Relevant bibliographies by topics / Seismic study of Kenya Rift

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Academic literature on the topic 'Seismic study of Kenya Rift'

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Published: 4 June 2021
Last updated: 1 February 2022

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Journal articles on the topic "Seismic study of Kenya Rift"

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Conti, Paolo, Marco Pistis, Stefano Bernardinetti, Alessio Barbagli, Andrea Zirulia, Lisa Serri, Tommaso Colonna, Enrico Guastaldi, and Giorgio Ghiglieri. "Tectonic Setting of the Kenya Rift in the Nakuru Area, Based on Geophysical Prospecting." Geosciences 11, no. 2 (February 11, 2021): 80. http://dx.doi.org/10.3390/geosciences11020080.

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In this paper, we present results of tectonic and geophysical investigations in the Kenya Rift valley, in the Nakuru area. We compiled a detailed geological map of the area based on published earlier works, well data and satellite imagery. The map was then integrated with original fieldwork and cross sections were constructed. In key areas, we then performed geophysical survey using Electrical Resistivity Tomography (ERT), Hybrid Source Audio MagnetoTelluric (HSAMT), and single station passive seismic measurements (HVSR). In the study area, a volcano-sedimentary succession of the Neogene-Quaternary age characterized by basalts, trachytes, pyroclastic rocks, and tephra with intercalated lacustrine and fluvial deposits crops out. Faulting linked with rift development is evident and occurs throughout the area crosscutting all rock units. We show a rotation of the extension in this portion of the Kenya rift with the NE–SW extension direction of a Neogene-Middle Pleistocene age, followed by the E–W extension direction of an Upper Pleistocene-Present age. Geophysical investigations allowed to outline main lithostratigraphic units and tectonic features at depth and were also useful to infer main cataclasites and fractured rock bodies, the primary paths for water flow in rocks. These investigations are integrated in a larger EU H2020 Programme aimed to produce a geological and hydrogeological model of the area to develop a sustainable water management system.
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Schofield, Nick, Richard Newton, Scott Thackrey, Douglas Watson, David Jolley, and Chris Morley. "Linking surface and subsurface volcanic stratigraphy in the Turkana Depression of the East African Rift system." Journal of the Geological Society 178, no. 1 (September 11, 2020): jgs2020–110. http://dx.doi.org/10.1144/jgs2020-110.

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The Northern Kenya Rift is an important natural laboratory for understanding continental rifting processes. However, much of the current understanding of its geological evolution is based on surface outcrops within footwall highs due to a lack of subsurface geological constraints. In this paper, we present an investigation of the Cenozoic stratigraphy and volcano-tectonic relationship of the volcanic sequences within the Turkana Depression (namely the North Lokichar, North Kerio and Turkana Basins). We integrate regional seismic reflection data collected as part of ongoing petroleum exploration in the area with lithological and biostratigraphic data from new wells that were drilled in 2014 and 2015 (Epir-1 and Emesek-1). This has allowed linking and extrapolation of the detailed stratigraphy of the paleontologically important Lothagam site to the volcanic sequences within the Napedet Hills, North Lokichar, North Kerio and Turkana Basins. The site of the Plio-Pleistocene-age Turkana Fault, which separates the North Lokichar Basin from the Turkana and North Kerio Basins, appears previously to have acted as a focus of Middle Miocene volcanism c. 5 Ma prior to the main period of movement on the fault. Our study highlights how subsurface and outcrop information can be combined to give a more in-depth knowledge of the magmatic history within rift basins.
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Wamalwa, Antony Munika, Kevin L. Mickus, and Laura F. Serpa. "Geophysical characterization of the Menengai volcano, Central Kenya Rift from the analysis of magnetotelluric and gravity data." GEOPHYSICS 78, no. 4 (July 1, 2013): B187—B199. http://dx.doi.org/10.1190/geo2011-0419.1.

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In this study, we qualitatively analyze detailed gravity and broadband magnetotelluric data in and surrounding the Menengai volcano of the East African rift in Kenya to assess geothermal potential of the region. Three-dimensional gravity models obtained by inverting residual gravity anomalies and 2D resistivity models obtained by inverting the transverse electric and transverse magnetic magnetotelluric modes show several common features. Our models show that a low-resistivity zone above a higher resistivity zone correlates with a low-density region located 1–4 km beneath the volcano. These zones may be related to a high temperature gradient or hydrothermally altered, fractured rocks. Additionally, a low-resistivity ([Formula: see text]) and a low-density region located approximately 4–6 km below the volcano may be related to molten material that is the source of heat for the geothermal system. The low-resistivity ([Formula: see text]) regions that correlated with a denser ([Formula: see text]) region within the caldera are bounded by high-resistivity ([Formula: see text]), high-density ([Formula: see text]) volcanic units implying that the dense and electrically resistive volcanic material is relatively cool and lacks significant fluid content that can lower resistivity. At shallow depths, 0.5–1.5 km below the caldera, a low-resistivity and low-to-moderate density region is interpreted as a zone with high fracture density that consists of clay minerals resulting from hydrothermal alteration. These results agree well with the results from previous seismic studies on the depth of the suggested molten rocks.
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KRISP working group. "Structure of the Kenya rift from seismic refraction." Nature 325, no. 6101 (January 1987): 239–42. http://dx.doi.org/10.1038/325239a0.

