Reblog: Mount Thorbjorn

July 20, 2020: The Icelandic Met Office reports an earthquake in another part of the Reykjanes area. While noting this area has had swarms, they write:

The current seismic activity appears to coincide with a series of North-Souh trending tectonic faults. This would indicate these events are of a tectonic nature, but most likely they are the result of stress triggering related to the ongoing magmatic unrest on the Reykjanes Peninsula, which commenced in January this year. Since multiple magmatic instrusions have now occurred beneath the Peninsula since this time, we cannot rule out that the current seismic swarm is the result of an intrusion beneath Fagradalsfjall.

If earthquake activity is related to a magmatic intrusion, then the same hazards would apply as stated previously for Svartsengi/Grindavík, e.g. possibilty of a fissure eruption comprising lava fountaining, lava flows, gas emissions etc.

Possible scenarios:

1) Seismic swarm wanes in the coming days/weeks. Potential for rockslides in the region.

2) Intensity of swarm increases with the occurrence of larger magnitude earthquake – up to M6.0.

3) Magma instrusion occurs in the vicinity Fagradalsjall:

i) Leads to an effusive eruption

ii) Intrusive activity declines and magma body solidifies

The current volcanic unrest in the Reykjanes peninsula keeps changing with time and it is difficult to anticipate its evolution in the future. The origin of this swarm will be verified after the acquisition of new ground deformation data later this week.

June 22, 2020: The area began inflating again in mid-May, and seismicity is up, per the Met Office.

May 6, 2020: Per the GVP, they have lowered the aviation code to Green. Yay!

May 2, 2020: There is no new word posted on the Icelandic Met website, and no news of the meeting that had been scheduled for April 8th. Perhaps it’s an effect of the current coronavirus crisis, which certainly is more urgent.

Nevertheless, per the website, the same possible outcomes are in effect.

April 12, 2020, 11:16 a.m., Pacific: Saturday, authorities reported a third underground magma intrusion, though it is deeper than the two known ones. No imminent eruption is expected. The big news is that chances for an M6 or higher quake have increased, with so much seismic activity — now roughly 8,000 quakes since this began!

My source for this is a post by Jon Frimann and this news report (Icelandic).

That article quotes volcanologist Kristin Jonsdottir on the new intrusion. Per Google Translate:

There are no signs that the magma is moving closer to the surface. There are indications of a new magma deposit west of the Reykjanes peninsula. So they have become three. Kristín says that this is the first time that the magma insert is so clearly seen on meters and satellite images. The new magma deposit is at a much more depth than the two magma deposits at Thorbjörn.

April 5, 2020, 5:35 p.m., Pacific: The GVP goes into a little more detail on their bulletin page:

There were more than 6,000 earthquakes recorded beneath the Reykjanes peninsula as of 26 March, making this period of unrest the largest seismic crisis ever recorded in this part of the country since digital monitoring started in 1991, according to IMO. The seismicity occurred across three main volcanic systems: Eldey, Reykjanes-Svartsengi, and Krýsuvík. Uplift continued to be detected in the Thorbjorn area totaling about 70-80 mm; the deformation rate was lower than in January and February. Deformation modeling suggested that recent inflation was caused by a second magmatic intrusion at a depth of 3-4 km in an area W of Thorbjorn, close to the intrusion that occurred at the beginning of the year. GPS data suggested a small deformation pattern detectable over a regional area, far beyond the Thorbjorn area.

April 4, 2020, 4:57 p.m., Pacific: Some 6,000 quakes have been recorded in this area, more than any other documented event. