Repeated earthquakes are rattling Greece’s volcanic island of Santorini. The quakes are prompting authorities to dispatch rescuers with tents, a sniffer dog and drones and to shut down schools on four islands.

Schools were closed and emergency crews deployed on the volcanic Greek island of Santorini on Monday after a spike in seismic activity raised

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.

Greek authorities have issued a warning to visitors to one of its most famous islands due to a surge in volcanic activity.

Increased volcanic activity in Greece’s famed tourist hotspot of Santorini has prompted the country’s civil protection minister to call a meeting with local and disaster response officials.