A strong 5.1-magnitude tremor has hit just west of the island of Cephalonia in the Ionian Sea, western Greece. The quake, which hit at 1:15 a.m. local time (2315 GMT), had its epicenter 5 kilometres 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. An 5.7-magnitude earthquake on January caused widespread damage in the island, leaving hundreds homeless for days as their homes suffered severe damage and more than a dozen people were injured.