The 1722 Algarve earthquake occurred on 27 December 1722. It was felt throughout the Portuguese region of

Algarve The Algarve (, , ) is the southernmost NUTS statistical regions of Portugal, NUTS II region of continental Portugal. It has an area of with 467,495 permanent inhabitants and incorporates 16 municipalities (concelho, ''concelhos'' or ''município ...

and destroyed a large area in southern

Portugal Portugal, officially the Portuguese Republic, is a country on the Iberian Peninsula in Southwestern Europe. Featuring Cabo da Roca, the westernmost point in continental Europe, Portugal borders Spain to its north and east, with which it share ...

generating a local

tsunami A tsunami ( ; from , ) is a series of waves in a water body caused by the displacement of a large volume of water, generally in an ocean or a large lake. Earthquakes, volcanic eruptions and underwater explosions (including detonations, ...

that flooded the shallow areas of

Tavira Tavira (), officially the City of Tavira (), is a Portuguese town and municipality, capital of the ''Costa do Acantilado'', situated in the east of the Algarve on the south coast of Portugal. It is east of Faro and west of Huelva across the riv ...

. It is unclear whether its source was located onshore or offshore and therefore, what was the

tectonic Tectonics ( via Latin ) are the processes that result in the structure and properties of the Earth's crust and its evolution through time. The field of ''planetary tectonics'' extends the concept to other planets and moons. These processes ...

source responsible for the event. Some scientific research work has concluded that the earthquake and tsunami was probably generated offshore, close to . It occurred 33 years before

1755 Lisbon earthquake The 1755 Lisbon earthquake, also known as the Great Lisbon earthquake, impacted Portugal, the Iberian Peninsula, and Northwest Africa on the morning of Saturday, 1 November, All Saints' Day, Feast of All Saints, at around 09:40 local time. In ...

which remains a major event in Portuguese history, mainly due to its effects on

Lisbon Lisbon ( ; ) is the capital and largest city of Portugal, with an estimated population of 567,131, as of 2023, within its administrative limits and 3,028,000 within the Lisbon Metropolitan Area, metropolis, as of 2025. Lisbon is mainlan ...

which was wiped out by structural collapse, fire and then the flooding from a tsunami that raced up the

Tagus The Tagus ( ; ; ) is the longest river in the Iberian Peninsula. The river rises in the Montes Universales between Cuenca and Teruel, in mid-eastern Spain, flows , generally westward, and empties into the Atlantic Ocean in Lisbon. Name T ...

River. Most of the documentation of the 1722 event was sent to Lisbon for archiving and became lost after the fire that followed the 1755 earthquake. But the few surviving written records of the 1722 earthquake describe a destructive series of events affecting several Algarvean localities with earth tremors so strong that they made the bells ring out in Tavira, Faro and

Loulé Loulé () is a city and Concelho, municipality in the region of Algarve, Faro District, district of Faro, Portugal. In 2021, the population of the entire municipality was 72,373 inhabitants, in an area of approximately . The municipality has two p ...

. In Tavira a caravel moored on the river Gilão was left high and dry before the tsunami hit with the dumbfounded crew able to walk to shore. The magnitude is estimated at 6.5 to 7.8 on the moment magnitude scale; due to poor documentation, its magnitude is not well constrained. The earthquake of 1722 was probably caused by a

diapirism A diapir (; , ) is a type of intrusion in which a more mobile and ductilely deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh–Taylor ...

where dense rock from deeper levels under high pressure pierced shallower materials. As a result, buildings in

Albufeira Albufeira (, ), officially the City of Albufeira (), is a List of cities in Portugal, city and Concelho, municipality of Faro District in the Algarve region of southern Portugal. The population in 2021 was 44,158, in an area of . The city proper ...

, Faro, Lagoa and Loulé were also severely damaged or, in some cases, destroyed. In the 2010s, studies of seismic risk estimated there would be around 12,000 deaths if an earthquake equal to that of 1722 occurred then during peak season, because population density was significantly higher in the coastal areas of Algarve in the early 21st century, when it had already become a popular international travel destination, than in the 18th century, and construction of high-rise buildings built without proper anti-seismic measures were pervasive in the decades preceding such studies.

See also

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