A state of emergency was declared on Santorini Thursday after a magnitude 5.2 earthquake shook the Greek island late Wednesday. The tremor is the latest — and strongest — in a series of quakes that have struck the island since last week,

Thousands of people are fleeing the Greek island of Santorini as increased seismic activity spurs fears of a more powerful earthquake at the site of one of the largest volcanic eruptions in history.

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.