Tag Archives: earthquakes

Türkiye-Syria Earthquakes, 6th February 2023

Fig 1: Rescue workers in in Osmaniye, Turkey.  Cropped from image by Onur Erdoğan, Public Domain, Wiki Commons

It’s approximately one month on from 6th February 2023 when a 7.8 magnitude earthquake struck on the south western end of the East Anatolian Fault Zone at 01:18 UTC (04:18 local time) 32.4km west northwest of the town of Gaziantep.  This, followed by large aftershocks, including a very shallow 7.5 magnitude earthquake to the north of the first quake, caused catastrophic damage in central and southern Turkey, and northern and western Syria.  The 7.5 earthquake signalled the rupturing of a second fault zone, the Sürgü-Misis Fault.  The final fatality number is not yet available but, at the time of writing, fatalities exceeded 50,000, with hundreds of thousands injured and millions displaced.  Our thoughts are with the victims, including those facing a long road to recovery.

We have taken a look at the earthquakes surrounding the Anatolian Plate from the start of January 2023 to 1st March 2023. 

Tectonic Settings

The Anatolian Plate lies between the Eurasian Plate, Arabian Plate and African Plate.  The African Plate is moving at a rate of 2.15cm per year in a north easterly direction, the Eurasian Plate is moving south, relative to the African Plate, at a rate of 7-14mm per year, the Arabian Plate is moving northward at a rate of 15-20mm per year and the Anatolian Plate is moving south west at the rate of 21mm per year. The relative motions are accommodated by the North Anatolian Fault, East Anatolian Fault, Bitlis – Zagros Fold and Thrust Belt and Dead Sea Transform Fault System.

Fig 2: Image by Roxy – Own work, CC BY-SA 3.0, Wiki Commons

The East Anatolian Fault is a 500km long fault zone which marks the plate boundary between the Anatolian and Arabian Plates; the boundary is a transform one with left lateral strike slip seismic activity and a slip rate of 10mm per year. The Anatolian Plate is pushed westward by the Arabian Plate moving northwards towards the Eurasian Plate. 

The East Anatolian Fault is a single fault between Karliova and Çelikhan.  After Çelikhan the fault zone splits into north and south strand, both of which include multiple faults.  The Sürgü-Misis Fault makes up the northern strand; it is a 380km long stretching between Çelikhan and Karataş; the eastern parts of the east-west section are made up of the Çardak and Sürgü faults; the sytem changes direction at the Göksun bend dividing into seven north east trending fault systems – the Karataş, Yumurtalık, Toprakkale, Savrun, Misis, Çokak and Düziçi-İskenderun faults.  The Sürgü-Misis Fault system connects to the Cyprus Arc via the Misis-Kyrenia fault system.   The southern strand of the East Anatolian Fault is less certain; the East Anatolian Fault may extend to the north of Cyprus; and, the NNE trending Türkoğlu-Amik section (the Karasu Fault Zone) may be a separate fault, linking the Dead Sea Transform to the East Anatolian Fault. The Karasu Rift has had Quaternary volcanic activity on northern part and sides of the rift between Kirikhan, Reyhanli and Fevzipaşa in an area 94km long and 12-25km wide.

The North Anatolian Fault, another strike slip fault, accommodates the relative motion between the Anatolian Plate and the Eurasian Plate.  The North Anatolian Fault and the East Anatolian Fault meet the Bitlis – Zagros Fold and Thrust Belt, where the Arabian Plate subducts under the Eurasian Plate, at the Karliova Triple Junction.

Not very far to the west, the African Plate is subducting under the Anatolian Plate at the Cyrpus Arc.  The Dead Sea Transform Fault System to the south marks the transform boundary between the Arabian and African Plates.  The East Anatolian Fault meets the Dead Sea Transform Fault System at the Maras Triple Junction.

Earthquake Plots

We initially plotted the earthquakes from 1 January 2023 to 25 February 2023 for the area 34.47361°N, 25.22222°E to 42.25833°N, 44.45056°E.  We then looked at 35.3122°N, 32.50944°E to 41.21667°N, 42.70056°E, focussing on the East Anatolian Fault. The results are shown in the following videos and earthquake density plot.

