A subglacial eruption is underway at Iceland’s Bardarbunga volcano, where there have been thousands of earthquakes in the past week, Iceland’s Meteorological Office said Saturday. Seismic data suggests that volcanic lava is melting ice beneath the Vatnajokull glacier, said seismic vulcanologist Melissa Pfeffer, Reuters reports. It’s unclear whether the eruption will break through the ice and shoot steam and ash into the atmosphere.