Thousands of people have been evacuating Santorini after days of increased seismic activity that is threatening some of the island’s cliff-top houses. Quakes have been felt on Santorini every few minutes for several days,

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.

Multiple earthquakes are rattling Santorini, a volcanic island in Greece, prompting authorities to dispatch rescuers with tents, a sniffer dog and drones, and to shut schools on four islands.