Iceland earthquakes, 18000 in a week! Fagradalsfjall Volcano

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Summary:
Initially 18,000 earthquakes in a week, then subsequent ruptures in the earth, multiple cones ejecting lava, and now a new volcano, Fagradalsfjall
NYTimes, March 04 - Iceland has experienced 18,000 earthquakes since last week: Volcanologists think an eruption could be imminent in the southwestern part of the island after 800 years of dormancy.
SE corner of Iceland. USGS doesn't show any earthquakes during the last week.

https://en.vedur.is/earthquakes-and-volcanism/earthquakes (mostly less then 2 Mag)

Back in November 2019, an article on the Northern Volcanic Zone
https://advances.sciencemag.org/content/5/11/eaax6642

The current activity in question is in the SE quadrant though. Does this imply a magmatic intrusion in the SE quadrant of Iceland?
 

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  • #2
phinds
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the whole thing seems pretty shaky to me :smile:
 
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  • #3
Astronuc
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USGS doesn't show any earthquakes during the last week.
This is because USGS only reports earthquakes of Mag 4 or greater from the rest of the world, while showing earthquakes Mag 2.5+ in the US.

However today - M 5.2 - 10 km ENE of Vogar, Iceland
https://earthquake.usgs.gov/earthquakes/eventpage/us7000dgpz/region-info
  • 2021-03-07 02:01:28 (UTC) about 10 miles or 16 km from central Reykjavik.
  • 64.027°N 22.191°W
  • 10.0 km depth
And several earthquakes of Mag 4+. Seems some peak magnitudes are increasing.
 

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  • #4
Astronuc
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M 5.1 - 10 km ENE of Vogar, Iceland
  • 2021-03-10 03:14:40 (UTC), Wednesday
  • 64.018°N 22.180°W
  • 10.0 km depth
and more 4+. No sign of diminishing activity.
 

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  • #5
Astronuc
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M 4.5 - 8 km ESE of Hafnarfjörður, Iceland
  • 2021-03-14 12:34:38 (UTC)
  • 64.037°N 21.771°W
  • 10.0 km depth
Iceland Met Office reports a 5 Mag. People are being warned to stay away from steep terrain in order to avoid rock slides and boulders that may be loosened and roll downhill.
Sunday
14.03.2021
12:34:3663.867-22.2834.6 km5.099.03.9 km S of Fagradalsfjall
 
  • #6
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M 5.4 - 8 km SW of Álftanes, Iceland
https://earthquake.usgs.gov/earthquakes/eventpage/us7000djaw/executive
  • 2021-03-14 14:15:26 (UTC)
  • 64.044°N 22.129°W
  • 10.0 km depth
This is the strongest quake yet during the last two weeks. The Icelandic Met Office (IMO) reported that seismicity on Reykjanes peninsula in the area between Krýsuvík, Kleifarvatn and Svartsengi volcanic system has been increasing during the past week.

https://www.volcanodiscovery.com/ea...753/mag5quake-Mar-14-2021-ICELAND-REGION.html
 

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  • #7
jim mcnamara
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@davenn - what is the lower limit of detection for your seismograph? I.e., some of these events are visible?
 
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Some recent articles indicated that folks near Reykjavik are losing sleep over the many earthquakes, which apparently is unprecedented. However, the matter has come up in the recent past when earthquake activity increased.

The current activity concerns the Reykjanes peninsula and potential volcanic activity, i.e., magma rising to the surface with a potential volcanic eruption.

Jul 3 2018 - https://icelandmag.is/article/ask-expert-why-are-there-so-many-earthquakes-iceland

Back on February 24, 2021, the Iceland Met Office reported an 5.7 Mag earthquake, which seems to have been the beginning of the thousands of earthquakes since.
A series of earthquakes hit Southwest Iceland shortly after 10 am, the largest one of magnitude 5.7. (10:06, 3.3 km south-southwest of Keilir mountain)
. . . .
The second one, which hit at 10:18, measured 4.9 and originated 3.2 km west of Fagradalsfjall mountain on the Reykjanes peninsula. More quakes have followed.
https://icelandmonitor.mbl.is/news/news/2021/02/24/series_of_earthquakes_hits_southwest_iceland/
https://icelandmonitor.mbl.is/news/news/2021/03/04/seismic_activity_increases_again/
 
  • #9
davenn
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@davenn - what is the lower limit of detection for your seismograph? I.e., some of these events are visible?


