Origins of soil magnetism in alluvial-lacustrine environments: Insights from Early Pleistocene paleosols of the northern Kenyan rift

BackgroundAedes aegypti is widely distributed in the tropics and sub-tropics and is a major vector of several arboviruses, such as dengue and chikungunya viruses. Mapping the behavioral and genetic divergence among the mosquito populations can enhance our understanding of spatiotemporal variation in disease transmission.MethodsCross-sectional surveys were carried out between 2022 and 2023 to investigate egg-laying abundance in ovitraps as well as adult abundance in BG Sentinel traps baited with carbon dioxide. Both trap types were deployed in outdoor environments in two peri-urban areas in the Rift Valley and coastal regions of Kenya. A subset of the adult specimens was screened for arbovirus infections, and the mitochondrial cox-1 gene was analyzed to estimate genetic differences between the populations. Engorged specimens were also typed to determine host feeding sources.ResultsAedes egg density was significantly higher in Marigat in the Rift Valley than in Ukunda at the coast (p = 0.006), despite recording a lower ovitrap positivity rate. By contrast, adult female abundance was twofold greater in Ukunda than in Marigat (p < 0.0001). A higher human blood feeding rate (HBI = 0.68) in Ukunda compared to Marigat (HBI = 0.29) correlated with higher proportional abundance of the domestic than of the forest Ae. aegypti ecotype. Haplotype network analysis revealed a high mitochondrial diversity dominated by population-specific haplotypes. Limited haplotype sharing between Ukunda and Marigat populations suggests a restricted maternal gene flow and localized population structuring. While all the samples tested negative for pathogenic arboviruses, insect-specific viruses (ISVs) in the families Flaviviridae (Cell fusing agent virus and uncharacterized flavivirus-like sequences (Flaviviridae sp.)) and Phenuiviridae (Phasi Charoen-like virus) were detected, which varied between the two ecological environments.ConclusionWe observed geographic differences in egg and adult capture rates of Ae. aegypti, which correlate poorly, providing valuable information for Aedes surveillance and control. Heterogeneity in entomological, genetic and virological factors likely shapes geographic differences in dengue occurrence and spread.Supplementary InformationThe online version contains supplementary material available at 10.1186/s41182-026-00961-3.

Palearctic migratory little stints (Calidris minuta) can acquire resistant bacteria from contaminated environments and facilitate their transboundary spread. This two-year repeated cross-sectional study assessed the frequency and distribution of multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales. Isolates were recovered from fecal samples of C. minuta foraging at the shores of Lakes Bogoria (low anthropogenic activities) and Magadi (high anthropogenic activities), as well as from peripheral freshwater sources shared by birds, humans, livestock and wildlife. A total of 184 fecal samples and 48 water samples were collected upon the birds' arrival from the Arctic (cohort 1) and pre-departure from the Rift Valley lakes (cohort 2). Samples were cultured, bacterial isolates were identified using MALDI-TOF MS platform and tested against 12 antimicrobials using the Kirby-Bauer disk method. Of the 294 isolates (16 genera and 33 species), Enterobacter spp (31.0%, n = 91) and Escherichia coli (17.3%, n = 51) predominated. Resistance was highest for ampicillin (50%) and lowest for meropenem (1.0%). The predominant MDR phenotype was a combination of resistances to ampicillin, tetracycline, and sulfamethoxazole-trimethoprim. Specifically, 38 (12.9%) isolates were MDR, 37 (12.6%) co-expressed ESBL-MDR traits, and 19 (6.5%) were ESBL producers that did not meet MDR criteria. Enterobacter spp showed the highest frequencies of MDR (8.2%, n = 24) and combined ESBL-MDR (4.8%, n = 14) phenotypes, while Acinetobacter spp (3.4%, n = 10) were the most frequent ESBL producers. The statistically non-significant differences (p > 0.05) across study areas, sample sources, and cohorts suggest that resistant strains are pervasive throughout these landscapes, irrespective of anthropogenic pressures. This is the first study to link C. minuta to the antimicrobial resistance (AMR) epidemiological circuit. Our findings underscore the need to include migratory wild birds in AMR surveillance and utilizing whole-genome sequencing to accurately trace the origin and dissemination pathways of AMR strains.

