Α 4.4-magnitude earthquake shook the sea area northwest of the Ionian island of Zakynthos on Thursday.
A preliminary reading by the Athens Institute of Geodynamics showed the tremor occurred at a depth of 13 kilometres.
No injuries or damages were immediately reported.
The European Mediterranean Seismological Centre measured the quake at 4.9.
The area has experienced extensive seismic activity since a 6.4 magnitude quake hit the same area in late October.