Melanie Siegburg: Tectono-magmatic interaction at the Boset volcanic complex in the Main Ethiopian Rift

PhD Overview

The tectonic mapping includes fracture distribution, directions, displacements and relative age relations of fractures compared to lava flows. We use these constraints to characterise the development of rifting at the Boset volcanic complex in the MER. Further analyses of orientations and distributions of fissures, craters and cones may indicate the magmatic interaction within the rifting system through time. Structural mapping results are supported by petrological and geochemical analyses of lava flows from the Boset volcanic complex. This study emphasizes the importance of structural mapping in an active continental rift to understand the tectonic and magmatic development in the past and outline potential tectonic and volcanic hazards for the future.

BGA PGRIP presentation (poster)

The East African rift system provides important insights into the interaction of tectonism and magmatism during continental break. Pre-existing fractures within the rift system may provide pathways for rising magma, and consequently influence the orientation of craters and cones at the surface. Alternatively, ascending pressurised melts and / or pressure variation within sub-volcanic magma plumbing systems may initiate new fractures within the local stress field. The relative role of these will be examined at the Boset volcanic complex, the largest stratovolcano in the Main Ethiopian Rift. The Boset volcanic complex covers an area of 600 km²-, and, although it is surrounded by major population centres, with up to 4 million people within 100 km radius, little is known about the past history of tectonic or magmatic activity. Boset comprises the northern Berichia stratovolcano and the southern Gudda caldera which both lie along a NNE-SSW fissure. The overall fracture system comprises mainly rift-related extensional faults, striking NNE-SSW with individual faults having displacement of up to 50 m. On top of the Gudda caldera as well as north of Berichia volcano, several cones and craters are oriented along the continuation of the fissure. Here, a 2-m resolution digital elevation model derived from a NERC ARSF LIDAR survey, together with satellite images and field observations will be presented, along with an analysis of structural and magmatic features.

About the Conference

The conference was well organised and had a broad spectrum of geophysical topics. It was interesting to see how detailed and wide scaled single PhD projects are.

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