Ragnar Th. Sigurdsson has been photographing volcanoes in Iceland for four decades, so it makes sense that he’s keeping a close eye on the latest activity at Bardarbunga (Bárðarbunga), which rests on the northwestern edge of the Vatnajökull ice cap. Bardarbunga, which is classified by Iceland’s meteorological office as its second-highest mountain, is topped with glacial ice.