The eruption at Fagradalsfjall has halted. No lava has been erupted in the period 18 September to 18 October 2021 (or to the time of writing). The seismic swarm at Kelir has lessened. Gas emissions have decreased. The aviation code has therefore been lowered.
The eruption will not be declared over for some time. It is not possible to tell if this is a temporary lull or the eruption has ended; the eruption may resume at the same location in Fagradalsfjall or at a new fissure. As the authorities have pointed out, this can only be determined in retrospect.
The volcanic hazards are currently: gas, high temperatures both in the area and the lava field, earthquakes and rockfalls.
It’s been a few days since we looked at the latest earthquake swarm at Kelir, which is on-going. Here are the updated plots.
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.
An Armchair Volcanologist 
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