Residents on the popular island of Santorini have experienced hundreds of earthquakes this week while researchers have revealed a new magma chamber underneath the Kolumbo submarine volcano.

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. The ministry of civil protection’s announcement will provide authorities faster access to state resources.

The Greek island has a long history of earthquakes, but what is causing the recent series of quakes has scientists perplexed.