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Henry, W. J., J. Mechie, P. K. H. Maguire, M. A. Khan, C. Prodehl, G. R. Keller, and J. Patel. "A Seismic Investigation of the Kenya Rift Valley." Geophysical Journal International 100, no. 1 (January 1990): 107–30. http://dx.doi.org/10.1111/j.1365-246x.1990.tb04572.x.

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Thybo, H., P. K. H. Maguire, C. Birt, and E. Perchuć. "Seismic reflectivity and magmatic underplating beneath the Kenya Rift." Geophysical Research Letters 27, no. 17 (September 1, 2000): 2745–48. http://dx.doi.org/10.1029/1999gl011294.

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Simiyu, Silas M., and G. Randy Keller. "Seismic monitoring of the Olkaria Geothermal area, Kenya Rift valley." Journal of Volcanology and Geothermal Research 95, no. 1-4 (January 2000): 197–208. http://dx.doi.org/10.1016/s0377-0273(99)00124-9.

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KHAN, AFTAB, PETER MAGUIRE, BILL HENRY, and MARTIN HIGHAM. "KRISP 85 - An international seismic investigation of the Kenya Rift." Geology Today 2, no. 5 (September 1986): 139–44. http://dx.doi.org/10.1111/j.1365-2451.1986.tb01056.x.

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Gajewski, Dirk, Andreas Schulte, Don Riaroh, and Hans Thybo. "Deep seismic sounding in the Turkana depression, northern Kenya Rift." Tectonophysics 236, no. 1-4 (September 1994): 165–78. http://dx.doi.org/10.1016/0040-1951(94)90175-9.

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Keller, G. R., James Mechie, L. W. Braile, W. D. Mooney, and Claus Prodehl. "Seismic structure of the uppermost mantle beneath the Kenya rift." Tectonophysics 236, no. 1-4 (September 1994): 201–16. http://dx.doi.org/10.1016/0040-1951(94)90177-5.

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Dissertations / Theses on the topic "Seismic study of Kenya Rift"

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Young, Philippa Anne Victoria. "A local earthquake study near Lake Bogoria in the Kenya Rift." Thesis, University of Leicester, 1989. http://hdl.handle.net/2381/34988.

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A 20 X 30 km2, 15 station, seismic network operated for 3 months in 1985, near Lake Bogoria in the Kenya Rift. The array provided both continuous and triggered seismic data. This thesis is concerned with the local earthquakes which occurred within 30 km of the network, in a 50 X 80 km2 study area including parts of the Rift shoulder and the central trough. 572 small events (ML < 2.7) could be located accurately (+2 km) in 3 dimensions. Unexpectedly, most of the seismic activity is associated with the major faults of the Rift shoulder, rather than the younger, minor faults in the central trough. A linear group of events in the central trough do not correspond to any surface feature, and seem to indicate a buried fault. The depth distribution of the seismicity peaks at 9 km and diminishes below 12 km, and the "brittle-ductile" transition is inferrred to occur within a 12 - 16 km depth range. This distribution is similar to those in other young intracontinental regions, suggesting a normal crustal rheology. Only a few events provided well-constrained focal mechanisms. Normal, steeply dipping, N-S striking fault plane solutions could be fitted to almost all events in the central trough. 12 of the best solutions were used to determine the stress orientation, the results indicated near-horizontal E-W extension, but this direction was poorly constrained. Suitable seismograms displayed shear wave polarisation and splitting compatible with the predictions of Extensive Dilatancy Anisotropy (EDA) theory. Instrinsic anisotropy, due to the basement fabric, is probably present, but the EDA should dominate the observations, thus allowing a determination of present-day stress orientation. Suprisingly, two dominent polarisation directions were seen in different parts of the array, indicating a change from E-W to NW-SE "tension" within the network.
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Henry, William John. "A seismic investigation of the Kenya Rift Valley." Thesis, University of Leicester, 1987. http://hdl.handle.net/2381/35038.

