Tag Archives: Svartsengi

Update on the Ongoing Earthquake Swarm on the Reykjanes Peninsula

14.03.2021: The magma intrusion on the Reykjanes Peninsula appears to be edging further southward. The longer this continues, the more likely an eruption.  New plots added (Figs 13 – 15).

Update 14.03.2021

We have moved updates to the beginning of this post. The original post from 9 March 2021 and the earlier update are below.

We have updated our plots to 14.03.2021 17:46 for the area between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W .  Here are the results; the magma intrusion appears to be edging slowly further southwards, if we use the Department of Civil Protection’s line that the earthquake locations are the best indicator at the moment of where the magma is.

Fig 13:  Geodensity plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 24.02.21 to 14.03.21. Earthquakes over 5M are shown. © Copyright remains with the author; all rights reserved, 2021.
Fig 14: Geoscatter plot by the author of the of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 24.02.21 to 14.03.21. © Copyright remains with the author; all rights reserved, 2021
Fig 15: Depth v Latitude scatter plot by the author of the of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 24.02.21 to 14.03.21.  © Copyright remains with the author; all rights reserved, 2021

For the current status and advice, please consult IMO.

The Armchair Volcanologist

Update 12.03.2021

Since we wrote [our original post], the earthquake swarm continues unabated with several thousand more earthquakes and some more tremor pulses.

The Department of Civil Protection report today includes the following:

“Earthquake activity now reaches up to the Nátthagi valley south of Fagradalsfjall, which suggests that the southernmost end of the magma path lies there.  

The magma path continues to expand although there is some uncertainty regarding the pace of the magma flow. Data has indicated that the magma path has been moving towards the south coast in the last few days, but latest surveys do not indicate that the path has moved notably in the last 24 hours. 

With view of the eruption history and geological research, a volcanic fissure opening south of Fagradalsfjall and reaching the ocean is unlikely. Given the current circumstances, an undersea eruption with associated ash eruption is therefore unlikely.     

As has been stated earlier in the Science Board’s notifications, while the magma path continues to expand it must be assumed that an eruption may occur in the area. The longer the current situation lasts, the more likely an eruption becomes. “

They also note that gas measurements are being taken in the area.

Our updated plots show the seismic activity moving further southward, notably the geodensity plot in Fig 12.  There is also some parallel activity further west on a much smaller scale.

Fig 9: Geoscatter plot by the author of earthquake occurring on the Reykjanes Peninsula between 22.02.21 to 12.03.21.  © Copyright remains with the author; all rights reserved, 2021.
Fig 10: Geoscatter plot by the author of the of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 12.03.21. © Copyright remains with the author; all rights reserved, 2021.
Fig 11: Depth v Longitude & Latitude scatter plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 12.03.21.  © Copyright remains with the author; all rights reserved, 2021.
Fig 12: Geodensity plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 12.03.21. © Copyright remains with the author; all rights reserved, 2021.

For the current status and advice, please consult IMO.

The Armchair Volcanologist

09.03.2021

An eruption considered likely; magma c. 1km below the surface.

Good Afternoon!

Despite the earlier tremor pulses, the Krýsuvík Volcanic System has not yet erupted.  However, as seismicity continues to be intense, with well over 34,000 earthquakes recorded by Iceland’s SIL system now since 24 February 2021, it is thought that an eruption is likely. 

The latest report from Iceland’s Civil Protection Service Council on March 8, 2021, states that if an eruption occurs, the most likely scenario is still a fissure eruption between Fagradalsfjall and Keilir.  A magma intrusion (they use the term tunnel) is forming in the region, with most recent activity at its southern end.  Magma has now reached an upper depth of c. 1 km.  GPS and satellite readings indicate that the magma flow has decreased in the past week.  If the intrusion continues to grow, further surges in seismic activity can be expected.

The earthquakes trending westward from the vicinity of the magma intrusion are thought to be the result of the crust accommodating the intrusion.  No other magma movement has been detected during this swarm. 

So where are Fagradalsfjall and Keilir?  Here is a map (with directions on how to drive from one to the other, not that we would recommend that at the moment).

Fig 1: Extract from Google Maps showing the location of Fagradalsfjall and Keilir.

