Supervisors: (Geography) and (
Importance of the area of research:
The Ethiopian Rift is home to more than 60 volcanoes believed to have been active during the last 10,000 years, and the country has a population of ~90 million. The geological record of past explosive volcanism in this region has been little studied, with few key sites providing coherent tephrostratigraphic sequences and limited association of widespread ash with its volcanic source. Reflecting the exposure of a growing population and the limited knowledge of these volcanoes, many are listed at the highest level of risk by a recent World Bank report on volcanic hazards.
Volcanic ashes from explosive eruptions are preserved as visible and non-visible layers within many Ethiopian lake sediment archives. These sequences provide an exceptional opportunity to detail the nature, timing and frequency of past eruptions, and contribute to an improved hazard assessment. Additionally, records will support chronologies for palaeoenvironmental and archaeological studies in the Rift and adjacent areas.
Detailed records of past explosive volcanism offer critical insight as to the future hazards posed by the many under-studied volcanic centres within the Ethiopian Rift.
Through the characterisation, correlation and dating of visible and non-visible tephra layers within late Quaternary – Holocene lake sediment sequences, this project will take a tephrostratigraphic approach to reconstruct the history of explosive volcanism in the Ethiopian Rift. These 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 the Rift and adjacent Afar region.
What the student will do:
The project will involve sediment and core sampling in the Ethiopian Rift Valley and sub-sampling during visits to other laboratories (e.g. Laccore repository, Minneapolis), 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, and the student will learn to construct and refine tephra age-models using Bayesian age-modelling approaches.
The student will benefit by collaboration with other members of the Tephra Research Group, and working alongside the projects Nature and impacts of Middle Pleistocene volcanism in the Ethiopian Rift (Oppenheimer, funded by the Leverhulme Trust) and RiftVolc (Marie Edmonds, funded by NERC).
Aspinall, W., Auker, M., Hincks, S., Mahony, T., Nadim, F., Pooley, J., Sparks, R.S.J. & Syre E. 2011. Volcano hazard and exposure in GFDRR priority countries and risk mitigation measures. In: Volcano Risk Study 0100806001-R: Washington, D.C., Global Facility for Disaster Reduction and Recovery.
Martin-Jones, C., Lane, C.S., Pearce, N. J. G., Smith, V.C., Lamb, H. F., Oppenheimer, C., Asrat, A., & Schaebitz, F. In press. Glass compositions and tempo of post-17 ka eruptions from the Afar Triangle recorded in sediments from lakes Ashenge and Hayk, Ethiopia. Quaternary Geochronology.
Hutchison, W., Fusillo, R., Ple, D.M., Mather, T.A., Blundy, J.D., Biggs, J., Yirgu, G., Cohen, B.E., Brooker, R.A., Barfood., D.N. and Calvert, A.T. 2016. A pulse of mid-Pleistocene rift volcanism in Ethiopia at the dawn of modern humans. Nature Communications 7: 13192.
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