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In August of 1985 the crustal structure underlying the Kenya rift valley was investigated by long range explosion seismology. The experiment (KRISP85) consisted of two seismic lines in the central sector of the rift, one along the axis (140 km) and the other across it (50 km). Interpretation of the data, including time-term analysis and ray tracing has yielded the following information. The thickness of rift infill varies from about 6 km below Lake Naivasha to about 2 km and 1.5 km below Lake Magadi and Lake Bogoria respectively. The underlying material has a P-wave velocity of 6.05 +/- 0.03 km/s which suggests the rift is underlain by Precambrian metamorphic basement. A localised high velocity zone identified to the east of Nakuru may be associated with basic intrusive material. The P-wave velocity increases discontinuously to 6.45 +/- 0.05 km/s at a depth of 12.5 +/- 1-0 km. This depth is similar to that inferred for the brittle-ductile transition zone from a study of local seismicity in the Lake Bogoria region. A high P-wave velocity layer (7.1 +/- 0.15 km/s) occurs at 22 +/- 2 km depth which might be associated with a sill-like basic intrusion in the lower crust. An upper mantle velocity of 7.5 +/- 0.2 km/s (unreversed) is reached at a depth of 34.0 +/- 2.0 km. This implies that only moderate crustal attenuation has occurred beneath the central sector of the rift. No evidence was obtained for the existence of an "axial intrusion" reaching to shallow levels below the rift and causing crustal separation as suggested by previous studies. Relative residuals determined for 46 teleseismic events recorded by a 15 station, small aperture seismic array in the vicinity of Lake Bogoria indicate considerable lateral heterogeneity in the upper crust. An Aki inversion of the relative residuals has revealed the existence of two distinct low velocity zones which may be associated with magma chambers.
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Masotti, Roberta. "Seismic structure across the Kenya Rift Valley : data analysis and geodynamic implications." Thesis, University of Leicester, 1995. http://hdl.handle.net/2381/35064.

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During the 1990 Kenya Rift International Seismic Project (KRISP 90) a 450 km E-W crustal refraction profile was undertaken across the Kenya Rift, a late Tertiary to Recent extensional feature associated with extensive volcanic activity. The P-wave data have been analysed using 2-D ray-tracing, finite difference and reflectivity dynamic modelling. A simultaneous velocity and travel time inversion has been applied to the forward model to test its uniqueness and resolution. The analyses show an asymmetric sedimentary basin which is thickest against the rift's major western boundary fault. The crustal velocities vary from 6.2 km/s in the Archaean craton to the west of the rift to about 6.0 km/s in the Proterozoic orogenic belt along the remainder of the profile. The crustal thickness outside the rift varies from 38 3 km adjacent to the rift's western margin and 34 2 km to the east. Beneath the rift itself the thickness is only 30 2 km. The upper mantle velocity is generally about 8.0 km/s except beneath the rift where it is consistently low at 7.6 - 7.8 km/s. This anomalously low velocity suggests a 5 - 6% partial melt. The combined seismic and gravity model supports the contention that convective processes in the mantle are dynamically supporting the uplifted East African Plateau. Kinematic and dynamic modelling of the S-wave field show that upper crustal phases have been recorded only outside the rift. Mid and lower crustal S arrivals do not seem to have been attenuated underneath the rift axis, precluding an extensive hot regime at lower crustal depth. A reflected phase is observed from an interface within the mantle beneath the western flank of the rift. Detailed analyses of this phase confirm the presence of a high velocity layer (8.4 km/s) below 60 km: compositional anomalies as well as crystal orientation have been suggested as an explanation for the observed velocity structure. This evidence may delimit the lateral extent of the upper mantle low velocity zone underneath the graben itself. A model of extension via simple shear in the upper crust and pure shear in the lower crust and upper mantle is suggested. The presence of a small diapir under the Kenya Rift, radiating from a 'weak' plume seated under the East African Plateau, is envisaged; the diapir appears to have spread asymmetrically towards the Proterozoic lithosphere to the east of the rift.
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Sakkas, Vassilis A. "Combined transient electromagnetic and magnetotelluric study of the southern Kenya Rift Valley." Thesis, University of Leicester, 1999. http://hdl.handle.net/2381/30437.

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The transient electromagnetic (TEM) method and the magnetotelluric (MT) technique have been applied to determine the electrical resistivity structure across the southern Kenya Rift Valley. The main profile extends from the shores of Lake Victoria, west of the Rift Valley, to the north of the Chyulu Hills volcanic chain, 150 km SE of the rift. A second profile runs parallel to the Chyulu Hills volcanic trend. Data from 19 stations along the two profiles have been processed using classical techniques and in the case of MT, analysed with modern tensor decomposition methods. The TEM data have facilitated the removal of static shift effects from the MT data and recovery of the near-surface (<300 m) geoelectric structure. One-dimensional joint inversion of TEM and MT data yielded an approximate geoelectric structure for the region. Subsequent two-dimensional modelling has revealed a more realistic resistivity distribution for the complex environment of the Kenya Rift. A resistive (>2000 .m) Archaean crust 30 km thick, with a 10-12 km mid-crustal conductive (100 .m) zone, resting on a moderately resistive (100 .m) mantle appears at the west end of the main profile. A conductive fault-like zone extending to mantle depths in the area of the Oloololo Escarpment coincides with the exposed boundary between the Archaean Nyanza Craton and the Proterozoic Mozambique Belt. A poorly constrained highly resistive (>10000 .m) (Proterozoic ?) crust is found at the western flank of the rift. Low resistivities (<50 .m) are found down to the base of the crust in the rift zone and are possibly due to the presence of sedimentary fill deposits at shallow depths, and the presence of magmatism and partial melt at deeper levels. East of the rift a less sharply defined geoelectric margin, offset from the accepted topographic and geologic boundary of the rift, marks the transition to a more resistive (1000 .m.) Proterozoic crust. Significantly enhanced conductivities (<100 .m) are implied in the complex 3-D region of the Chyulu Hills.
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Chukudebelu, Josiah Udemadu. "A seismic study of the crust in and around the Gregory rift." Thesis, Durham University, 1987. http://etheses.dur.ac.uk/6719/.