Many of the East African Rift Valley lakes are soda lakes that have attracted considerable research interest over the last decades with a focus on their extraordinarily high bioproductivity, high concentration of dissolved organic carbon (DOC), and diverse microbial communities. Yet, the distribution of trace metals, particularly dissolved rare earth elements (REE) and yttrium in these soda lake systems remain poorly constrained. We report data for surface water samples from eight rift valley lakes from the Kenyan part of the East African Rift. Speciation calculations accounting for both organic and inorganic complexation of REE were performed using PHREEQC by implementing the Humic Ion-Binding Model VII. Previous studies on REE in soda lake systems identified two characteristic features of the shale normalized REE patterns: (i) a very strong enrichment of heavy over light REE with (Pr/Yb) SN ratios well-below unity, and (ii) a distinct positive Ce anomaly ((Ce/Ce*) SN ≫ 1). The REY distribution in soda lakes of the East African Rift in Kenya follow this behavior, clearly showing a strong enrichment of heavy over light REE. Speciation calculations suggest that even at the observed high DOC concentrations (up to 8.19 mmol/kg), REE di-carbonate complexes still dominate, corroborating previous speciation calculations which only considered the inorganic REE complexes. Contrary to expectations, however, these soda lakes do not show pronounced positive Ce anomalies, a feature previously only observed at Mono Lake, USA. Whereas the presently available data does not fully resolve the Ce systematic in soda lake environments, the new data suggest high DOC as a key factor for masking the formation of positive Ce anomalies in the soda lake waters.

The Paka geothermal field, located in the Northern Kenya Rift segment, is influenced by tectonic extension and magmatic activity that drives crustal uplift and hydrothermal circulation. While most previous gravity studies in this region targeted depths beyond 6 km, shallow intrusive structures crucial for geothermal resources remain poorly resolved. This study applied regional Bouguer anomaly mapping and 3D gravity inversion to characterise density variations, intrusive heat sources, and favourable structural settings for resource development. Gravity data were processed with a Bouguer density of 2.0417 g/cm3, anomaly separation through upward continuation, and 3D VOXI inversion in Geosoft Oasis. Results reveal a broad negative Bouguer anomaly (–126 to –103 mGal) about 20 km wide, with superimposed narrower anomalies (~5 km wide) in the northern caldera. These align with NW–SE, NE–SW, and N–S fault trends, consistent with regional tectonic structures. Near-surface pyroclastic sediments (0–250 m, 2.1–2.3 g/cm3) overlie a denser caprock (250–700 m, 2.25–2.45 g/cm3) interpreted as hydrothermally altered tuffs. At ~2.5 km depth, low-density zones (1.75–1.8 g/cm3) suggest water reservoirs or altered tuffs. A high-density mafic intrusion, likely of trachytic to basaltic magma origin, was identified between 2.0 and 3.1 km depth (volume ~475 ±10 % km3; 2.50–2.90 g/cm3), serving as the primary heat source. The associated reservoir beneath the summit lies at ~2.2 km depth with an estimated volume of 120 ±10 % km3. Structural continuity links Paka to Silale and Korosi volcanoes along the rift axis. The findings of this study highlight the summit region as the most promising drilling target for sustainable geothermal development.

Micro, Small, and Medium Enterprises (MSMEs) significantly contribute to Kenya’s GDP and play a crucial role in job creation. Despite their importance, many MSMEs face challenges such as inadequate skills, limited access to technology, and barriers to scaling their operations. Recognizing these gaps, the KIRDI-KIEP training initiative was designed to unlock the potential of MSMEs by promoting technology dissemination and hands-on capacity building. The program not only offered practical training but also extended support through incubation programs and access to Common Manufacturing Facilities (CMFs). These resources gave entrepreneurs the opportunity to experiment, innovate, and refine their products in a supportive environment. The training aimed to equip participants with the skills and knowledge needed to launch viable commercial enterprises, address production challenges, and drive economic growth. Participants were selected based on business readiness, technology needs assessment, gender inclusivity, and a focus on youth empowerment. Priority was given to technologies with high market demand and community impact, including animal feed formulation, honey processing, fruit and vegetable dehydration, dairy processing, and soap and detergent production. The primary challenge for SMEs is limited competitiveness due to regulatory and infrastructure hurdles. This training provided practical skills to enhance scalability, competitiveness, and commercialization, contributing to sustainable development and economic growth.

