GNGTS 2014 - Atti del 33° Convegno Nazionale

GNGTS 2014 S essione 2.2 123 Code in use at the time of their construction. Otherwise the local subsoil condition is very complex and can cause significant amplification effects. In fact in the area site effects can be related to lithostratigraphic amplification of soft soil overlaying stiff basement; fine-grained soils interposed within, or placed above, the coarse-grained breccias (residual soils known as “red soils”); man-made fills; underground caves; topographic effect� �������� �� ��� ���������� . Instead, in the historical centre of L’Aquila settled by old masonry buildings, the damage distribution seems to be greatly affected by vulnerability problems (Milana et al. , 2011; Tertulliani et al. , 2012; Totani et al. , 2012; Amoroso et al. , 2014). In this respect many geological, geophysical and geotechnical investigations were performed, and still ongoing, for supporting the reconstruction planning of the town mainly related to seismic microzonation studies and research activities. In this work the available data were integrated with new geological and geophysical studies along the southern edge of the downtown, the most damaged of L’Aquila, to analyze the role of morphology and geology on seismic vibration. In particular an intense campaign of noise measurements was carried out along transects from the top of L’Aquila hill towards the Aterno river valley (Fig. 1). The analyzed data show strong and polarized peaks �� ��� ���������������������� �������� ������ ��� in the horizontal-to-vertical spectral ratios (H/ V) at low frequency (< 1 Hz) and locally at high frequency (> 5 Hz) highlighting a complex seismic site response of the area in terms of lithostratigraphic and topographic effects. Along Saint Apollonia trench, one of the steep scarps along the southern edge of L’Aquila hill, the sub- Fig. 1 – Geolithological map of L’Aquila terrace with geophysical and geotechnical investigations.