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Data used for the present study were recorded at the small aperture cross-linear array station which was installed at Kaptagat (in NW Kenya) by the University of Durham. The seismic array data from local earthquakes have been analysed by velocity/azimuth filtering technique. Apparent velocities and azimuths for first and later arrival phases were measured for local rift events from the immediate east, for local events from the south west and for more distant rift events to the north and south of Kaptagat. Data from local rift events originating from the immediate east of Kaptagat were used in the present analysis to study the structure of the lithosphere beneath the Gregory rift at about 0.5 N latitude. The first arrival data (apparent velocities and azimuths) were determined to a high degree of accuracy. The first and later arrival data have been interpreted in terms of a simple two layer model with a horizontal refracting interface at a depth of 13 + 5 km and having upper and lower layer uniform velocities of 5.8 + 0.2 km/ s and7.2 + 0,2 km/s respectively. The minimum lateral extent of the top surface of this refractor is estimated at about 30 km. A maximum dip of about 6 on the interface is allowed by the data. In the preferred three layer model, a 10 km thick top horizontal layer of velocity 5.8 km/s overlies a 10 km thick intermediate layer in which velocity increases uniformly from6.0 km/s at 10 km depth to 7.5 km/s at a depth of 20 km. The intermediate layer, in turn, overlies a 7.6 km/s refractor. The models derived from the present data are consistent with the theory that upward perturbation of the lithospher asthenosphere boundary giving rise to domal uplift, lithospheric tension and magmatic activity, is the primary causeof rifting.
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Longfield, Lynsey. "Challenges and Opportunities Shaping Smallholders’ Engagement with Formal and Informal Markets for Food and Livelihood Security: A Rift Valley, Kenya Case Study Analysis." Thesis, Université d'Ottawa / University of Ottawa, 2014. http://hdl.handle.net/10393/31603.

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This case study analysis looks at four communities in Rift Valley, Kenya including Matisi, Moi’s Bridge, Sirende and Waitaluk. The research focuses on the role of markets in achieving food and livelihood security for the smallholders in these communities and smallholders’ perceptions of the roles of the Government of Kenya and other institutions in facilitating market access. The largest challenges to market participation, as reported by the smallholders in the studied communities, include low yields, weather inconsistencies, and lack of land. In terms of the Government of Kenya, many smallholders noted the benefits of participating in groups as they are subsequently offered training or field days and subsidies. A significant group of respondents did comment on their lack of interest in joining similar groups as they were seen as unstable or corrupt. The potential roles of formal and informal markets to increase food security were also analyzed. All smallholders wished to be participating in informal markets, but twenty-five percent were constrained by the lack of surplus produce. Similarly, although many reported their desire to be participants in formal markets lack of surplus produce, price fluctuations, inconsistent weather patterns, transportation costs and post- harvest losses or food waster were recognized as significant barriers. In order to mitigate these constraints, most smallholders recommended subsidies on inputs and the overall restructuring of markets. It is recommended that organizations and governments implement a livelihood diversification policy program or initiative to diversify and intensify agricultural activities and other non-agricultural activities. This case study analysis demonstrates the need to recognize the importance of local contexts, specifically Rift Valley as much of the research done in Kenya is found in Nairobi and surrounding areas and cautions labeling communities as food secure based on favorable conditions.
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Green, Walter Verney. "Lithospheric seismic structure of the Cenozoic Kenya Rift and the Precambrian Midcontinent Rift from teleseismic tomography." 1991. http://catalog.hathitrust.org/api/volumes/oclc/27408594.html.

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Thesis (Ph. D.)--University of Wisconsin--Madison, 1991.
Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.
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Park, Yongcheol. "Upper Mantle seismic velocity structure beneath the Kenya Rift and the Arabian Shield." 2007. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2027/index.html.

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Books on the topic "Seismic study of Kenya Rift"

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Novak, Olaf. A wide-angle seismic study of the SE-flank of the Kenya Rift in corporating a multidisciplinary interpretation. Dublin: University College Dublin, 1997.

