Eruptive activity at the new fissure in Meradalir stalled on 21st August 2022 at around 6:00 am. The seismic tremor ceased following the emission of a blue grey plume. Lava was seen on webcams to be still flowing from the crater just before then. We await to see whether or not this is the end of this eruptive episode.
To quote IMO, “A new chapter is about to begin in the Fagradalsfjall fires, but whether the seismic activity will recur and it will erupt again in the near future or not, time will tell.”
What do we know of the eruption so far? The eruption started on 3rd August 2022. The initial discharge rate was c. 32 cubic metres per second, dwindling to 2 cubic metres per second by 16th August 2022. The total volume of lava emitted by 16th August 2022 was 12 million cubic metres, c. 8% of that emitted by the Geldingadalir eruption last year. At the crater the lava is 20 to 30 metres deep and 40 metres deep by the crater rims, themselves. Over the rest of the lava field the lava is between 5 and 15 metres deep. The new lava has displaced cooling older lava causing it to rise by 3 to 5 metres in places.
The lava composition is similar to the basalt emitted by Geldingadalir in September 2021. The K2O / TiO2 ratio ranges from 9.3 to 9.4 and the MgO is around 8.4 wt(%).
So, it was hours, not days! The eruption started near Fagradalsfjall / Meradalir yesterday at around 13:18 about 1.5 km north of Stóra-Hrut on a north-easterly southwest fissure. The onset was detected by a local webcam and later confirmed by scientists. The alert level is currently orange (Volcanic eruption is underway with no or minor ash emission.)
Like the previous eruption, lava is contained by the local geography so no infrastructure is currently threatened. Gas emissions are, however, a hazard. The lava flow is estimated to be 5 – 10 times that of Geldingadalir at 32 cubic meters per second in the first 24 hours; gas emissions may well be similarly larger.
Visitors are advised not to approach the site at the moment. When the site is open, bear in mind that it is not an easy walk, so for the fit only, and visitors should be properly prepared, including having gas masks and metres.
At the time of updating, we did not have confirmation of the coordinates of the eruption site, so we have guessed based on maps of the fissure. The plots will be updated when more up to date information becomes available.
Seismic activity continues in the Svartsengi area, extending to the Sundhnúkur crater row. The earthquakes in the vicinity of Mount Þorbjörn appear to be getting shallower today as at the time of writing.
The Sundhnúkur crater row erupted c. 2,360 years ago. It is accredited with creating the Hópsnes/Þórkötlustaðanes land spit to the east of Grindavík.
Fig 8: Bird’s eye view of the Svartsengi area and Gringavík. Image from Google Earth; yellow text added by the author.
Here are our updated earthquake plots to 26th May 2022 15:06.
The following video shows both the geoscatter plots by day from 17th April 2022 to 26th May 2022 in the swarm for the western Reykjanes Peninsula, and the scatter plots for the same period for the area around Mount Þorbjörn.
While the earthquake plots are highly suggestive of more shallow magma ascent, we need to bear in mind that this area is on the plate boundary, the Mid Atlantic Ridge. Some of the seismic activity may be existing faults moving to accommodate the magma. Time will tell when and where magma emerges.
For the latest updates and alerts, please consult with IMO or the local authorities.
Armchair Volcanologist
Original Post 24th May 2022
The earthquake swarm that started on 17th April 2022 on the western Reykjanes Peninsula continues. Today we are plotting activity at the Svartsengi area near Mount Þorbjörn, which lies to the north of Grindavík, Iceland. We have used Mount Þorbjörn as the marker for Svartsengi in our plots.
Fig 1: Image cropped from one by Arian Zwegers of the Blue Lagoon looking towards Mount Þorbjörn. Published under CC-BY SA-2.0. Source: Þorbjörn (mountain) – Wikipedia
IMO reports that there has been significant uplift of 40mm to 45mm during the swarm in the area north of Grindavík indicative of magmatic activity.
