Seismic Microzonation Mapping for Urban and Land Sustainable Planning in High Seismicity Areas (L’Aquila Municipality, Central Italy): The Contribution of 2D Modeling for the Evaluation of the Amplification Factors

This paper illustrates the outcomes of a third-level Seismic Microzonation project carried out in pilot areas of the Municipality of L’Aquila, Italy, an area characterized by recent strong seismic activity (6 April 2009 Mw 6.3 earthquake and central Italy 2016 seismic sequence—Mw 6.0 and 6.5 events). The primary aim was to develop numerical maps for urban and land planning to mitigate seismic risk, in line with the guidelines of the Italian Civil Protection Department. The local amplification assessment was organized through various sequential and/or parallel activities, including geotechnical and geophysical investigations and characterization, seismic input and numerical code selection, acquisition of 2D microtremor arrays, and comparison between 1D and 2D numerical modeling of seismic site response. This case study introduces several innovations to the microzonation procedures outlined in current Italian and European regulations, such as the use of microtremor arrays to assess a reliable subsoil model and a new procedure for associating amplification factors to each microzone. The results obtained are significant both for the detailed seismic characterization of the territory and for providing methodological indications useful for similar future studies. The use of 2D models is integrated into the flowchart for producing third-level microzonation maps, offering valuable tools within the framework of urban and land management from a perspective of territorial sustainability.