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E434: Tephra records of explosive volcanism along the Kenyan Rift (Lead Supervisor: Christine Lane, Geography)

Supervisors: Christine Lane (Geography), Clive Oppenheimer (Geography) and Dr Amy Donovan (Geography)

Importance of the area of research:

The record of past explosive volcanism in the East African Rift is poorly constrained, preventing accurate quantification of volcanic risk. In the Kenyan Rift, more than 20 volcanic centres are known to have been active during the last 10,000 years, and more than half of these have populations of >10,000 living within a 30 km radius. Despite the proximity of people and volcanoes, research into the past eruption record is limited. A few key sites provide coherent tephrostratigraphic sequences but there is limited association of widespread ash deposits with their volcanic source. Consequently, the frequency of explosive volcanic events on a regional basis, or from individual volcanoes, is not known. Volcanic ashes are however preserved in stratigraphic order, as visible and non-visible layers, within many Kenyan lake sediment archives. These sequences provide an exceptional opportunity to detail the nature, timing and frequency of past eruptions, and contribute to an improved regional hazard assessment. Additionally, such tephrostratigraphic records will support chronologies for palaeoenvironmental and archaeological studies in the Rift and adjacent areas.

Project summary:

Detailed records of past explosive volcanism offer critical insight as to the future hazards posed by the many under-studied volcanic centres within the Kenyan Rift.

The project will take a tephrostratigraphic approach to reconstruct the history of explosive volcanism along the Kenyan Rift. Visible and non-visible tephra layers from late Quaternary-Holocene lake sediment sequences from across Kenya (e.g. Lake Challa, Lake Victoria, Lake Turkana), will be characterised, correlated and dated. The results will be used to explore how far detailed and precisely-dated records, of past explosive eruptions can be used to build probabilistic hazard models for assessing the local to regional risk of ash-fall events.

What the student will do:

The project will involve sediment and core sampling in the field as well as sub-sampling sediment cores during visits to other laboratories (e.g. LacCore repository, Minneapolis; Ghent University), followed by visible and cryptotephra analysis in the Cambridge Tephra Laboratory. Tephra layers will be characterised using petrographic and geochemical techniques (e.g. WDS-EPMA, LA-ICPMS) and using this data, tephra layers will be correlated to other distally recorded layers and where possible, to proximal surface exposures. As necessary, radiocarbon and Ar-Ar dating may be carried out. The student will learn to construct and refine tephra and sediment core age-models and quantify volcanic frequency using statistical approaches.

The successful candidate will be based within the Climate and Environment Dynamics research group in the Department of Geography at Cambridge and will benefit from the support of an active and interdisciplinary research environment. The student will work alongside other members of the Cambridge Tephra Laboratory and the Cambridge Volcanology Group, as well as international project partners on, e.g. the DeepCHALLA project (Lane, funded by NERC).

Please contact the lead supervisor directly for further information relating to what the successful applicant will be expected to do, training to be provided, and any specific educational background requirements.

References:

Pyle, David M. 1999. Widely dispersed Quaternary tephra in Africa. Global and Planetary Change, vol 21, pp. 95-112.

Martin-Jones, C.M., Lane, C.S., Pearce, N.J.G., Smith, V.C., Lamb, H.F., Schaebitz, F., Viehberg, F., Bornw, M.C., Frank, U., Astrat, A. In press. Recurrent explosive eruptions from a high risk Main Ethiopian Rift volcano throughout the Holocene. Geology.

Jenkins, S., Magill, C., McAneney, J., & Blong, R. 2012. Regional ash fall hazard I: a probabilistic assessment methodology. Bulletin of Volcanology, vol. 74, pp. 1699-1712.

Follow this link to find out about applying for this project.

Other projects available from the Lead Supervisor can be viewed here.

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