Seismic zones 1, 2, 3 and 4: what they mean for buyers

Every Italian municipality is classified in a seismic zone (zona sismica), from 1 to 4. The figure is easy to find, but also easy to misread: the zone tells you how hazardous the area is, not how safe the house you are looking at is.

The four zones

The classification dates from a 2003 government order (ordinanza) and, since 2006, has used the peak ground acceleration (PGA) with a 10% probability of being exceeded in 50 years, on rock.

The Regions update the classification with their own decisions, and some use sub-zones, for example 2A and 2B in Lazio, 1a and 2b in Basilicata or 3S in Piedmont. The up-to-date national list is published by the Civil Protection Department (Dipartimento della Protezione Civile): in the version of 31 May 2025 about 800 municipalities are in zone 1, about 2,300 in zone 2, about 3,000 in zone 3 and about 1,700 in zone 4.

What the zone does not tell you

The zone applies to the whole municipality. Within the same municipality the expected shaking varies from place to place and can be amplified by soft ground, slopes or made ground. Above all, the zone says nothing about the building: a well-designed house in zone 1 can be safer than an old, neglected house in zone 3.

That is why the Italian building code (Norme tecniche per le costruzioni, currently NTC 2018) requires new buildings to be designed for the hazard at the exact location, not just the zone.

The questions to ask, zone by zone

In zones 1 and 2

• What year was the building designed? The updated earthquake standards apply to designs from July 2009; before then, many municipalities were not yet classified or were classified under less strict rules.
• What is the structure made of: reinforced concrete, load-bearing masonry, steel?
• Has seismic improvement or upgrading work been done? Is there a seismic risk classification for the building, for example for work under the sismabonus (the tax incentive for earthquake-proofing)?
• Are there cracks, subsidence or recent structural work that is not documented?

In these zones it is worth having an engineer or a geometra (building surveyor) look at the building before the preliminary contract, especially for old masonry houses or buildings with added storeys.

In zone 3

Strong earthquakes are rare but possible, and many municipalities have only moved into zone 3 in the last twenty years: older buildings were not designed with earthquakes in mind. Ask the design year and the type of structure, and watch out for changes such as removed load-bearing walls or widened openings.

In zone 4

The hazard is low. Questions about the condition of the structure are still useful, as they are part of assessing any house.

How to check your municipality and the exact point

You can find the municipality's zone in the Civil Protection list, and the PGA at any point on INGV's MPS04 seismic hazard map. Our report shows both for the address, with the acceleration value at the point and its uncertainty range, and reminds you that a qualified engineer or surveyor is needed to assess the building.

For the rest of the checks, from the area to the documents, see What to check before buying a house in Italy.