The characteristics of unstable hillslope response to seismic shaking were investigated in a site of south-central Italy (Caramanico Terme), where 5 accelerometric stations had been installed in different litho-stratigraphic and topographic conditions: 1) a mudstone outcrop; 2) a landslide in colluvial deposits overlying a mudstone substratum; 3) the same colluvial deposits upslope the landslide crown; 4) the rim of a steep gorge in heavily fractured limestones; 5) a limestone outcrop on gentle slope. Recordings of events of magnitude from 1.4 to 5.7 at distances from 5 to 160 km were compared with those of several stations of the National Accelerometric Network. The comparative analysis revealed some peculiarities of the seismic response in the sites examined. In particular, a significant amplification was found on the landslide body and on the gorge rim, accompanied by energy polarization along directions related to the orientations of the main topographic features (e.g. maximum slope). A spectral analysis of horizontal ground motion along different azimuths pointed out a similar directivity for site specific spectral peaks. This suggests that combined litho-stratigraphic and topographic effects can locally determine conditions that significantly enhance seismic shaking, thereby increasing slope susceptibility to failure.

Response of landslide-prone hillslopes to seismic shaking: evidence of amplification and spectral polarization from an accelerometric monitoring network at Caramanico Terme (Italy)

DEL GAUDIO, Vincenzo;PIERRI, Pierpaolo
2007

Abstract

The characteristics of unstable hillslope response to seismic shaking were investigated in a site of south-central Italy (Caramanico Terme), where 5 accelerometric stations had been installed in different litho-stratigraphic and topographic conditions: 1) a mudstone outcrop; 2) a landslide in colluvial deposits overlying a mudstone substratum; 3) the same colluvial deposits upslope the landslide crown; 4) the rim of a steep gorge in heavily fractured limestones; 5) a limestone outcrop on gentle slope. Recordings of events of magnitude from 1.4 to 5.7 at distances from 5 to 160 km were compared with those of several stations of the National Accelerometric Network. The comparative analysis revealed some peculiarities of the seismic response in the sites examined. In particular, a significant amplification was found on the landslide body and on the gorge rim, accompanied by energy polarization along directions related to the orientations of the main topographic features (e.g. maximum slope). A spectral analysis of horizontal ground motion along different azimuths pointed out a similar directivity for site specific spectral peaks. This suggests that combined litho-stratigraphic and topographic effects can locally determine conditions that significantly enhance seismic shaking, thereby increasing slope susceptibility to failure.
978-0-975-4295-32
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11586/137212
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