Authorities have declared a state of emergency on a second Greek island as a series of earthquakes continued to rattle the south-eastern Aegean Sea region.

The emergency measure announced on the island of Amorgos follows a similar decision for nearby Santorini on February 7 after thousands of unusual tremors were registered in an undersea area

A state of emergency has been declred in Santorini, a volcanic island and popular tourist destination in Greece, as an 'earthquake swarm' that began earlier this month continues. Since 31 January, more than 800 tremors with a magnitude of three and above have been recorded.