Abstract: Background: Antiretroviral therapy (ART) has significantly improved survival among people living with human immunodeficiency virus (PLHIV), yet drug resistance mutations (DRMs) continue to threaten treatment outcomes globally. Adolescents remain particularly vulnerable to DRMs due to biological, behavioural and structural factors. However, little is known about the factors associated with DRMs in the South Rift Valley (SRV) of Kenya. Aim: To assess factors associated with DRMs among ART-experienced adolescents in SRV. Setting: Eighty-two HIV clinics located in Nandi, Kericho, Bomet and Narok counties in Kenya’s SRV region. Methods: A retrospective cohort study was conducted among 226 ART-experienced adolescents aged 10–19 years with virologic failure, selected through simple random sampling. Plasma samples were genotyped to identify HIVDRMs using the Stanford HIV Drug Resistance database. Demographic, clinical and behavioural information was obtained from medical records and questionnaires. Descriptive statistics, Chi-square tests and logistic regression were performed to determine factors associated with DRMs. Results: The median age was 17 years (IQR: 15–18); 51.3% was male and 65% was orphans. Bivariate analysis identified several factors significantly associated with DRMs: ART duration (p = 0.030), enhanced adherence counselling (EAC) sessions (p = 0.001), ART regimen type (p = 0.001), CD4 count (p = 0.030), caregiver occupation (p = 0.029), and orphan status (p = 0.049). Conclusion: Longer ART duration, multiple EAC sessions and use of non-nucleoside reverse transcriptase inhibitor (NNRTI)-based regimens were associated with DRMs. These findings underscore the need for strengthened adherence support, early regimen optimisation and targeted interventions for adolescents at higher risk of resistance. Contribution: The study provides evidence to guide clinical and policy strategies aimed at improving ART outcomes among adolescents in Kenya.

The Kenya plume drives rift formation and magmatism along the Kenya Rift, yet its components remain obscured by lithospheric overprinting on mafic volcanics. We present whole-rock geochemical data for mantle-derived silicic rocks from Suswa, sampled at the reworked craton margin of the Kenya Rift where continental lithosphere profoundly influences mafic rock compositions. These rocks exhibit high SiO2 (54.9–60.4wt.%), total alkalis (Na2O + K2O = 9.3–13.8wt.%) and lithophile elements (Rb, Th-U, Nb-Ta and rare earth elements (REE); typically 10–100× chondrite and primitive mantle values), alongside low MgO (< 1.3wt.%). Their isotopic signatures show variable 87Sr/86Sr (0.7036–0.7056), depleted Nd-Hf isotopes (143Nd/144Nd = 0.51282–0.51285, 176Hf/177Hf = 0.28291–0.28293) and moderately radiogenic Pb isotopic ratios (206Pb/204Pb = 19.99–20.20, 207Pb/204Pb = 15.73–15.84 and 208Pb/204Pb = 39.82–39.97). The more depleted Nd isotopes compared to those of mafic rocks ( < ~ 0.51275) in the reworked craton margin and the northern Tanzania Craton, indicate minimal lithospheric incorporation. Low MgO contents, positive correlations of MgO with Al2O3, CaO, TiO2, P2O5, Ba, Sr and Eu, and characteristic REE and trace-element patterns support fractionation involving olivine, pyroxene, plagioclase, Ti oxide and apatite. Low Ba/Nb ratios, constant Rb/Nb and La/Nb ratios, and a negative 87Sr/86Sr–SiO2 correlation preclude significant crustal contamination in most samples. Integrated Sr-Nd-Pb-Hf isotopic and trace-element systematics, combined with regional data, reveal a multi-component mantle source: plume-derived HIMU and depleted common mantle (C) components, plus a lithosphere-derived EMII component. Quantitative two-component mixing models, using the plume end-member (C modified by HIMU-derived melt) and the lithospheric mantle end-member (EMII modified by HIMU-derived melt), indicate 10–20% lithospheric contribution to the Suswa source. Critically, the identification of the C component within these depleted rocks, supported by literature data, confirms its presence within the Kenya plume. This underscores the imperative of targeting volcanic sequences with minimal lithosphere contamination to resolve the primary plume components beneath continents.Supplementary InformationThe online version contains supplementary material available at 10.1038/s41598-025-22868-5.