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The invisible violence in Kenya: A case study of Rift Valley and Western regions. Nairobi, Kenya: Konrad Adenauer-Stiftung e.V., 2011.

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N, Pretty Jules, Kiara J. K, Thompson John, Munyikombo L. S, and Kenya. Soil & Water Conservation Branch., eds. The impact of the catchment approach to soil and water conservation: A study of six catchments in Western, Rift Valley, and Central Provinces, Kenya, 1993. [Nairobi] Kenya: Soil and Water Conservation Branch, Ministry of Agriculture, 1993.

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Book chapters on the topic "Seismic study of Kenya Rift"

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Henry, W., J. Mechie, P. K. H. Maguire, J. Patel, G. R. Keller, C. Prodehl, and M. A. Khan. "A seismic refraction study of the crustal structure of the South Kenya Rift." In Properties and Processes of Earth' Lower Crust, 169–72. Washington, D. C.: American Geophysical Union, 1989. http://dx.doi.org/10.1029/gm051p0169.

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Perry, Brian, Bernard Bett, Eric Fèvre, Delia Grace, and Thomas Fitz Randolph. "Veterinary epidemiology at ILRAD and ILRI, 1987-2018." In The impact of the International Livestock Research Institute, 208–38. Wallingford: CABI, 2020. http://dx.doi.org/10.1079/9781789241853.0208.

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Abstract This chapter describes the activities of the International Livestock Research Institute (ILRI) and its predecessor, the International Laboratory for Research on Animal Diseases (ILRAD) from 1987 to 2018. Topics include scientific impacts; economic impact assessment; developmental impacts; capacity development; partnerships; impacts on human resources capacity in veterinary epidemiology; impacts on national animal health departments and services; impacts on animal health constraints in developing countries; impacts on ILRI's research and strategy; the introduction of veterinary epidemiology and economics at ILRAD; field studies in Kenya; tick-borne disease dynamics in eastern and southern Africa; heartwater studies in Zimbabwe; economic impact assessments of tick-borne diseases; tick and tick-borne disease distribution modelling; modelling the infection dynamics of vector-borne diseases; economic impact of trypanosomiasis; the epidemiology of resistance to trypanocides; the development of a modelling technique for evaluating control options; sustainable trypanosomiasis control in Uganda and in the Ghibe Valley of Ethiopia; spatial modelling of tsetse distributions; preventing and containing trypanocide resistance in the cotton zone of West Africa; rabies research; the economic impacts of rinderpest control; applying economic impact assessment tools to foot and mouth disease (FMD) control, the southern Africa FMD economic impact study; economic impacts of FMD in Peru, Colombia and India; economic impacts of FMD control in endemic settings in low- and middle-income countries; the global FMD research alliance (GFRA); Rift Valley fever; economic impact assessment of control options and calculation of disability-adjusted life years (DALYs); RVF risk maps for eastern Africa; land-use change and RVF infection and disease dynamics; epidemiology of gastrointestinal parasites; priorities in animal health research for poverty reduction; the Wellcome Trust Epidemiology Initiatives; the broader economic impact contributions; the responses to highly pathogenic avian influenza; the International Symposium on Veterinary Epidemiology and Economics (ISVEE) experience, the role of epidemiology in ILRAD and ILRI and the impacts of ILRAD and ILRI's epidemiology; capacity development in veterinary epidemiology and impact assessment; impacts on national animal health departments and services; impacts on animal health constraints in developing countries and impacts on ILRI's research and strategy.
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"Is the Kenya Rift a New Plate Margin? A Regional Geophysical Study." In Looking into the Earth, 345–60. Cambridge University Press, 2000. http://dx.doi.org/10.1017/cbo9780511810305.022.

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Okello, Julius Juma. "Use of Information and Communication Tools and Services by Rural Grain Traders." In Technology, Sustainability, and Rural Development in Africa, 152–67. IGI Global, 2013. http://dx.doi.org/10.4018/978-1-4666-3607-1.ch011.

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Poor access to agricultural market information is a major factor constraining the performance of agricultural markets in developing countries. The search for new strategies for resolving this constraint has led to several ICT-based market information service (MIS) projects in developing countries. At the same time, the rapid penetration of new generation ICT tools (especially mobile phones) has resulted in wider application of these tools in agriculture. This paper examines the use of ICT tools and ICT-based services by rural grain traders in Kenya. It is based on data collected from 204 traders in Western and Rift Valley regions of Kenya. The study finds widespread use of ICT tools by grain traders. It also finds that the tools are used by grain traders to obtain market information, including information on price, volume, and where to source and sell grains, among others. The implications of these findings are that market development agents must focus on removing constraints limiting the use of ICT tools in rural areas. Spurring greater use of ICT tools has the potential to reduce transaction costs and improve the performance of rural agricultural markets.
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Stiros, Stathis. "Earthquakes." In The Physical Geography of the Mediterranean. Oxford University Press, 2009. http://dx.doi.org/10.1093/oso/9780199268030.003.0030.

