(ATHENS, Greece) — A strong earthquake off a western Greek tourist island early Friday morning was felt as far away as Athens, but no major damage or injuries were immediately reported.

The main harbor for the island of Zakynthos in the Ionian Sea was damaged though it was still functional, civil protection agency press spokesman Spyros Georgiou said. Power was lost in the island capital and main town, also called Zakynthos, but no major damage was reported there.

“We’re checking out the villages on the island, where there are several older buildings,” he told The Associated Press. “The lack of electricity is a problem, but technicians are trying to restore power.”

The fire service said rockfalls were reported in another part of the island, and part of a church wall collapsed on the mainland town of Pyrgos, in the southern Peloponnese area. A couple of people were treated for minor injuries.

Georgiou said a precautionary tsunami warning was issued, although none had materialized two hours after the quake.

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 village of Mouzaki is near the popular tourist resort of Laganas.

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.

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