Earthquakes

What we use

• Seismic classification of municipalities from the Civil Protection Department (Dipartimento della Protezione Civile), updated to 31 May 2025 with the Regions' decisions. Every municipality is in a seismic zone (zona sismica) from 1 (the most hazardous) to 4. Some Regions use sub-zones, for example 2A or 3S. Licence CC BY 4.0.
• MPS04 seismic hazard map from INGV (the National Institute of Geophysics and Volcanology): for a grid of points across Italy it gives the peak ground acceleration (PGA) that has a 10% probability of being exceeded in 50 years, on rock. Licence CC BY 4.0.
• Seismic microzonation studies collected by the Civil Protection Department and published by CNR-IGAG on the WebMS portal: where the municipality has a study, they show how much the ground at that spot amplifies shaking compared with bedrock, and whether there are landslides, liquefaction or faults. Licence CC BY 4.0.

How we use them

The report shows the municipality's zone and calculates the PGA at the address point as a weighted average of the four nearest grid points, with its uncertainty range. Where a microzonation study exists, a separate block describes how the ground under the property responds: amplification factor and any instability reported. The report does not redistribute the study's geometries.

Limits

• The seismic zone is used for land planning: it tells you how hazardous the area is, not how safe a building is.
• The PGA is calculated on rock: soft ground can amplify the shaking, which is what microzonation measures.
• Not every municipality has a microzonation study: where it is missing the report says so, because not knowing does not mean the ground is sound.
• To assess a building you need the year it was designed, the standards used and a check by a qualified engineer or surveyor under the Italian building code (Norme tecniche per le costruzioni, NTC 2018).

Official pages: seismic classification and INGV's MPS04. Read more: Seismic zones 1, 2, 3 and 4: what they mean for buyers.