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Modelling S-wave velocity structure beneath the central main Ethiopian rift using receiver functions

Modelling S-wave velocity structure beneath the central main Ethiopian rift using receiver functions
Modelling S-wave velocity structure beneath the central main Ethiopian rift using receiver functions
We applied the receiver function (RF) technique on high-quality teleseismic earthquake data recorded by the RiftVolc broadband network from February 2016 to October 2017. We calculate RFs at 17 stations, which are inverted to estimate Vs, and Vp/Vs structure beneath the Central Main Ethiopian Rift and the Eastern plateau. The observed slow S-wave velocity (Vs) in the uppermost crust (<6 km depth) is interpreted as sedimentary and/or volcanic layers. Beneath the rift valley, crustal Vs is heterogeneous both laterally and with depth. In particular, slow Vs (∼2–3 km/s) is localised beneath volcanic centres in the upper-mid crust but ubiquitously slow in the lower crust with Vs as low as ∼3.5 km/s common. The slow lower crust is associated with high Vp/Vs ratios of ∼1.9–2.0. The Vs and Vp are consistent with the observed seismic velocities, and interpreted the presence of the small fraction (<5%) of partial melt from previous seismic imaging studies of the lower crust. In addition, the velocity contrast is small between the lower crust and upper mantle. The results suggest that partial melt in the lower crust beneath magmatically active rifts might be more widespread than previously thought and an important component of the magma plumbing system. In contrast, Vs is far more homogeneous and faster beneath the Eastern Plateau, with a distinct velocity contrast between the crust and upper mantle suggesting less crustal deformation than what is observed beneath the central rift zone.
Main Ethiopian rift, Vp/Vs, crustal structure, intrusion, magma plumbing, moho depth, partial melt, volcanic centres
Kibret, Birhanu A.
353b131c-0ca4-4063-9c62-60a407d0c862
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65
Kibret, Birhanu A.
353b131c-0ca4-4063-9c62-60a407d0c862
Ayele, Atalay
730f62fb-c461-4a4e-b52d-b143a7936df6
Keir, Derek
5616f81f-bf1b-4678-a167-3160b5647c65

Kibret, Birhanu A., Ayele, Atalay and Keir, Derek (2022) Modelling S-wave velocity structure beneath the central main Ethiopian rift using receiver functions. Frontiers in Earth Science, 10, [773783]. (doi:10.3389/feart.2022.773783).

Record type: Article

Abstract

We applied the receiver function (RF) technique on high-quality teleseismic earthquake data recorded by the RiftVolc broadband network from February 2016 to October 2017. We calculate RFs at 17 stations, which are inverted to estimate Vs, and Vp/Vs structure beneath the Central Main Ethiopian Rift and the Eastern plateau. The observed slow S-wave velocity (Vs) in the uppermost crust (<6 km depth) is interpreted as sedimentary and/or volcanic layers. Beneath the rift valley, crustal Vs is heterogeneous both laterally and with depth. In particular, slow Vs (∼2–3 km/s) is localised beneath volcanic centres in the upper-mid crust but ubiquitously slow in the lower crust with Vs as low as ∼3.5 km/s common. The slow lower crust is associated with high Vp/Vs ratios of ∼1.9–2.0. The Vs and Vp are consistent with the observed seismic velocities, and interpreted the presence of the small fraction (<5%) of partial melt from previous seismic imaging studies of the lower crust. In addition, the velocity contrast is small between the lower crust and upper mantle. The results suggest that partial melt in the lower crust beneath magmatically active rifts might be more widespread than previously thought and an important component of the magma plumbing system. In contrast, Vs is far more homogeneous and faster beneath the Eastern Plateau, with a distinct velocity contrast between the crust and upper mantle suggesting less crustal deformation than what is observed beneath the central rift zone.

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Published date: 17 March 2022
Keywords: Main Ethiopian rift, Vp/Vs, crustal structure, intrusion, magma plumbing, moho depth, partial melt, volcanic centres

Identifiers

Local EPrints ID: 456161
URI: http://eprints.soton.ac.uk/id/eprint/456161
PURE UUID: 8b9372bd-71f0-4160-9841-8e3733685c3e
ORCID for Derek Keir: ORCID iD orcid.org/0000-0001-8787-8446

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Date deposited: 26 Apr 2022 15:09
Last modified: 09 Nov 2022 02:43

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Contributors

Author: Birhanu A. Kibret
Author: Atalay Ayele
Author: Derek Keir ORCID iD

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