An updated map by the Icelandic Meteorological Office shows the different hazard levels assessed for areas around the latest eruption on the Reykjanes Peninsula.
The eruption from volcanic fissures in the ground—the fourth in as many months—began late on Saturday night and, as of Wednesday afternoon was still going at a "relatively stable" rate. Surveys of the new lava flows are due to be published shortly, along with an estimate of the lava field's size.
The Icelandic Met Office previously said the lava had spread across an area of approximately 5.85 square kilometers (2.26 square miles).
The new lava has largely flowed over an area already covered by previous eruptions. The first of those occurred in mid-December, after more than a month of seismic activity in the region, the second came on January 14, and the third early February.
Volcanic fissures have been opening up above an approximately 9.3-mile-long vertical dike of magma—which runs northeast to southwest—formed in a weak point in the Earth's crust. This is being fed by a horizontal intrusion, causing crustal uplift around the nearby geothermal power plant at Svartsengi.
The updated hazard map shows the area along the dike—where much of the lava has flowed—is considered the most dangerous by officials.
Areas to the south of the lava field and the coastal fishing town of Grindavík—which has been evacuated and suffered damage in an earlier eruption—have been deemed high risk, while those to the northwest, where lava has also flowed, including Svartsengi, have a "considerable" hazard.
The Icelandic Met Office said that the risk of sinkholes, fault movements and gas pollution contributed to the high hazard assessment for the area around Grindavík.
Officials previously expressed concern about the southern tongue of the lava flow—which came within 350 meters (1,148 feet) of the coastal road near Grindavík—reaching the sea, which could cause volcanic explosions and release toxic gases. The Icelandic Met Office said on Sunday "conditions would be life-threatening" within a 1,640-feet radius were this to occur.
However, on Wednesday, it said that "little or no movement has been detected" in the lava flows to the south.
Each of the eruptions has released pressure from the vertical dike and led to a reduction in crustal uplift around Svartsengi. But pressure from magma pushing into the Earth's crust has then risen again each time, propagating magma in the dike and building until another eruption occurs.
Volcanologists have previously told Newsweek that the December 18 eruption could mark the start of over a century of volcanic activity in the region.
The Icelandic Met Office said that there were "clear signs" of land inflation at Svartsengi around when the eruption first occurred, but that the inflation rate had possibly decreased on Sunday.
However, it cautioned that further measurements would be needed to determine whether the latest eruption had relieved enough of the pressure underground for the time being.
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Aleks Phillips is a Newsweek U.S. News Reporter based in London. His focus is on U.S. politics and the environment. ... Read more
