German Vulkane.net wrote following:

Medium magnitude 5.4 earthquake
off the west coast of Portugal was felt in Lisbon

This morning at 04:11:39 UTC, a moderate earthquake of magnitude 5.4 occurred off the west coast of Portugal. The hypocenter was detected at a depth of 16 kilometers. The epicenter was located 50 km south-southwest of Sesimbra and about 90 km from the national capital Lisbon. Houses there began to shake and numerous reports were received, with the furthest coming from Morocco, over 850 kilometers away.

Nevertheless, no major damage has been reported so far. However, the quake was strong enough to cause minor damage to buildings, such as cracks in the facades.

Initially, the magnitude was even classified as Mb 5.9, but was later reduced. The GFZ Potsdam determined a moment magnitude Mw of 5.0 and warned of aftershocks.

The earthquake today was the strongest earthquake

in the region since 2009, when there was a magnitude Mb 5.0 quake.

Prime Minister Paulo Range told the press that the quake was a good opportunity to test the response capacity of the civil protection system.

In tectonic terms, the earthquake was linked to the collision of the European and African plates. This causes subduction in the Gulf of Cadiz. The faults in this area are part of the larger Azores-Gibraltar fault system, which stretches from the Azores to the Strait of Gibraltar. This system plays a key role in the tectonic evolution of the region and is closely linked to subduction and associated geological processes. The earthquake occurred on one of the fault zones associated with this area.

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Lisbon 1755

a very strong seaquake occurred in the region, as a result of which large parts of Lisbon were destroyed. (also due to overwhelming tsunamis, which by the way also affected England and Ireland with devastating floods) Of course, there are now fears that the quake could have been just the prelude to a catastrophic earthquake. The Lisbon 1755 earthquake was felt all the way to Sweden, where it creates light waves in the Vänern lake.

What I was not aware of...

Lisbon 1722 !

Apparently there was another very strong earthquake in 1722 in Southern Portugal/Spain. However the one from 1755, was enormous, with between 8.5 to 9.0 in strength. Apparently one of the strongest and most devastating ever to have occurred in Europe. Lisbon which was the culture city of Europe - and its utter devastation - also had strong repercussions to culture in entire Europe.