An earthquake measuring 6.3 on the Richter scale according to Spain’s seismological institute said shook Spain, Portugal and Morocco early on Thursday.
There were no immediate reports of major damage or casualties.
The epicentre of the quake, which occurred at 2:37 am (0137 GMT) was in the Atlantic Ocean about 100 kilometres (60 miles) southwest of Cape St Vincent in Portugal and at a depth of 58 kilometres, the National Geographic Institute said.
The US Geological Survey measured the quake at 5.7 magnitude on its different moment magnitude scale. It said the quake struck at a shallow depth of 10 kilometers.
Spanish media said the quake was felt in the cities of Seville, Cordoba and Huelva.
It said emergency services had received numerous calls asking for information about the quake but no reports of damage or casualties.
The quake was felt across Portugal but emergency services said they received no reports of damage.
The quake was also felt in Morocco’s Atlantic coast cities of Tangiers, Rabat and Casablanca, but civil protection authorities said they had received no reports of injuries or damage.