Ground deformation measurements are important indicators of subsurface changes which may inform potentially catastrophic events such as structural damage to buildings or dams, derailing of rail lines, and slope failur...Ground deformation measurements are important indicators of subsurface changes which may inform potentially catastrophic events such as structural damage to buildings or dams, derailing of rail lines, and slope failure. Consequently, there is a need for studies to quantify these measurements especially in areas predisposed due to these conditions. One such area is the Menengai caldera in the East African rift where faulting, magmatism and large-scale human activities are happening. This research investigates the magnitude of deformation experienced in Menengai-Subukia area and the relationship with spatial distribution of active faults and human activities such as geothermal development and land use. Sentinel 1 images for the duration 2015 to 2021 were processed in the Sentinel Application Platform (SNAP) using the Terrain Observation with Progressive Scans SAR (TOPSAR) technique. The interferograms showed that subsidence exists within Menengai Geothermal Field (MGF). Structural mapping consisted of automatic lineament extraction in PCI Geomatica using Sentinel 1 images to generate line density map accompanied with Rose diagram which showed concentration and orientation of faults. These faults are attributed to the uplift and subsidence in Menengai caldera due to extension of the stress regime of magma activity below the caldera. Supervised image classification was carried out on Sentinel 2 images in ENVI to generate Land Use Land Cover maps. Validation was done for some reference points (geothermal wells/power plants) and compared with results from the interferograms. This was done by fitting a graphical model of the GPS data and corresponding deformation obtained from the Sentinel 1 interferograms. The findings suggest that the most probable cause of deformation in the area is due to geothermal activities and groundwater abstraction. These techniques, coupled with continuous monitoring could be useful for land-use planning and prediction of geological hazards.展开更多
A study was carried out to isolate and screen actinomycetes for antimicrobials from Menengai Crater in Kenya. The actinomycetes were isolated using starch casein agar, Luria Bertani agar and starch nitrate agar. Prima...A study was carried out to isolate and screen actinomycetes for antimicrobials from Menengai Crater in Kenya. The actinomycetes were isolated using starch casein agar, Luria Bertani agar and starch nitrate agar. Primary screening for antagonism was carried out using perpendicular method while secondary screening was done using agar disk technique. Extraction of the antimicrobials was carried out using ethyl acetate. Sensitivity testing of the crude extracts against Staphylococcus aureus, Bacillus subtilis, Escherichia faecalis, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Xanthomonas campestris, Erwinia carotovora, Candida albicans, Alternaria alternate and Fusarium oxysporum was carried out using agar well technique. Biochemical tests and carbon source requirements were used in characterization of the selected antimicrobial producers. M1 was the best agar medium for isolation of actinomycetes. The number of actinomycetes from regions A, B, C, and D in the crater varied significantly (F = 27.50 P = 0.000). Out of the 156 actinomycetes isolates, 20 isolates were positive for both primary and secondary screening for antimicrobials. There was no significant difference in the zones of inhibition in primary screening of the actinomycetes for antagonistic properties against the test pathogens (F = 1.6957 P = 0.0838). The zones of inhibition after secondary screening varied significantly (F = 2.4473 P = 0.0089). Likewise, there was a significant difference (F = 6.6046 P = 0.001338) in the zones of inhibition after exposing the pathogens to ethyl extracts of the selected antagonistic actinomycetes. There is need to purify and characterize the antimicrobials obtained from the present study.展开更多
文摘Ground deformation measurements are important indicators of subsurface changes which may inform potentially catastrophic events such as structural damage to buildings or dams, derailing of rail lines, and slope failure. Consequently, there is a need for studies to quantify these measurements especially in areas predisposed due to these conditions. One such area is the Menengai caldera in the East African rift where faulting, magmatism and large-scale human activities are happening. This research investigates the magnitude of deformation experienced in Menengai-Subukia area and the relationship with spatial distribution of active faults and human activities such as geothermal development and land use. Sentinel 1 images for the duration 2015 to 2021 were processed in the Sentinel Application Platform (SNAP) using the Terrain Observation with Progressive Scans SAR (TOPSAR) technique. The interferograms showed that subsidence exists within Menengai Geothermal Field (MGF). Structural mapping consisted of automatic lineament extraction in PCI Geomatica using Sentinel 1 images to generate line density map accompanied with Rose diagram which showed concentration and orientation of faults. These faults are attributed to the uplift and subsidence in Menengai caldera due to extension of the stress regime of magma activity below the caldera. Supervised image classification was carried out on Sentinel 2 images in ENVI to generate Land Use Land Cover maps. Validation was done for some reference points (geothermal wells/power plants) and compared with results from the interferograms. This was done by fitting a graphical model of the GPS data and corresponding deformation obtained from the Sentinel 1 interferograms. The findings suggest that the most probable cause of deformation in the area is due to geothermal activities and groundwater abstraction. These techniques, coupled with continuous monitoring could be useful for land-use planning and prediction of geological hazards.
文摘A study was carried out to isolate and screen actinomycetes for antimicrobials from Menengai Crater in Kenya. The actinomycetes were isolated using starch casein agar, Luria Bertani agar and starch nitrate agar. Primary screening for antagonism was carried out using perpendicular method while secondary screening was done using agar disk technique. Extraction of the antimicrobials was carried out using ethyl acetate. Sensitivity testing of the crude extracts against Staphylococcus aureus, Bacillus subtilis, Escherichia faecalis, Escherichia coli, Klebsiella pneumoniae, Salmonella typhi, Xanthomonas campestris, Erwinia carotovora, Candida albicans, Alternaria alternate and Fusarium oxysporum was carried out using agar well technique. Biochemical tests and carbon source requirements were used in characterization of the selected antimicrobial producers. M1 was the best agar medium for isolation of actinomycetes. The number of actinomycetes from regions A, B, C, and D in the crater varied significantly (F = 27.50 P = 0.000). Out of the 156 actinomycetes isolates, 20 isolates were positive for both primary and secondary screening for antimicrobials. There was no significant difference in the zones of inhibition in primary screening of the actinomycetes for antagonistic properties against the test pathogens (F = 1.6957 P = 0.0838). The zones of inhibition after secondary screening varied significantly (F = 2.4473 P = 0.0089). Likewise, there was a significant difference (F = 6.6046 P = 0.001338) in the zones of inhibition after exposing the pathogens to ethyl extracts of the selected antagonistic actinomycetes. There is need to purify and characterize the antimicrobials obtained from the present study.
