A warning sign blocks the road to Bardarbunga volcano, more than 12 miles away, in the northwest region of the Vatnajokull glacier on Aug. 19, 2014. (REUTERS/Sigtryggur Johannsson)

The Icelandic Meteorological Office elevated its aviation warning to red, the highest on its four-point scale, near the Bardarbunga volcano in Iceland after an eruption late Thursday night.

A fissure eruption started in the Holuhraun Lava Field north of the Vatnajokull ice cap, prompting the Icelandic Air Traffic Control to close down the airspace up to 18,000 feet around the volcano, the Wall Street Journal reported. The red alert means an eruption is imminent or already in progress and that a significant emission of ash is likely, according to the Icelandic Meteorological Office.

No volcanic ash has been detected , the Department of Civil Protection said.

“With the remains of Cristobal pushing over Iceland late in the weekend and early next week, there is a chance the winds above the volcano could push ash and debris south over the central and even western Atlantic,” AccuWeather.com senior meteorologist Alan Reppart said. “Depending on how the storm dissolves, this may bring an even stronger push of winds southward into the Atlantic over the end of the week.”

In 2010, Iceland’s ice-capped Eyjafjallajokull volcano spewed lava and ash, creating a cloud that closed down air travel across Europe for six days. More than 100,000 flights were canceled, affecting some 10 million people, Businessweek reported.

The Bardarbunga volcano has been hit by several recent tremors, the BBC reported. Then earlier this week, a small volcanic eruption was detected under the Dyngjujokull glacier, prompting a red alert that was later lowered to orange because there was little volcanic activity.

Bardarbunga is Iceland’s second highest mountain.

According to the Icelandic Meteorological Office:

The volcano is placed in northwestern Vatnajökull ice cap and therefore covered with ice. … A caldera in the volcano’s crown, 11 km long on the longer side, is covered with approximately 850 m thick glacial ice. Eruptions related to the central volcano can occur anywhere in the caldera, on the sides of the volcano and also in the fissure swarms to the NA and SW of the volcano, for a distance up to 100 km from the central volcano.