Dairy farming underpins rural livelihoods in Kenya but is increasingly vulnerable to climate variability while contributing to greenhouse gas emissions. Climate-Smart Agriculture (CSA) practices offer pathways for resilience and mitigation, yet most previous studies assess single practices in isolation, overlooking complementarities, trade-offs, and regional differences. This study examines the joint adoption of five CSA practices—feed management, improved breeding, manure management, animal health, and milk value addition—using survey data from 447 dairy farmers in Kisii and Uasin Gishu counties, complemented with high-resolution rainfall and temperature records. A Multivariate Probit (MVP) model revealed high adoption of breeding (87 ​%), animal health (85 ​%), and feed management (81 ​%), while manure management (39 ​%) and milk value addition (22 ​%) lagged. Regional contrasts were evident: Kisii farmers favored manure management (44 ​%), while Uasin Gishu led in feed management (89 ​%) and value addition (39 ​%). Strong complementarities emerged between feed management and breeding, animal health and feed management, and manure management and value addition, with no evidence of substitutability. Adoption was shaped by climate factors (rainfall, temperature), socio-economic characteristics (gender, age, household and herd size, farm size), and institutional access (cooperatives, credit, extension, early warning systems). Findings underscore that bundled CSA strategies are more effective than isolated interventions, providing comparative, policy-relevant insights for promoting climate-resilient dairy farming in Kenya and similar smallholder systems. • Geospatial analysis informs climate smart agriculture (CSA) studies. • CSA practices show synergy in simultaneous adoption. • Gridded meteorological data outperforms farmer perceptions on climate change. • CSA adoption shaped by climate, socio-economic, and institutional factors. • Multivariate Probit model captures simultaneous CSA adoption decisions.

ABSTRACT Cainochoerus is an extinct suid (Mammalia, Artiodactyla) taxon of very small size, found in multiple late Neogene sites in southern and eastern Africa. Despite its wide geographic distribution and temporal range (ca. 10–4.4 Ma), it remains a rare taxon in eastern Africa. Here we report new dentognathic material representing the first reported occurrence of Cainochoerus from the Late Miocene (6 Ma) Lemudong’o Formation, Kenya. This includes the first known deciduous upper premolar attributed to this taxon in eastern Africa. The dental metrics are generally consistent with those attributed to Cainochoerus africanus from Langebaanweg, South Africa. The maxillary molars are closely similar in morphology to those from Lothagam, Kenya, with slight differences in the upper second molar. Because Cainochoerus africanus is the only known Late Miocene small suid in Africa, we attribute these fossils to Cainochoerus cf. africanus. This discovery adds another mammalian species to the faunal community of the Lemudong’o Formation and slightly expands the geographic range of Cainochoerus to the southern Kenyan Rift.

Characterization of 3D fault structures in the Paka geothermal field using TDR and HGM filters on Bouguer gravity data: Implications for geothermal fluid flow dynamics in the northern Kenya Rift

Background: Kenya is among the high-risk geographical zones especially for the African- endemic variant of Burkitt Lymphoma (BL). It accounts for up to half of all children cases of non-Hodgkin’s lymphomas in tropical Africa. There is limited published data on the clinico-demographic features of BL at Moi Teaching and Referral Hospital (MTRH) despite it being a major center for referral of oncology patients from the North Rift, Western and Nyanza regions of Kenya. Objective: The main objective of this study was to describe the demographic patterns and clinical features of BL among patients attending MTRH from 2017 to 2022. Design: A descriptive cross sectional retrospective study design was used. Results: Out of the 85 cases studied, the most affected ages were between 6-10 years (36%). Males (64%) were affected almost twice more than females (36%). Rift Valley had the highest number of cases (42%), while Western and Nyanza regions contributed 25% each. The abdomen was the primary site of tumor in most cases (54%), while the jaw was affected in 30% of the cases. Combined abdomen and jaw involvement was seen in 4% of the cases. Weight loss was the most frequent symptom (33%), night sweats and fever were also noted. The most common clinical signs were lymphadenopathy (55%) and pallor (23%). Conclusion: Commonly affected age range is between 6-10 years, boys seen to be affected almost twice as much as girls. Rift Valley is the most commonly affected region. The most common presenting complaint is an abdominal mass with associated local symptoms and classical B-symptoms of fever, night sweats and weight loss. Keywords: Burkitt lymphoma, Demographic patters, Clinical features

