Uncertain If and When Magma Underneath Reykjanes Peninsula Reaches the Surface Skip to content

Uncertain If and When Magma Underneath Reykjanes Peninsula Reaches the Surface

By Gréta Sigríður Einarsdóttir

Photo: Photo: Golli. Keilir mountain, Reykjanes peninsula.

The increase in seismic tremors detected this afternoon continues but has reduced slightly in intensity this evening. If an eruption is to occur on the Reykjanes peninsula, it will likely produce lava but no ash and won’t threaten inhabited areas. Geophysicist Páll Einarsson stated in Kastljós this evening that it’s certain that magma is on the move underneath the area, but it’s harder to predict how and when it will behave. 

Seismic tremor continues although its intensity is reduced

At 2.20 pm today, a sudden increase in seismic tremor was detected throughout most of Iceland’s national seismic network. The tremor, which comprises many small, overlapping earthquakes, is sourced from a region 2 km southwest of Keilir on the Reykjanes Peninsula. Similar bursts of tremor have been observed ahead of previous volcanic eruptions in Iceland. Magma movements are a likely cause for the ongoing signal, and it is possible that an effusive (lava-producing) eruption could occur close to Keilir. According to the Icelandic Met Office, the tremor has continued although its intensity has reduced slightly after 5 PM. At the time of writing, no volcanic eruption is ongoing and experts are awaiting further data. As a precaution for domestic and international air travel, the volcanic aviation colour code for the Reykjanes Peninsula has been elevated from yellow (elevated unrest) to orange (heightened unrest). The orange alert represents the third-highest level, with red reserved for an imminent or ongoing volcanic eruption.

Magma is moving under the surface but it’s uncertain if, when, or how it will reach the surface

After today’s press briefing, earthquake hazards coordinator Kristín Jónsdóttir stated that the tremor pulse at Litli-Hrútur was an indication that the earth’s surface was rapidly spreading apart due to the magma passage travelling towards mt. Keilir and that magma was nearing the surface. “This increases the likelihood of an eruption. It’s still not a certain outcome and we don’t know when an eruption might occur. It could take days or even weeks. “

Geophysicist Páll Einarsson said in this evening’s Kastljós that the tremor pulse meant that the magma intrusion was growing longer or closer to the surface. Magma was on the move but it was hard to predict how it would behave. The amount of magma underneath the surface is unknown but their best estimate was 10-20 million cubic meters of magma. 

What to expect?

Reykjanes peninsula eruptions tend to be small. They usually last for a week or so and a common amount of lava produced is 0.1 cubic km. In comparison, the lava produced in the Holuhraun eruption, admittedly an especially large one, was 1.4 cubic km. An eruption in the projected location would not threaten inhabited areas or produce any significant amount of ash likely to halt air traffic.

Further spaceborne radar images should become available late this evening and could shed more light on the development in the Reykjanes Peninsula. Around 1700 earthquakes have been detected since midnight, the largest one M4,1 at 02:12 AM, with mostly smaller quakes this afternoon.

The Department of Civil Protection and Emergency Response has prepared some information on what to expect from a Reykjanes eruption and how to prepare for such an event. 

What type of eruption can be expected? 

Volcanic eruptions in Reykjanes are usually fissure eruptions on land (lava eruptions) that last for several days or weeks. Sometimes signs come shortly before an eruption begins, but not always.  Eruptions of this type are often accompanied by lava flows and toxic gases can also be released into the atmosphere. The lava flows slowly; at a walking speed. It is unlikely that the lava will spread as far as residential areas. If so, it would take a considerable amount of time. 

Lava and ash 

Low to medium lava flow and insignificant quantities of pumice and ash can be expected. Ash and pumice can cause irritation and become harmful if the eruption becomes larger. Volcanic fumes can form when water vapor combines with volcanic gas. Ash from eruptions of this kind is insignificant and not large enough to reduce visibility significantly. Ash and pumice can be released into the atmosphere at any time throughout the course of the eruption and can persist for many days. 

Those living in the vicinity of volcanic eruptions should follow closely the news and public announcements concerning gas pollution. Official bulletins are issued at least twice a day and follow the weather forecast.


Volcanic eruptions in the Reykjanes region are likely to occur away from inhabited areas and do not call for a quick response from residents. The most important thing is to stay calm and follow the news, especially concerning air pollution and ashfall. 

 People should avoid excursions in the area of the eruption site. All traffic in the area, by car or on foot is forbidden. 


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