Iceland cut its ash alert level for aviation to orange from red on Sunday after raising it to the maximum level earlier in the day because of a fresh eruption from a fissure in the Bardarbunga volcano system.
"No ash has has been detected. The aviation colour code for Bardarbunga has therefore been reset to orange," the Meteorological Office said in a statement.
A new eruption in Iceland's Bardarbunga volcano system system spewed lava more than 50 metres in the air on Sunday, initially prompting authorities to raise their warning of the risk of ash to aviation from orange to red, which is the highest level on a five-colour scale and indicates an eruption is imminent or underway, with a risk of spewing ash.
Iceland's largest volcanic system, which cuts a 190 km long and up to 25 km wide swathe across the North Atlantic island, has been hit by thousands of earthquakes over the last two weeks and scientists have been on high alert.
In 2010, an ash cloud from the Eyjafjallajokull volcano, in a different region of Iceland, closed much of Europe's air space for six days.
The latest eruption has not led to ash clouds, however.
"There is no ash, only lava," Eggert Magnusson at the National Crisis Coordination Centre said.
The current eruption began around 1 a.m. ET prompting the Icelandic Meteorological Office to raise its aviation warning code to red from orange for the Bardarbunga area.
Eruption stronger than Friday's
Earlier Sunday, Iceland's aviation authorities had declared a danger area which reaches from the ground to 6,000 feet around the volcano.
The Department of Civil Protection and Emergency Management said the eruption is along a 1.5-kilometre front.
'The eruption is producing 50- to 60-metre high lava fountains.' - Armann Hoskuldsson, geologist
"The eruption is producing 50- to 60-metre high lava fountains," Armann Hoskuldsson, a geologist at the University of Iceland told Reuters earlier Sunday.
"The lava flow from the fissure is about 10-20 times more than Friday morning."
Two days ago, a 600 metre-long fissure in a lava field north of the Vatnajokull glacier, which covers part of the Bardarbunga system, erupted.
That eruption only lasted for a few hours and was not in an area covered by ice and did not produce ash. The risk of an ash cloud is highest when there is a sub-glacial eruption as meltwater and magma mix to produce ash particles.
The new eruption is very close to Friday's and is not under the glacier.
"It is almost in the same location. The crack has only extended a little bit further to the north," Magnusson said.
Last week, scientists estimated around 400 million cubic meters of lava had flowed out from under the volcano in a long dyke. The eruption on Friday was at its tip.
Aviation disruption unlikely
Although Sunday's fissure eruption was more powerful than the one on Friday, experts said the situation is contained and is unlikely to result in the same level of aviation chaos as in 2010.
In April of that year, the Eyjafjallajokul eruption wreaked havoc on millions of travellers. More than 100,000 flights were cancelled after officials closed Europe's air space for five days out of fear that volcanic ash could damage jet engines.
Dave McGarvie, a volcanologist at Britain's Open University, said the fissure eruptions produce only very small amounts of ash — they produce mostly lava — and are highly unlikely to cause any aviation disruption.
"It's good news in the sense that it appears to be very small, very contained," he said. "It's not spreading under the glacier — if it did, you'll get a lot of flooding."
He said Icelandic authorities are mostly concerned that the main volcano under the ice cap will erupt, but there are no signs so far that this is imminent.