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Earthquakes have played a major role in the evolution of the Mediterranean landscape. They are the most important geohazard in the region and huge sums are invested annually in seismic monitoring, hazard zoning, and earthquake prediction, and in the design of earthquake-resistant buildings and infrastructure. Large earthquakes of magnitude >7.0 have been recorded across the region and the archaeological record shows that earthquakes have posed a major hazard to human settlements for thousands of years (Ambraseys 1971; Shaw et al. 2008; Bottari et al. 2009; Figure 16.1 and Table 16.1). The study of Mediterranean seismicity started about 2,400 years ago when the first earthquake catalogue was compiled in ancient Greece (Papazachos and Papazachou 1997; Guidoboni et al. 1994). This key development predated, by several centuries, the construction of the first seismograph in China (Bullen and Bolt 1985). Since these early developments a great deal of research has been carried out to improve our understanding of earthquakes and associated hazards in the Mediterranean region and to provide protection from them. Earthquake resistant buildings—such as houses with timber bracing—were introduced in Asia Minor in the seventeenth century (Kirikov 1992; Simopoulos 1984; Stiros 1995) and the first strict anti-seismic construction regulations were implemented on the island of Levkas, Greece, in the nineteenth century under British Rule (Stiros 1995). The first ‘modern’, regional-scale earthquake maps and catalogues were compiled as early as the middle of the nineteenth century (Mallet 1858). Despite this progress, the death toll from Mediterranean earthquakes is still high and earthquakes in the region continue to surprise geoscientists. For example, the diffuse pattern of seismicity that is especially characteristic characteristic of the eastern Mediterranean (Figure 16.2) is not easily reconciled with existing plate tectonic models, and many faults that are believed to demarcate plate boundaries (such as the Jordan Rift) are currently quiescent (Figure 16.3). Similarly, the 1995 Grevena-Kozani earthquake was a surprise for scientists, for it hit the heart of what was believed to be an aseismic region in northern Greece (Stiros 1998a). Furthermore, key aspects of the geodynamic background of the Mediterranean region remain a matter of debate.
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Conference papers on the topic "Seismic study of Kenya Rift"

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Masinde, Abiud, Cleophas Simiyu, Innocent Murunga, George Muia, Aaron Waswa, and Justus Barongo. "A Preliminary Assessment of the Hydrocarbon Potential of Kerio Valley Basin: Gravity and Magnetic Interpretation." In SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2546156-ms.

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ABSTRACT The aim of the study was to assess the hydrocarbon prospectivity of the Kerio Basin in the Kenya Rift. An Isostatically corrected anomaly map produced from a Bouguer anomaly grid was filtered using a Hanning low pass filter of order 2 to remove low wavelengths. Four profiles were extracted from the grid to give 1D interpretation along straight lines. Magnetic grid was corrected for IGRF, diurnal, filtered using a 1 Hz low pass 10km Hanning filter to reduce noise, later, reduced to equator to place all anomalies directly over underlying sources and make anomalies less complicated. Tilt derivative of the magnetic grid was used to estimate depth to basement. The residual analytic signal anomaly map derived from the magnetic grid was used to capture the response of existing near surface magnetic signatures even the reversely magnetized ones. Kerio basin is characterised by low gravity anomalies ranging between 35mGals to −100mGals related to variations in quantities of sediments deposited. Gravity profiles show that sediment thickness gradually increases to the south where we expect hydrocarbon accumulation. The magnetic anomaly map reveals low susceptibility rocks of between −20nT to −200nT to the south of the basin. Magnetic tilt depth indicates sediment thickness of 2.0-3.5Km above the basement. This corresponds to both gravity and magnetic interpretation of the same area. Integration of these data with seismic and other constraints may help gauge the hydrocarbon potential and reduce exploration uncertainty in the southern area of the Kerio Basin.
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Osukuku, Godfred, Abiud Masinde, Bernard Adero, Edmond Wanjala, and John Ego. "Integrated Geophysical Interpretation of Kerio Valley Basin Stratigraphy, Kenya Rift." In SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2670415-ms.

