"It was felt very strongly, it had a long duration," local governor Efthimios Sokos told state-run NET television.
"Since April, we've had four earthquakes of more than magnitude-5, so people are generally anxious."
The Athens' Geodynamic Institute, which monitors earthquakes, said the quake occurred at 2:50 p.m. (1150GMT) near the city of Agrinio, about 200 kilometers (125 miles) northwest of Athens.
The U.S. Geological Survey earlier said the quake had a preliminary magnitude of 5.0.
The discovery of the submarine has unveiled a few "inconsistencies." For example, how can one explain the fact that the sub was found where it needed to be searched for from the start?
This problem is not limited to the situation with the "whale prison" in Russia's Far East, because many people buy tickets to go to oceanariums and turn a blind eye to the problem