Fig 3:  Video by the author of earthquake plots from 1 January 2023 to 1st March 2023, latitude v depth, Geoscatter, earthquake count and longitude v depth.  Key: cyan circles denote current earthquakes <4.5M, green stars, current earthquakes between 4.5M and 5.5K, yellow stars, current earthquakes between 5.5M and 6.5M and red stars, current  earthquakes over 6.5M; and, grey circles denote previous earthquakes <4.5M, green stars, previous earthquakes between 4.5M and 5.5K, yellow stars, previous  earthquakes between 5.5M and 6.5M ,and red stars, previous  earthquakes over 6.5M.  © copyright remains with the author, 2023; all rights reserved.
Fig 4. Video by the author of the Geoscatter plot of the East Anatolian Fault and by earthquakes in groups of 10 from 6 February 2023 to 1st March 2023.  Key: red circles denote current earthquakes <7.0M and red stars denote current earthquakes >7.0M, and dark red circles, previous earthquakes <7.0M and black stars, previous earthquakes >7.0M. © copyright remains with the author, 2023; all rights reserved.
Fig 5: Video of a rotating 3D scatter plot of the earthquakes in the East Anatolian Fault for the period 6 February 2023 to 1st March 2023. Colour denotes age: red, the oldest, and yellow, the newest. © copyright remains with the author, 2023; all rights reserved

The geodensity plot shows that most activity occurred on the Sürgü-Misis Fault to the west and east of the 7.5M earthquake.

Fig 6: Geodensity plot by the author of earthquakes occurring between 35.3122°N, 32.50944°E to 41.21667°N, 42.70056°E, from 6th February 2023 and 1st March 2023. Red triangles denote volcanoes with dated activity in the Holocene and blue triangles denote volcanoes with activity in the Holocene of unknown date. © copyright remains with the author, 2023; all rights reserved.
Fig 7: Surface rupture from the two earthquakes as shown by analysing before and after satellite images. The first rupture on the East Anatolian Fault was 190km long and the second on the Sürgü-Misis Fault was 38km long (Image credit: Copernicus/NERC/COMET)

Most of the faults within the East Anatolian Fault Zone seem to have moved in the period we looked at. However, the scale of our plots may be misleading. Our plots do show a tenuous link between the East Anatolian Fault and the Cyprus Arc.  There was some activity on the Arc preceding the 7.8 earthquake. After shocks have migrated through the fault system towards the Arc.   There is no obvious link with the Dead Sea Transform Fault in the time period selected but geologically-speaking that is a very short period.

Armchair Volcanologist

© copyright remains with the author; all rights reserved, 2023.

Sources & Further Reading

Raw earthquake data was downloaded from EMSC, https://www.emsc-csem.org

“Paleoseismology of the western Sürgü–Misis fault system: East Anatolian Fault, Turkey”, Tamer Y. Duman, Hasan Elmacı, Selim Özalp, Akın Kürçer, Meryem Kara, Ersin Özdemir, Ayhan Yavuzoğlu & Çağıl Uygun Güldoğan,  Mediterranean Geoscience Reviews volume 2, pages411–437 (2020) https://link.springer.com/article/10.1007/s42990-020-00041-6

Updates on Activity at Fagradalsfjall, Cumbre Vieja, and Askja as of October 2021

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.

Fig 17:  Analysis of the swarm by depth and magnitude by the author.  © Copyright remains with the author; all rights reserved, 2021.
Fig 18:  Video of geoscatter plots and scatter plots of the current swarm by the author.  © Copyright remains with the author; all rights reserved, 2021.

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. 

Armchair Volcanologist

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

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.
Fig 13:  Seismic signal, source: IGN

We have updated our earthquake data and have plotted the swarm from 27 September 2021to present.  The results are shown in the video below.

Fig 14: Analysis of the earthquake swarm from 11 September 2021 to present by the author.  © Copyright remains with the author; all rights reserved, 2021.
Fig 15: Video showing geoscatter plots and scatter plots by the author of the swarm from 27/09/2021 to present

Armchair Volcanologist

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

Sources:

El Mundo: www.elmundo.es

VolcanoDiscovery:  www.volcanodiscovery.com

IGN: www.ign.es

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)).

Fig 8: Geoscatter plot of the current swarm SSW Mount Kelir by the author. Colour denotes time (using earthquake number), red is the oldest and yellow the youngest.  © Copyright remains with the author; all rights reserved, 2021

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. 

Fig 9: Numerical analysis of the swarm by the author.  © Copyright remains with the author; all rights reserved, 2021.

The possible ascent of the swarm is more visible in the scatter plot looking at it in an easterly direction.

Fig 10: Scatter plot of the swarm by the author.  Colour denotes time (using earthquake number), red is the oldest and yellow the youngest. © Copyright remains with the author; all rights reserved, 2021.