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Abstract This research work attempts to map out the stratigraphic sequence of the Kerio Valley Basin using magnetic, gravity and seismic data sets. Regional gravity data consisting of isotactic, free-air and Bouguer anomaly grids were obtained from the International Gravity Bureau (BGI). Magnetic data sets were sourced from the Earth Magnetic Anomaly grid (EMAG2). The seismic reflection data was acquired in 1989 using a vibrating source shot into inline geophones. Gravity Isostacy data shows low gravity anomalies that depict a deeper basement. Magnetic tilt and seismic profiles show sediment thickness of 2.5-3.5 Km above the basement. The Kerio Valley Basin towards the western side is underlain by a deeper basement which are overlain by succession of sandstones/shales and volcanoes. At the very top are the mid Miocene phonolites (Uasin Gishu) underlain by mid Miocene sandstones/shales (Tambach Formation). There are high gravity anomalies in the western and southern parts of the basin with the sedimentation being constrained by two normal faults. The Kerio Valley Basin is bounded to the west by the North-South easterly dipping fault system. Gravity data was significantly of help in delineating the basement, scanning the lithosphere and the upper mantle according to the relative densities. The basement rocks as well as the upper cover of volcanoes have distinctively higher densities than the infilled sedimentary sections within the basin. From the seismic profiles, the frequency of the shaley rocks and compact sandstones increases with depths. The western side of the basin is characterized by the absence of reflections and relatively higher frequency content. The termination of reflectors and the westward dip of reflectors represent a fault (Elgeyo fault). The reflectors dip towards the west, marking the basin as an asymmetrical syncline, indicating that the extension was towards the east. The basin floor is characterized by a nearly vertical fault which runs parallel to the Elgeyo fault. The seismic reflectors show marked discontinuities which may be due to lava flows. The deepest reflector shows deep sedimentation in the basin and is in reasonable agreement with basement depths delineated from potential methods (gravity and magnetic). Basement rocks are deeper at the top of the uplift footwall of the Elgeyo Escarpment. The sediments are likely of a thickness of about 800 M which is an interbed of sandstones and shales above the basement.
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Christopherson, Kevin. "The Greater Etom Area (GEA): A New Phase of Exploration in the South Lokichar Basin, Turkana County, Northern Kenya." In SPE/AAPG Africa Energy and Technology Conference. SPE, 2016. http://dx.doi.org/10.2118/afrc-2585029-ms.

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ABSTRACT East Africa is an integral part of the Tullow business. Tullow has been active for over ten years in the onshore rift basins of East Africa, which began with the opening of the Uganda Lake Albert Rift Basin in 2006 following the drilling of Mputa-1. We developed multiple sub-surface evaluation tools and an understanding on how rift success factors can combine during the drilling of the Lake Albert Basin that we then applied to the Tertiary rifts of Kenya. Extensive Full Tensor Gradiometry (FTG), seismic and drilling has taken place over the last five years in Kenya. This has established the South Lokichar basin as a significant oil basin with significant remaining exploration upside. Up until 2015 exploration drilling in the South Lokichar utilized 2D seismic data. The acquisition of 3D seismic in the north and west of the basin has allowed an improved definition of the structural framework and highlighted additional exploration potential. The Etom-2 well spud in November 2015 highlights the value of this 3D seismic in complex structural settings. Etom-1 was planned and drilled on 2D seismic and encountered 10 m of oil pay. Subsequent re-mapping based upon the 3D seismic revealed that the Etom structure was more complicated than originally interpreted and that Etom-1 had drilled into a collapse graben and not tested the structural crest of the field. Etom-2 targeted the up-thrown northern fault block which was not penetrated by the Etom-1 well and encountered 102 m of oil pay. The northern part of the South Lokichar basin is structurally complex and the 3D seismic provided the required detail to highlight that Etom-1 hadn't properly tested the Etom structure. Further mapping of the 3D seismic in the area around Etom-2 has identified multiple follow-up prospects that could be part of a new play domain in the northern part of the South Lokichar Basin. These targets are the focus for Exploration drilling that is due to commence in Q4 2016.
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Ziniukov, R., V. Sudakov, and S. Usmanov. "Integrated case study of fractured reservoir: from core to seismic scale." In EAGE/AAPG Workshop on Reducing Exploration Risk in Rift Basins. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.202076032.

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Phoosongsee, Jidapa, Christopher K. Morley, and Angus J. Ferguson. "Reservoir characterization of Early Miocene to Pleistocene using seismic attributes: case study from Songkhla Basin, Gulf of Thailand." In EAGE/AAPG Workshop on Reducing Exploration Risk in Rift Basins. European Association of Geoscientists & Engineers, 2019. http://dx.doi.org/10.3997/2214-4609.202076018.

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Zhu, Hongtao, Yawen He, and Hongliu Zeng. "Seismic interpretation of tectono-sedimentary framework of a continental rift basin: A case study of Ed3 Member, Dongying Formation, Paleogenge, in QHD29-2 block, Bohai Bay, China." In SEG Technical Program Expanded Abstracts 2012. Society of Exploration Geophysicists, 2012. http://dx.doi.org/10.1190/segam2012-1394.1.

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Chakraborty, Suvajit, Satyapal Negi, Alok Kumar, and Nitesh Pandey. "Static Modeling of Deepwater Syn-Rift Reservoir Using Trend Analysis and Conceptual Geological Model in Absence of Effective Seismic Attributes: A Case Study from Mesozoic Reservoir, Offshore East Coast of India." In SPE Oil and Gas India Conference and Exhibition. Society of Petroleum Engineers, 2017. http://dx.doi.org/10.2118/185416-ms.

