Urban seismic network development for site effects evaluation in Trieste

Only the first level of seismic microzonation (SM1), performed in 2016, is available for the city of Trieste. A seismic noise measurements campaign was conducted in the municipality during 2022 in the different homogeneous microzones in the seismic perspective (MOPS), defined by SM1. The main purpose was to verify the behaviour within each MOPS, and the results have shown that the hypothesis of a homogenous microzone is not always verified: in many cases, high behavioural variability was found within the same. Therefore, MOPS seem to be a good tool for general first-level evaluation, but they do not appear to be accurate enough for detailed site-effect evaluation. A recent study demonstrated that second-level microzonation national abacuses (MS2) are not applicable in the Friuli Venezia Giulia Region since, being a simplified method, they underestimate the site response. For this reason, a new urban accelerometric seismic network was implemented in Trieste with the purpose of seismic monitoring and to evaluate the site effects which have been validated using numerical simulation.