04.10. 2021: Update on the Cumbre Vieja Eruption

Fig 6: Plot of earthquakes from 11/09/2021 to 04/10/2021 10:13:11 by the author.   © Copyright remains with the author; all rights reserved, 2021
  • Part of the main cone collapsed at c. 9:10 pm last night; some vents have now merged.
  • Effusive activity has increased.  Lava flows have merged; the flow is 1km wide at its widest point.
  • The lava delta is now 29.7 hectares.  This has impacted the surfing beach at Los Guirres.
  • 400 hectares of land has been covered by lava and 4,819 hectares covered by ash.  1,047 buildings have been damaged, including 947 destroyed.
  • 20% of the banana crop has been lost. The village  of La Bombilla, built for banana plantation workers, is now under threat.
  • The seismic swarm is ongoing, with most recent earthquakes between 7km  – 14km depth.

We have updated our earthquake plots for the most recent swarm (11/09/2021 to 04/10/2021 14:30:59).  The swarm reactivated on Day 17.

Fig 7: Earthquake  plots by the author for the swarm 11/09/2021 to present. © Copyright remains with the author; all rights reserved, 2021

Sources for updates as before: El Mundo and IGN.

01.10.2021 (original post)

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.

Fig 2a: Plots by the author of the earthquake swarm from 27/09/2021 to present. Geodensity plot on the left and geoscatter plot on the right.  The colour code in the geoscatter plot is time: red is the oldest, yellow the newest. Time is approximated by earthquake sequence.  © Copyright remains with the author; all rights reserved, 2021.
Fig 2b: Plots by the author of the earthquake swarm from 27/09/2021 to present. Scatter depth v longitude plot on the left and scatter depth v latitude plot on the right.  The colour code is time: red is the oldest, yellow the newest. Time is approximated by earthquake sequence.  © Copyright remains with the author; all rights reserved, 2021.

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. 

Fig 4: Plots by the author of the most recent earthquake activity at Cumbre Vieja.  For plotting purposes, the activity has been labelled as a new swarm, which started on 27 September 2021. Green circles are the current swarm earthquakes < 3.0M; red stars are current swarm earthquakes ≥3.0M; grey circles are earthquakes < 3.0M from 2017 to 26.09.2021; and cyan stars are earthquakes ≥3.0M from 2017 to 26.09.2019 (all are in fact from the previous swarm starting 11 September 2021).  © Copyright remains with the author; all rights reserved, 2021.

We have compiled a video of the earthquake swarms from 2017 to present.

Fig 5: Video by the author showing the progress of the earthquake swarms from 2017 to present. © Copyright remains with the author; all rights reserved, 2021.

Askja

Seismicity is still occurring.  The Icelandic authorities are continuing to monitor this.  The aviation code is still yellow. 

We have not had time to update our earthquake plots, but will do so in due course.

Armchair Volcanologist

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

Sources:

Plots are the authors own work.

Information and raw earthquake data:

Fagradalsfjall: Home-page – Icelandic Meteorological Office | Icelandic Meteorological office (vedur.is)

Cumbre Vieja: Instituto Geográfico Nacional (ign.es) & EL MUNDO – Diario online líder de información en español

A Quick Look at Iceland: Total Earthquakes by Year 2009 to 23 October 2020

Good Morning!

While we are waiting to see if there is any volcanic activity at Grímsvötn or her neighbours, let’s take a look at how the current seismic activity in Iceland compares to previous years. 

Our database, comprised of earthquake data downloaded from IMO (see Sources below), now goes back to 29 December 2008 and extends to 23 October 2020, although we may reupload the last week soon because IMO may have been in the process of updating the record when we downloaded the data. 

Fig 1: Iceland: Total Earthquakes by Year and Magnitude by the author, using data downloaded from IMO (see Sources below).  © Copyright remains with the author; all rights reserved, 2020.

From our graph, we can see that the total number of earthquakes was up in 2010, 2014, 2017 and 2020.  In 2010, Eyjafjallajökull erupted, in 2014, Barðarbunga erupted at the Holuhraun fissure; in 2017, there was no subaerial volcanic activity, although Katla may have had some subglacial activity, and, in 2020, there is rifting both in the Reykjanes Peninsula and Tjörnes Fracture Zone but we have yet to see what, if any, volcanic activity emerges.  Interestingly, the 2011 eruption of Grímsvötn did not push the total earthquakes up in 2011.

Let’s take a look at activity by region. Here we look at the four main volcanic regions: the Tjörnes Fracture Zone, Vatnajökull, Myrdalsjökull and the Reykjanes Peninsula, where there is most seismic activity.

Fig 2: Iceland Total Earthquakes by Region and Year by the author, using data downloaded from IMO (see Sources below). Note: not all regions

Fig 3: Iceland Total Earthquakes > 2.0M by Region and Year by the author, using data downloaded from IMO (see Sources below). Note: not all regions are shown.  © Copyright remains with the author; all rights reserved, 2020.

