Tag Archives: Geldingadalsgos

Caribbean, Iceland, La Soufrière St. Vincent, Reykjanes Peninsula

Update on the eruptions at Fagradalsfjall and La Soufrière St Vincent, and status of Mount Pelée

Good Afternoon!

Fig 1: Image from Civil Protection / Webcam 11.05.2021

Fagradalsfjall

At the time of writing the eruption at Fagradalsfjall is not only continuing unabated but getting stronger.  After the opening of five new fissures, eruptive activity has focused on one crater, fissure 5. Lava now covers the Geldingadalur valley floor and threatens to engulf the first cones; lava has been flowing steadily into Meradalir since 24 April 2021.

Eruptive activity changed from continuous fountaining with effusive lava flows to periodic jetting after midnight on 2 May 2021. The change is thought to be due to degassing of the magma in the upper part of the eruption channel where a small chamber may have formed.  Each jet is now accompanied by strong gas emissions.  Lava flow, itself, is mostly being carried in lava channels under the crater rim, rather than ejected in the current jets so periodic jetting has not adversely impacted the output.

The onset of jetting can be seen in the tremor plots from local stations. We have included KRI because, being further away, we can see more of the lower frequency lines.

Fig 2: Tremor plots for KRI and MER showing the onset of jetting on 02 May 2021. Source: IMO
Fig 3: Unrest seen on seismometers near the eruption sites with pulses in volcanic activity from midnight on 2 May 2021.  Source: IMO
Fig 4: This image shows the unrest on days 8-9. May. Source:  IMO

Some stats as at 10 May 2021 (Source: Institute of Earth Sciences (hi.is))

  • Area of the Geldingadalsgos lava field: 1.78 Km2 (1.41Km2, 03 May 2021)
  • Volume of erupted lava: 30.7 million m3 (23.0 million m3, 03 May 2021)
  • Lava discharge rate: 12.9m3/s, (7.5m3/s, 03 May 2021)
  • Mg0: varies from 8.5 to 9.8
  • K20/Ti202 ratio: increasing from 0.1 to 0.3

In the first two weeks of the eruption lava flow decreased steadily from 7-8m3/s to 4-5m3/s.  In the second two weeks, five new fissures opened with lava flow varying between 5 – 8m3/s.  In the two weeks to 3 May 2021, one crater dominated with lava flow increasing.  In the week to 10 May 2021, there has been a large increase in the output of lava to 12.9m3/s; the lava field now covers an area of 1.78km2 with a volume of 30.7 million m3.  It is thought that the increase in output reflects changes in the lava channel from the mantle to the surface; it has widened over time.

Changes in chemical composition may mean that materials are mixing in the upper mantle before ascent or there is less partial mantle melt in the magma.  If the latter, the eruption will end when the mantle source is sufficiently reduced.

Geldingadalsgos is still a toddler compared to Holuhraun; Geldingadalsgos’ eruption rate is 5% – 10% of the average eruption rate at Holuhraun between September 2014 and February 2015. Let’s hope it stays that way as it is a lot closer to residential areas.

La Soufrière St. Vincent

The alert status was lowered to orange after a period of relative quiescence on 6 May 2021; only a few long period events and volcano-tectonic earthquakes are occurring each day.  People are allowed back into the orange zone but the red zone remains an exclusion zone.

The last explosive event was on 22 April 2021.  However, a possible lava spine was spotted on photos on 27 April 2021.  Tephra fills the crater, increasing the risk of pyroclastic flows should eruptive activity pick up again.  In the meantime, lahars are the main hazard.

Mount Pelée

Mount Pelée remains on alert level yellow.  Volcano tectonic events are occurring and seismic activity remains at above baseline level.  An area of brown and dead vegetation was confirmed on 8 February 2021 caused by diffuse CO2 emissions; the vegetation has not recovered.   The volcano is slowly reawakening.

Armchair Volcanologist

© Copyright remains with the author; all rights reserved, 2021.

Sources and Further Reading:

In the text and:

Iceland

Icelandic Met Office: https://en.vedur.is/ (English site)

Icelandic Met Office: https:// vedur.is/ (Icelandic site)

Reykjavik Grapevine: https://grapevine.is/

Department of Civil Protection and Emergency Management | Almannavarnir

La Soufrière St. Vincent

St Vincent and the Grenadines:  https://news784.com/

Barbados: https://www.nationnews.com/

Mt Pelée

Observatoire volcanologique et sismologique de Martinique (OVSM – IPGP): http://www.ipgp.fr/fr/ovsm/observatoire-volcanologique-sismologique-de-martinique-ovsm-ipgp

Iceland, Reykjanes Peninsula

New Fissures Open Near Geldingadalur, Fagradalsfjall, Iceland

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?

