Seismic imaging of the western Iberian crust using ambient noise: Boundaries and internal structure of the Iberian Massif

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• 作者：Graç ; a Silveira^a ; ^b ; ^{mdsilveira@fc.ul.pt} ; Nuno Afonso Dias^a ; ^b ; Antonio Villaseñ ; or^c
• 关键词：Seismic interferometry ; Ambient noise ; Surface-wave tomography ; Iberian Peninsula ; Iberian Massif
• 刊名：Tectonophysics
• 出版年：2013
• 出版时间：18 March, 2013
• 年：2013
• 卷：589
• 期：Complete
• 页码：186-194
• 全文大小：4674 K

文摘

We present new Rayleigh-wave dispersion maps of the western Iberian Peninsula for periods between 8 and 30 s, obtained from correlations of seismic ambient noise, following the recent increase in seismic broadband network density in Portugal and Spain. Group velocities have been computed for each station pair using the empirical Green's functions generated by cross-correlating one-day-length seismic ambient-noise records. The resulting high-path density allows us to obtain lateral variations of the group velocities as a function of period in cells of 0.5¡ã ¡Á 0.5¡ã with an unprecedented resolution. As a result we were able to address some of the unknowns regarding the lithospheric structure beneath SW Iberia. The dispersion maps allow the imaging of the major structural units, namely the Iberian Massif, and the Lusitanian and Algarve Meso-Cenozoic basins. The Cadiz Gulf/Gibraltar Strait area corresponds to a strong low-velocity anomaly, which can be followed to the largest period inverted, although slightly shifted to the east at longer periods. Within the Iberian Massif, second-order perturbations in the group velocities are consistent with the transitions between tectonic units composing the massif.