The Sao Vicente earthquake of 2008 April and seismicity in the continental shelf off SE Brazil: further evidence for flexural stresses

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dc.contributor.authorAssumpcao, M.
dc.contributor.authorDourado, J. C. [UNESP]
dc.contributor.authorRibotta, L. C.
dc.contributor.authorMohriak, W. U.
dc.contributor.authorDias, Fabio L.
dc.contributor.authorBarbosa, J. R.
dc.contributor.institutionUniversidade de São Paulo (USP)
dc.contributor.institutionUniversidade Estadual Paulista (Unesp)
dc.contributor.institutionTechnol Res Inst
dc.contributor.institutionPetrobras SA
dc.date.accessioned2014-05-20T15:34:06Z
dc.date.available2014-05-20T15:34:06Z
dc.date.issued2011-12-01
dc.description.abstractThe continental margin and shelf of most stable intraplate regions tend to be relatively more seismically active than the continental interior. In the southeast continental margin of Brazil, a seismic zone extends from Rio Grande do Sul to Espirito Santo, with seismic activity occurring mainly along the continental slope and suggesting a close relationship with flexural stresses caused by the weight of the sediments. In this region, earthquakes with magnitudes larger than 5 m(b) occur every 20-25 yr, on average. The focal mechanism solutions of previous earthquakes in this zone indicated reverse faulting on planes dipping approximately 45 degrees. with horizontal P-axes. The recent 5.2 m(b) earthquake of 2008 April 23 occurred 125 km south of Sao Vicente and was well recorded by many stations in SE Brazil, as well as at teleseismic distances in North America and Africa. Its focal depth was 17 km, locating the hypocentre in the lower crust. A well-determined focal mechanism solution shows one vertical nodal plane and one subhorizontal nodal plane. The P- and T-axes exhibit large dips, which were confirmed by a regional moment tensor inversion. This unusual orientation of the fault mechanism can be attributed to a rotation of the principal stress directions in the lower crust caused by flexural effects due to the load of recent sedimentation.en
dc.description.affiliationUniv São Paulo, IAG, BR-05508090 São Paulo, Brazil
dc.description.affiliationState Univ São Paulo, IGCE UNESP, BR-13506900 Rio Claro, SP, Brazil
dc.description.affiliationTechnol Res Inst, IPT, BR-05508901 São Paulo, Brazil
dc.description.affiliationPetrobras SA, Rio de Janeiro, Brazil
dc.description.affiliationUnespState Univ São Paulo, IGCE UNESP, BR-13506900 Rio Claro, SP, Brazil
dc.description.sponsorshipConselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
dc.description.sponsorshipIdCNPq: 309724/2009-0
dc.description.sponsorshipIdCNPq: 30.0460/2010-4
dc.format.extent1076-1088
dc.identifierhttp://dx.doi.org/10.1111/j.1365-246X.2011.05198.x
dc.identifier.citationGeophysical Journal International. Malden: Wiley-blackwell, v. 187, n. 3, p. 1076-1088, 2011.
dc.identifier.doi10.1111/j.1365-246X.2011.05198.x
dc.identifier.fileWOS000297114400002.pdf
dc.identifier.issn0956-540X
dc.identifier.urihttp://hdl.handle.net/11449/42423
dc.identifier.wosWOS:000297114400002
dc.language.isoeng
dc.publisherWiley-Blackwell
dc.relation.ispartofGeophysical Journal International
dc.relation.ispartofjcr2.528
dc.rights.accessRightsAcesso restrito
dc.sourceWeb of Science
dc.subjectEarthquake source observationsen
dc.subjectSeismicity and tectonicsen
dc.subjectIntra-plate processesen
dc.subjectLithospheric flexureen
dc.subjectSouth Americaen
dc.titleThe Sao Vicente earthquake of 2008 April and seismicity in the continental shelf off SE Brazil: further evidence for flexural stressesen
dc.typeArtigo
dcterms.licensehttp://www.oxfordjournals.org/access_purchase/self-archiving_policyp.html
dcterms.rightsHolderWiley-blackwell
unesp.author.orcid0000-0003-0378-8406[1]

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