From a simpler scatter plot and a geodensity plot, we can see much of the activity has occurred near Mt Þorbjörn or Svartsengi in the area enclosed in the green box below.
An earthquake swarm started on the Reykjanes Peninsula on 17th April 2022 and is continuing at the time of writing. This swarm is part of a larger volcano-tectonic episode that started at the end of 2019 on the Reykjanes Peninsula, including the eruption at Geldingadalir.
Local volcanologists are reporting now that recent ground deformation of 3.5cm suggests a magma intrusion in the vicinity of Svartsengi, north of the town of Grindavík. Magma is believed to be pooling at a depth of c. 4km between Mount Þorbjörn and the Eldvörp crater row. This is an area which can produce large earthquakes of 6.5M. People are advised to avoid areas where landslip is likely.
Fig 1: Image cropped from a photo by Roman Zacharij of Grindavik, Iceland (Source: Wikimedia Commons, Public Domain).
We have updated our earthquake plots to show the swarm to date. Our plots exclude an earthquake occurring earlier today with a depth of 40.7km to keep the detail in the plots showing depth; the earthquake omitted is 19/05/2022, 00:11:14, 63.77°N , 22.75°W, 40.7km, 1 magnitude. Since we downloaded the data at 09:55 am today, there has been a 3.0 magnitude, 4.9 km NNE of Grindavík.
Our plots show possible doming in the vicinity of Mount Þorbjörn and the Svartsengi Volcanic System.
Seismic activity at Fagradalsfjall, Iceland, has remained low. The recent swarm is now considered over. The aviation code has been lowered to yellow as a result.
We have updated the earthquake plots for Fagradalsfjall, Iceland, for the swarm which started on 21 December 2021.
The swarm had an intense initial period while magma moved along a lateral dike, followed by a less intense period, accompanied by magma ascent. The Icelandic Met Office, IMO, say that the swarm is following the same pattern as that which preceded the eruption in March 2021.
Magma is ascending under Fagradalsfjall, itself. The outlying earthquakes, e.g., at Svartsengi and Krýsuvík, are what Iceland calls triggered earthquakes. Triggered earthquakes are tectonic in nature, arising as local faults respond to magma movement.
Following a drop in seismicity over the past couple of days, visitors are now advised to avoid the area.
A similar drop in seismicity was observed immediately before the March 2021 eruption.
If the volcano does erupt again, this would be considered a new eruption in the same place; the earlier eruption was declared over three months after the cessation of activity on 19 September 2021.
Update 28/12/2021
The earthquake swarm at Fagradalsfjall, Iceland, is continuing. While the swarm has slowed down a bit, 19,000 earthquakes have been recorded by the automatic SIL system since the swarm started. 14 earthquakes over 4.0 magnitude have occurred. An alert for the risk of rockfall and landslides in the area has been raised; visitors are advised to stay away from the area.
We have plotted the confirmed earthquakes from 20 December 2021 to 28 December 12:50. This shows the dike propagation south west of Geldingadalur, with additional activity near Kýsuvík and Svartsengi.
Only time will tell where and when lava will emerge. In the meantime, if you are lucky enough to be in the area, be aware of the risk of rock fall and landslip.
A large earthquake swarm started at Fagradalsfjall late on 21 December 2021, 2-4 km NE of Geldingadalir, thought to be caused by a lateral dike intrusion. Due to the increased seismic activity, the aviation code was raised to Orange yesterday, 22 December 2021.
Fig 1: Icelandic Met Office, IMO’s map of the swarm. Source: IMO
The eruption at Fagradalsfjall had stalled on 18 September 2021, with no new lava flows to the time of writing. Ground deformation indicated that magma was still flowing into the crust.
Fig 2: Ground deformation at Krýsuvík. The red line denotes the start of the March 2021 eruption. Source: IMO
We have downloaded and plotted the earthquakes from 1 September 2021 to 23 September 2021 (source for raw data: IMO ). This includes the swarm which started near Mount Kelir in late September 2021, which may or may not have heralded the current reactivation of the dike.
