Lowermost mantle anisotropy near the eastern edge of the Pacific LLSVP: constraints from SKS–SKKS splitting intensity measurements

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dc.contributor.authorDeng, Jie
dc.contributor.authorLong, Maureen D.
dc.contributor.authorCreasy, Neala
dc.contributor.authorWagner, Lara
dc.contributor.authorBeck, Susan
dc.contributor.authorZandt, George
dc.contributor.authorTavera, Hernando
dc.contributor.authorMinaya, Estela
dc.date.accessioned2018-08-06T15:45:33Z
dc.date.available2018-08-06T15:45:33Z
dc.date.issued2017-05-05
dc.description.abstractSeismic anisotropy has been documented in many portions of the lowermost mantle, with particularly strong anisotropy thought to be present along the edges of large low shear velocity provinces (LLSVPs). The region surrounding the Pacific LLSVP, however, has not yet been studied extensively in terms of its anisotropic structure. In this study, we use seismic data from southern Peru, northern Bolivia and Easter Island to probe lowermost mantle anisotropy beneath the eastern Pacific Ocean, mostly relying on data from the Peru Lithosphere and Slab Experiment and Central Andean Uplift and Geodynamics of High Topography experiments. Differential shear wave splitting measurements from phases that have similar ray paths in the upper mantle but different ray paths in the lowermost mantle, such as SKS and SKKS, are used to constrain anisotropy in D″. We measured splitting for 215 same station-event SKS–SKKS pairs that sample the eastern Pacific LLSVP at the base of the mantle. We used measurements of splitting intensity(SI), a measure of the amount of energy on the transverse component, to objectively and quantitatively analyse any discrepancies between SKS and SKKS phases. While the overall splitting signal is dominated by the upper-mantle anisotropy, a minority of SKS–SKKS pairs (∼10 per cent) exhibit strongly discrepant splitting between the phases (i.e. the waveforms require a difference in SI of at least 0.4), indicating a likely contribution from lowermost mantle anisotropy. In order to enhance lower mantle signals, we also stacked waveforms within individual subregions and applied a waveform differencing technique to isolate the signal from the lowermost mantle. Our stacking procedure yields evidence for substantial splitting due to lowermost mantle anisotropy only for a specific region that likely straddles the edge of Pacific LLSVP. Our observations are consistent with the localization of deformation and anisotropy near the eastern boundary of the Pacific LLSVP, similar to previous observations for the African LLSVP.es_ES
dc.description.peer-reviewPor pareses_ES
dc.formatapplication/pdfes_ES
dc.identifier.citationDeng, J., Long, M., Creasy, N., Wagner, L., Beck, S., Zandt, G., ... Minaya, E. (2017). Lowermost mantle anisotropy near the eastern edge of the Pacific LLSVP: constraints from SKS–SKKS splitting intensity measurements.==$Geophysical Journal International, 210$==(2), 774–786. https://doi.org/10.1093/gji/ggx190es_ES
dc.identifier.doihttps://doi.org/10.1093/gji/ggx190es_ES
dc.identifier.govdocindex-oti2018
dc.identifier.journalGeophysical Journal Internationales_ES
dc.identifier.urihttp://hdl.handle.net/20.500.12816/2261
dc.language.isoenges_ES
dc.publisherOxford University Presses_ES
dc.relation.ispartofurn:issn:0956-540X
dc.rightsinfo:eu-repo/semantics/closedAccesses_ES
dc.subjectSeismic anisotropyes_ES
dc.subjectDeformationes_ES
dc.subjectMantlees_ES
dc.subjectElastic waveses_ES
dc.subjectEarth scienceses_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.00es_ES
dc.subject.ocdehttp://purl.org/pe-repo/ocde/ford#1.05.04es_ES
dc.titleLowermost mantle anisotropy near the eastern edge of the Pacific LLSVP: constraints from SKS–SKKS splitting intensity measurementses_ES
dc.typeinfo:eu-repo/semantics/articlees_ES

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