Abstract. The methane index (MI) is an organic geochemical index that uses isoprenoid glycerol dialkyl glycerol tetraethers (GDGTs) as a proxy for methane cycling. Here, we report results from sediments in core MAG14-2A that span almost 500 ka in Lake Magadi, Kenya. The deposits show abrupt shifts between high and low MI values through calcareous, tuffaceous and zeolitic silts. The MI switches “off” (MI &lt; 0.2) and “on” (MI &gt; 0.5) through the core with bulk organic matter enriched in 13C during “MI-off” periods (∼ −18 ‰) in the upper part of the core, whereas 13C is lower (−22 ‰ to −25 ‰) in lower parts of the sedimentary sequence. Sediments deposited when the MI switches “on” showed δ13COM values as low as −89.4 ‰, but most values were within the range of −28 ‰ to −30 ‰, which is consistent with contributions from methanogens rather than methanotrophs. Thus, the likely source of these high MI values in Lake Magadi is methanogenic archaea. Our results show that hydrothermal inputs of bicarbonate-rich waters into Lake Magadi combined with further evaporative concentration cause a shift in the dominant archaeal communities, alternating between two stable states.

Many countries face the problem of refugees and internal displacement. Internal displacement is not new to Kenya and is a recurring problem that impacts displaced children’s education. One factor affecting displacement is banditry, stemming from community fights over resources. This paper uses theoretical and conceptual arguments to explore the causes and effects of internal displacement on learning, focusing on banditry and how they can be mitigated. Fraser’s social justice theory has been used to frame this discussion. Three questions guided this inquiry: What causes internal displacement in the Northern Rift Valley of Kenya? What challenges do internally displaced learners in Northern Rift Valley face? What strategies can be used to mitigate the challenges internally displaced learners face? The paper argues for a social justice framework to address and alleviate internally displaced persons’ challenges in the North Rift Valley of Kenya.

Fault characterization is a crucial aspect of exploring geothermal resources. Recent research approves lineament mapping as a useful tool in structural studies. It is largely problematic to decipher the lineaments that are specifically linked to faults, ridges, or other tectonic structures. The study aims to characterize faults from lineaments using magnetic data from the Magadi-Nguruman area, west of Lake Magadi within the Kenyan Rift system. The magnetic data was reduced to pole before lineament generation using the Center of Exploration Targeting (CET) processes and Euler Deconvolution. A rose diagram was used to determine the orientation of the 21 major lineaments. Seven cross-sectional slices across the lineaments provided the data for calculating Euler solutions for the linear magnetic anomaly sources. The obtained Euler plots delineated the approximate depth, dip angles, identity, and strike of the structures linked to the lineaments. The case study results characterized 80% of the generated lineaments as faults with a general strike in the N-S direction. The dipping angles of the detected faults ranged between 36° and 83°, with the majority dipping towards the southern basement of Lake Magadi. The depth ranges of the detected faults were between 0.25 km and 0.74 km. The trends observed in this work are consistent with the reported regional fault orientations, thus qualifying the protocol used in this work. Magadi-Nguruman is sufficiently faulted for a possible geothermal system near Lake Magadi.

Effective management of inventory is essential for the survival and success of a business. Failure to implement proper inventory management practices leads to poor financial performance as well as business failure. The purpose of this study was to determine the relationship between inventory holding management practice and financial performance of small and medium enterprises in the South Rift region. The study's adopted a cross sectional research design. The target population was 2,003 SMEs operating in the South Rift Valley of Kenya. Sample of 167 SMEs were selected using stratified random sampling. The population was divided into twelve strata’s where simple sampling techniques was used to select respondents from each stratum. Validity of the research instrument was ascertained through expert’s opinion while reliability was tested using Chronbach Alpha Coefficient where a value of 0.876 was actualized which reveals that the instrument was reliable. The collected data was analyzed using descriptive and inferential statistics. Tables, graphs were used to present the study results. Linear regression models were used to examine and explain the relationship between different working capital management practices and financial performance in the Southern Rift Valley region. The Pearson correlation results indicate that inventory holding management practice (r = 0.287, p &lt;0.05). The study recommends that SMEs should be educated on inventory management so as to avoid financial difficulty and the need to reduce dependency on external debt and equity financing. This study provided insights on inventory management practices and financial performance of SMEs that inform on policy decisions and practical recommendations to be adopted by SMEs in the Southern Rift Valley region and beyond. Keywords: Financial Performance, Inventories Holding Management Practice, Small and Medium Enterprises

