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,

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.

Schools were closed and emergency crews deployed on the volcanic Greek island of Santorini on Monday after a spike in seismic activity raised concerns about a potentially powerful earthquake.