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Seismic anisotropy reveals a dynamic link between adjacent magmatic segments prior to dyke Intrusion

Seismic anisotropy reveals a dynamic link between adjacent magmatic segments prior to dyke Intrusion
Seismic anisotropy reveals a dynamic link between adjacent magmatic segments prior to dyke Intrusion
Seismic anisotropy has increasingly been proposed as a tool in the monitoring of magmatic systems and potential forecasting of volcanic eruptions. We present a detailed study of how seismic anisotropy evolves in an active magmatic rift segment before, during, and after a dyke intrusion in the Afar depression, Ethiopia. Results show that seismic anisotropy prior to the dyke intrusion is controlled by a complex and deforming magma plumbing system beneath the adjacent Dabbahu and Manda‐Hararo magmatic segments. Approximately eight days prior to the dyke intrusion in the Dabbahu segment, the pattern of anisotropy, coupled with lower crustal seismicity, is best explained by the inflation of a lower crustal magma reservoir in the Manda‐Hararo segment. This is the only clearly observed precursory change in seismic anisotropy. During the dyke intrusion, the magnitude of seismic anisotropy increases twofold, before rapidly returning to predyke values once the intrusion has ended. Combining our observations with models of magmatically induced crustal stress, we propose that when the deep magma reservoir beneath the Dabbahu segment becomes overpressured, inflation is triggered in the magma reservoir of the neighboring Manda‐Hararo segment. This provides strong evidence for a hydraulic link between the deep magma systems of the neighboring rift segments and that magma reservoirs beneath the Dabbahu segment can be fed by the lateral flow of magma from an adjacent segment. Our results demonstrate that seismic anisotropy has the potential to be a powerful tool for monitoring deformation in the magma plumbing systems of active volcanoes.
0148-0227
1-17
Illsley-Kemp, Finnigan
c24ef4cb-cbf9-4a58-af8d-da9c7eabd84d
Greenfield, Tim
08324ab8-4581-4a8c-a133-f12b23b8a79b
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Illsley-Kemp, Finnigan
c24ef4cb-cbf9-4a58-af8d-da9c7eabd84d
Greenfield, Tim
08324ab8-4581-4a8c-a133-f12b23b8a79b
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

Illsley-Kemp, Finnigan, Greenfield, Tim and Keir, Derek (2018) Seismic anisotropy reveals a dynamic link between adjacent magmatic segments prior to dyke Intrusion. Journal of Geophysical Research, 123, 1-17. (doi:10.1029/2018JB016420).

Record type: Article

Abstract

Seismic anisotropy has increasingly been proposed as a tool in the monitoring of magmatic systems and potential forecasting of volcanic eruptions. We present a detailed study of how seismic anisotropy evolves in an active magmatic rift segment before, during, and after a dyke intrusion in the Afar depression, Ethiopia. Results show that seismic anisotropy prior to the dyke intrusion is controlled by a complex and deforming magma plumbing system beneath the adjacent Dabbahu and Manda‐Hararo magmatic segments. Approximately eight days prior to the dyke intrusion in the Dabbahu segment, the pattern of anisotropy, coupled with lower crustal seismicity, is best explained by the inflation of a lower crustal magma reservoir in the Manda‐Hararo segment. This is the only clearly observed precursory change in seismic anisotropy. During the dyke intrusion, the magnitude of seismic anisotropy increases twofold, before rapidly returning to predyke values once the intrusion has ended. Combining our observations with models of magmatically induced crustal stress, we propose that when the deep magma reservoir beneath the Dabbahu segment becomes overpressured, inflation is triggered in the magma reservoir of the neighboring Manda‐Hararo segment. This provides strong evidence for a hydraulic link between the deep magma systems of the neighboring rift segments and that magma reservoirs beneath the Dabbahu segment can be fed by the lateral flow of magma from an adjacent segment. Our results demonstrate that seismic anisotropy has the potential to be a powerful tool for monitoring deformation in the magma plumbing systems of active volcanoes.

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Illsley-Kemp_et_al-2018-Journal_of_Geophysical_Research%3A_Solid_Earth - Version of Record
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Accepted/In Press date: 24 October 2018
e-pub ahead of print date: 24 October 2018
Published date: 8 November 2018

Identifiers

Local EPrints ID: 426085
URI: http://eprints.soton.ac.uk/id/eprint/426085
ISSN: 0148-0227
PURE UUID: 430ebafe-6963-4537-8cfc-5d7593ee924e
ORCID for Finnigan Illsley-Kemp: ORCID iD orcid.org/0000-0002-7114-033X
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 13 Nov 2018 17:30
Last modified: 09 Jan 2022 03:36

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Contributors

Author: Finnigan Illsley-Kemp ORCID iD
Author: Tim Greenfield
Author: Derek Keir ORCID iD

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