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Insight on the crustal stress state in Faial and Pico Islands (Azores), from analysis of aftershocks of the 1998 earthquake

2020-11Journal article Restricted access
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dc.contributor.authorDias, Nuno
dc.contributor.authorTellez, Julia
dc.contributor.authorMatias, Luis
dc.date.accessioned2021-01-18T14:34:50Z
dc.date.available2021-01-18T14:34:50Z
dc.date.issued2020-11
dc.description.abstractThe seismicity in the Azores plateau can be of volcanic or tectonic origin, the latter usually more destructive, especially in the central group of islands. In this study we aimed to obtain crustal stress indicators from seismic data collected in July 1998, following the July 9th M5.8 earthquake that struck near Faial and Pico islands. The maximum horizontal stress (SHmax) azimuth was obtained from two methods. For the seismogenic volume, the SHmax was obtained from single and composite focal mechanisms, whereas the state of stress beneath the seismic network was derived from shear-wave splitting analysis of local earthquakes. The composite focal mechanisms were obtained from a waveform clustering method applied to identify "identical" earthquakes. The seismic anisotropy analysis could be applied to only six stations, the polarization of the first S arrival being stable, and with a secondary perpendicular pulse arriving 0.6-0.24 s later. The focal mechanisms provided a NW-SE SHmax with azimuth range of 96 degrees-114 degrees, and an associated transition of normal-fault to strike-slip dominant regime consistent with the estimated regional field of 110 degrees-120 degrees, and coherent with movement along three fault systems. Inland the SHmax azimuths present greater variability. In Faial, the stations located north of the Caldeira present a stable azimuth of 151 degrees-153 degrees and are consistent with the effect of a NNW-SSE fault system present in the islands, rotating to 50 degrees-77 degrees in the eastern sector of the Pedro Miguel Graben, probably due to a complex interaction of the WSW-ENE dominant fault system with old eroded volcanic complexes that segmented the island into several blocks. In Pico island, the SHmax direction azimuth ranges from 93 degrees to 135 degrees, in a radial pattern around the island's main stratovolcano, overlapping the regional stress field.pt_PT
dc.description.versioninfo:eu-repo/semantics/publishedVersionpt_PT
dc.identifier.citationDIAS, Nuno Afonso; TELLEZ, Julia; MATIAS, Luís – Insight on the crustal stress state in Faial and Pico Islands (Azores), from analysis of aftershocks of the 1998 earthquake. Pure and Applied Geophysics. ISSN 0033-4553. Vol. 177, N.º 11 (2020), pp. 5169-5187pt_PT
dc.identifier.doi10.1007/s00024-020-02558-1pt_PT
dc.identifier.eissn1420-9136
dc.identifier.issn0033-4553
dc.identifier.urihttp://hdl.handle.net/10400.21/12639
dc.language.isoengpt_PT
dc.peerreviewedyespt_PT
dc.publisherSpringerpt_PT
dc.relationPDCTM1999MAR15255- FCTpt_PT
dc.relationMASHA - Multiscale Approach for Seimovolcanic Hazard investigation in the Azores
dc.subjectSeismicity and tectonicspt_PT
dc.subjectAnisotropypt_PT
dc.subjectWaveform cross-correlationpt_PT
dc.subjectCrustal stresspt_PT
dc.subjectOceanic plateauspt_PT
dc.titleInsight on the crustal stress state in Faial and Pico Islands (Azores), from analysis of aftershocks of the 1998 earthquakept_PT
dc.typejournal article
dspace.entity.typePublication
oaire.awardTitleMASHA - Multiscale Approach for Seimovolcanic Hazard investigation in the Azores
oaire.awardURIinfo:eu-repo/grantAgreement/FCT/POCI/POCTI%2FCTA%2F39158%2F2001/PT
oaire.citation.endPage5187pt_PT
oaire.citation.issue11pt_PT
oaire.citation.startPage5169pt_PT
oaire.citation.titlePure and Applied Geophysicspt_PT
oaire.citation.volume177pt_PT
oaire.fundingStreamPOCI
person.familyNameDias
person.familyNameMatias
person.givenNameNuno
person.givenNameLuis
person.identifier1348964
person.identifier693396
person.identifier.ciencia-idDB10-5086-2205
person.identifier.ciencia-id6418-129D-A73E
person.identifier.orcid0000-0001-7672-4476
person.identifier.orcid0000-0002-8086-4874
person.identifier.ridB-2778-2008
person.identifier.ridK-7347-2012
person.identifier.scopus-author-id56640885300
person.identifier.scopus-author-id6701795172
project.funder.identifierhttp://doi.org/10.13039/501100001871
project.funder.nameFundação para a Ciência e a Tecnologia
rcaap.rightsclosedAccesspt_PT
rcaap.typearticlept_PT
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