoretical scientific basis for disaster reduction and the prevention of ground fissures in the Kenya Rift Valley.

INVESTIGATION ON ENTREPRENEURIAL VIABILITY OF INDIGENOUS INNOVATIONS IN KENYA. A SURVEY OF BARINGO AND NAKURU COUNTIES ON MURSIK MILK.

Indigenous innovations can aid developing nations embark on a cumulative path of positive growth by providing great opportunities to stimulate economic growth leveraged on indigenous knowledge, cultural practices and resources residing within native communities. Mursik is milk preservation traditional technology among Kalenjin community in the Great Rift Valley in Kenya. The community is renown worldwide for producing dominant athletes in the world, especially in long distances races such as marathons. The trademark heroic welcome of these athletes is a sip of this prized Mursik. Over the years scanty businesses have attempted to market this milk in food outlets with a few also attempting to process and pack it. However, the success and commercial performance or future potential has remained unknown. This study therefore aimed at investigating on entrepreneurial viability Mursik so as to propose a framework model for its commercialization that can be generalized to other related indigenous innovations that abound in diverse communities in Kenya. Specifically, the study determined supply side characteristics, demand side characteristics, innovation€™s characteristics, and moderating effect of innovation promoters. Data was obtained using semi-structured questionnaires administered on a snow-balled sample of size of 59 accessed enterprises. However, only 35 of those enterprises completed the data collection adequately for analysis. The selected enterprises comprised caterers, hotels, foods outlets and processors where Mursik. Each provided one respondent who was the senior manager or entrepreneur of the enterprise. The findings obtained indicated that whereas there was huge supply of milk in the proximal catchment area the supply was not consistent and suppliers preferred delivering it to large milk processors who had not yet adopted Mursik as part of their line of products. Further, the consumption demand for Mursik was dominated by members of the indigenous Kalenjin community and who also preferred home brewed Murisk for better quality and its cultural associations. The innovation itself strongly possessed necessary characteristics for potential for massive adoption. It was also found to elicit a lot of interest with new users who were willing to try it. However, the knowledge and technology transfer capacity was very constraining. The traditional production process was also inevitably slow and would not be consistent with rapid production process associated with most milk products in fast moving consumer goods. The researcher therefore recommends an experimental study on technology improvement to enable rapid production and yet maintain quality and value attributed to the original Mursik product, and also determination of means of value packaging, promotion and distribution beyond the traditional users of the product.

Evaluating Agricultural Extension Training and Education as Information-inputs for Maize Productivity in a Rural Set-up of North-Rift, Kenya

Maize (Zea mays L.) is an important source of staple food in Kenya. Research innovations and physical inputs, and the capacity of farmers to use them are major ingredients for crop productivity enhancement. This study evaluated agricultural extension training and formal education as elements of farmers’ capacity to use innovations and inputs. The study was conducted in a rural setup of North Rift in Kenya. Data were gathered by use of interview schedules through cross-sectional survey from 502 households sampled purposively and by simple random sampling. Welch’s t-test and Mann-Whitney U test were used to test for differences between means. 42.8% of the participants reported that they had not received agricultural extension training, 57.2% had. 65.2% had up to primary level education, 34.8% had secondary and above. Formal education up to primary was regarded as basic. Results indicated that fertilizer-use rates and maize yields differed significantly between groups ‘who had received Extension training’ and those who ‘had not been trained’; t (482.785) = -9.228, P = .000 and t (496.513) = -7.095, P = .000, respectively. Regarding formal education, fertilizer-use rates and maize yields differed significantly between ‘basic education’ category and ‘higher than basic’; t (332.28) = -5.699, P = .000 and t (290.29) = -5.438, P = .000 respectively. The alternative Mann-Whitney U test showed similar results. Effect sizes as measured by Eta-squared (ƞ2) ranged from .06 (medium) to .1445 (large). It is concluded that Agricultural extension training had a highly significant influence on maize productivity. Formal education showed a positive impact on fertilizer-use adoption and maize productivity. This study has significance in the formulation of policy on agricultural extension training and investments to ensure all segments of society are equipped with relevant information for crop yield enhancement and food security.

