68% of the metropolitan stock predates the 1958 seismic legislation (Público, February 2023). Soil conditions in the Baixa, parts of Marvila, and along the river amplify ground motion. CML estimates roughly half of Lisbon buildings would not survive a major earthquake without significant damage.

Close to the Africa-Eurasia plate boundary. Highest insurance risk tariff alongside Lisbon. High share of holiday-home and short-term-rental properties altered multiple times. Pool and outbuilding additions often lack structural calculation.

August 2024 earthquake epicentre 58 km west of Sines; February 2025 event 14 km from Seixal. The peninsula's industrial corridor has older industrial conversions in residential use, and the southern coast shares the same offshore fault exposure as Lisbon.

Most active seismic regime in Portuguese territory, with historical destructive earthquakes on most islands and active volcanism. Building stock varies sharply by island and era; the M5.0+ event frequency is materially higher than the mainland.

Lower seismic exposure but not zero. Structural defects concentrate around moisture-driven deterioration, foundation issues on clay soils, and flat-roof pathology in mid-20th-century stock that accelerates structural deterioration through infiltration.

Lowest seismic exposure on the mainland. Generic structural issues remain: ageing reinforced concrete, settlement, and renovation interventions made without structural calculation under DL 95/2019 / Portaria 302/2019.