ATHENS, Greece — Greece’s government declared a state of emergency on Santorini on Thursday after hundreds of undersea earthquakes shook the resort island for nearly a week.

Earthquakes rattled Greece’s volcanic island of Santorini every few minutes overnight and into Wednesday as authorities bolstered emergency plans in case the hundreds of temblors over the past few days are a harbinger of a larger quake to come.

Since last week, thousands of residents have left the island by plane and ferry, as hundreds of earthquakes continue to shake the region.