Hi Jim,

Being on the opposite side of the world, it would have to be a minimum of M6.5 and a shallow event <15km
For an example of a mid M6 event at a distance, there's a M6.6 on my seismo at the moment that is at the top end
of the Pacific - Kamchatka Peninsula, it's 22km deep. If it was only 5 to 10km deep, the amplitude would have been
much larger.
My Seismograms (sydneystormcity.com)
I posted a seismogram in that other thread about the New Zealand events showing the difference in amplitude
of two M5.9 quakes. The difference is quite significant


D
 
  • #11
anorlunda
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Can the seismograph spectra help us to distinguish strike-slip fault quakes, versus magma movement, versus subsea landslides?
 
  • #12
davenn
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Can the seismograph spectra help us to distinguish strike-slip fault quakes, versus magma movement, versus subsea landslides?


Yes, magma movement doesn't produce P and S signatures, rather it's a continuous signal.
This is called harmonic tremor. will try and find a seismogram of such

EDIT: OK here we go ......

harmonic tremor.jpg
 
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  • #13
Astronuc
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The Icelandic Met Office (IMO) reported that seismicity on Reykjanes peninsula in the area between Krýsuvík, Kleifarvatn and Svartsengi volcanic system has been increasing during the past week.
From the Iceland Met Office,
The Krýsuvík-Trölladyngja volcanic system on the Reykjanes Volcanic Zone has been moderately active in the Holocene (last 8000 years). The last eruptive episode, consisting of two eruptions separated by 37 years, occurred in the 12 century CE, the lava flows reaching to the sea on the north and south coast of the peninsula.

The NE-SW trending volcanic system comprises a 50 km long, composite fissure swarm without a developed central volcano. Maximum elevation is ~400 m a.s.l. The system has no ice cover but a large lake lies within the system.

The characteristic activity is effusive basaltic eruptions producing lava flows covering some tens of km2 and minor tephra deposits. Eruption frequency during the last 3000 years is 1 eruption per 750 years.
The last time Krýsuvík erupted was 12th century CE, so perhaps an eruption is due. Currently, the
Aviation colour code is Orange and Activity level is Moderate.
http://icelandicvolcanos.is/?volcano=KRY# (Click on Catalogue information for details)
https://en.vedur.is/earthquakes-and-volcanism/earthquakes/reykjanespeninsula/#view=map

Interestingly, to the east (SE Iceland) is Grímsvötn. The Aviation colour code is Yellow, but Activity level is High.
http://icelandicvolcanos.is/?volcano=GRV#
 

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  • #14
Astronuc
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The Iceland site now has a warning: An eruption has started in Fagradalsfjall.
https://icelandmonitor.mbl.is/news/news/2021/03/19/eruption_has_started_in_fagradalsfjall/
https://icelandmonitor.mbl.is/news/news/2021/03/18/earthquakes_on_reykjanes_peninsula_explained/

https://grapevine.is/news/2021/03/19/breaking-eruption-at-fagradalsfjall/

The aviation colour code for Krýsuvík has changed from Orange to Red indicating an eruption.
http://icelandicvolcanos.is/?volcano=KRY
https://volcano.si.edu/showreport.cfm?doi=GVP.WVAR20210303-371030
From Iceland Met Office:
Date Time Lat LongDepthMQuality Location
Friday
19.03.2021
05:48:1163.798-22.7824.5 km3.799.03.8 km W of Reykjanestá
Friday
19.03.2021
05:47:5263.802-22.7824.8 km3.499.03.8 km W of Reykjanestá
Friday
19.03.2021
05:41:4363.810-22.7835.0 km3.599.04.0 km WNW of Reykjanestá
Friday
19.03.2021
05:29:1863.751-22.7044.9 km3.199.05.5 km S of Reykjanestá
Friday
19.03.2021
05:27:4863.810-22.7905.5 km3.799.04.3 km WNW of Reykjanestá

https://en.vedur.is/about-imo/news/earthquake-swarm-in-reykjanes-peninsula
Updated 19.03 23:20