Near real-time estimation of high spatiotemporal resolution rainfall from cloud top properties of the MSG satellite and commercial microwave link rainfall intensities

High spatiotemporal resolution rainfall is needed in predicting flash floods, local climate impact studies and agriculture management. Rainfall estimation techniques like satellites and the commercial microwave links (MWL) rainfall estimation have independently made significant advancements in high spatiotemporal resolution rainfall estimation. However, their combination for rainfall estimation has received little attention, while it could benefit many applications in ungauged areas. This study investigated the usability of the random forest (RF) algorithm trained with MWL rainfall and Meteosat Second Generation (MSG) based cloud top properties for estimating high spatiotemporal resolution rainfall in the sparsely gauged Kenyan Rift Valley. Our approach retrieved cloud top properties for use as predictor variables from rain areas estimated from the MSG data and estimated path average rainfall intensities from the MWL to serve as the target variable. We trained and validated the RF algorithm using parameters derived through optimal parameter tuning. The RF rainfall intensity estimates were compared with gauge, MWL, Global Precipitation Measurement (GPM) Integrated Multi-satellitE Retrievals for GPM (IMERG) and European Organisation for the Exploitation of Meteorological Satellites (EUMETSAT) Multisensor Precipitation Estimate (MPE) to evaluate its rainfall intensities from point and spatial perspectives. The results can be described as good, considering they were achieved in near real-time, pointing towards a promising rainfall estimation alternative based on the RF algorithm applied to MWL and MSG data. The applicative benefits of this technique could be huge, considering that many ungauged areas have a growing MWL network and MSG and, in the future, Meteosat Third Generation (MTG) coverage.

Tectonic Control of Groundwater Recharge and Flow in Faulted Volcanic Aquifers

AbstractGroundwater dynamics in continental rift zone settings remain poorly understood because of the spatial heterogeneity in flow, storage, and recharge dynamics. The Central Kenya Rift is an excellent example where, though groundwater is important for domestic, irrigation, and geothermal energy exploitation, its hydrogeological properties remain largely unknown. Existing conceptual groundwater models assume flow from the high‐elevation, humid rift flanks to the low‐elevation, semiarid rift floor, but the role of the faults that fracture the aquifers is commonly unaccounted for. We applied geochemical, isotopic (δ18O, δD, 87Sr/86Sr, 3H‐3He), multivariate statistical methods, and knowledge of geological structures to determine recharge sources, flow, and residence times to revise the conceptual flow model. Results show that groundwater is primarily recharged by meteoric waters, river input, and Lake recharge. The faults impart a control on the groundwater flow within four sub‐compartments. Major differences in flow patterns exist between the eastern and western rift flanks: surface and groundwater transfer from the eastern flanks to the rift floor occurs via relay ramp structures, and flow on the west side takes place laterally from the high escarpment. Although 3H‐3He dating shows that the age of groundwater ranges from a few to >>50 years, most of the groundwater in the rift‐floor area is free of 3H and was recharged before the 1960s. Hence, we propose that these areas receive episodic recharge and represent the most sensitive groundwater resources in the rift. To inform sustainable groundwater development, a robust monitoring network is required to capture the heterogeneous groundwater dynamics.

Holocene bidirectional river system along the Kenya Rift and its influence on East African faunal exchange and diversity gradients

East Africa is a global biodiversity hotspot and exhibits distinct longitudinal diversity gradients from west to east in freshwater fishes and forest mammals. The assembly of this exceptional biodiversity and the drivers behind diversity gradients remain poorly understood, with diversification often studied at local scales and less attention paid to biotic exchange between Afrotropical regions. Here, we reconstruct a river system that existed for several millennia along the now semiarid Kenya Rift Valley during the humid early Holocene and show how this river system influenced postglacial dispersal of fishes and mammals due to its dual role as a dispersal corridor and barrier. Using geomorphological, geochronological, isotopic, and fossil analyses and a synthesis of radiocarbon dates, we find that the overflow of Kenyan rift lakes between 12 and 8 ka before present formed a bidirectional river system consisting of a "Northern River" connected to the Nile Basin and a "Southern River," a closed basin. The drainage divide between these rivers represented the only viable terrestrial dispersal corridor across the rift. The degree and duration of past hydrological connectivity between adjacent river basins determined spatial diversity gradients for East African fishes. Our reconstruction explains the isolated distribution of Nilotic fish species in modern Kenyan rift lakes, Guineo-Congolian mammal species in forests east of the Kenya Rift, and recent incipient vertebrate speciation and local endemism in this region. Climate-driven rearrangements of drainage networks unrelated to tectonic activity contributed significantly to the assembly of species diversity and modern faunas in the East African biodiversity hotspot.

