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.

A spike in seismic activity on Santorini has spooked many on the island with concerns about a potentially powerful earthquake. Residents and visitors were advised to avoid large indoor gatherings and areas where rock slides could occur,

In Fira, Santorini’s main town, local authorities have set up gathering points for residents though no evacuation orders are in place right now. However, it’s been agreed by seismologists that these quakes could be an indicator of an impending seismic event.