An eruption has started on Sundhnúksgígaröð crater row
Updated at 17:30
Updated hazard assessment map due to the eruption near Sundhnúkar
The Icelandic Meteorological Office has issued an updated hazard assessment map, valid until 15:00 on 18 July unless activity changes. The alert level for the volcanic system remains at the highest level, 3.
The hazard assessment is based on recent observations and shows the following:
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The eruptive fissure has lengthened and now extends farther north than previous fissures since December 2023.
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Lava flow continues but has decreased in intensity.
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Most of the lava is accumulating east of the fissure and is likely to fill depressions in the area.
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Seismic activity has decreased significantly, now measuring only a few small earthquakes per hour.
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Gas emissions and wildfires continue to contribute to pollution.
Volcanic tremor and activity
The eruption at Sundhnúksgígaröð continues, but measurements show a decline in its intensity since this morning. The image below shows the development of tremor measurements at seismic station Fad, north of Fagradalsfjall. The lines represent vibration strength across different frequency bands.
Strong tremor was recorded early this morning as the eruption began but has steadily decreased since.
Lava extent
The map below is based on ICEYE satellite observations taken shortly before noon today and shows the extent of the lava from this eruption. At that time, the lava field covered approximately 3.2 km².
The map also shows the estimated location of the eruptive fissure at Sundhnúksgígaröð at around 12:00. Lava has flowed north and northeast from the source, spreading widely across Kálffellsheiði and toward Svartsengi.
The light purple color indicates the new lava field, red lines mark fissures, and the brown grid delineates the observation area and populated areas.
Sulfur dioxide in the atmosphere
Wildfires are currently considered the greatest hazard to inhabited areas, but pollution from these fires is not detected by SO₂ monitors and is not reflected in the current air quality forecast.
The image below shows sulfur dioxide (SO₂) concentrations over Iceland at 13:33 on 16 July 2025, according to Sentinel-5P satellite measurements. Colors indicate pollution strength: light blue for low concentrations, reddish-brown for high concentrations.
High concentrations are measured over the Reykjanes Peninsula, extending west and southwest over the ocean with the wind.
Hazard assessment for the eruption
Below is the hazard assessment map from the Icelandic Meteorological Office, showing the current assessment of hazards due to the eruption near Sundhnúksgígaröð and how hazard zones are defined based on the current situation. The map describes both existing hazards and those that could develop if activity continues.
All defined observation areas on the map are colored yellow (some hazard), but the map also highlights red zones where the greatest hazards from lava, tephra, and gas pollution could occur.
The hazard assessment map will next be updated on 18 July unless changes in activity or weather require earlier action.
The hazard assessment describes the hazards currently present in the area as well as those that could develop if activity continues in the Svartsengi system.
Updated at 12:00
The latest observations show that the eruption is no longer confined to a single fissure. The larger fissure at the Sundhnúkur crater row is estimated to be about 2.4 km long. In addition, a smaller fissure has opened west of Fagradalsfjall and was estimated at about 500 meters in length during an aerial survey by the Icelandic Meteorological Office and the Icelandic Coast Guard.
Updated at 08:45
Seismic activity has decreased during the early morning, but lava flow continues, moving both east and west, with a greater flow to the east. Poor visibility limits the overview, particularly to the west.
So-called "witch's hair" has been reported drifting in the wind. These are fine glass fibers formed when lava droplets cool rapidly and stretch. They are very light and can travel long distances. Witch's hair can cause skin and eye irritation, and people are advised to take precautions when outdoors near the eruption site.
High levels of gas pollution are being measured in Reykjanesbær but are decreasing. Residents are advised to stay indoors, keep windows closed, and turn off ventilation systems. It is best to breathe through the nose.
This report will be updated as new data becomes available. An updated hazard map is being prepared and will be published later today.
Updated 5:20
Southeasterly winds today, gas pollution can be expected over Reykjanesbær, Vogar, Sandgerði and Garð.
A link to IMO's gas dispersion.
Updated at 5:05
The eruptive fissure is approximately 700 to 1000 m long. The fissure has been propagating to the north since the eruption started.
Lava is mostly flowing to the SE and is not approaching any infrastructure.
Below is a screenshot from a webcamera located just north of Fagradalsfjall and is looking towards SW.
Updated at 3:56
An eruption has started. The location is southeast of Litla-Skógfell.
Updated at 3:10
The earthquake activity is more intense north of the area where the swarm started.
The hazard assessment has been updated.
Updated at 2:25
The earthquakes in the seismic swarm are mostly occurring at 4 to 6 km depth. That indicates that magma is not moving towards the surface at this point.
Updated at 2:11
According to seismicity and real time GNSS data the dike forming below the Sundhnúksgígar crater row is moving southwards rather than north.
Updated at 01:55
According to real time GNSS data the deformation is still minor indicating that the seismicity is still small compared to previous events.
Updated at 01:20
Intense seismic swarm has started on the Sundhnúkur Crater Row and monitoring data
Intense seismic swarm has started on the Sundhnúksgígar Crater Row and monitoring data is indicating that an dike intrusion has started. The likelihood of an eruption remains high while the intrusion is ongoing.
The seismicity is located between Stóra-Skógfell and Sýlingarfell, a similar location as previous dike intrusion started on the Sundhnúksgígar Crater Row.
The news will be updated