Vignette experiment on the acculturation of internal migrants in the Kenyan Rift Valley

The acculturation process for internal migrants in ethnically diverse societies has received little academic attention. This is even less in the context of low-income countries where internal migration is often a cause of hostility. We filled this gap by building a more comprehensive picture of the dynamics of acculturation in the Rift Valley. This is particularly, so because Rift Valley has witnessed deep-seated ethnic intolerance between internal migrants and their hosts. We used a survey-based vignette experiment to assess the perceived relative importance of nine migrant characteristics for four acculturation preferences. These include marginalisation, separation, assimilation, and integration. Using a conditional logistic regression model to analyse the vignette experiment's data, we found that levels of education and experience of ethnic discrimination were perceived as substantial contributors to acculturation processes. We concluded by relating the findings to policies aimed at enhancing the experience of acculturation in order to produce more positive outcomes.

Giant dwarf crocodiles from the Miocene of Kenya and crocodylid faunal dynamics in the late Cenozoic of East Africa.

We describe two new osteolaemine crocodylids from the Early and early Middle Miocene of Kenya: Kinyang mabokoensis tax. nov. (Maboko, 15 Ma) and Kinyang tchernovi tax. nov. (Karungu and Loperot, 18 Ma). Additional material referable to Kinyang is known from Chianda and Moruorot. The skull was broad and dorsoventrally deep, and the genus can be diagnosed based on the combined presence of a partial overbite, a subdivided fossa for the lateral collateral ligament on the surangular, and a maxilla with no more than 13 alveoli. Phylogenetic analyses based on morphological and combined morphological and molecular data support a referral of Kinyang to Osteolaeminae, and morphological data alone put the new taxon at the base of Euthecodontini. Some Kinyang maxillae preserve blind pits on the medial caviconchal recess wall. Kinyang co‐occurs with the osteolaemine Brochuchus at some localities, and together, they reinforce the phylogenetic disparity between early Neogene osteolaemine‐dominated faunas and faunas dominated by crocodylines beginning in the Late Miocene in the Kenya Rift. The causes of this turnover remain unclear, though changes in prevailing vegetation resulting from tectonic and climatic drivers may provide a partial explanation.

Lithospheric Structure underneath the Archean Tanzania Craton and Adjacent Regions from a Joint Inversion of Receiver Functions and Rayleigh-Wave Phase Velocity Dispersion

Abstract Lithospheric structure beneath the Archean Tanzania craton and adjacent regions, including segments of the East African rift system (EARS) and the Proterozoic–early Paleozoic orogenic belts between the EARS and the craton, is imaged by a joint inversion of receiver functions and Rayleigh wave dispersion measurements derived from ambient seismic noise for shorter periods and teleseismic data for longer periods. Our resulting crustal thickness, crustal VP/VS measurements and 3D shear-wave velocity model for the upper 120 km show a clear spatial correspondence with major surficial geological features. The new results suggest the presence of a mafic layer in the bottom of the crust of the entire Archean craton, which is previously only identified beneath the southern portion of the craton. High crustal VP/VS values measured in the Rungwe Volcanic Province and most areas of the Kenya and Tanganyika rift segments can be attributed to a combined result of basaltic sediments atop the crust, magmatic intrusion, and crustal partial melting. The Kivu Volcanic Province and parts of the Kenya rift segment are characterized by localized lower-than-normal crustal VP/VS values and shear velocities in the lower crust and uppermost mantle, which, given the presence of large volume of CO2 from surficial observations, can be best interpreted by CO2-filled fractures or conduits. Lower-than-normal shear velocities in the uppermost mantle are revealed beneath almost the entire study region with the lowest values found in all the three volcanic provinces. The low velocities are indicative of an underplated layer formed by mantle-derived magmatic materials trapped below the Moho. The relatively low velocities beneath the volcanic provinces might be caused by a higher degree of partial melting in the uppermost mantle.

Model test study on the formation and development of underground erosion ground fissures in the Kenya Rift Valley

Model test study on the formation and development of underground erosion ground fissures in the Kenya Rift Valley