Seismic and infrasound networks to study the volcano Oldoinyo Lengai (SEISVOL)

• Applicant: Professorin Dr. Miriam Christina Reiss
• Subject Area: Geophysics
• Term: from 2018 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 408905534

Oldoinyo Lengai in the North Tanzanian Divergence (NTD) is the only active natrocarbonatite volcano world-wide and presents an important endmember magmatic system in a young rift segment of the East African Rift System (EARS). This volcano typically experiences long-duration episodes of natrocarbonatitic effusions with intermittent short-duration explosive eruptions. These changes may be driven by stress interactions between different magma networks beneath Oldoinyo Lengai and neighboring rift volcanoes or caused by a complex differentiation process in which, driven by CO2, natrocarbonatitic magma is exsolved from one magma chamber. To better understand the role of the stress interactions and magma plumbing on the eruptions dynamics, this proposed study aims to constrain the subsurface magmatic architecture of Oldoinyo Lengai, and a zone of ongoing seismicity and intrusive activity below the extinct 1 Ma-old Gelai shield volcano and active Naibor Soito monogenetic cone field. We will install a temporary dense seismic network and infrasound sensors closely situated around the active Oldoinyo Lengai edifice. These networks will significantly reduce the detection threshold of volcano-tectonic events, allowing us to observe temporal changes in the magmatic system and provide detailed imaging of the globally-unique Oldoinyo Lengai plumbing system.Key research objectives are: 1) to study whether a carbonatitic volcanic system produces the same kind of volcanic events as their basaltic counter parts by analyzing seismic events, 2) deduce the vent activity from infrasound observations and compare these to the observed seismicity to better constrain their source processes, 3) image the subsurface with ambient noise tomography to detect the number of magma chambers and overall plumbing system and 4) image changes in the magmatic system regarding seismic velocities and stress over time using ambient noise cross correlations and shear-wave splitting analyses of local earthquakes.

• DFG Programme: Research Grants
• International Connection: Russia, Tanzania, USA
• Cooperation Partners: Professorin Cynthia Ebinger, Ph.D.; Professor Dr. Tobias Fischer; Dr. Andrey Jakovlev; Dr. Emmanuel Owden Kazimoto; Professorin Dr. Evelyne Mbede; James Muirhead, Ph.D.; Professor Dr. Alfred Muzuka
• Co-Investigator: Dr. Christoph Sens-Schönfelder