At around 21:15 UTC today, 19 March, a volcanic eruption began at Geldingadalur, close to Fagradalsfjall on the Reykjanes Peninsula. The eruption was first seen on a web camera positioned close the mountain. It was also confirmed on thermal satellite imagery.
At the time of writing, the weather on the peninsula is wet and windy, and an orange glow can be seen in low clouds on the horizon from Reykjanesbær and Grindavík. The eruption site is in a valley, about 4.7 km inland from the southern coast of the peninsula. The coastal town of Grindavík is the closed populated region to the eruption site, located approximately 10 km to the southwest.

Earthquake activity in the region of the magma intrusion has been lower in recent days, and there is presently no intense seismicity occurring in the region. Earlier in the day, several low-frequency earthquakes were recorded below Fagradalsfjall. There are presently no reports of ash fall, although tephra and gas emissions are to be expected. In line with well-rehearsed contingency plans, the aviation colour code for the Reykjanes Peninsula has been elevated to red, signifying an eruption in progress. Additional domestic restrictions have been put in place, including the closure of Reykjanesbraut – the main road from the capital region to Reykjanesbær and the international airport at Keflavík.
. . .
 
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  • #17
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Potsdam allows filters, and I couldn't found any > M2.0 in the last two days.
 
  • #19
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Well, the Iceland Met Office is reporting earthquakes in the Reykjanes peninsula.

https://en.vedur.is/media/uncategorized/Monitor-map-45x25-cm-unrest-en-20210309.png

https://en.wikipedia.org/wiki/Krýsuvík_(volcanic_system)
Fagradalsfjall is in the Krýsuvík (or Krísuvík), also Krýsuvík-Trölladyngja, volcanic system

The article states: "The Krýsuvík system has a tendency to phreatic explosions, often within rifting episodes and/or eruption series. The underground of Reykjanes peninsula is soaked with water (high groundwater level as well as saline sea water in cave systems)." Could be exciting there.

I'm guessing Fagradalsfjall will get its Wikipedia page soon, and Krýsuvík will get updated.

From the article: https://en.vedur.is/about-imo/news/earthquake-swarm-in-reykjanes-peninsula
Updated 03.03.

On 1 March, the Scientific Advisory Board of the Icelandic Civil Protection met to discuss the latest monitoring results from the seismic unrest on the Reykjanes Peninsula. In particular, the latest satellite-based radar (InSAR) image was reviewed. The displacements in the InSAR scene show more ground deformation than can be explained by the earthquake activity alone. The most likely explanation is that magma intrusions are occurring close to Fagradalsfjall, where the earthquake activity has persisted in recent days. The latest satellite results will be processed with additional geodetic modelling to better understand the causes of the ground deformation.

Looks like they have been expecting the eruption. They have a lot of good data.

Update: https://www.ruv.is/frett/2021/03/19/volcanic-eruption-what-we-know-so-far
  • A narrow tongue of lava is flowing south-south-west and another to the west. The fissure is around 500-700 metres long. The eruption started very quietly, with no tremor. The Met Office became aware of the eruption because people reported its glow. The first report came at 21.20.
  • The Met Office has now put the official start time of Geldingadalsgos (as the eruption is being called) at 20.45.
https://www.mbl.is/frettir/innlent/2021/03/19/bein_lysing_eldgos_i_fagradalsfjalli/

https://www.ruv.is/frett/2021/03/20/geophysics-professor-people-can-sleep-soundly
No worries. Just go home and go to sleep.
Magnús Tumi Guðmundsson, the noted geophysics professor, told RÚV a short while ago that Geldingadalsgos is a very small volcanic eruption, though a little bigger than the Fimmvörðuháls eruption was. He says there is no explosive activity and not a great deal of lava flow.
 
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  • #20
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This morning the aviation colour code for Krýsuvík has returned to Orange.

