A fresh series of quakes hit the Greek island of Santorini early on Thursday, part of an unprecedented seismic wave that has baffled scientists and led to a mass exodus of residents. Schools on more than a dozen islands in the Cyclades island group in the Aegean Sea have been shut as a precaution until Friday,

Experts say the Greek island of Santorini has been hit by more than 1,000 earthquakes, but they're not linked to the region's active volcanoes.