Residents of Grindavik, a fishing town in southwestern Iceland, have evacuated and a state of emergency has been declared, as local authorities say a volcanic eruption may be imminent.

The region has been seismically volatile for a while, as hundreds of small earthquakes have been recorded in the past two weeks and a 5.1 magnitude earthquake struck on Friday.

Moreover, Iceland’s Meteorological Office said Saturday that a 6.2-mile corridor of magma, or semi-molten rock, extends under the community and is spreading. Magma is called lava when it is on the surface.

But how do you tell when a volcano is about to erupt? And what are the major risks from an eruption?

Northeastern Global News spoke with Daniel Douglass, teaching professor in marine and environmental sciences at Northeastern’s Marine Science Center, about what is happening in Iceland geologically, the risks from a volcanic eruption, and more.

Read more from Northeastern Global News.

Photo by AP Photo/Marco Di Marco