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dc.contributor.authorFarrugia, Daniela-
dc.contributor.authorPaolucci, Enrico-
dc.contributor.authorD’Amico, Sebastiano-
dc.contributor.authorGalea, Pauline-
dc.date.accessioned2017-04-10T12:34:44Z-
dc.date.available2017-04-10T12:34:44Z-
dc.date.issued2016-08-
dc.identifier.citationFarrugia, D., Paolucci, E., D’Amico, S., & Galea, P. (2016). Inversion of surface wave data for subsurface shear wave velocity profiles characterized by a thick buried low-velocity layer. Geophysical Journal International, 206(2), 1221-1231.en_GB
dc.identifier.urihttps://www.um.edu.mt/library/oar//handle/123456789/18196-
dc.descriptionThe study formed part of the SIMIT project (Integrated Italy-Malta Cross-Border System of Civil Protection) (B1-2.19/11) part-financed by the European Union under the ItaliaMalta Cross-Border Cooperation Programme, 2007–2013.en_GB
dc.description.abstractThe islands composing the Maltese archipelago (Central Mediterranean) are characterized by a four-layer sequence of limestones and clays. A common feature found in the western half of the archipelago is Upper Coralline Limestone (UCL) plateaus and hillcaps covering a soft Blue Clay (BC) layer which can be up to 75 m thick. The BC layer introduces a velocity inversion in the stratigraphy, implying that the VS30 (traveltime average sear wave velocity (VS) in the upper 30 m) parameter is not always suitable for seismic microzonation purposes. Such a layer may produce amplification effects, however might not be included in the VS30 calculations. In this investigation, VS profiles at seven sites characterized by such a lithological sequence are obtained by a joint inversion of the single-station Horizontal-to-Vertical Spectral Ratios (H/V or HVSR) and effective dispersion curves from array measurements analysed using the Extended Spatial Auto-Correlation technique. The lithological sequence gives rise to a ubiquitous H/V peak between 1 and 2 Hz. All the effective dispersion curves obtained exhibit a ‘normal’ dispersive trend at low frequencies, followed by an inverse dispersive trend at higher frequencies. This shape is tentatively explained in terms of the presence of higher mode Rayleigh waves, which are commonly present in such scenarios. Comparisons made with the results obtained at the only site in Malta where the BC is missing below the UCL suggest that the characteristics observed at the other seven sites are due to the presence of the soft layer. The final profiles reveal a variation in the VS of the clay layer with respect to the depth of burial and some regional variations in the UCL layer. This study presents a step towards a holistic seismic risk assessment that includes the implications on the site effects induced by the buried clay layer. Such assessments have not yet been done for Malta.en_GB
dc.language.isoenen_GB
dc.publisherOxford University Pressen_GB
dc.rightsinfo:eu-repo/semantics/openAccessen_GB
dc.subjectEarthquake hazard analysisen_GB
dc.subjectSurface waves (Seismology) -- Maltaen_GB
dc.subjectRayleigh wavesen_GB
dc.subjectGeophysical surveys -- Maltaen_GB
dc.subjectClay -- Analysisen_GB
dc.titleInversion of surface wave data for subsurface shear wave velocity profiles characterized by a thick buried low-velocity layeren_GB
dc.typearticleen_GB
dc.rights.holderThe copyright of this work belongs to the author(s)/publisher. The rights of this work are as defined by the appropriate Copyright Legislation or as modified by any successive legislation. Users may access this work and can make use of the information contained in accordance with the Copyright Legislation provided that the author must be properly acknowledged. Further distribution or reproduction in any format is prohibited without the prior permission of the copyright holder.en_GB
dc.description.reviewedpeer-revieweden_GB
dc.identifier.doi10.1093/gji/ggw204-
Appears in Collections:Scholarly Works - FacSciGeo

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