No visible activity at the eruptive fissure that opened yesterday
Seismic activity has decreased, although notable micro seismicity persists
Updated April 2, at 15:15 UTC
- No eruptive activity has been observed at the fissure since yesterday afternoon, although glowing is still visible in the new lava field.
- The dike that formed yesterday is nearly 20 km long and is the longest one observed since the seismic unrest began in November 2023.
- Since yesterday morning, the ground has subsided more than 25 cm at the GPS station in Svartsengi (SENG) and continues to subside, although at a much slower rate.
- Approximately 90% of the magma that had accumulated in the magma chamber beneath Svartsengi since the end of the previous eruption in December 2024 has already transferred into the dike that formed on April 1.
- Over time, the likelihood of a new eruptive opening forming along the dike is decreasing, though it cannot be ruled out due to ongoing microseismicity in the area.
- Displacements were recorded on several GPS stations within Grindavík in connection with fault movements.
No activity has been observed at the eruptive fissure since yesterday afternoon, though glowing is still visible in the newly formed lava. The area remains unstable and hazardous. Measurements show that the lava volume erupted yesterday was about 0.4 million cubic meters. This estimate is based on data collected by experts from the Icelandic Institute of Natural History during an aerial survey of the eruption site yesterday afternoon. The lava field formed is the smallest one observed since the eruption sequence at Sundhnúkur crater row began in December 2023. Its volume is approximately 1/6 of the lava field from the January 2024 eruption, which was the second smallest event in the sequence.
The map shows the extent of the lava field formed during
yesterday's eruption, based on measurements by the Icelandic Institute of
Natural History.
Despite the small lava field, the dike that formed yesterday is nearly 20 km long—the longest since the onset of seismic unrest in November 2023. This suggests that the vast majority of magma that left the magma chamber beneath Svartsengi, about 90% of the volume accumulated since the previous eruption in December 2024, was used in forming the dike, and only a small portion reached the surface north of Grindavík.
Since yesterday morning, ground subsidence of more than 25 cm has been recorded at the GPS station in Svartsengi (SENG). The latest GPS measurements, from 8 a.m. this morning, confirm that subsidence is ongoing, though it has slowed significantly. Most of the magma that had accumulated since the last eruption has now moved from Svartsengi into the newly formed dike.
The graph shows 4-hour solutions for the GPS station SENG, located in Svartsengi. The data displays displacements in the north, east, and vertical directions (top, middle, bottom).
In connection with faulting within Grindavík, displacements were measured at several GPS stations in the town. The largest displacements occurred in the eastern part of the town. For instance, vertical movement of just over 10 cm and horizontal displacement of 5–8 cm was recorded at a station on Austurvegur. In the western part, horizontal movement of about 6 cm was measured at the station on the western edge of town. The total displacement observed within Grindavík since the onset of the event yesterday morning is up to about 50 cm, distributed over several faults in the area.
Seismicity and deformation have decreased since last night
Since the magma intrusion began around 06:30 yesterday morning, approximately 2,400 earthquakes have been detected in connection with the dike formation. The dike propagated steadily northeast until about 21:00 last night. Since then, activity has remained focused north of Fagradalsfjall and extending past Keilir. Seismic activity continues at a moderate level, but earthquake magnitudes have generally decreased compared to yesterday, as illustrated in the accompanying figure. Deformation measurements also indicate that the dike extends beyond Keilir, aligning with the distribution of seismicity.
Seismic activity above the dike from 06:30 on April 1 to 12:00 on
April 2. Top right: earthquake magnitude. Middle graph: number of earthquakes
per hour. Lower left: earthquake latitudes. Lower right: earthquake longitudes.
Likelihood of new eruptive opening decreasing over time
Given the current development in the southern part of the dike—marked by the absence of eruptive activity and low seismicity—it is increasingly unlikely that the eruption which began yesterday will reinitiate. Regarding the northeastern part of the dike, the likelihood of a new eruptive opening is also considered lower with time, although it cannot be ruled out due to persistent microseismicity in the area.
Deformation measurements over the coming days will provide a clearer picture of whether magma continues to flow from Svartsengi into the dike and how magma accumulation beneath Svartsengi evolves.
The hazard assessment has been updated and is valid until 15:00 on Friday, April 4, if no changes occur. Key updates include:
- Zone 3 (Sundhnúkur crater row): Overall hazard level now assessed as high (red), down from very high (purple).
