A 5.5 magnitude earthquake shook the southwestern area of the Peloponnese in Greece in the early hours of Monday.
Its epicentre was offshore, 26 km (16 miles) west of the town of Methoni at a depth of 30.4 km, the US Geological Survey said.
There were no early reports of serious damage or injuries, Reuters reported citing officials.
An aftershock was measured at 3.3, the head of the Athens Geodynamic Institute, Gerasimos Papadopoulos, told Greek TV ERT.
The Peloponnese is a peninsula, separated from mainland Greece by the Corinth canal.