Ambient noise tomography of the East African Rift in Mozambique
Seismic ambient noise tomography is applied to central and southern Mozambique, located in the tip of the East African Rift (EAR). The deployment of MOZART seismic network, with a total of 30 broad-band stations continuously recording for 26 months, allowed us to carry out the first tomographic stud...
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ftbirkbeckcoll:oai:eprints.bbk.ac.uk.oai2:15591 2023-05-15T14:02:04+02:00 Ambient noise tomography of the East African Rift in Mozambique Domingues, Ana Silveira, G. Ferreira, A.M.G. Chang, S.-J. Custódio, S. Fonseca, J.F.B.D. 2016-03 https://eprints.bbk.ac.uk/id/eprint/15591/ https://doi.org/10.1093/gji/ggv538 unknown Oxford Journals Domingues, Ana and Silveira, G. and Ferreira, A.M.G. and Chang, S.-J. and Custódio, S. and Fonseca, J.F.B.D. (2016) Ambient noise tomography of the East African Rift in Mozambique. Geophysical Journal International 204 (3), pp. 1565-1578. ISSN 0956-540X. Earth and Planetary Sciences Article PeerReviewed 2016 ftbirkbeckcoll https://doi.org/10.1093/gji/ggv538 2022-01-09T08:58:22Z Seismic ambient noise tomography is applied to central and southern Mozambique, located in the tip of the East African Rift (EAR). The deployment of MOZART seismic network, with a total of 30 broad-band stations continuously recording for 26 months, allowed us to carry out the first tomographic study of the crust under this region, which until now remained largely unexplored at this scale. From cross-correlations extracted from coherent noise we obtained Rayleigh wave group velocity dispersion curves for the period range 5–40 s. These dispersion relations were inverted to produce group velocity maps, and 1-D shear wave velocity profiles at selected points. High group velocities are observed at all periods on the eastern edge of the Kaapvaal and Zimbabwe cratons, in agreement with the findings of previous studies. Further east, a pronounced slow anomaly is observed in central and southern Mozambique, where the rifting between southern Africa and Antarctica created a passive margin in the Mesozoic, and further rifting is currently happening as a result of the southward propagation of the EAR. In this study, we also addressed the question concerning the nature of the crust (continental versus oceanic) in the Mozambique Coastal Plains (MCP), still in debate. Our data do not support previous suggestions that the MCP are floored by oceanic crust since a shallow Moho could not be detected, and we discuss an alternative explanation for its ocean-like magnetic signature. Our velocity maps suggest that the crystalline basement of the Zimbabwe craton may extend further east well into Mozambique underneath the sediment cover, contrary to what is usually assumed, while further south the Kaapval craton passes into slow rifted crust at the Lebombo monocline as expected. The sharp passage from fast crust to slow crust on the northern part of the study area coincides with the seismically active NNE-SSW Urema rift, while further south the Mazenga graben adopts an N-S direction parallel to the eastern limit of the Kaapvaal craton. We conclude that these two extensional structures herald the southward continuation of the EAR, and infer a structural control of the transition between the two types of crust on the ongoing deformation. Article in Journal/Newspaper Antarc* Antarctica BIROn - Birkbeck Institutional Research Online (Birkbeck University of London) Geophysical Journal International 204 3 1565 1578 |
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Open Polar |
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BIROn - Birkbeck Institutional Research Online (Birkbeck University of London) |
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ftbirkbeckcoll |
language |
unknown |
topic |
Earth and Planetary Sciences |
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Earth and Planetary Sciences Domingues, Ana Silveira, G. Ferreira, A.M.G. Chang, S.-J. Custódio, S. Fonseca, J.F.B.D. Ambient noise tomography of the East African Rift in Mozambique |
topic_facet |
Earth and Planetary Sciences |
description |
Seismic ambient noise tomography is applied to central and southern Mozambique, located in the tip of the East African Rift (EAR). The deployment of MOZART seismic network, with a total of 30 broad-band stations continuously recording for 26 months, allowed us to carry out the first tomographic study of the crust under this region, which until now remained largely unexplored at this scale. From cross-correlations extracted from coherent noise we obtained Rayleigh wave group velocity dispersion curves for the period range 5–40 s. These dispersion relations were inverted to produce group velocity maps, and 1-D shear wave velocity profiles at selected points. High group velocities are observed at all periods on the eastern edge of the Kaapvaal and Zimbabwe cratons, in agreement with the findings of previous studies. Further east, a pronounced slow anomaly is observed in central and southern Mozambique, where the rifting between southern Africa and Antarctica created a passive margin in the Mesozoic, and further rifting is currently happening as a result of the southward propagation of the EAR. In this study, we also addressed the question concerning the nature of the crust (continental versus oceanic) in the Mozambique Coastal Plains (MCP), still in debate. Our data do not support previous suggestions that the MCP are floored by oceanic crust since a shallow Moho could not be detected, and we discuss an alternative explanation for its ocean-like magnetic signature. Our velocity maps suggest that the crystalline basement of the Zimbabwe craton may extend further east well into Mozambique underneath the sediment cover, contrary to what is usually assumed, while further south the Kaapval craton passes into slow rifted crust at the Lebombo monocline as expected. The sharp passage from fast crust to slow crust on the northern part of the study area coincides with the seismically active NNE-SSW Urema rift, while further south the Mazenga graben adopts an N-S direction parallel to the eastern limit of the Kaapvaal craton. We conclude that these two extensional structures herald the southward continuation of the EAR, and infer a structural control of the transition between the two types of crust on the ongoing deformation. |
format |
Article in Journal/Newspaper |
author |
Domingues, Ana Silveira, G. Ferreira, A.M.G. Chang, S.-J. Custódio, S. Fonseca, J.F.B.D. |
author_facet |
Domingues, Ana Silveira, G. Ferreira, A.M.G. Chang, S.-J. Custódio, S. Fonseca, J.F.B.D. |
author_sort |
Domingues, Ana |
title |
Ambient noise tomography of the East African Rift in Mozambique |
title_short |
Ambient noise tomography of the East African Rift in Mozambique |
title_full |
Ambient noise tomography of the East African Rift in Mozambique |
title_fullStr |
Ambient noise tomography of the East African Rift in Mozambique |
title_full_unstemmed |
Ambient noise tomography of the East African Rift in Mozambique |
title_sort |
ambient noise tomography of the east african rift in mozambique |
publisher |
Oxford Journals |
publishDate |
2016 |
url |
https://eprints.bbk.ac.uk/id/eprint/15591/ https://doi.org/10.1093/gji/ggv538 |
genre |
Antarc* Antarctica |
genre_facet |
Antarc* Antarctica |
op_relation |
Domingues, Ana and Silveira, G. and Ferreira, A.M.G. and Chang, S.-J. and Custódio, S. and Fonseca, J.F.B.D. (2016) Ambient noise tomography of the East African Rift in Mozambique. Geophysical Journal International 204 (3), pp. 1565-1578. ISSN 0956-540X. |
op_doi |
https://doi.org/10.1093/gji/ggv538 |
container_title |
Geophysical Journal International |
container_volume |
204 |
container_issue |
3 |
container_start_page |
1565 |
op_container_end_page |
1578 |
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1766272152633344000 |