We see that the eruption of Eyjafjalljokull increased the number of earthquakes in Myrdalsjökull but not to the extent that the eruption of Barðarbunga at the Holuhraun fissure and subsidence in the caldera pushed up the earthquakes for Vatnajökull in 2014 and subsequent years.  In fact, the total number of earthquakes in all regions, except Myrdalsjökull, has remained elevated since Holuhraun.

Our database does not extend back far enough to draw any firm conclusions, however, it would appear that rifting events such as Holuhraun produce far more earthquakes than volcanic activity on its own. 

Tjörnes Fracture Zone and on the Reykjanes Peninsula

This rather begs the question as to what is happening this year with the large earthquake swarms both in the Tjörnes Fracture Zone and on the Reykjanes Peninsula.  Unless our database does not go back far enough, neither the 2011 Grímsvötn nor the 2014 Barðarbunga eruption was preceded by such large earthquake swarms in other regions.

The fact that there is significantly raised activity this year in both regions suggests to us that we may be witnessing the normal plate separation on the Mid Atlantic Ridge (it is not entirely smooth), possible local magma ascent, and / or the plates accommodating an ascending blob of magma from the mantle plume, which is believed to be under the Vatnajökull icecap. There is ground deformation at several spots under the Vatnajökull icecap which points to magma ascent. 

IMO have reported that there could be a magmatic intrusion at depth on the Reykjanes Peninsula; this is supported by ground deformation. 

Gas measurements, ground deformation and recent seismic activity at Grímsvötn (not enough to show in our graphs but above the background levels for the volcanic system) have led to the Icelandic authorities to consider that an eruption is possible there in the not too distant future and to raise the alert level a notch (see earlier article). 

It is too soon to tell whether or not the rifting events, themselves, will result in eruption(s); it is possible that it is just a coincidence that we are seeing two large rifting events at roughly the same time – both areas are seismically active.  Time will tell. 

In the meantime, we will continue to watch.

The Armchair Volcanologist

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

Sources:

For raw earthquake data and updates:

Icelandic Met Office: https://en.vedur.is/

Famous Eruptions – Introduction

All good books on volcanoes describe well-known eruptions, including Vesuvius 79 AD, Tambora 1815, Krakatau 1883, Mount Peleé 1902, Katla 1918, Mount St. Helens 1980, Pinatubo 1991.  Who are we to be any different?

There is a good reason for this. Most famous eruptions are large and explosive, causing loss of life and considerable property damage – in other words, headline-grabbing.   Later eruptions have impacted aviation – volcanic ash and jet engines are not a good mix; airports near erupting volcanoes are closed and flights re-routed to avoid the ash clouds. 

Catastrophic events are the reason volcanology is such an important subject. Understanding these and other eruptions is important to find out how to minimise the risk; i.e. reduce loss of life.

Researchers have shown that volcanoes usually very kindly give us some warning in the lead up to an eruption.  Magma is viscous, rarely moves fast and, when moving, causes earthquakes, usually small, but some are felt without equipment.  As magma ascends, degassing starts to occur, some of which is detectable at the surface.  Rising magma also causes ground deformation, e.g.  it causes the volcano to inflate, measurable by tilt-meters and GPS, and some of which may even be visible to the naked eye (Mount St Helens). 

I read somewhere that the first piece of equipment required to monitor a volcano is a seismometer, the second is another seismometer, as is the third; earthquakes are often the first sign of impending trouble (if I can remember / find the source, I will accredit it properly). Scientists observing volcanoes will have a raft of equipment in place: seismometers, GPS stations, tilt-meters and gas monitoring; satellite monitoring may also detect ground deformation.  Drones may be used to inspect craters which are not readily accessible or where it would be unsafe to visit. Our maps of Iceland include some GPS stations as markers to indicate where the earthquakes are occurring but still evidence that Iceland has several in place at its active volcanoes.

Given that volcanoes give some warning, why are people killed?  Unfortunately, magma ascent and the build up to an eruption is a slow process with many stops and starts.  A major eruption may be preceded by a few small throat clearing events before the volcano unleashes the main eruption. An evacuation may take place, but if it is quiet between the precursors and the main event, people may think that the volcano has finished and return home to be at ground zero at the wrong time, irrespective of whether or not any alert is in place. People living close to volcanoes tend to be farmers with strong bonds to both their land and livestock. On the other hand, the volcano may not behave as expected – e.g. a phreatic eruption or edifice failure.  Volcano hazard assessment is an interesting topic for future posts.

We will also look at some of the more famous eruptions over the coming weeks.

We’ve already touched a bit on Katla (The Katla Volcanic System, Myrdaksjökull – the not so cuddly Katla) and Mount St Helens (Mount St Helens – 18 May 1980 Eruption) so we’ll carry on by looking at Tambora’s 1815 eruption (Tambora 1815).

The Armchair Volcanologist

7 July 2020

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