Assessment of liquefaction potential in the framework of seismic microzonation using different approaches

Seismic Microzonation studies aim to map and determine the seismic ground response and the susceptibility to instability phenomena, such as liquefaction, landslides or surface faulting. According to Italian government laws, seismic microzonation is evaluated following three Levels of detail (I, II and III), with increasing complexity. In areas susceptible to instability phenomena, in-depth investigations typical of Level III are necessary to verify the safety conditions. In this framework, the liquefaction potential was evaluated for a zone prone to seismically induced liquefaction located on the eastern Sicily (Italy). The stress-based method was employed to evaluate the susceptibility to seismic-induced liquefaction considering the results derived from Dynamic Probe Super Heavy tests. They have the advantage, compared to Standard Penetration Tests, of providing continuous values with depth. Three different approaches were used to define the seismic action: the simplified approach proposed by the Italian seismic code, the selection of a suite of ground motion records and the definition of a combination of synthetic seismograms reproducing the 1908 seismic event. The results show that the use of a suite of ground motion records compatible, on average, with the target spectrum built according to the Italian seismic code, is conservative compared to the other two approaches. Furthermore, the level of liquefaction severity encountered in the investigated area is high, demonstrating the need for mitigation actions. The findings obtained in this study allow to optimize the allocation of economic resources and are useful for future similar works.