Preliminary seismic microzonation in a mountain municipality of Tuscany (Italy)
Abstract
In this paperwe describe a microzonation survey carried out at a mountain Municipality (Piteglio, Northern Apennines). We complemented the available data by conducting 106 microtremor measurements for Horizontal-to- Vertical Spectral Ratio (HVSR) analysis. Most of the data concern the three major rural villages (Piteglio-Prataccio, Popiglio and Prunetta). Furthermore, we installed a field mobile seismic station at two of the major villages, in order to obtain earthquakes recordings. The HVSR analysis shows amplification effects due to eluvial or colluvial deposits overlying the seismic bedrock, even for areas previously mapped as bedrock outcrops. Most zones characterized by sandstone outcrops show peaked HVSR traces. This observation could be also interpreted in terms of a topographic effect. In contrast, areas characterised by chaotic materials (olistostrome) generally exhibit a flat HVSR. Other areas of seismic amplification were identified on alluvial and landslide deposits. Results byHVSR analysis arewell correlated with available data from geo-technical and geophysical surveys, thus allowing to invert HVSRs for the physical properties of the subsoil. Subsoil properties can thus be extrapolated also in areas for which only measurements of seismic noise are available. Moreover, noise HVSRs agree well with those from earthquakes recorded at the different selected sites.
- Publication:
-
Open Geosciences
- Pub Date:
- October 2015
- DOI:
- 10.1515/geo-2015-0045
- Bibcode:
- 2015OGeo....7...45M
- Keywords:
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- site effect;
- microzonation;
- HVSR;
- microtremors