- Zone 4 (Grindavík): Hazard level reduced to considerable (orange), from high (red), as the likelihood of a new eruptive opening has decreased.
- Zone 6: Hazard level now considered considerable (orange), previously high (red).
Geological inspection and monitoring of faults within Grindavík does not fall under the jurisdiction of the Icelandic Meteorological Office. However, GPS data from the IMO indicate fault movements within Grindavík related to the dike intrusion that formed on April 1.
The hazard map issued by the Icelandic Meteorological Office does not take into account the personal risk associated with entering the marked zones. The IMO refers instead to the risk assessment prepared by the Government Task Force on Grindavík and the recommendations of the Police Commissioner of Suðurnes.
Updated April 1st at 21:40 UTC
Based on webcam observations, no eruptive activity is visible at the fissure that opened this morning just north of Grindavík. Only minor glow is detectable here and there along the eruption fissure and within the lava field.
Seismic activity and deformation due to magma movement continue at the northeastern end of the dike that formed today. In total, seismic activity has been recorded across a roughly 20 km long area, extending from the southern end of the eruptive fissure to the location where seismicity is now most intense.
The earthquakes are still occurring at considerable depth, and there are no signs that the migrating magma is approaching the surface. According to model calculations from this afternoon, approximately 15 million cubic meters of magma had flowed from Svartsengi into the dike beneath the Sundhnúkur crater row, with only a small fraction of that volume having reached the surface. Prior to the eruption, around 22 million cubic meters of magma had accumulated in the magma reservoir beneath Svartsengi since the last eruption, suggesting that there may still be potential for further magma movement.
As long as seismic activity and deformation continue within the dike, the possibility of a new eruptive fissure opening must be considered. The most likely location for such an opening is in the area where seismic activity is currently most intense. Should an eruption occur, it may be accompanied by significant seismic activity, potentially noticeable to residents in Vogar.
Map showing reviewed earthquakes on the Reykjanes Peninsula since 6 AM, April 1st.
Updated April 1st at 18:30 PM
Volcanic activity north of Grindavík continues to decrease, with little visible activity on webcams or in recent drone footage. However, seismic activity continues. Earthquake activity near the southern part of the magma dike, close to Grindavík, has decreased, while activity at the northern end of the dike continues with similar intensity and has shifted even further north in recent hours. The seismic activity now extends almost 9 km farther north than the northernmost eruption fissure formed during the August 2024 eruption. The largest earthquakes have been around magnitude 3 and have been felt in Vogar, which is about 7 km northwest of the active area.
The map shows the location of earthquakes recorded today, April 1, 2025, along with known fault lines in the area. It indicates that the dominant fracture orientation in the region is NE-SW. No known fractures are mapped in the Vogar area.
Deformation measurements show that magma is still flowing from Svartsengi into the dike beneath the Sundhnúkur crater row. The seismic activity suggests that the magma is moving northeast. Earthquakes are occurring at depths of approximately 4–6 km, and deformation data from this area is currently being analyzed. As long as significant seismic activity and deformation continue, there remains a possibility that magma could reach the surface again in the Sundhnúkur crater row or nearby where activity is most concentrated.
The following map shows the lava extent as of 12:34 PM, formed by the eruption that began this morning. The map is based on ICEYE satellite imagery.
The hazard assessment has been updated and is valid until 3:00 PM tomorrow, April 2, unless conditions change. The hazard level for Zone 3 (Sundhnúkur crater row) remains very high (purple). In Zone 4 (Grindavík), the hazard level has been downgraded to high (red), due to reduced risk from ashfall and gas pollution. Changes have also been made to the hazard levels in Zones 7 and 5, which have been raised from moderate (yellow) to considerable (orange) due to ongoing seismic activity near the northeastern end of the dike.
Updated April 1st at 14:40 PM
According to webcam observations, the volcanic activity appears to have decreased significantly in the past hour.
Seismic activity is still ongoing but is mostly located at the northern and southern part of the dike intrusion.
Deformation measurements still show continued movement to the northeast, indicating that magma is still flowing into the dyke
Updated April 1st at 12:35 PM
The total length of the eruptive fissure is now about 1,200 meters and continues to extend southward.
