Footage of the volcano was captured by the Icelandic Meteorological Office
Initial aerial footage of the Reykjanes Peninsula showed a relatively small eruption so far, with two streams of lava flowing in opposite directions.
The eruption could be seen from the outskirts of Reykjavík, Iceland's capital, which is about 32 kilometres away.
The Department of Emergency Management said it was not preparing to evacuate nearby residents. It reasoned that the volcano is in a remote valley, about 2.5 kilometres from the nearest road.
The Fagradals Mountain volcano had been dormant for 6,000 years, and the Reykjanes Peninsula hadn’t seen an eruption of any volcano in 781 years.
There had been signs of a possible eruption recently, with earthquakes occurring daily for the past three weeks. However, volcano experts were still taken by surprise because the seismic activity had calmed down before the eruption.