Seismicity of the Bora–Tullu-Moye volcanic field, 2016-2017
Seismicity of the Bora–Tullu-Moye volcanic field, 2016-2017
The Bora‐Tullu Moye (TM) volcanic field is a geothermal energy prospect in the central Main Ethiopian Rift, but little is known about the seismicity of the region. Here we document seismic activity between February 2016 and October 2017, locating more than a 1,000 seismic events of local magnitude 0 to 2.7. This provides new insights into fluid movement and deformation beneath what we only now realize is a complicated volcanic system. A discrete cluster of events lies beneath TM, but, surprisingly, most of the seismicity lies in two clusters that are beneath neither the Bora or TM edifices. In these regions, we use earthquake cluster orientations, fault plane solutions, and fast seismic shear‐wave orientations to show that seismicity is triggered by hydrothermal circulation of fluids along preexisting fractures. The fractures trend in multiple directions and are, in general, not parallel to rifting related structures. Instead, the fractures are parallel to structures created during previous caldera forming eruptions at both Bora and TM. Highly fractured regions such as this could be attractive targets for geothermal power generation. We estimate a minimum depth for a magmatic body beneath TM to be 6.5 km using the mapped brittle‐ductile transition. Frequency analysis of the earthquake waveforms reveal the bulk of the events to be volcano tectonic, but some low‐frequency seismicity is present at a depth of 5 km beneath the TM edifice triggered by high pore fluid pressures.
Greenfield, Tim
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Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Kendall, J-Michael
746f7fc0-ee9e-4436-89d6-a6f26cdec6aa
Ayele, Atalay
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1 February 2019
Greenfield, Tim
08324ab8-4581-4a8c-a133-f12b23b8a79b
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Kendall, J-Michael
746f7fc0-ee9e-4436-89d6-a6f26cdec6aa
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
Greenfield, Tim, Keir, Derek, Kendall, J-Michael and Ayele, Atalay
(2019)
Seismicity of the Bora–Tullu-Moye volcanic field, 2016-2017.
Geochemistry, Geophysics, Geosystems.
(doi:10.1029/2018GC007648).
Abstract
The Bora‐Tullu Moye (TM) volcanic field is a geothermal energy prospect in the central Main Ethiopian Rift, but little is known about the seismicity of the region. Here we document seismic activity between February 2016 and October 2017, locating more than a 1,000 seismic events of local magnitude 0 to 2.7. This provides new insights into fluid movement and deformation beneath what we only now realize is a complicated volcanic system. A discrete cluster of events lies beneath TM, but, surprisingly, most of the seismicity lies in two clusters that are beneath neither the Bora or TM edifices. In these regions, we use earthquake cluster orientations, fault plane solutions, and fast seismic shear‐wave orientations to show that seismicity is triggered by hydrothermal circulation of fluids along preexisting fractures. The fractures trend in multiple directions and are, in general, not parallel to rifting related structures. Instead, the fractures are parallel to structures created during previous caldera forming eruptions at both Bora and TM. Highly fractured regions such as this could be attractive targets for geothermal power generation. We estimate a minimum depth for a magmatic body beneath TM to be 6.5 km using the mapped brittle‐ductile transition. Frequency analysis of the earthquake waveforms reveal the bulk of the events to be volcano tectonic, but some low‐frequency seismicity is present at a depth of 5 km beneath the TM edifice triggered by high pore fluid pressures.
Text
Greenfield et al 2018 Geochemistry, Geophysics, Geosystems
- Accepted Manuscript
More information
Accepted/In Press date: 19 November 2018
e-pub ahead of print date: 11 December 2018
Published date: 1 February 2019
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Local EPrints ID: 427981
URI: http://eprints.soton.ac.uk/id/eprint/427981
ISSN: 1525-2027
PURE UUID: bfa62fdd-7096-4ad3-b093-f69cdd519cd6
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Date deposited: 06 Feb 2019 17:30
Last modified: 16 Mar 2024 04:06
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Author:
Tim Greenfield
Author:
J-Michael Kendall
Author:
Atalay Ayele
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