The Icelandic Meteorological Office received a report that a hot water pipeline has broken in the northern part of Grindavík. This confirms that significant fault movements have occurred within the town.
Ongoing seismic activity is being recorded along the entire dike intrusion, with the most intense activity at the northeastern end. The intrusion now extends over 3 km further to the northeast than observed in previous eruptions. Deformation data also show continued displacement toward the northeast. This indicates that magma is still moving through the dike intrusion.
Updated April 1st at 11:00 AM
The fissure has extended southward. A new eruptive fissure has opened a few hundred meters inside the protective barriers north of Grindavík – between the barriers and the town itself.
(The new fissure opening is on the left on the photo).
The weather forecast indicates southwesterly winds today (Tuesday), carrying volcanic gas northeastward, including over the capital area. Winds are expected to calm in the evening, concentrating the gas pollution mainly around the eruptive fissure. Tomorrow morning (Wednesday), winds will shift to northwesterly and later westerly, dispersing the gas southeastward and later eastward – including over Þorlákshöfn and the Ölfus region. The gas dispersion forecast can be found here.
Seismic activity continues at the southern end of the magma intrusion and also north of Stóra-Skógfell. Earthquakes have also been measured near Reykjanestá, which are likely triggered (fault-slip) earthquakes due to stress release related to the activity in the Sundhnúkur crater row. More information about the activity can be found here .
Updated April 1st at 10:30 AM
Initial reports from the Coast Guard surveillance flight indicate that the fissure is now about 700 meters long and has remained relatively stable, although it cannot be ruled out that it may extend further north or south. Seismic activity and deformation measurements continue to show ongoing activity.
The hazard assessment has been updated. The alert level for the Sundhnúkur crater row (Zone 3) has been raised to very high hazard (purple), and in Grindavík (Zone 4) has been increased from high hazard (red) to very high hazard (purple). This hazard assessment is valid until April 2 at 10:30 AM, unless conditions change.
Updated April 1st at 10:00 AM
The fissure is now about 500 meters long and has reached through the protective barrier north of Grindavík. The fissure continues to grow, and it cannot be ruled out that it may continue to open further south.
Updates from the Coast Guard helicopter are still awaited.
The map shows the fissure that is now about 500 m. long.
Updated April 1st at 9:45 AM
An eruption has started just north of the protective barrier near Grindavík.
A Coast Guard helicopter will take off shortly to confirm the exact location and size of the eruption.
The length of the magma intrusion under the Sundhnúkur crater row that has already formed is about 11 km, which is the longest measured since November 11, 2023.
More information will be available soon.
Given the current wind direction, gas pollution from the eruption will be carried northeast toward the capital area. It is not possible to predict the intensity of the pollution.
Here is a link to the Icelandic Met Office's gas dispersion forecast.
Updated April 1st at 9:20 AM
The hazard assessment has been updated due to a magma intrusion in the Sundhnúkur crater row. As a result of the intrusion, the likelihood of a volcanic eruption has increased.
The hazard level in area 3 has been raised from “high hazard” to “very high hazard” (purple), and in area 4 (Grindavík), the hazard level has been raised from “considerable hazard” (orange) to “high hazard” (red).
The updated hazard assessment is valid until 9:00 AM on April 2, provided that conditions do not change.
Updated April 1st at 8:20 AM
Signals from GPS meters are stronger than those observed during recent events in the Sundhnúkur crater row. This indicates that a considerable amount of magma is currently on the move.
The signals show that magma is moving both to the northeast and southward toward Grindavík. At this stage, it is not possible to determine where the magma will emerge, but it's noteworthy that the southern displacement of deformation signals was not observed during the eruption that began in November 2024.
Emergency responders in Grindavík have reported that earthquakes can be felt in the town, and signs of deformation are also visible there, suggesting that fault movements could occur within the town itself.
Updated on April 1st at 7.25 AM
An earthquake swarm began at around 6:30 AM this morning on the Sundhnúks Crater Row. The swarm is located between Sýlingarfell and Stóra-Skógfell, in a similar are as seen prior to previous eruptions.
The earthquake swarm was followed by a clear change in deformation and pressure changes in boreholes operated by HS Orka. Both independent measurements were a clear sign of the onset of a magma intrusion.
No magma has reached the surface as of now, but an eruption is likely to occur.
The new will be updated.
