GNGTS 2019 - Atti del 38° Convegno Nazionale

GNGTS 2019 S essione 2.2 327 LOCAL SEISMIC RESPONSE: CORRELATION BETWEEN SEISMIC MOTION PARAMETERS AND GEOPHYSICAL INDICATORS D. Attolico 1,2 , G. Cultrera 2 , D. Famiani 2 1 Department of Earth and Geoenvironmental Sciences, Aldo Moro University of Bari, Italy 2 National Institute of Geophysics and Volcanology, Rome, Italy Introduction. Site effects control the local seismic response, due to the way of transmission of seismic waves from the bedrock to the Earth surface, and they modify amplitude, frequency and duration of the seismic waveforms. Thanks to the large amount of data available on well- studied areas, it is nowadays possible to look for the geological, morphological, geophysical and geotechnical indicators which better describe site effects and control signals characteristics (such as amplification, duration and other signals modifications), by using advanced statistical methods. Previous studies (i.e. Cultrera et al. , 2014) investigated the correlation between different site response spectral ratios, but they were not able to find a robust link with the geological settings, due to the paucity of information. The present work represents a step forward to define possible correlations between different kinds of seismological and geological data, by using different data from a well-studied intermountain basin. Test area. The “test” site used for this work is the intermountain basin of Montereale, located at the transition between the Gran Sasso and the Laga structural-paleogeographic domains in the highly seismic Apennine axial zone (Abruzzo region, Italy; Fig. 1). The development of the basin is linked mainly to the Quaternary activity of the NW–SE trending Capitignano Fault System, but it is also influenced by the NW–SE trending S. Giovanni Fault System (Chiarini et al. , 2014). This area has been struck by the Central Italy seismic sequence 2016-18 (Improta et al. , 2019), and its mainshocks have been recorded by the MTR permanent seismic station of RAN network (run by the Italian Civil Protection Department), located in the Montereale village, with a maximum value of PGAforAugust 24, 2016 of 79.13 cm/s 2 . For this reason, it was investigated by the INGV EMERSITO emergency group for site effects studies and for microzonation purposes (Cultrera et al. , 2016); EMERSITO group installed 24 temporary seismic stations during two different periods of time (august - december 2016); later, 16 temporary seismic stations were installed in the same area to better investigate the basin. Fig. 1 - Georeferenced map of the 24 temporary seismic stations installed by EMERSITO (fuchsia triangles) and 16 temporary stations installed for a noise experiment (blue dots) on Carta Geologica dei bacini della Laga e del Cellino e dei rilievi carbonatici circostanti (Centamore et al. , 1991).