We have plotted the confirmed earthquakes for week 8 and week 9 2021, plus a few hours of yesterday, between 63.7°N, 21.0°W to 64.4°N, 23.0°W download from IMO’s site.  Here are the latest plots for the Reykjanes Peninsula, 63.7°N, 21.0°W to 64.4°N, 23.0°W:

Fig 2: Geodensity plot by the author of earthquake occurring on the Reykjanes Peninsula between 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.
Fig 3: Geoscatter plot by the author of earthquake occurring on the Reykjanes Peninsula between 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.

If we zoom in on the area between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W we can take a closer look at the intrusion, itself, (or the earthquakes magma movement is causing).  The area was selected to take in Svartsengi, Fagradalsfjall, Keilir and Krýsuvík.

Fig 4: Geoscatter plot by the author of the of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.
Fig 5: Depth v Longitude scatter plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.
Fig 6: Depth v Longitude & Latitude scatter plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.
Fig 7: Geodensity  plot by the author of earthquakes occurring between 63.83314°N, 22.55148°W to 63.96605°N, 21.8566°W from 22.02.21 to 08.03.21 16:00.  © Copyright remains with the author; all rights reserved, 2021.

Since we downloaded the data for the above plots, IMO have reported another short-lived burst in seismic activity at 05:20 this morning with a seismic tremor Mt. Fagradalsfjall, south of the intrusion.

IMO have produced a map of the dike intrusion and the areas of seismic activity that are arising due to the increased tension in the crust caused by the intrusion.

Fig 8: Map by the Icelandic Met Office showing the dike intrusion and the areas of stress.

For the current status and advice, please consult IMO.

The Armchair Volcanologist

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

Sources:

Icelandic Meteorological Office (IMO): https://en.vedur.is/

Map in Fig 8: https://en.vedur.is/about-imo/news/earthquake-swarm-in-reykjanes-peninsula

Department of Civil Protection: Vísbendingar að kvikugangurinn liggi suður af Fagradalsfjalli  (Scroll down the page for the English version).

Seismic Activity on the Reykjanes Peninsula

28 February 2021 (updated 2 March 2021 with the addition of earthquake plots showing rifting / dike formation)

Good Evening!

A large earthquake swarm started on 24 February 2021 on the Reykjanes Peninsula in the vicinity of the Krýsuvík volcanic system between Kleifarvatn and Svartsengi.  At the time of writing the swarm is still ongoing with over 7,200 earthquakes record by Iceland’s SIL system.  Three earthquakes of 5.0M or more have been recorded: 5.7M and 5.0M on 24 February and a 5.2 on 27 February 2021. 

The alert level for the Krýsuvík volcanic system has been raised to yellow following sightings of steam jets in geothermal areas in the region after the 5.7M and 5.0M.

The Icelandic Met Office have attributed this swarm to the recent re-awakening of volcano-tectonic activity on the Peninsula.

We downloaded the confirmed earthquakes from IMO’s site to take a look. We plotted earthquake density for Week 8, 2021, earthquake locations for February 2021 and earthquakes by month from January 2009 to February 2021.

From our plots we can see the awakening of the volcano-tectonic activity with the upkick in number of earthquakes from December 2019.  The current swarm is part of this activity.

Fig 1: Geodensity plot by the author of the earthquakes occurring on the Reykjanes Peninsula for Week 8 2021.  The locations of the earthquakes of 5.0M and more are shown by black stars. Blue triangles denote volcanoes.  © Copyright remains with the author; all rights reserved, 2021.
Fig 2: Earthquake plot by the author of earthquakes occurring on the Reykjanes Peninsula in February 2021. Yellow stars denote earthquakes over 3.0M, orange stars over 4.0M and red stars over 5.0M. Blue triangles denote volcanoes.  The rectangle shows the area plotted.  © Copyright remains with the author; all rights reserved, 2021.
Fig 3: Plot by the author of number of earthquakes by month occurring on the Reykjanes Peninsula from January 2009 to February 2021© Copyright remains with the author; all rights reserved, 2021.
Fig 4: Geodensity plot by the author of earthquakes on the Reykjanes Peninsula between 1 December 2019 and 28 February 2021. © Copyright remains with the author; all rights reserved, 2021.

At the time of writing, it is not possible to predict whether or not this activity will result in a local eruption in the near future.  Only time will tell.

Update 1 & 2 /03/2021

Since writing the swarm has continued, with more than 15,000 earthquakes since it began last week.