We are no longer updating this post; future updates will be included in new posts.
Update 2 12.10.2021: Plots of the Earthquake Swarm SSW of Mount Kelir, 27/09/2021 to Date
Fig 16: Mount Kelir, cropped from an image by Michal Klajban, published under CC BY-SA 4.0. Source: Wikimedia Commons
Mount Kelir is at the northern end of the earthquake swarm which started on 22 February 2021. In that swarm, earthquakes started near Mount Kelir and migrated towards and beyond Fagradalsfjall prior to the eruption at Geldingadalir on 19 March 2021.
The current swarm which started on 27 September 2021 near Mount Kelir is ongoing at the time of writing. Over 10,000 earthquakes have been recorded, of which IMO have confirmed c. 1,245. It is thought that an eruption may ensue near Mount Kelir.
We have plotted the earthquakes and made a video of the geoscatter and scatter plots.
Whether or not a new eruptive site emerges, magma migrates to the existing site at Fagradalsfjall, or, it all quietens down, only time will tell. At the moment the swarm is migrating SSW.
Source for raw earthquake data: Icelandic Met Office: IMO
12.10.2021 1: Update on La Palma Seismicity
Good Morning!
Let’s take look at status of the eruption and seismicity at La Palma.
The eruption is still going strong. The cone has grown substantially, despite partial collapses.
Fig 11: Cone growth. On the left, the new cone on 20 September, 2021, cropped from an image by Eduardo Robaina, published under CC BY-SA 3.0; on the right, screen shot earlier today from RTVC
The following was reported earlier today:
The lava reached the cement works, Callejón de la Gata, today. Local residents were confined to their homes due to the risk of toxic fumes from burning chemicals.
A large volume of lava was emitted after the wall of the lava lake [cone?] was destroyed.
The northern arm of the lava flow is now 300 metres from the sea and expected to make a new lava delta near the beach of Perdido.
591.1 hectares have been affected by lava. This includes 132 hectares of crops , of which 70 hectares were banana crops; 33 hectares vineyards; and, 8 hectares avocado crops.
The maximum width of the lava flow is 1,520 metres.
1,281 buildings have been impacted, of which 1,186 have been destroyed.
The lava delta is now 34 hectares.
Seismicity remains high. To date, over 35,000 earthquakes have been recorded. The most recent earthquakes remain below 10km, with depths reaching more than 20km.
The high level of seismicity is thought to indicate rising magma because there have been spasmodic tremors and a strong volcanic tremor at 18 Hz; the latter may be from depressurisation of magma at a depth of c. 10km. In the absence of increased ground deformation, it is not known when or how magma may reach the surface. If it reaches the surface, it may follow the current conduit or emerge at new fissures.
Fig 12: Amplitude of seismic signal, source: IGN. Green line denotes onset of the eruption.
04.10.2021: Update Fagradalsfjall Seismic Swarm near Kelir
The swarm near Mount Kelir is ongoing. IMO report that 6.200 earthquakes have occurred in the swarm, although c.624 have been confirmed at the time of writing (Sources: IMO_Earthquakes and Skjálfta-Lísa (vedur.is)).
We have analysed and plotted the swarm. It would appear that the swarm is ascending but still in the crust. The largest earthquake with a magnitude of 4.16 had a depth of 5.669 km.
Good Morning! Today we provide an update on Fagradalsfjall, Cumbre Vieja (with video of earthquake swarms) and Askja.
Fagradalsfjall, Iceland
Fig 1: Mount Kelir, cropped from an image by Michal Klajban, published under CC BY-SA 4.0. Source: Wikimedia Commons
Fagradalsfjall celebrated the six-month anniversary of the start of the eruption, which occurred on 19 March 2021, by taking a break. Low level activity has been observed since 18 September 2021.
An earthquake swarm stared on 27 September 2021 south of Mount Kelir. This is located near the northern end of the earthquake swarms earlier this year which preceded the eruption at Geldingadalir.
We have plotted the swarm to see what is going on.
