The seismicity continues at increasing levels.
Earthquakes have continues to pick up both in numbers and strength.
4 quakes on 24 December were recorded, of which 3 with magnitudes of 4 and 1 with a maximum magnitude of 4.8. 3000 earthquakes have been detected in total since the seismic crisis started on 21 December.
The activity has been intensifying and more frequent under the Fagradalsfjall volcano, but it also occurred near Grindavík and Kleifarvatn.
The latest interferogram measurements (InSAR) detected same pre-eruptive ground deformation (see attached image) as seen in late February reflecting continued magma intrusion and migration under the surface, supported also by continued deformation of the surface.
intense seismic activity continues
Update Fri 24 Dec 2021 02:10

Ground deformation measured during 16-22 Dec in the area of Fagradalsfjall (image: IMO)
The elevated seismic activity continues.
2000 earthquakes have been detected in total over the last 17 hours at 5-8 km depth suggesting that the flux of magma rising within the volcano is significant and most likely scenario of an imminent eruption is considered to occur in Geldingadalir eruption site.
GPS instruments detected a rapid ground deformation, another tell-tale sign of an impending eruption, which is similar to the pre-eruption measurements before 19 March.
Source: Icelandic Meteorological Office volcano activity update 23 December 2021seismic activity has been picking up since yesterday, Aviation Color Code raised to orange
Update Thu 23 Dec 2021 01:38

Distribution of earthquakes over the past 24 hours (image: IMO)
The Icelandic Meteorological Office (IMO) detected an
increasing trend of seismic activity began yesterday.
18 quakes at regular intervals of 1 to 10 per minute have been recorded located 2-4 km northeast of Geldingadalir followed by a significant rise of seismic energy at about 00:30 local time.
26 quakes during the past 24 hours were recorded with magnitudes of 3 or more.
1400 earthquakes have been detected in total over the last 24 hours, of which the largest quake with a maximum magnitude of 4.9 occurred at 09:23 local time and was widely felt on the SW corner.
Earthquakes and the increase in seismic activity reflect magma intrusions at shallow level and likely push its way into same dikes as it used to erupt before.
As mentioned in the
latest report, the expansion continues to be measured meaning that magma is probably accumulating under the surface and it's difficult to predict what will happen next.
Based on the increased seismic activity, the IMO has changed the Aviation Color Code to "orange".
volcano remains quiet even three months since eruption ceased
Update Sun 19 Dec 2021 20:33

Degassing activity at the volcano on 15 Dec (image: MBL)
It has been three months yesterday since the last lava flow was seen at the eruption site. The eruption that began on 19 March, lasted exactly 6 months.
"Of course, it is always a matter of saying exactly when a particular eruption is over, because volcanic activity can be very cyclical", says Sara Barsotti, director of volcanic eruptions at the Icelandic Meteorological Office.
"We have been pointing out ever since the earthquakes in Geldingadalur began that the Reykjanes peninsula is active in terms of earthquakes and volcanic activity, and history tells us that volcanic activity there occurs in cycles", says Sara.
Expansion continues to be measured meaning that magma is probably accumulating under the surface and it's difficult to predict what will happen next.
eruption site is currently calm for now, slight inflation detected
Update Fri 19 Nov 2021 20:04

Yellow-to-red colors depict a new inflation on the Reykjanes peninsula (image: IMO)
The effusive eruption at the volcano has already ended or has remained mostly calm since 18 September as lava flows have stopped.
During the eruption, instruments continued to detect a deflation over the eruption site as magma used to leave from the deep chamber and pushed its way up to the surface.
However, GNSS and InSAR instruments observed a new inflation on the Reykjanes peninsula since the end of September. This is likely reflecting a renewed magma intrusion and migration under the surface, supported also by continued deformation of the surface.
A swarm of small earthquakes occurred in late September, located in the south of Keilir area, that may be related to a new batch of magma rising inside the volcano's conduits, although no new ground deformation has been detected during this time period.
The current inflation may not be associated with a new impending eruption.
This may take years or decades what will happens next at Reykjanes peninsula.
Source: Icelandic Meteorological Office volcano activity update 19 November 2021Fagradalsfjall volcano (Reykjanes peninsula, Iceland): lava overflowed dam and cut off another hiking trail to eruption site
Sat, 18 Sep 2021, 04:14
04:14 AM | BY: MARTIN

Lava flows crossed the hiking trail (image: @EIlyinskaya/twitter)

Aerial view of lava flows filling up the Nátthagi valley (bottom right) (image: @EIlyinskaya/twitter)