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Riandini, P. "Structural Evolution Using Seismic Low Frequency Magnitude Approach: A Case Study on Defining Strike-Slip Development in West Natuna Basin, Indonesia." In Digital Technical Conference. Indonesian Petroleum Association, 2020. http://dx.doi.org/10.29118/ipa20-g-290.

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West Natuna Basin (WNB) is located in the centre of Sunda Shelf in South China Sea; bordered by the Sunda Shelf's basement to the south, the Natuna Arch to the east, and the Khorat Swell to the north. Tectonic evolution of the WNB has imparted a complex structural history of extension, compression and wrenching related to Cenozoic regional tectonic events, for which the structural evolution reflects a history of Late Eocene-Early Oligocene rifting and Middle-Late Miocene inversion. The regional strike-slip movement that associates to the Three Pagodas Fault System has long been recognised at WNB. However, the understanding of this strike-slip behaviour has not previously been investigated despite its important role in reservoir mapping. This study aims to demonstrate how new approaches of seismic attributes analysis combined with structural evolution through palinspastic reconstruction will define the structural geometry as a key point for fault relationship in the production field. Structure map and cross section are generated by integrating wells data and 3D seismic to identify structural trends. Seismic low frequency magnitude has been generated as an attribute to define faults through Spectral Decomposition method. As the faults feature on the seismic are more related to low or even absent of energy, these attributes provide robust attributes to identify four morphology in study area that represent different structural geometry and history. Seismic interpretation shows the structure commences in the early part of the Late Eocene that developed as NE-SW rifting. The rifting is initiated due to creation of pull-apart basins, as part of the WNW-ESE sinistral strike-slip fault development. The major sinistral strike-slip development was accommodated by collision of India that causes onset of rotation of Sundaland. In relation to the oblique NNE-SSW compression, Middle-Late Miocene inversion follows the post-rift deformation. This condition accommodates the development of NW-SE right lateral strike-slip on the marginal fault and result in N-S trending horsetail structure development that plays a role as an essential structure for reservoir trap.This research verifies that the combination between recent re-evaluations of the 3D seismic and its attributes can identify more detailed fault positions to generate better definitions of fault patterns. Therefore, palinspastic restoration becomes one of the classic approaches that brings further comprehension of the fault pattern’s structural evolutions, which leads to the site-development and production’s improvements.
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Nguyen, Son T. T., Tan N. N. Nguyen, Hung N. T. N. T. Tran, and Quan A. A. Ngo. "Integration of 3D Geological Modeling and Fault Seal Analysis for Pore Pressure Characterization of a High Pressure and High Temperature Exploration Well in Nam Con Son Basin, a Case Study Offshore Vietnam." In International Petroleum Technology Conference. IPTC, 2021. http://dx.doi.org/10.2523/iptc-21797-ms.

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Abstract The pore pressure profile of an exploration well in high pressure and high temperature (HPHT) A-Field of Nam Con Son Basin was initially predicted along the wellpath in tandem with the analogy to an offset well to design a drilling program of penetrating the unreachable sedimentary formation. The scheme had driven mud weight to encounter the pressure ramp but resulted in underbalance and influx into the wellbore that incurred downtime for well control. Subsequently, formation pressure measurement conceded the substantial disparity over the offset well so the post-drill study was conducted towards with 3D geological modeling and fault seal analysis to gain insight into overpressure generation mechanisms of the field. Seismic interval velocity, density, resistivity data are applied for generating the validated pore pressure profile of exploration well on both Eaton and Bowers methods with calibration on formation pressure measurement for Middle and Lower Miocene Sequences. Besides, the cutting edge 3D modeling is approached to construct a robust structural and fault framework as well as to condition and upscale ultimate shale volume, pressure gradient, and overburden stress for facies and pressure distribution. The sealing capacity of a fault is quantified in terms of the pressure acting on the fault surface that is required to be exceeded for the fault to become unstable and slip including simulations of formation juxtaposition mapping, fault clay content prediction, fault flow indicators, and transmissibility. Upon completion of the 3D model, the fault surfaces which are mapped by shale volume could provide a detailed geometry and lithology juxtaposition analysis for the fault planes. The results of the high Shale Gouge Ratio (SGR), very low fault permeability, and relatively high fault rock thickness imply that the studied faults act as a baffle to fluid flow. However, from juxtaposition observation, the displacement broadens with depth in some parts of faults and the lateral stress increases through the sync-rift stage of Middle Miocene could be a cause of overpressure in this studied area. The 3D pore pressure and stress regime integrated with fault seal analysis in the model are generally obtained to provide both vertical and spatial overpressure characterization and advantages for well drilling plan and reservoir production. From the drilling aspect, a fault stability study can optimize the maximum allowable mud weight to not exceed while drilling so that fault reactivation does not take place. From a depletion perspective, understanding of stress variations due to lowering reservoir pressure with time can be incorporated with fault seal analysis.
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