GNGTS 2024 - Atti del 42° Convegno Nazionale

Session 2.2 GNGTS 2024 A GEOLOGICAL GEOPHYSICAL APPROACH FOR THE LARGE-SCALE EVALUATION OF SEISMIC AMPLIFICATION IN THE PLAIN AREA: EXAMPLE OF THE BRESCIA BASIN (PIANURA PADANA) G. Caielli 1 , R. de Franco 1 , I. Gaudiosi 2 , A. Mendicelli 2 , M. Moscatelli 2 , G. Norini 1 , D. Rusconi 1 , M. Simionato 2 . 1 ISTITUTO DI GEOLOGIA AMBIENTALE E GEOINGEGNERIA – CNR - Milano - Italy 2 ISTITUTO DI GEOLOGIA AMBIENTALE E GEOINGEGNERIA – CNR - Montelibreo - Italy This presentaCon aims to answer the scienCfic quesCon: how to model the expected effects of site seismic amplificaCon at different scales in a plain environment where the informaCve contribuCon of the geological-morphological survey is almost nil but widespread spaCal informaCon deriving from well geo-straCgraphy and few direct geophysical measurements in the well and indirect from surface are available. We present the result of the analyses of the data available from surface geophysical studies with the aim of creaCng a database of the physical parameters characterizing the lithotypes outcropping to the depth of the “seismic” bedrock that is hypothesized coinciding with the top of the early Pleistocene, named “red disconCnuity)”, in the area of the Brescia basin (CARG-ISPRA). Quaternary deposits will be analyzed in order to associate geological units with engineering- geological units (UGT) and abribute the Vs and Vp values. For the reconstrucCon of the surface part, it has been decided to use seismic microzonaCon studies (MS). The data and informaCon retrieved and analyzed have been collected in a data-base, each survey contains the idenCficaCon code, the geographical coordinates, layer thickness and velocity values. The fundamental objecCve of the work is the associaCon of UGT to each layer idenCfied and inserted in the tables of geophysical measurements. Then using well for the hydrogeological data, we try to assign to each layer the UGT. The results of 246 geophysical surveys and 623 hydrogeological data, mainly water wells, were analyzed. These were the starCng point for the staCsCcal analyses carried out with ArcGis and ArcGis Pro. The staCsCcal analyses carried out relate above all to the velociCes Vs and available Vp subset. Using the informaCon derived from the analysis, it has been possible the abribuCon of the velocity range Vs to each UGT recognized within the Brescia basin.