EGU2020-2419
https://doi.org/10.5194/egusphere-egu2020-2419
EGU General Assembly 2020
© Author(s) 2023. This work is distributed under
the Creative Commons Attribution 4.0 License.

Imaging active magmatic systems at Oldoinyo Lengai volcano (Tanzania) via earthquake distribution and seismic scattering and absorption mapping

Miriam Christina Reiss1, Luca De Siena2, Georg Rümpker1, and Emmanuel Owden Kazimoto3
Miriam Christina Reiss et al.
  • 1Institute for Geosciences, Goethe University Frankfurt, Frankfurt am Main, Germany (reiss@geophysik.uni-frankfurt.de)
  • 2Institute of Geosciences, Johannes Gutenberg University Mainz, Mainz, Germany
  • 3CoNAS, University of Dar es Salaam, Dar es Salaam, Tanzania

Oldoinyo Lengai volcano, located in the Natron Basin (Tanzania), is the only active natrocarbonatite volcano world-wide. As such, it presents an important endmember magmatic system, which occurs in a young rift segment (~3 Ma) of the East African Rift System. At this volcano, effusive episodes of long-duration are interrupted by short-duration explosive eruptions. At the end of February 2019, we installed a dense seismic network and four infrasound stations as part of the SEISVOL - Seismic and Infrasound Networks to Study the Volcano Oldoinyo Lengai - project. The seismic network spans an area of 30 x 30 km and encompasses Oldoinyo Lengai volcano, the extinct 1 Ma-old Gelai shield volcano, the active Naibor Soito monogenetic cone field and surrounding fault population. Here, we present temporal earthquake distributions combined with 2D absorption and scattering imaging.

On average, we report up to 34 earthquakes per day within and in the vicinity of our network. Given the dense station spacing, we are able to lower the detection threshold to -1.0 ML with a MC of -0.3. During the first months of data acquisition, the seismicity is clustered in distinct areas as background seismicity and in intermittent seismic swarms:

To image the magmatic plumbing system, we map scattering and absorption of the seismic dataset using the MuRAT (Multi-Resolution Attenuation Tomography) code. Our preliminary results show two well-resolved high-absorption and high-scattering anomalies below Oldoinyo Lengai and the Gelai intrusion in 2007 at all frequencies. With decreasing frequency (increasing depth) the anomalies converge, suggesting a link of the plumbing systems at depth.

How to cite: Reiss, M. C., De Siena, L., Rümpker, G., and Kazimoto, E. O.: Imaging active magmatic systems at Oldoinyo Lengai volcano (Tanzania) via earthquake distribution and seismic scattering and absorption mapping, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-2419, https://doi.org/10.5194/egusphere-egu2020-2419, 2020.

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