A new lava flow map depicts the affected area of hiking trail (image: @EIlyinskaya/twitter)

Lava flows just before the overtook the artificial dam (image: @EIlyinskaya/twitter)
After the resumption of the effusive eruption at the current site one week ago, the activity shows signs of increasing.
It proves a formation of new lava flows in the upper part of the Nátthagi valley that have continued to fill up the valley.
The effusion of lava continues at elevated discharge rate. This is most likely reflecting at higher pace of the lava that overtook the artificial dam, crossed the hiking trail and leading towards the southern ring road.
Nátthagi valley by now is largely filled with lava flows.
Fagradalsfjall volcano (Reykjanes peninsula, Iceland): high-resolution lava flow map update
Thu, 16 Sep 2021, 05:59
05:59 AM | BY: MARTIN

A new lava flow map of the current eruption from 15 September (image: @geoviews/twitter)
A new lava flow map of the current eruption site has been published and updated today. The map depicts a spreading field of lava that continues to advance gradually and slowly filling up the valley of Nátthagi.
The lava flows have filled up valleys of the Geldingadalir, Meradalir, Meradalur and Nátthagi since the eruption started.
The picture also shows all artificial barriers marked as red lines.
Fagradalsfjall volcano (Reykjanes peninsula, Iceland): activity is back after 7 days of calm and illuminates sky over Grindavik
Tue, 14 Sep 2021, 03:29
03:29 AM | BY: MARTIN

Fountaining continues at the lava field in Geldingadalir valley (image: @EIlyinskaya/twitter)

Glowing steam at the current eruption site from live webcam accompanies the activity at the time of this update (image: Youtube/RÚV)

Lava flow returned to the main crater (image: @szharangi/twitter)

Glowing steam illuminates the sky over Grindavik (image: @Vedurstofan/twitter)
After the longest break of 7 days of apparent calm in the effusive activity, it picked up again on 11 September as
a new lava flow returned to the western flank of the main crater and continues to descend into the Geldingadalir valley.
Small lava fountains are being observed in the field of lava in the Geldingadalir valley and continue to erupt.
The activity quickly intensified accompanied by a strongly rising signal of volcanic tremor indicating rapid magma flux towards the surface.
Timelapse video of the returned effusive eruption on 11 September showing illuminated sky over Grindavik (source: @ar_etsch/twitter)
Fagradalsfjall volcano (Reykjanes peninsula, Iceland): eruption continues with regular pulses of lava fountains
Thu, 26 Aug 2021, 16:16
16:16 PM | BY: T

Lava fountain and two lava flows this morning at Fagradalsfjall in Iceland (image: RUV webcam)
The eruption continues in a very similar way as during the past days, with alternating pulses of lava erupting from the vent and quiet phases, at a rhythm of 12-16 hours approximately between the lava pulses.
During the active phases, the crater fills with lava and "boils" over, often forming fountains, and forms multiple lava flows on the surface.
This morning, a new lava flow made its way towards the south and then turned east, while a smaller lava flow emitted a bit further to the west continued southwards towards Natthagi valley (s. image).
The size of the cone is constantly growing although its diameter at the top has decreased. As a consequence of the smaller volume of the bowl-shaped crater, the lava fountains are rising taller.
Activity oscillates like heartbeat from almost absence to spectacular lava overflows
Update Thu 19 Aug 2021 17:42

Eruption in Iceland this evening (image: RUV live webcam)

Oscillating tremor reflecting the regular magma surges (image: IMO)
The eruption continues with no signs of ending, even though it has been going through rhythmically alternating phases of very low to very high levels. Roughly every 24 hours, it changes from one to the other extreme.
When it is high, the crater is filled with a lava lake that overflows on its rims and produces spectacular flows, as can be seen in the recent video below or in the view of the webcam right now (attached); when it is low, there is usually no visible activity at the surface.
Video:
Volcanologist Þorvaldur Þórðarson explained that these lava pulses are likely caused by large gas bubbles rising through the magma in the underground feeding system, pushing the magma out of the vent onto the surface.
Since these lava surges come at very regular intervals, these large gas bubbles must rise in very orderly pattern. Nature likes such regular processes and creates order,- think of the rhythmic behavior of geysers, for example.
The gas bubbles that are responsible for the peaks of activity at Fagradalsfjall are of course orders of magnitude larger than most similar phenomena. Likely, they originate at the top of the magma source in the upper mantle at 15-17 km depth, and once large enough to overcome a critical threshold of some sorts, they start rising and pushing the magma column upwards, resulting in the surface activity seen a short time after.