While it is not clear what the cause of the swarm is (new magma or the crust adjusting to changes in tension), people are advised to avoid the area for the time being. If an eruption does occur near Kelir, it is expected to be similar to that at Fagradalsfjall. The aviation code is still orange.
Cumbre Vieja, Canary Islands
Fig 3: Cumbre Vieja eruption on 20/09/2021, cropped from an image by Eduardo Robaina, published under CC BY-SA 3.0. Source:Wikimedia Commons
The eruption is still going strong. The vents have produced ash columns, jetting lava and effusive lava flows.
Lava reached the sea, following the opening of a new vent earlier this week, which emitted more effusive lava. The lava travelled at 300 m/hr, crossing the coastal road and cascading over 100m high cliffs at Los Guirres. The lava is forming a delta, which has reached an impressive size 21 hectares.
There are now four eruptive vents: a new effusive vent opened 400m north of the main vent on Thursday; and, two more opened on Friday 15 metres apart and 600m north west of the main cone. Lava from Thursday’s new vent also made it to the sea via a flow parallel to the original one. A fumarolic field has developed on the north side of the main vent.
Over 80 million cubic metres of lava have been erupted. Sadly, this has damaged 1,005 buildings, of which 870 have been destroyed. 30.2km of road has been impacted, of which 27.7km have been destroyed. Ash now covers 3,172.9 hectares of land.
SO2 levels are higher but not considered a risk for the population at the moment.
Earthquakes are occurring near the area start of the swarm which preceded the eruption. They are deeper than the earlier swarm leading to concern that lava may be fed from a deeper reservoir. We have plotted the current swarm and previous swarms from 2017 to date.
Time to check out the current status of the volcanoes we have been following, especially as the situation has changed for some.
Askja
Fig 1: Image of Askja caldera by M Ryan, USGS, public domain.
Inflation, thought to be caused by a magma intrusion at a depth of 2km-3 km, started in early August. GPS data and satellite images detected uplift of 5cm per month; the uplift centred on the western edge of the Öskjuvatn caldera.
The aviation code was raised to yellow on 9 September 2021, following near vertical uplift of 7cm.
The epicentres of current earthquake swarm are mostly to the east of the Öskjuvatn caldera following a near linear route, starting at, or near, the area of maximum earthquake density for the period 1995 to 09.09.2021, and heading for the Viti explosion crater; seismic activity is on the opposite side from the area of maximum uplift.
Seismicity for 2021 looks pretty similar; the current swarm follows the pattern of earlier seismicity.
Fig 4a: Crater at Fagradalsfjall erupting on 14 September 2021.
The crater at fissure 5 has grown considerably since we last posted about it; it now dominates the surround hills. The eruption paused on 2nd September 2021, taking a well-earned break; steam and gas emissions continued. The eruption resumed a couple of days ago. The aviation code remains orange.
Fig 5: Merapi 2011 with Prambanan in the foreground, cropped from an image of Prambanan by Arabsalam, published under CC BY-SA 4.0. Source: Prambanan Java243. Prambanan is an 8th Century Hindu temple compound located approximately 17 kilometres (11 mi) northeast of the city of Yogyakarta and designated a UNECSO World Heritage Site.
Both lava domes situated below the south west caldera rim continue to grow, producing numerous pyroclastic flows and avalanches.
The alert level remains at thee and there is a 3km – 5km exclusion zone.
Grímsvötn
A jökulhlaup started on 1 September 2021 from the western Skaftlá caldera; the peak flow rate reached 520 m3/s on 2 September 2021. Warnings were issued of the hazard from H2S from water draining from the caldera lake. The ice-shelf had subsided 1m by 5 September 2021.
On 6 September 2021, the peak flow rate increased to 610 m3/s, thought to be due to a second release of water from the caldera lake – this time on the eastern side.
The aviation code remains at yellow.
Fig 6: Top image shows the water levels reached at Eldvatn and the lower one, flow rate. Source: IMO
La Soufrière St. Vincent
The last ash emissions were on 22 April 2021. Seismicity has since remained low. Gas and steam plumes have been observed rising from the crater.