The Department for Civil Protection has advised on 1 March 2021, that satellite images show deformation in the area has increased more than expected, indicating possible magma inflow.

We can see from the local GPS stations that there has been significant uplift near Krýsuvík.

Fig 5: Composite GPS plots for KRI, SENG and THOB.

We have also produced scatter plots by day for the swarm in week 8, 2021 which show possible rifting or dike formation.

Fig 6: Lat v Lon Scatter plot by the author of earthquakes in the swarm in week 8, 2021 on the Reykjanes Peninsula.  Red is day 1 (22/02/2021) yellow is day 7 (28/02/2021).  © Copyright remains with the author; all rights reserved, 2021.
Fig 7: Depth v Lon Scatter plot by the author of earthquakes in the swarm in week 8, 2021 on the Reykjanes Peninsula.  Red is day 1 (22/02/2021) yellow is day 7 (28/02/2021).  © Copyright remains with the author; all rights reserved, 2021.
Fig 8: Depth v Lat Scatter plot by the author of earthquakes in the swarm in week 8, 2021 on the Reykjanes Peninsula.  Red is day 1 (22/02/2021) yellow is day 7 (28/02/2021).  © Copyright remains with the author; all rights reserved, 2021.

IMO are updating the list of earthquakes for week 8, 2021, at the time of writing. For up-to-date information, please consult IMO.

The Armchair Volcanologist

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

Sources:

Raw earthquake data and status: the Icelandic Meteorological Office:  www.en.vedur.is

Department of Civil Protection and Emergency Management | Almannavarnir

GPS: http://gps.vedur.is/mapGPS.php

A Quick Update on Activity on the Reykjanes Peninsula

Good Afternoon!

The earthquake swarm which started in December 2019 is continuing, let’s have a quick update on the stats.

Statistics

There have been 19,675 earthquakes in the Reykjanes Peninsula area 64.4°N, 23.0°W to 63.7°N, 21.0°W for the period 1 Jan 2016 to 14 June 2020, of which 14,258 (72%) have occurred in the last six months, most associated with the swarm near Svartsengi.

Fig 1: Statistics for the earthquake swarm to date by the author.  Month from start refers to the start of our data extraction (January 2016). © Copyright remains with the author; all rights reserved, 2020.

Seismic Activity

Our updated scatter plots show that there is more shallow small earthquake activity above the lithosphere than in our earlier plots. 

Fig 2: Latitude v Longitude geoscatter plot and depth plot for earthquake activity in the vicinity of Svartsengi 1/01/2016 to 14/06/2020 by the author.  Green dots denote earthquakes <2M; yellow dots, earthquakes greater than or equal 2.0M and less than 3.0M; red stars, greater than or equal to 3M.  © Copyright remains with the author; all rights reserved, 2020

Geodensity Plots

The geodensity plots for months 48 (December 2019) onwards (Figs 3.1 and 3.2) show that the most intense action started to the east of Mt Thorbjörn and has migrated west to Svartsengi and beyond.

Fig 3.1 Geodensity plots: top row months 48 and 49 (December 2019 and January 2020); bottom row month 50 and 51 (February 2020 March 2020) by the author. Note that the colour intensity is calculated based on the data set for the specified month. © Copyright remains with the author; all rights reserved, 2020
Fig 3.2 Geodensity plots: top row months 52 and 53 (April 2020 and May 2020); bottom row month 54 (June 2020, to 14/06/2020) by the author. Note that the colour intensity is calculated based on the data set for the specified month.  © Copyright remains with the author; all rights reserved, 2020.

Uplift

IMO has confirmed that uplift has resumed in the vicinity of Mount Þorbjörn.  Ground deformation is clearly visible on the GPS plots.

Fig 4: Uplift in the vicinity of Mt Þorbjörn as shown in recent GPS plots published by IMO: GPS Þorbjörn. THOB moved south eastwards, SENG moved north eastwards and ELDC moved westward; all showed uplift.

Summary

We are still looking at an unusually large swarm, accompanied by continued uplift in the vicinity of Mt Þorbjörn.

At the time of writing, there has been no change in the uncertainty phase declared by Icelandic Civil Protection .

The Armchair Volcanologist

15 June 2020

Sources:

Raw earthquake data and GPS plots downloaded from the Icelandic Met Office: https://en.vedur.is

Earthquake plots are the author’s own work.

