Stato di fratturazione di ammassi rocciosi ed effetti di risposta sismica locale: Confronto tra due casi di studio in Italia Centrale

Hailemikael Salomon, Martino Salvatore, Paciello Antonella, Scarascia Mugnozza Gabriele

Research output: Contribution to journalArticle

Abstract

Comparison of results obtained from seismic response studies in two similar carbonate ridges respectively located in the Nera River valley and in the Amaseno River valley (Central Apennines - Italy) are discussed. The studies relied on an integrated methodological approach, which combined geological, geomechanical and seismometric investigations. Geological and geomechanical surveys were aimed at defining the stratigraphic and structural setting of the outcropping formations and the jointing conditions of the rock masses. Velocimetric records of both ambient noise and small-magnitude earthquakes were analysed in order to identify amplification conditions. The analyses were carried out in the time domain, through directional energy evaluation, and in the frequency domain, through H/V spectral ratios and spectral ratios with respect to a reference station. Although the carbonate ridges exhibit similar geological, geomorphological and structural features, this comparison highlighted the occurrence of a significant seismic amplification only in the carbonate ridge close to the Nera river valley. This effect was observed in a narrow fault zone characterized by the presence of intensely jointed and mylonitic rock masses, located inside moderately jointed rock masses, and is the result of specific geometries and significant impedance contrasts. On the contrary, analysis conducted in the carbonate ridge close to the Amaseno river valley showed the absence of significant seismic amplification related to adjacency of moderately jointed rock masses, unable to produce significant seismic impedence contrasts. Two schematic interpretative models of local seismic response were constructed for the ridges, taking into account the jointing conditions of the rock masses and the structural settings of the investigated areas.
Original languageItalian
Pages (from-to)288 - 289
Number of pages2
JournalRendiconti Online Societa Geologica Italiana
Volume6
Publication statusPublished - 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Geology

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