Seismic Microzonation (SM) is a key tool for planning strategies for risk mitigation; it represents the assessment of Local Seismic Hazard by identifying and mapping, at scale 1:10.000 or higher, zones with homogeneous seismic behavior within a given geographic area. SM studies are complementary to the Regional Seismic Hazard (RSH) studies, which calculate with probabilistic and deterministic methods ground motion parameters at a site under conditions of rigid and flat soil (NTC 08).
In the 2008, the Conference of Regions and Autonomous Provinces of Italy and the Civil Protection Department publish the "Indirizzi e criteri per la Microzonazione Sismica" (“Guidelines for Seismic Microzonation”, 2015).
The “Guidelines for Seismic Microzonation” is a national reference document for studies to estimate the seismic risk of a territory.They describe the principles and elements for basic studies and for applications in land and emergency planning. This document also describes operational tools for the implementation of Seismic Microzonation studies, including the schedule investigations and the production of thematic maps.
The seismic microzonation (SM) identifying zones with homogeneous seismic behavior. The identified microzones are classified basing on the expected local ground motion in case of earthquake, and are subdivided into:
- stable zones, where no substantial deviations are expected from the ground motion produced by a seismic event on rigid and flat soils;
- stable zones prone to local amplification, where ground motion is amplified because of local stratigraphic and morphological conditions;
- instability- prone zones, where permanent instabilities, slope instability, liquefaction, differential settlement, active and capable faults, are expected.