Athens, Greece:
A strong 5.1-magnitude tremor has hit just west of the Greek island of Cephalonia in the Ionian Sea.
The quake, which hit at 1:15 am local time (2315 GMT), had its epicenter 5 kilometers (3.1 miles) underwater, the Athens Geodynamic Institute reports.
There have been no immediate reports of damage or injuries. A 4.7-magnitude quake hit the island Friday.
The area often produces very strong quakes. The island was flattened in 1953 by a 7.2-magnitude tremor.