Panic after 6.1 magnitude earthquake rocks Greece Crete, second in a week (WATCH)

A 6.1-magnitude earthquake hit off the Greek islands of Crete and Santorini on Thursday, the US Geological Survey said. The strong quake struck 82 kilometres (51 miles) northeast of Crete's capital Heraklion, at a depth of 68 kilometres, the USGS said.

The region popular with tourists has been rattled by multiple tremors in recent months, prompting schools in Santorini and neighbouring islands to close temporarily.

This tremor follows a similar 6.1-magnitude earthquake that struck just a week ago near the island of Kasos, off Greece’s southern coast. That quake also rattled parts of the eastern Mediterranean but caused no immediate reports of damage.

Thousands of earthquakes, mainly of low magnitude, were recorded from late January between the islands of Santorini, Amorgos, Ios and Anafi in the Cyclades group southeast of the Greek mainland.

The seismic swarm caused no casualties or significant damage.

Located where the African and Anatolian tectonic plates converge, the Aegean Sea is often hit by quakes.

But the region had not experienced a phenomenon of such magnitude since records began in 1964, experts said.