Earthquakes in Lisbon
Lisbon was almost completely destroyed by the November 1, 1755 earthquake, tsunami, and fire — one of the deadliest natural disasters in European history, killing an estimated 30,000-40,000 people. The Azores-Gibraltar Transform Fault remains active southwest of Lisbon and could generate another major earthquake.
Why Does Lisbon Face Earthquake Risk?
The Azores-Gibraltar Transform Fault (AGFZ) passes southwest of Portugal and is capable of generating M8+ earthquakes like the one in 1755. While the exact source of the 1755 earthquake is still debated, the same fault zone that generated it remains seismically active today.
Active Fault Systems
- Azores-Gibraltar Transform Fault
- Marquês de Pombal Fault
- São Vicente Cape Fault
Safety Advice
IPMA and LNEC monitor seismicity in Portugal. Lisbon's low-lying riverside neighborhoods, especially the Baixa district built on the 1755 rubble fill, are particularly vulnerable to amplified shaking and liquefaction.
Historical Earthquake Context
The November 1, 1755 Lisbon earthquake (estimated M8.5-9.0) struck on All Saints' Day and killed 30,000-40,000 people in Lisbon through earthquake, tsunami, and subsequent fire. It is considered one of the worst natural disasters in European history and fundamentally shaped Enlightenment philosophy.
Fault Maps & Tectonic Setting
Tectonic and seismic hazard maps from Wikimedia Commons, USGS, and NASA — open licenses (CC / Public Domain)
Maps sourced from Wikimedia Commons, USGS, and NASA under open licenses. Attribution required where specified. Click any map to enlarge.
FAQ
Frequently Asked Questions
Could another 1755-style earthquake hit Lisbon?
Yes, but the probability is low over a short time horizon. The same Azores-Gibraltar fault zone that caused the 1755 disaster remains active and capable of generating a similar event. Scientists estimate the recurrence interval for a M8.5+ event in this zone at approximately 1,000-2,000 years.
How seismically active is Lisbon?
Lisbon experiences regular low-level seismicity from the Azores-Gibraltar Transform Fault Zone (AGFZ) offshore, and occasional moderate events from the Lower Tagus Valley Fault. Multiple M4-5 earthquakes are felt in Lisbon each decade. The most significant recent events were the 1969 offshore earthquake (M7.9) and a 2007 M6.0 event southwest of Cape St. Vincent.
What earthquake faults affect Lisbon?
The Azores-Gibraltar Transform Fault Zone (AGFZ) southwest of Portugal is capable of M8+ earthquakes — it was the source of the 1755 disaster. The Lower Tagus Valley Fault passes beneath the Tagus estuary near Lisbon and is capable of a M7.0+ event. Both sources pose distinct hazard scenarios for the city.
Is Lisbon prepared for a major earthquake?
Portugal has invested in seismic reinforcement of critical infrastructure and public buildings since the 1990s. Lisbon's LNEC (National Civil Engineering Laboratory) has developed detailed urban vulnerability assessments. However, much of the historic Baixa district was rebuilt on rubble fill after 1755 that could liquefy in a future event.
Where can I see live earthquake data for Lisbon?
Track earthquakes near Lisbon on the Earthquake Globe app or at earthquakes.site/map?country=portugal. IPMA (ipma.pt) provides real-time Portuguese earthquake data. ANEPC (anepc.gov.pt) coordinates civil protection response for seismic and tsunami emergencies in Portugal.
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