On Monday, a volcano began erupting in southwest Iceland, the country's most populous region. Fountains of lava rose high into the air and the glow lit up the sky miles away in the center of the capital Reykjavik.
The fissure, which is about 2.5 miles long and growing rapidly, is not far from the Svartsengi power plant and the town of Grindavík, which was evacuated last month because of increased seismic activity, leading to fears that an eruption was likely.
In the initial assessment on Monday evening, volcanologists had said that the eruption had occurred in one of the worst locations and posed a significant and immediate threat to both the evacuated city and the geothermal power plant.
But after volcanologists had the opportunity to fly over the site of the eruption on the Reykjanes Peninsula, the immediate situation did not appear to be as dire as first feared, although the scale of the eruption was larger than expected and the direction of the lava flow was still unpredictable.
“This is larger than previous eruptions on Reykjanes,” Magnus Gudmundsson, a volcanologist and one of the first people to observe the eruption from the air, told The New York Times.
According to Kristín Jonsdottir, head of the volcanic activity department at the Icelandic Meteorological Office, lava is currently flowing just 2.5 kilometers north of Grindavík, or 1.6 miles.
However large the eruption may be and the town of Grindavík has been evacuated, it currently poses no danger to people, a police official, Ulfar Ludviksson, told reporters.
Still, authorities warned people not to get too close. Hjordis Gudmundsdottir, a spokeswoman for the Ministry of Civil Protection, urged people to stay away from the area, stressing that it was “not a tourist volcano.”
“The crack size is increasing rapidly,” she said in an interview.
While an eruption had been expected for weeks following a series of earthquakes, Monday's eruption occurred without immediate warning. The Blue Lagoon, one of Iceland's most popular tourist destinations and located nearby, reopened to guests on Sunday as fears of an impending eruption eased.
According to the Icelandic Meteorological Office, thousands of earthquakes have been recorded in Iceland since the end of October. In November, as homes and roads were damaged, authorities declared a state of emergency and evacuated Grindavik, a town of more than 3,000 people near the volcano.
The country has experienced this many times.
In the last two years alone, there have been four outbreaks on the Reykjanes Peninsula, the most populous corner of Iceland and home to the capital. When Grindavik was ordered to evacuate on November 11, authorities said in a statement that the country was “highly prepared for such events.”
“Iceland has one of the most effective volcanic eruption preparedness measures in the world,” the website says.
Authorities raised the flight warning to orange as a volcanic eruption could pose a danger to aircraft in the North Atlantic as ash spewed into the sky.
But on Monday evening, Iceland's main airport, Keflavik, remained open, and that eruption did not produce ash that grounded flights.
One of the most memorable eruptions in Iceland's recent past involved the Eyjafjallajökull volcano in 2010. Although this eruption was relatively small and caused no fatalities, the impact was widespread, with a resulting ash cloud paralyzing much of European air traffic for more than a week .
The Eyjafjallajokull (pronounced EYE-a-fyat-la-jo-kutl) volcano was dormant for nearly two centuries before coming back to life more than 13 years ago.
Iceland has many volcanoes.
Volcanic eruptions are not uncommon in Iceland, which has fewer than 400,000 residents and about 130 volcanoes. Since the 19th century, not a decade has passed without one, the Icelandic tourist website tells interested visitors. The occurrence of eruptions remains “completely random”.
The country straddles two tectonic plates, which are themselves separated by an underwater mountain range from which molten hot rock, or magma, emanates.
Recent seismic activity has not affected one of Iceland's best-known volcanoes, Katla, which some scientists fear could erupt. Katla has erupted five times since 1721, with intervals ranging from 34 to 78 years. The last big one was in 1918.