GNGTS 2013 - Atti del 32° Convegno Nazionale

At AR03 the SSR results are in good agreement with SSR data, since the SSR transfer function well reproduces the shape of H/V spectral ratio. Also in this case the SSR amplitude is higher. For AR4 station the H/V peak at about 1.2 Hz is also present in SSR data, even tough in this case a strong amplification in found at frequency of about 2 Hz and at higher frequency. For this station SSR results show very strong amplification factors confirming what inferred by geological data. We can conclude that both HVNSR and SSR data are able to detect a good quality reference site just in the historical Arpino city centre. The widely diffuse Santopadre formation, outcropping both in a part of the city centre and in the surrounding areas shows some important variation in seismic response with low amplitude broad band amplification in some areas and quite strong amplification with sharp peaks in the city centre just few meters apart from the reference site. This result is confirmed by a paper that describes in detail the damages Arpino suffered during the 1915 Avezzano event (Esu and D’Elia, 1967). In this work the authors pointed out that the most damaged part of the city centre was founded just on the Santopadre formation. Some major amplification effect is found using both HVNSR and SSR approaches in expansion area located in the river valley west to the city centre. Conclusions. In this paper we describe the results obtained by analysing the data collected by a set of seismic stations installed in the city of Arpino (Central Italy) during the seismic sequence of February – April 2013. Starting from MS1 results the selection of the recording site was based on the geological information derived from the MOPS characteristics. This allowed detecting the geological 394 GNGTS 2013 S essione 2.3