The very earth people were walking on, the solid foundation on which lives were built, shook violently - and although the length of time doesn’t look very much, the continual shaking and rumbling and falling of buildings must have felt like it was going on forever.

It was 9.40am on the morning of 1st November 1755, and it was All Saint’s Day. It created gaps up to 5 metres wide in the city centre, killing an estimated 60,000 people in Lisbon alone. Powerful shaking demolished public buildings and about 12,000 dwellings, with falling churches, monasteries, nunneries, and chapels trapping the faithful attending mass inside, where burning candles quickly created blazing infernos.

Then came the tsunami, probably known at the time as a ‘seismic sea wave’, as the Japanese word ‘tsunami’ (translated as ‘harbour wave’) had probably never been heard of. The sea receded, revealing a bed of mud littered with shipwrecks and lost cargo. Approximately 40 minutes later, a 6-metre-high tsunami engulfed the harbour and downtown area, rushing up the Tagus River so fast that people riding on horseback had to gallop to higher ground for fear of being carried away.

What was life like then?

In 1755, Lisbon was the fourth-largest European city and was known for its wealth, prosperity, and sophistication. It was one of the most beautiful cities in Europe, with an estimated population of 200,000. Palaces and churches impressed visitors because of their opulence and magnificent splendour - it was the centre of the world’s gold trade.

Three distinct tremors shook this beautiful city, followed by a tsunami and a devastating fire. Current scientific and geological analysis point to an estimated magnitude of 8.5 on the Richter scale for the quake, and caused damage to a great part of the city: not only to buildings but also the treasures the city and its people had accumulated.  

Other places were affected

Lisbon was not the only Portuguese city affected by the catastrophe. Throughout the south of the country, destruction was devastating. The tsunami destroyed some coastal fortresses in the Algarve and, at lower levels, several houses were destroyed. Almost all the coastal towns and villages of the Algarve were damaged, with the exception of Faro, which was protected by the sandy banks of Ria Formosa. In Lagos, the waves reached the top of the city walls. Other towns, such as Peniche, Cascais, Setúbal and even Covilhã in central inland Portugal were affected either by the earthquake, the tsunami, or both. The shock waves destroyed part of Covilhã's castle walls and its large towers, and damaged several buildings in Cova da Beira, and were felt as far as Salamanca, Spain. In Setúbal, parts of the Fort of São Filipe de Setúbal were damaged.

Earthquakes in the area

Only 33 years before, there had been another severe earthquake that destroyed a large area in southern Portugal, generating a local tsunami that flooded the shallow areas of Tavira. Unfortunately, most of the documentation of the December 1722 event was sent to Lisbon for archiving and became lost in the fire of the 1755 earthquake. But the few surviving written records of the 1722 earthquake describe a destructive series of events affecting several Algarvean localities with tremors so strong that they made the bells ring out in Tavira, Faro and Loulé, and with an estimated magnitude of 7.8, it was strong enough to cause widespread damage.

Earthquakes happen every day all over the world, along both tectonic plate edges and interiors, with Japan being a hotspot. They are one of the most quake-prone countries in the world, and experience some 1,500 a year, though some are too small to be felt. Worldwide, The National Earthquake Information Centre now locates about 20,000 earthquakes around the globe each year, or a staggering figure of around 55 per day.

Back home here, seismic monitoring by the Portugal Earthquake Report records small ones daily - most too small to be felt – either on land or at sea, and worldwide they are still almost impossible to predict, even in this day and age.


Marilyn writes regularly for The Portugal News, and has lived in the Algarve for some years. A dog-lover, she has lived in Ireland, UK, Bermuda and the Isle of Man. 

Marilyn Sheridan