Abstract The seismic velocity structure beneath East Africa suggests interconnected corridors of hot mantle are upwelling beneath the continent. However, the geochemical evidence for deep mantle in Ethiopia‐Kenya‐Tanzania volcanism is sparse questioning the existence of superplume. The development of new geothermal fields in the region offers the opportunity to access high temperature magmatic‐hydrothermal fluids. Well gases from the geothermal field in the Menengai caldera in the central Kenya Rift have C‐He isotope systematics that are dominated by magmatic volatiles. High precision Ne isotope data confirm a primordial deep mantle that has experienced long‐term convective isolation like that beneath Hawaii is present beneath the Kenyan rift. The Ne isotope composition of the gases is indistinguishable from volatiles in basalts from the Afar plume and Western Rift (and significantly more precise) providing the first geochemical evidence for a common deep mantle beneath the entirety of the East African Rift System.

The Kerio Valley Basin is a classic half-graben within the Eastern Branch of the East African Rift System, although to date its tectonostratigraphic evolution has been interpreted only through an incomplete stratigraphic record exposed along structural highs. This study examines a 3 km thick volcano-sedimentary succession recorded within a hydrocarbon exploration well, Cheptuket-1, located within the hanging wall of the Kerio Valley Basin. A suite of silicic extrusive volcanic and volcaniclastic rocks are also recorded, calibrated by a dense collection of thin-sections from 84 side-wall cores. These volcanic rocks include phonolite lava flows. Through documentation of the well stratigraphy and integration of newly acquired 40 Ar/ 39 Ar age dates from outcrop, we detail a substantially revised, simpler tectonostratigraphic evolution of this basin. Cheptuket-1 penetrated a Middle Miocene to recent stratigraphic succession, bottoming in metamorphic basement, probably through a fault plane. Several phases of lake development are elucidated, including both pre- and syn-mechanical rifting, with the latter phase containing beds exhibiting high organic matter content. This study ultimately represents a rare insight into a near complete rift-basin hanging-wall succession, as well as detailing a workflow for characterizing mixed volcanic and sedimentary successions.

The Olkaria Volcanic Complex and adjacent Longonot volcano in the Southern Kenya Rift host major geothermal resources yet also pose volcanic hazards owing to their long histories of explosive eruptions. Olkaria is a multicentred dome complex consisting of lava domes, craters and fissures produced following the eruption of peralkaline comenditic rhyolites. Longonot is a trachytic caldera hosting a central summit crater, situated <10 km east of Olkaria, with pumice and ash eruptions being a dominant feature. This study reconstructs their evolution through detailed field, geochemical and geochronological investigations of widespread pyroclastic deposits. Logging sequences of pumice and ash fallout and pyroclastic density current deposits enables establishing a regional stratigraphic framework spanning the past 42 ka. Ten key eruptive units record explosive phases at Olkaria and Longonot, with eight 40 Ar/ 39 Ar ages and a radiocarbon date providing the first accurate age constraints of both volcanoes. The oldest explosive deposits identified in our field area are associated with the large-magnitude Maiella Pumice (MP) eruptions (338–333 ka), representing one of the first explosive silicic peralkaline eruptions in the Southern Kenya Rift. Within Olkaria, the earliest preserved deposits in our tephrostratigraphic framework are 42–37 ka pyroclastic density currents (OP) and pumice fallouts (OFB) representing early rhyolitic dome eruptions. Overlapping deposits reveal Longonot concurrently experienced repetitive large explosive eruptions emplacing pumice fall deposits from 37 ka to 17 ka (LAP). After 17 ka, LAP eruptions were punctuated by a single eruption of mixed basaltic trachyandesite, trachyandesite and trachyte pumice (LMx), followed by persistent trachyte ash venting at Longonot (LA1). Simultaneously, Olkaria transitioned to localised lava dome construction and collapse generating block-and-ash flows from 17 ka to 14 ka (OD1–2). Younger Longonot ash eruptions (LA2) and recent 191 ± 23 cal yr BP effusive–explosive activity at Olkaria's Ololbutot centre (OD3) reveals both volcanoes have remained active throughout the Holocene. Minimum estimated magnitudes for widespread fall units at both systems range between 4 and 5 (DRE deposit volumes of 0.04–0.35 km 3 ), representing substantial regional hazards, with eruption frequencies averaging up to one moderate–large eruption (magnitude 4–5) every ∼2000 years for Longonot and one small–moderate explosive eruption (magnitude ∼3) every ∼200 years for Olkaria until ca. 10 ka, after which eruptions are significantly smaller and more localised. Statistical analysis of pumice glass geochemistry enables the fingerprinting of Olkaria deposits to likely source vents, tracking spatial-temporal variability across the complex. The larger explosive eruptions at both Olkaria and Longonot dispersed voluminous pyroclastic material (pumice and/or ash), which generated up to 1-m-thick deposits located ∼20 km from its source vent in the case of Longonot, suggesting up to 200,000 people could be impacted from future similar magnitude eruptions, emphasising the necessity to combine eruptive history reconstructions with hazard analysis to advance preparedness and mitigation strategies. • Olkaria and Longonot have a long, interspersed explosive history spanning 340 kyrs. • Tephrostratigraphy reveals spatial-temporal variability of vent locations. • Regional tectonics may facilitate eruption cycles between the two systems. • Future explosive eruptions pose a significant hazard.

