Iceland Volcano Eruption Update: Magma Dike 'Wider' Than Scientists Thought

Fresh modeling reconstructing the evolution of a magma dike pushing up through the Earth's crust underneath Iceland suggests that it "could be wider than initially assessed" and therefore could pose a threat for longer, the nation's meteorological office has said.

In an update on Sunday afternoon, the Icelandic Met Office said a "seismic swarm" had occurred around the intrusion from midnight the same day, indicating an increase in pressure within the dike, where an eruption is deemed most likely. Over the course of an hour, 170 small earthquakes were detected, with one reaching a magnitude of three.

Between 1,500 and 1,800 earthquakes a day have been recorded from November 10 until last week, when adverse weather interfered with seismic recording equipment. The tectonic activity has seen cracks appear in the ground and prompted local authorities to evacuate the coastal fishing town of Grindavik, which sits near the course of the dike.

The magma intrusion—a rapidly forming, vertical sheet of molten rock—has formed close to the town, on a southwesterly peninsula on Iceland's main island, in a weak point in the Earth's crust, and is estimated to be around 9.3 miles (15 kilometers) long.

There, magma is thought to be half a mile or less from the surface. The Icelandic Met Office said the latest burst of earthquakes were measured at a depth of 1.8 to 3 miles (3 to 5 kilometers) along the dike, with the greatest number occurring to the northeast of Grindavik.

At the same time, a pool of horizontal magma has pushed a region around 6 miles (10 kilometers) across up by about 1 inch (3 centimeters), which has occurred previously. The Icelandic Met Office said on November 23 there appeared to be a "strong connection" between the uplift and the dike, with the volcanic reservoir flowing into the intrusion.

Experts believe that, if an eruption were to occur, it would most likely take place somewhere along the path of the dike.

The Icelandic Met Office said that the area with the "highest likelihood" of eruption was the middle part of the dike, between the Hagafell mountain and Sylingarfell, another mountain close to Grindavik. It added that because the intrusion was thought to be wider below the surface, it was estimated that it would take a few months before the magma that had intruded into the dike would solidify.

In recent weeks, authorities in Iceland have built earth walls, along with conduits and canals, around Grindavik and Svartsengi, a nearby geothermal power plant, in a bid to direct lava away from buildings in the event of an eruption.

Andrew Hooper, a geophysicist at the University of Leeds in the U.K., previously told Newsweek that an eruption could occur within the town. He said an eruption would see ash ejected locally to the area of emission, while lava could travel for miles. Others have said there was disagreement among geologists about the likely nature of the eruption should it occur.

The last time a major eruption took place in Iceland was in 2010, when the Eyjafjallajokull volcano erupted several times causing a massive ash cloud to spread over Europe and North America, leading to severe disruption to air travel.