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Stratification of the earth beneath the Azores from P and S receiver functions

2010-10-15Journal article Open access
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dc.contributor.authorSilveira, Graça
dc.contributor.authorVinnik, Lev
dc.contributor.authorStutzmann, E.
dc.contributor.authorFarra, V.
dc.contributor.authorKiselev, Sergei
dc.contributor.authorMorais, Iolanda
dc.date.accessioned2012-03-14T12:17:03Z
dc.date.available2012-03-14T12:17:03Z
dc.date.issued2010-10-15
dc.description.abstractSeismic recordings of IRIS/IDA/GSN station CMLA and of several temporary stations in the Azores archipelago are processed with P and S receiver function (PRF and SRF) techniques. Contrary to regional seismic tomography these methods provide estimates of the absolute velocities and of the Vp/Vs ratio up to a depth of similar to 300 km. Joint inversion of PRFs and SRFs for a few data sets consistently reveals a division of the subsurface medium into four zones with a distinctly different Vp/Vs ratio: the crust similar to 20 km thick with a ratio of similar to 1.9 in the lower crust, the high-Vs mantle lid with a strongly reduced VpNs velocity ratio relative to the standard 1.8, the low-velocity zone (LVZ) with a velocity ratio of similar to 2.0, and the underlying upper-mantle layer with a standard velocity ratio. Our estimates of crustal thickness greatly exceed previous estimates (similar to 10 km). The base of the high-Vs lid (the Gutenberg discontinuity) is at a depth of-SO km. The LVZ with a reduction of S velocity of similar to 15% relative to the standard (IASP91) model is terminated at a depth of similar to 200 km. The average thickness of the mantle transition zone (TZ) is evaluated from the time difference between the S410p and SKS660p, seismic phases that are robustly detected in the S and SKS receiver functions. This thickness is practically similar to the standard IASP91 value of 250 km. and is characteristic of a large region of the North Atlantic outside the Azores plateau. Our data are indicative of a reduction of the S-wave velocity of several percent relative to the standard velocity in a depth interval from 460 to 500 km. This reduction is found in the nearest vicinities of the Azores, in the region sampled by the PRFs, but, as evidenced by SRFs, it is missing at a distance of a few hundred kilometers from the islands. We speculate that this anomaly may correspond to the source of a plume which generated the Azores hotspot. Previously, a low S velocity in this depth range was found with SRF techniques beneath a few other hotspots.por
dc.identifier.citationSilveira G, Vinnik L, Stutzmann E, Farra V, Kiselev S, Morais I. Stratification of the Earth beneath the Azores from P and S receiver functions. Earth and Planetary Science Letters. 2010; 299 (1-2): 91-103.por
dc.identifier.issn0012-821X
dc.identifier.urihttp://hdl.handle.net/10400.21/1298
dc.language.isoengpor
dc.peerreviewedyespor
dc.publisherElsevier Science BVpor
dc.relation.ispartofseries1-2
dc.subjectReceiver functionspor
dc.subjectHotspotspor
dc.subjectMantle transition zonepor
dc.subjectAzorespor
dc.subjectMantle structure beneathpor
dc.subjectMid-atlantic ridgepor
dc.subjectConverted wavespor
dc.subjectSouthern Africapor
dc.subjectRayleigh-wavepor
dc.subjectTomographypor
dc.subjectVelocitypor
dc.subjectIcelandpor
dc.subjectPlumespor
dc.subjectLithospherepor
dc.titleStratification of the earth beneath the Azores from P and S receiver functionspor
dc.typejournal article
dspace.entity.typePublication
oaire.citation.conferencePlaceNetherlandspor
oaire.citation.endPage103por
oaire.citation.issue299por
oaire.citation.startPage91por
oaire.citation.titleEarth and Planetary Science Letterspor
person.familyNameSilveira
person.familyNameVinnik
person.familyNameMorais
person.givenNameGraça
person.givenNameLev
person.givenNameIolanda
person.identifier91922
person.identifier.ciencia-id1116-1080-16F3
person.identifier.ciencia-id981A-43E4-A5B2
person.identifier.orcid0000-0002-2110-2554
person.identifier.orcid0000-0002-1135-6200
person.identifier.orcid0000-0002-2633-6202
person.identifier.ridA-3081-2009
person.identifier.ridF-6438-2013
person.identifier.scopus-author-id6602698071
person.identifier.scopus-author-id6603452215
rcaap.rightsrestrictedAccesspor
rcaap.typearticlepor
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relation.isAuthorOfPublication274ab7b0-7205-4772-a163-e9d446f95ff5
relation.isAuthorOfPublication1b04043e-28e4-4458-9282-d888d3b3d7ae
relation.isAuthorOfPublication.latestForDiscovery274ab7b0-7205-4772-a163-e9d446f95ff5

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