© Copyright remains with the author; all rights reserved, 2020

Recent Seismic Activity on the Reykjanes Peninsula

Good Afternoon!

There has been a large earthquake swarm on the Reykjanes Peninsula over recent months, still ongoing at the time of writing, albeit with reduced intensity.

So let’s take a look at what’s been going on.

Fig 1: Earthquake epicentres January 2016 to April 12, 2020 plotted by the author. © All rights reserved, 2020.

Geological Setting

The Reykjanes Peninsula lies at the south west tip of Iceland on the Mid Atlantic Ridge, the boundary between the North American and Eurasian Plates. The North American Plate is moving westwards in relation to the Eurasian Plate; transform and extension faulting accommodate the relative Plate motions.  The Reykjanes Volcanic Belt lies on the Reykjanes Peninsula, comprising five north east trending volcanic systems: Reykjanes, Svartsengi, Krýsuvík, Brennisteinsfjöll and Hengill.  The volcanic systems are fissure swarms. 

Earthquakes

The line of earthquake epicentres in Fig 1 shows the path of the Mid Atlantic Ridge.  These earthquakes were extracted from the data set used to generate the plots in the earlier post introducing Iceland.  The raw earthquake data is publicly available data downloaded from the Icelandic Meteorological Office for the period January 2016 to 12 April 2020. The plot above is still data-heavy (too much data to see what is happening) so I have extracted the earthquakes by month to see where and when most activity occurred. 

In the plots there is an impression of seismic activity trending along the Peninsula from the east to the west.  This impression is born out most strongly in the activity from month 48 onwards.  Although it should be noted that the level of activity for these months is unusually high.

Fig 2: Earthquake epicentres Month 48 (December 2019) plotted by the author. Earthquakes with magnitude ≥ 3.0 are shown as black stars. Blue triangles are the approximate location of the volcanic systems.  © Copyright remains with the author; all rights reserved, 2020.
Fig 3: Earthquake epicentres Month 49 (January 2020) plotted by the author. Earthquakes with magnitude ≥ 3.0 are shown as black stars. Blue triangles are the approximate location of the volcanic systems.  © Copyright remains with the author; all rights reserved, 2020.
Fig 4: Earthquake epicentres Month 50 (February 2020) plotted by the author.  Earthquakes with magnitude ≥ 3.0 are shown as black stars.  Blue triangles are the approximate location of the volcanic systems.  © Copyright remains with the author; all rights reserved, 2020.
Fig 5: Earthquake epicentres Month 51 (March 2020) plotted by the author. Earthquakes with magnitude ≥ 3.0 are shown as black stars.  Blue triangles are the approximate location of the volcanic systems.  © Copyright remains with the author; all rights reserved, 2020.
Fig 6: Earthquake epicentres Month 52 (April 1 to April 12, 2020) plotted by the author. Earthquakes with magnitude ≥ 3.0 are shown as black stars.  Blue triangles are the approximate location of the volcanic systems.  © Copyright remains with the author; all rights reserved, 2020.

There are several possible reasons for the east to west trending of the earthquake swarms:

  • the plates do not move smoothly past each other, so friction generates faults and earthquakes;
  • rifting is occurring to accommodate the upward motion of land further to the east, generated by the mantle plume in the vicinity of Vatnajökull; and /or,
  • magma intrusion in local volcanoes.

Let’s take a look at depth plots of earthquakes under the Reykjanes / Svartsengi area.  This shows that the earthquakes over 3 M are largely in the lithosphere.

Fig 7:  Analysis of earthquakes in the Svartsengi area by magnitude and depth by the author.  © Copyright remains with the author; all rights reserved, 2020

Plotting depth against longitude, effectively looking northwards through the swarms, also shows that most larger quakes are in the lithosphere but some over 2 M track towards the surface.  On its own, this is not enough to draw any conclusions over the likelihood of an eruption; field observations, including gas emissions and ground deformation are required to determine how close to the surface magma may be.

Fig 8:  Depth plot by the author of the earthquakes in the Reykjanes / Svartsengi area.  Green circles are earthquakes less than 2.0 M, yellow circles are earthquakes between 2.00 and 3.00 M, red stars are earthquakes over 3.00 M.  © Copyright remains with the author; all rights reserved, 2020.

These swarms were accompanied by local uplift, as shown by local GPS stations.

