How is the volcanic activitiy in Reykjanes Peninsula monitored? 

The IMO (Icelandic Meteorological Office) monitors the natural hazards in Iceland closely 24/7 through real-time measurements of earthquakes, GPS and other data. In case of a sudden change in the activity, the IMO specialists alarm the Civil Protection authorities immediately which act if considered necessary in order to respond to a possible emergency.  

Due to the recent seismic activity on the Reykjanes Peninsula, the IMO has now increased the number of measuring devices, and has access to other devices in the area, such as GPS (Global Positioning Satellites) stations and earthquake sensors. The GPS and seismic stations all stream data in real-time to the IMO. Additionally, aerial photos have been taken of the surface area to get a better picture of whether there are changes in the landscape. 

Will the earthquakes continue during the eruption?

When magma is finding its way into the Earth's crust it releases tension in the rocks which causes earthquakes. The pressure from the magma can also release earthquakes in the crust on each side of the magma intrusion due to tensional changes. If the magma finds its way to the surface in an eruption it releases the tension in the crust and thus it is most likely that the earthquake activity will decrease significantly. 

Is the eruption site dangerous?

The area is extremely dangerous and the eruption site can change without warning and put people in danger. 

The eruption is limited to a small area just east of Fagradalsfjall, in an area where the lava flow will most likely not cause any significant damage to any infrastructure. No volcanic ash is currently measured from the ongoing eruption. Gas pollution is not expected to cause discomfort, except close to the eruption sites. Common volcanic gases that are released are e.g. CO2 and SO2 and their concentration is closest to the eruptive fissures or craters. Volcanic eruption sites are in general DANGEROUS AREAS and people are advised not to travel to the area without good preparation and with safety in mind. There are many hollows where the gas can accumulate and be dangerous to people. Volcanic gasses might as well absorb any amount of O2. The Icelandic Meteorological Office publishes a forecast of the likelihood of gas pollution at ground level, while the Environment Agency of Iceland monitors air quality in inhabited areas. We also recommend looking at the information on the homepage of the Department of Civil Protection and Emergency Management .

How long can the eruption last?

Refraction measurements on the Reykjanes Peninsular show that the crust is in general about 15 km thick over the whole Peninsula, and below the crust we have the boundary of the crust and the mantle. Geophysical measurements can detect signs of magma or magma chambers in the Earth's crust, but there are no signs of either magma pockets or magma chambers on the Reykjanes Peninsula. Therefore, it can be expected that magma finding its way to the surface in eruptions on the Reykjanes Peninsula comes directly from the mantle.

Geochemical analyses by the University of Iceland's Institute of Earth Sciences on lava samples from the ongoing eruption have now confirmed that this is the case, i.e. that the magma is primitive and comes directly from a mantle source of a depth of 15-20 km. It is estimated that the ongoing magma flow is in the order of about 8 m3/s, and there have been no significant changes in the lava flow since the eruption began.


The intensity of the eruption can be monitored by interpreting e.g. tremor graphs from seismometers. Here is an example from late March, of a tremor graph from the seismometer FAF, which is located just east of Fagradalsfjall, at about 2.5 km away from the eruption fissure. The strength of the eruption is detected within the frequency range of 2-4 Hz (blue line). According to the tremor graph from late March, the strength of the eruption at that time had in no way diminished, but instead increased steadily.

But for how long can the eruption be expected to last? A direct connection has now been established from the mantle to the surface in Geldingadalir. Primarily, it is the amount of available magma at the boundary of the crust and mantle that determines how much material eventually reaches the surface. There are examples of shield volcanic eruptions on the Reykjanes Peninsula that lasted for many years and produced copious amounts of lava, e.g., Þráinsskjöldur, Sandfellshæð and Heiðin há which are the largest lava shields on the Reykjanes Peninsula, over 7000 years old, and it can be assumed that a direct connection was also established from the mantle to the surface in these eruptions, based on geochemical analysis of the lava. There are also other examples of eruptions in Iceland with no evidence of magma chambers in the crust, that also lasted for a long time, such as e.g., the Surtsey eruption from 1963-1967.

It is unknown at this time for how long the eruption in Fagradalsfjall will last but given the steady magma flow and other indicators the eruption could last for longer than first expected.

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