The alert level remains at orange.
Mount Pelée
Volcano-tectonic earthquakes are still occurring in the edifice at depths between 0.2km to 1.2km. The area of discoloured, downgraded, burned and dead vegetation remains on the south west flanks.
At the end of July 2021 underwater gas emissions started between St Pierre and the Prêcheur. This will be investigated to ascertain how it links with the volcano.
The aviation code remains at yellow.
Mount Nyiragongo
The volcano is still active. A [gravitational] collapse in the crater caused and ash plume; ash reached Goma. Incandescence was seen on 26th July 2021 and a gas and ash plume emerged on 4th August 2021.
Updated earthquake density video added (uses satellite image as background). 12.04.2021
Good Morning!
Geldingadalur – Where Are We at Now?
Since we last wrote, the new volcano at Geldingadalur has continued to erupt with a lava output rate between 5 m3 per second and 10 m3 per second, filling the Geldingadalur valley with more lava. The University of Iceland has confirmed that the early lava erupted has a magnesium content of 8.5%, a low titanium dioxide content and is more depleted in rare earth elements (low HREE to LREE ratio) than earlier historic lavas, indicating that it is a more primitive lava sourced from the lithospheric mantle at a depth of between 17 km and 20 km.
On 5 April 2021 at around midday, a new fissure opened up about 700 m north east of the original eruption site. The fissure, spotted by a sightseeing helicopter, was quickly confirmed by the RUV.is webcam monitoring Geldingadalur. Fortunately, no-one was in the vicinity at the time due to bad weather and sheer good luck; the site had been open to visitors at the time. The fissure is around 200 m long. Lava from the fissure is flowing into the Meradalir valley.
Fig 1: New fissure on 05.04.2021 in the foreground with lava flowing to Meradalir on the left of the image. The original Geldingadalur eruption is on the right of the image. Photo IMO.
Fig 2: Lava from the first new fissure entering Meradalir at 15:00 06.04.2021. The fissure itself is on the ridge in the background (Photograph: Public Protection/Björn Oddsson).
At around midnight on 6 April 2021, a second fissure opened up between the earlier fissure and the original eruption site. This had been preceded by a landslip earlier in the day. Lava from this fissure is now flowing into both the Geldingadalur and Meradalir valleys, linking the eruption sites. It is believed that the three eruption sites belong to the same fissure.
Fig 3: Photograph from Public Protection/Björn Oddsson showing the three eruption sites and lava flows.
Fig 4: Map showing the location of the three eruption sites from IMO. The fissures are shown as red lines and dots; and, lava flows are based on photography.
Unfortunately, one of the webcams set up by mbl.is to monitor the Geldingadalur cones was lost; its last image is shown below. We thank mbl.is for providing the webcam; we viewed its images with a lot of interest.
Fig 5: Screenshot from the mbl.is webcam.is set up to monitor the cones at Geldingadalur. This may be this webcam’s last image. The lava flow to the lower left of the image is from the newest fissure.
Like the original eruption site, neither fissure opening was heralded by an increase in seismicity in the immediate vicinity.
Seismicity Post the Initial Eruption
We have updated our earthquake plots for the period 19.03.2021 to 06.04.2021. We can confirm that there is very little earthquake activity in the vicinity of Geldingadalur. The fissures are not giving any seismic warning; seismic activity near Keilir dominates. It is perhaps surprising that magma has not made its way to the surface north east of Fagradalsfjall; does magma finds it easier to make its way through older fault-ridden Pleistocene rock that has not been covered in tougher historic lavas?
We have also tried our hand at making a video of the earthquake density plots by month from 2008 to 6 April 2021. Months are numbered from January 2008 (Month 1) to April 2021 (Month 160, which only has 6 days). If you make it all the way through, you will see that Fagradalsfjall has had several swarms, albeit much smaller than the current one. Enjoy!
An Armchair Volcanologist 
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