Tremors in the aftermath of an earthquake off the coast of Greece were felt in Malta in the early hours of Friday morning.

Some people took to Facebook to describe their own personal experience, with some describing how their sofa and lights shook, and others questioning whether there was an earthquake. 

The earthquake struck off a western Greek tourist island. The U.S. Geological Survey said the undersea quake was magnitude 6.8 and its epicenter was 33 kilometers (20 miles) southwest of Mouzaki in the southern part of the island. It had a depth of 14 kilometers and struck just before 2 a.m. local time (2300 GMT Thursday).

Greece's main earthquake monitoring center, Athens' University's Geodynamic Institute, measured the magnitude at 6.4, and said it had a depth of 5 kilometers. Measurements of quake strength can vary due to the equipment each institution uses and other factors.

Moderate foreshock and aftershock shook the area as well. 

The quake rattled the whole of western Greece and was strongly felt in the capital, 280 kilometers (174 miles) to the northeast of Zakynthos.

Greece lies in one of the world's most earthquake-prone regions, with thousands of quakes recorded every year. But few cause injuries or significant damage. In 1999, a magnitude 5.9 quake on the outskirts of Athens killed 143 people.

Zakynthos has had severe earthquakes in the past, and as a result has a very strict building safety code.

Map image by earthquake.usgs.gov