Back on March 10 - The Civil Protection and Emergency Management’s Science Board held an online meeting today in order to discuss the earthquake swarm in the Reykjanes Peninsula. The meeting was attended by specialists from the Icelandic Met Office, University of Iceland, Iceland Geosurvey (ÍSOR), the Environment Agency of Iceland, Icelandic Institute of Natural History, and Reykjavik Energy beside representatives from the Directorate of Health, Isavia-ANS and HS-Orka. Measuring and data that have been received the past 24 hours were reviewed at the meeting.
http://earthice.hi.is/press_release...gency_managements_science_board_march_10_2021

The meeting discussed the importance of closely monitoring the activity in the southern hills of Fagradalsfjall in order to see whether this activity was a signal that the magma path is expanding to the South, and an
satellite images received in the morning and the latest GPS measurements, which confirmed that magma accumulation continued to be restricted at the southern end of the magma path that reaches from Keilir to Fagradalsfjall. That place continues to be considered the most likely place in case of an eruption.

It appears that the expectations of the meeting were confirmed on March 19. Despite the history, a phreatic eruption has so far not occurred. France24 reports a small eruption.
https://www.france24.com/en/europe/20210320-iceland-volcano-reykjavik-eruption
"The eruption began at Fagradalsfjall in Geldingadalur at about 2045 GMT tonight. The eruption is considered a small one and the eruption fissure is about 500-700 metres (1640-2300 feet) long. The lava is less than 1 square kilometre (0.4 square miles) in size," the Icelandic Meteorological Office (IMO), which monitors seismic activity, said in a statement.

https://www.dw.com/en/iceland-halts-air-travel-following-volcanic-eruption/a-56935890

Some background, which is likely to be updated soon.
Geology and structure of the Reykjanes volcanic system, Iceland
https://www.sciencedirect.com/science/article/abs/pii/S0377027317305474

The seismic activity has decreased following the eruption.
 

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  • #21
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At around 20:45 UTC 19 March 2021, a volcanic eruption began at Geldingadalur, close to Fagradalsfjall on the Reykjanes Peninsula. The eruption was first seen on a web camera positioned close the mountain. It was also confirmed on thermal satellite imagery.

The eruption site is in a valley, about 4.7 km inland from the southern coast of the peninsula. The coastal town of Grindavík is the closed populated region to the eruption site, located approximately 10 km to the southwest.

The eruption is considered small at this stage and the eruptive fissure is appr. 500 - 700 m long. The area of the lava is covering an area that is appr. 500 m wide and considered less than 1 km2. Lava fountains are small and lava flows are currently a very local hazard. The seismic activity is minor and spread around the Fagradalsfjall area.
https://en.vedur.is/about-imo/news/earthquake-swarm-in-reykjanes-peninsula
They will update the information on this page as events occur and information is available.

Warning: An eruption ongoing at Fagradalsfjall. Risk of high concentration of volcanic gases in the area. Alert phase from the Civil Protection active for the area.
 
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  • #23
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https://www.icelandwonder.com/news/daytime-pictures-of-volcanic-eruption-in-geldingadalur/

https://www.vox.com/2021/3/20/22341888/iceland-dormant-volcano-erupted-fagradalsfjall-reykjavik
It was the first volcanic eruption in this part of Iceland — the Reykjanes Peninsula, home to Reykjavik, where most of the country’s residents live — in 781 years. And it was the first time this particular volcano had gone off in about 6,000 years.

The eruption, in the Geldinga Valley, was remote enough that evacuations were not necessary, and no structures were endangered.

Some pictures of the terrain to show where Fagradalsfjall and the eruption are located.
 

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  • #24
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Time to dust off the Secret Life of Walter Mitty movie and watch that scene of Sean Penn flying toward the volcano before it fully erupts while Ben Stiller is trying to figure out what to do.

It seems Mother Nature is getting very active from an ice storm in Texas to a heatwave in Iceland.
 
  • #25
davenn
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here's the best live cam site I have found for the new eruption .....

(2) Volcanic eruption in Iceland! - YouTube

scroll back some hours to when it was previously daylight


Edit, dang ... it's gone offline, hopefully it comes back
 
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