Fig 6: Earthquake density plot of the earthquake swarm post eruption (19.03.2021 20:45 to 06.04.2021) by the author. © Copyright remains with the author; all rights reserved, 2021.
Fig 7: Scatter plot of the earthquake swarm post eruption (19.03.2021 20:45 to 06.04.2021) by the author. © Copyright remains with the author; all rights reserved, 2021.

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!

Fig 9: Earthquake density plots by the author from Jan 2008 to April 2021. © Copyright remains with the author; all rights reserved, 2021.

As noted in earlier posts, for up-to-date advice and status, check out IMO or the Department for Civil Protection and Emergency, links below. 

The Armchair Volcanologist

© Copyright remains with the author; all rights reserved, 2021.

Sources: 

Icelandic Met Office: https://en.vedur.is/ (English site)

Icelandic Met Office: https:// vedur.is/ (Icelandic site)

Reykjavik Grapevine: https://grapevine.is/

Department of Civil Protection and Emergency Management | Almannavarnir

MBL webcams: Livestream of Fagradalsfjall Eruption  and New Webcam

Iceland, Reykjanes Peninsula

Krýsuvík Volcanic System, Aviation Code Red; A Volcanic Eruption Has Started Near Fagradalsfjall, Iceland

1 Comment

Good Evening,

19.03.2021

Fig 1: Eruption at at Geldingadalur. Image from IMO: A volcanic eruption has begun | News | Icelandic Meteorological office (vedur.is)

This was going to be a post with an update on the earthquake swarm on the Reykjanes Peninsula, but the magma beat me to it!  IMO has just confirmed that a volcanic eruption is underway near Fagradalsfjall at Geldingadalur.  The eruption started at 20:45 19.03.2021. It has been named as Geldingadalsgos, after the valley.  At the time of writing, the eruption is a small fissure eruption; the fissure is c. 0.5km long.

Fig 2: Hópsnes Lighthouse, Grindavik looking towards the Fagradalsfjall system.  Image cropped from one by Martin Morris, published under CC-BY-SA 2.0

The public have been  advised not under any circumstances go close to the eruption site or on Reykjanesbraut. First responders need to be able to drive freely to assess the situation. Scientists are working on assessing the eruption, the site and possibilities.

People living nearby in Þorlákshöfn have been instructed to stay indoors, close windows and turn up their heating to avoid exposure to any volcanic gases.  The Reykjanesbraut has been closed – the main road from the capital region to Reykjanesbær and the international airport at Keflavík.

Fig 3: Aviation code red; source IMO.
Fig 4: IMO’s confirmation of the eruption (third warning down). This is an extract from a screenshot of the page.

Here are the updated earthquake plots by the author, anyway.  The raw earthquake data has been obtained from IMO; this is confirmed earthquakes to date (19.03.2021 15:00). IMO’s page above gives the more recent earthquakes.

What we see from the plots is that seismic activity has now extended beyond Reykjanes to the west and the swarm is still active.  Activity in the swarm is densest to the NE and SW of Fagradalsfjall.   The depth plot shows that earthquakes in the swarm are tending to be smaller and shallower.

Extension of the swarm to the west is in keeping with the swarms which have occurred since December 2019. 

Fig 5: Geoscatter plot of the earthquake swarm by the author from 22.02.2021 to 19.03.2021 (15:00).  Colour indicates earthquake number from 22.02.2021. © Copyright remains with the author; all rights reserved, 2021.
Fig 6: Geodensity plot of the swarm between Svartsengi and Krýsuvík. by the author from 22.02.2021 to 19.03.2021 (15:00).  © Copyright remains with the author; all rights reserved, 2021.
Fig 7: Scatter plot of the earthquake swarm by the author from 22.02.2021 to 19.03.2021 (15:00).  Colour indicates earthquake number from 22.02.2021. © Copyright remains with the author; all rights reserved, 2021.
Fig 8: Scatter plot of earthquake depth v time (earthquake number in the swarm) by the author from 22.02.2021 to 19.03.2021 (15:00).  © Copyright remains with the author; all rights reserved, 2021.

Let’s hope that this is a “tourist eruption”; our thoughts are with anyone affected by this eruption.

For more up to date information, please consult IMO or the Department for Civil Protection.

The Armchair Volcanologist

© Copyright remains with the author; all rights reserved, 2021.

Sources:

Plots by the author.

Source for raw earthquake data: IMO

Icelandic Meteorological Office – IMO (@Vedurstofan) / Twitter

Department of Civil Protection and Emergency Management | Almannavarnir