The ongoing lava eruption, located at Holuhraun, an ice-free area north of the subglacial Bardarbunga volcano, shows no signs of diminishing. The lava now covers around 37 square kilometers, equal to around 60% of Manhattan.

The most dangerous place in Iceland

Dead birds, killed by the pollution from the eruption, have been found in the area. Vidir Reynisson, head of the National Police Commissioner's Departement of Civil Protection, stresses that there is a reason for the extensive closures around the eruption. He urges the public to respect closures. "This is the most dangerous place in Iceland, and people have to show caution, and we simply must ask people to think a little before they act."

Great ashfall to be expected

Reynisson says that the course of events has few parallels. Another eruption might suddenly start under the glacier, south of the current eruption, with ensuing flooding and extensive ashfall. Depressions which have been observed in the glacier are among the evidence pointing to that scenario, he adds. "If we assume that the eruption under the glacier would be a relatively small one, then a lot of ash should be expected in a 20-25 km radius (12-15 mi)." He explains that the density of the ash would be so high that people would not see out of the windshields of their cars.

Saving numerous people 'impossible'

Reynisson says that scientists and others working in the field are putting themselves in great danger. Authorities expect to be able to evacuate the 20-30 people who normally work near the eruption, but he says it would be impossible to rescue a great number of people in time.

Holuhraun eruption still stable after three weeks

No significant changes have been obvserved in the Holuhraun eruption. The output of lava has been stable for the three weeks since the eruption started, which is unusual, says Magnus Tumi Gudmundsson, professor of geophysicics at the University of Iceland, who has been working in the field for the past week. "This eruption keeps getting larger, and you need to go back to the Surtsey eruption to find something similar," Gudmundsson says, referring to the total volume of lava produced by the eruption. In 1963-1967, a submarine eruption formed a new island at Surtsey, south of Iceland.

Bardarbunga keeps shaking and sinking

Seismic activity in the Bardarbunga caldera is still intensive. Sunday morning, a M5.5 earthquake struck the volcano, one of the biggest quakes since the activity started in August. The largest earthquake to date was a M5.7 on 26 August.

Numerous earthquakes of magnitude 3.0 or above were detected Saturday and Sunday. The caldera has subsided by 26 m (85 ft) in the last few weeks, and a subsidence of 25 cm (10 in) was observed in tandem with the M5.5 earthquake Sunday morning.

This graph shows the subsidence of the Bardarbunga caldera in meters in the last two days. The graph at the bottom shows earthquakes in the area in the same period.

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This story, by the Icelandic National Broadcasting Service (RUV), was updated on 21 September 2014, at 22:57 GMT.

Updates in English will be posted at: ruv.is/volcano. Follow us on Twitter: @ruvfrettir