"The strong earthquake was measured at 5.3 with the epicentre on the edge of Trichonida lake (in western Greece), some 110 kilometres (70 miles) west of Athens," an Athens Geodynamic Institute official told Reuters. "First estimates show it may be part of the seismic activity in the area in recent weeks," he said.
The fire brigade said there were no reports of injuries.
Residents of the town of Agrinio, near the lake, said the tremor had sent them running out of their houses in fear.
"There was a loud rumble. The furniture started shaking, books fell off shelves and we left the house," Lucy Katefidi told Reuters.
A series of quakes in the past month have shaken western Greece and popular tourist islands, including Zakynthos in the Ionian Sea.