A methodology for advanced seismic microzoning using 2D analyses: the case study of Barberino di Mugello, Florence, Italy

The paper describes a study developed in the frame of the VEL/DOCUP projects promoted by the Regional Government of Tuscany (Central Italy) in order to mitigate the risk from earthquake. It concerns the assessment of local seismic effects aimed at drawing up a detailed seismic microzoning map for an area including some villages, industrial and commercial settlements close to the most important town of western Mugello, one of the highest seismicity zones of the Northern Apennine Chain. Geological subsoil modelling and geotechnical characterization of the area under study were performed by using the results of an in-depth survey including in situ and laboratory tests. On the basis of geomorphologic and lithostratigraphic data, a first level of seismic zoning map was prepared aimed to recognize areas involved in different kinds of geotechnical phenomena (amplification, slope-instability, liquefaction, etc.) and several representative cross sections were then identified for the whole area under study. Numerical 2D analyses were implemented on the selected cross sections to quantify the local seismic response on ground surface. The performed analyses allowed to recognize zones with different seismic response in term of a suitable selected amplification factor and to draw a Level 3 seismic microzonation map according to the procedure recommended by the Italian guidelines for microzoning. In this paper the results of twodimensional local seismic response analyses and advanced seismic microzonation mapping for the area under study are presented and discussed.