Schools remain shut and evacuation flights are underway as Greek holiday island Santorini was rattled by earthquakes for the fourth day in a row. A spike in seismic activity has been recorded on the volcanic island in the Aegean Sea since Friday,

The strongest earthquake recorded was magnitude 4.6 at 3:55 p.m. Sunday, at a depth of 14 kilometers (9 miles), the Athens Geodynamic Institute said.

Santorini is on high alert following over 200 undersea earthquakes, prompting authorities to close schools and deploy emergency crews. Though the quakes are not linked to its volcano, the increasing seismic activity is concerning,