Earthquakes are still rattling Greece’s volcanic island of Santorini every few minutes as authorities bolster their emergency plans in case the hundreds of temblors in recent days are a harbinger of a larger quake to come.

Santorini has been under a state of emergency following earthquakes, the strongest at 5.2 on the Richter scale. Over 11,000 people have evacuated, schools closed, and access restricted to certain areas.