Volcanoes in southwestern Iceland have been quiet for 800 years, but the period of rest may soon be over: More than 18,000 earthquakes have shaken the area in just over a week, leading scientists to believe that an eruption could be imminent, The New York Times reported.

The current earthquake swarm started on Feb. 24 with a 5.7-magnitude quake, the largest to date, and thousands of others have since followed. On Wednesday, more than 2,500 tremors were measured by the Icelandic Meteorological Office, followed by 800 more in the first hours of Thursday.

Geophysicists and volcanologists say these quakes are the culmination of over a year of intense seismic activity, and although most of the tremors have lasted a few seconds, with light shaking, they have rattled residents in the capital, Reykjavik, and the surrounding areas, where a majority of Iceland’s 368,000 residents live

The meteorological office said the resultant volcanic activity could occur near Fagradalsfjall, 20 miles south of Reykjavik, or near the Keilir mountain close by. 

Freysteinn Sigmundsson, a research professor of geophysics at the University of Iceland, stated, however, that any activity is unlikely to be as disruptive as the eruption that occurred in 2010, when another volcano in Iceland released a plume of ash so vast that it caused one of the most significant air-traffic interruptions in decades, stranding millions of passengers in Europe, some for weeks.