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Ambient noise tomography of the East African Rift in Mozambique

2016-03Journal article Restricted access
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dc.contributor.authorDomingues, Ana
dc.contributor.authorSilveira, Graça
dc.contributor.authorFerreira, Ana M. G.
dc.contributor.authorChang, Sung-Joon
dc.contributor.authorCustódio, Susana
dc.contributor.authorFonseca, João F. B. D.
dc.date.accessioned2016-04-13T14:52:11Z
dc.date.available2016-04-13T14:52:11Z
dc.date.issued2016-03
dc.description.abstractSeismic 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.pt_PT
dc.identifier.citationDOMINGUES, Ana; [et al] - Ambient noise tomography of the East African Rift in Mozambique. Geophysical Journal International. ISSN 1365-246X. Vol. 204, N.º 3 (2016), pp. 1565-1578pt_PT
dc.identifier.doi10.1093/gji/ggv538pt_PT
dc.identifier.issn1365-246X
dc.identifier.issn0956-540X
dc.identifier.urihttp://hdl.handle.net/10400.21/5965
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherOxford University Presspt_PT
dc.relation.publisherversionhttp://gji.oxfordjournals.org/content/204/3/1565.abstractpt_PT
dc.subjectSeismic tomographypt_PT
dc.subjectContinental margins: divergentpt_PT
dc.subjectCrustal structurept_PT
dc.titleAmbient noise tomography of the East African Rift in Mozambiquept_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage1578pt_PT
oaire.citation.issue3pt_PT
oaire.citation.startPage1565pt_PT
oaire.citation.titleGeophysical Journal Internationalpt_PT
oaire.citation.volume204pt_PT
person.familyNameSilveira
person.familyNameChang
person.givenNameGraça
person.givenNameSung-Joon
person.identifier91922
person.identifier.ciencia-id1116-1080-16F3
person.identifier.orcid0000-0002-2110-2554
person.identifier.orcid0000-0003-1434-1132
person.identifier.ridA-3081-2009
person.identifier.ridA-2114-2009
person.identifier.scopus-author-id6602698071
rcaap.rightsclosedAccesspt_PT
rcaap.typearticlept_PT
relation.isAuthorOfPublicationd4ff725a-b30b-4acb-906d-b60530a4994f
relation.isAuthorOfPublicationd31de855-ccda-4625-871a-888ac23416cc
relation.isAuthorOfPublication.latestForDiscoveryd31de855-ccda-4625-871a-888ac23416cc

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