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An active seismic zone in intraplate West Iberia inferred from high-resolution geophysical data

2018-04Journal article Open access
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dc.contributor.authorCustodio, Susana
dc.contributor.authorBatlló, Josep
dc.contributor.authorZahradnik, Jiri
dc.contributor.authorArroucau, Pierre
dc.contributor.authorSilveira, Graça
dc.contributor.authorHeimann, Sebastian
dc.contributor.authorMatos, Catarina
dc.date.accessioned2018-12-03T14:59:57Z
dc.date.available2018-12-03T14:59:57Z
dc.date.issued2018-04
dc.description.abstractIntraplate Iberia is a region of slow lithopsheric deformation (<1mm/yr) with significant historical earthquake activity. Recent high-quality instrumental data have shown that small-magnitude earthquakes collapse along clusters and lineaments, which however do not bear a clear relationship to geologically mapped active structures. In this article, we investigate the controls of these earthquake clusters. In particular, we study two of the identified clustersthe Arraiolos and the Evora seismic zones (ASZ and ESZ), located in the Western Ossa Morena Zone, southwest Iberia. The ASZ marks a sharp boundary between a seismically active region to its south and a more quiet region to its north. We revise historical earthquakes in order to clarify whether earthquake activity in the region is persistent. We use data from a local network to compute accurate epicenters, focal depth, focal mechanisms, and spatiotemporal clustering, thus characterizing ongoing small-scale fracturing. Finally, we analyze complementary data sets, including tomographic models, Global Navigation Satellite Systems data, magnetic anomalies, and gravity anomalies, in order to discuss the factors that control seismogenesis in the two seismic zones. Consistency between earthquake locations, focal mechanisms and Global Navigation Satellite Systems data suggests that the ASZ is an active right-lateral shear zone, which divides two blocks within the Western Ossa Morena Zone. The ESZ seems to localize microseismicity due to its granitic lithology. These results suggest that high-resolution geophysical data have the potential to reveal blocks with different seismogenic and rheological behaviors, which may be used to improve our understanding of fault systems and the assessment of earthquake hazard in slowly deforming regions. Plain Language Summary Mainland Portugal is a region of slow lithospheric deformation. This means that changes in Earth's outmost layerthe lithosphereoccur at very low rates (<1mm/yr). In such environments, faults producing earthquakes are not easy to identify at the Earth's surface, both because their evidence can be gradually erased by wind and water or simply because they do not reach the surface. Recent studies have shown that small earthquakes in mainland Portugal group together delineating seismically more active regions. In this article we focus in two particular groups of earthquakesthe Arraiolos and the Evora seismic zones (ASZ and ESZ) and we investigate why they occur in these particular locations. We obtain precise maps of earthquake epicenters. When possible, we also analyze the direction of slip during the earthquake and the orientation of the fracture on which it occurred. We compare our results with other data sets, such as images of the Earth's interior, that could give hints about the constitution of crust beneath the ASZ and the ESZ. Earthquakes epicenters show fault sections at depth in the ASZ. These faults separate two crustal blocks with distinct material properties. In the ESZ earthquakes are associated to contrasts in crustal materials.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationMATOS, Catarina; [et al] – An active seismic zone in intraplate West Iberia inferred from high-resolution geophysical data. Journal of Geophysical Research. Solid Earth. ISSN 2169-9313. Vol. 123, N. º 4 (2018), pp. 2885-2907pt_PT
dc.identifier.doi10.1002/2017JB015114pt_PT
dc.identifier.issn2169-9313
dc.identifier.issn2169-9356
dc.identifier.urihttp://hdl.handle.net/10400.21/9125
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherAmerican Geophysical Unionpt_PT
dc.relationPTDC/GEO-FIQ/2590/2014 - FCT project SPIDERpt_PT
dc.relationPD/BD/106019/2014 - FCTpt_PT
dc.relation13/CDA/2192 - Science Foundation Irelandpt_PT
dc.relation2016-PD-06 - Geological Survey of Irelandpt_PT
dc.relation.publisherversionhttps://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1002/2017JB015114pt_PT
dc.subjectIntraplate earthquakespt_PT
dc.subjectSlow lithospheric deformationpt_PT
dc.subjectActive faultspt_PT
dc.subjectWestern Iberiapt_PT
dc.subjectDeformação litosférica lentapt_PT
dc.subjectFalhas ativaspt_PT
dc.titleAn active seismic zone in intraplate West Iberia inferred from high-resolution geophysical datapt_PT
dc.typejournal article
dspace.entity.typePublication
oaire.citation.endPage2907pt_PT
oaire.citation.issue4pt_PT
oaire.citation.startPage2885pt_PT
oaire.citation.titleJournal of Geophysical Research. Solid Earthpt_PT
oaire.citation.volume123pt_PT
person.familyNameCustódio
person.familyNameBatlló
person.familyNameZahradnik
person.familyNameArroucau
person.familyNameSilveira
person.familyNameHeimann
person.familyNameMatos
person.givenNameSusana
person.givenNameJosep
person.givenNameJiri
person.givenNamePierre
person.givenNameGraça
person.givenNameSebastian
person.givenNameCatarina
person.identifierK-7598-2012
person.identifier91922
person.identifier.ciencia-id2113-1BF3-9A06
person.identifier.ciencia-id0113-6B7F-7071
person.identifier.ciencia-id1116-1080-16F3
person.identifier.orcid0000-0001-7457-4179
person.identifier.orcid0000-0002-2493-3070
person.identifier.orcid0000-0002-1307-2957
person.identifier.orcid0000-0003-4142-227X
person.identifier.orcid0000-0002-2110-2554
person.identifier.orcid0000-0003-0096-7193
person.identifier.orcid0000-0003-4373-4963
person.identifier.ridK-6985-2012
person.identifier.ridP-9682-2016
person.identifier.ridA-3081-2009
person.identifier.ridO-4749-2014
person.identifier.scopus-author-id15749783000
person.identifier.scopus-author-id6602397368
person.identifier.scopus-author-id7005627365
person.identifier.scopus-author-id14018877600
person.identifier.scopus-author-id6602698071
rcaap.rightsopenAccesspt_PT
rcaap.typearticlept_PT
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