Fig 9:  Uplift in the vicinity of Mt Thorbjörn as shown in recent GPS plots published by IMO: https://en.vedur.is/. THOB moved south eastwards and ELDC moved westward; both showed uplift.

IMO(3) has reported that the most likely explanation for the recent swarms and uplift is a magma intrusion near Mt Thorbjörn at depth; Mt Thorbjorn is located near the Blue Lagoon, Svartsengi. As to whether or not magma will reach the surface for an eruption and where it emerges, we will have to wait and see.  In the meantime, let’s look at the recent activity in historical times.

Historic Volcanic Activity

As noted earlier, the volcanic systems are fissure swarms.  Activity is driven by rifting which enables magma to reach the surface.  The most recent onshore volcanic activity took place between 940 AD and 1340 AD; later activity has been offshore.  Onshore lavas from these eruptions tend to be tholeiitic basalts (1). The systems are still active as demonstrated by current geothermal activity.

Hengill

Fig 10:  Image cropped from one by Hansueli Krapf, published under cc licence: CC BY-SA 3.0

The Hengill volcanic system is a series of fissure vents, crater rows and small shield volcanoes, with a highest point of 803m.  It lies at the triple junction of the Reykjanes Peninsula volcanic zone, the Western volcanic zone and the South Iceland seismic zone.  The lava types are basalt / picro-basalt, andesite / basaltic andesite and rhyolite. Hengill’s lavas are more complex that those to the west, reflecting its position at the triple junction. GVP(2) lists 13 Holocene eruptions ranging between VEI 0 and VEI 2; the last known eruption was a  VEI 2 in 150 AD.

Brennisteinsfjöll

The Brennisteinsfjöll volcanic system is a series of crater rows and small shield volcanoes, with a highest point of 610m.  Its lava types are basalt / picro-basalt.  GVP(2) lists 9 Holocene eruptions ranging between VEI 0 and VEI 2. One eruption, previously attributed to Hengill, occurred during a meeting of the Icelandic parliament at Thingvellier in 1000 AD.  The most recent eruption was a VEI 2 in 1341.

Krýsuvík

Fig 11:  Image cropped from one by Reykholt, published under creative commons licence: CC BY-SA 3.0

The Krýsuvík volcanic system is a series of crater rows and small shield volcanoes, with a highest point of 360m.  Like Brennisteinsfjöll, its lava types are basalt / picro-basalt.  GVP(2) lists 11 Holocene eruptions ranging from VEI 0 to VEI 2; the most recent of which was in 1340.  The Krýsuvík Fires spanned a period between 1151 and 1188, producing 36 km2 of lava.

Reykjanes & Svartsengi

Fig 12:  Image of Svartsengi Power Station from one by Jóhann Heiðar Árnason, published under creative commons licence: CC BY-SA 3.0

The Reykjanes volcanic system is a series of crater rows and small shield volcanoes, which extends offshore and includes several small islands.  Reykjanes highest point is 140m. The Reykjaneshryggur volcanic system is a submarine system which is considered part of Reykjanes.  GVP includes Svartsengi as a crater row of Reykjanes. Reykjanes lava types are basalt / picro-basalt.   GVP(2) lists 22 Holocene eruptions ranging between VEI 0 and VEI 4, of which the most recent was a VEI 0 in 1970; the VEI 4 was in 1226.  The 1226 eruption was part of the Reykjanes Fires which started in 1210 and lasted until 1240.

The area is one that has had a period of intense volcanic activity, so the recent earthquake swarms have generated a lot of interest.

Regular updates on seismic and volcanic activity in Iceland are published by the Icelandic Meteorological Office(3). 

The Armchair Volcanologist

14 May 2020

References & Further Reading:

  1. David W Peate, Joel A. Baker, Sveinn P. Jakobsson, Tod E. Waight, Adam J. R. Kent, Nathalie V. Grassineau, Anna Cecile Skovgaard , 2009. “Historic Magmatism on the Reykjanes Peninsula”, Contrib Mineral Petrol (2009) 157:359-382
  2. Smithsonian Institution Natural History Museum Global Volcanism Program (GVP): https://volcano.si.edu
  3. Icelandic Meteorological Office: https://en.vedur.is

Credits:

Raw earthquake data downloaded from the Icelandic Met Office: https://en.vedur.is

Plots are the author’s own work.

© Copyright remains with the author; all rights reserved, 2020.