Fears are increasing that the Greek island of Santorini will be hit by a strong earthquake after more than 200 undersea tremors were recorded in the vicinity over the weekend. Two earthquakes classified as “weak” took place in the early hours of Monday morning close to Santorini and the islands of Anafi,

According to officials, more than 11,000 people have left Santorini, with around 7,000 departing by ferry and 4,000 people leaving by air. Hundreds of earthquakes have rocked the island, the strongest of which was a magnitude five tremor on Tuesday.

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.