• We investigated geothermal gases from Homa Hills, Kenyan rift system, using neon, argon, krypton, xenon and nitrogen isotopes. • We applied high precision analysis of Kr and Xe by dynamic mass spectrometry • Fissiogenic Xe is dominated by 238 Uand not 244 Pu, pointing to rapid mantle turnover and crust formation in the Hadean • Both convective mantle and mantle plume sources have comparable radiogenic/fissiogenic Xe proportions, implying comparable degassing history in sharp contrast with helium and neon isotope systematics We investigated geothermal gases from Homa Hills, a carbonatitic complex situated along an adjacent branch of the Kenyan rift system, using neon, argon, krypton, xenon and nitrogen isotopes. Large quantities of gas were sampled in Giggenbach-type bottles (Giggenbach, 1975) and analyzed by dynamic mass spectrometry to resolve isotopic variations at high precision (0.01-0.1‰; Seltzer and Bekaert, 2022; Bekaert et al., 2023; 2024). Neon and nitrogen isotope compositions are consistent with parental magmas being derived from the convecting mantle. Xenon isotopic data present ubiquitous enrichments (relative to air) of 129 Xe from the decay of extinct 129 I (T 1/2 = 15.7 Myr) and 131-136 Xe f from fissions of 238 U (T 1/2 = 4.468 Myr) and/or 244 Pu (T 1/2 = 82 Myr). We also find slight excesses of 128 Xe (relative to 130 Xe and air), which could be due to subsurface isotopic fractionation during e.g., diffusive transport fractionation (DTF) and gravitational settling. However, the 128 Xe excesses are not accompanied by correlated Kr isotope excesses and plot off the empirical fractionation line defined from several other locations worldwide (Bekaert et al., 2023). Instead, a detailed isotope deconvolution suggests the occurrence of either chondritic Xe (with mantle 130 Xe consisting of up to 22 % of chondritic 130 Xe) or recycled Xe from the Archean atmosphere could explain the observed Xe isotope signatures. The latter possibility would have profound implications for models of mantle-surface exchange throughout Earth history. The fission spectra indicate a predominantly 238 U origin for fissiogenic Xe, with contribution of 244 Pu-derived Xe being negligible within uncertainties, implying extensive mantle degassing during the Hadean and Archean eons. The 129 Xe*/ 136 Xe* ratio (where * indicates non-atmospheric excesses of Xe isotopes) of Homa Hills samples correlates with other tracers of mantle/crust contributions such as He, Ar and N isotopes. Variations in 129 Xe*/ 136 Xe* among the different gases sampled at Homa Hills is mainly the result of contribution from fissiogenic Xe produced in uranium-rich crustal material. Therefore, this ratio may constitute a robust tracer of mantle-crust interactions. Given available high precision data (Bekaert et al., 2023; 2024; this work) together with mantle-derived rock data, 129 Xe*/ 136 Xe* appears homogenous in the convecting mantle, and comparable to values observed at mantle plumes. Such homogeneity is in sharp contrast with light noble gas systematics and may call for whole mantle convection and a core origin for He and Ne..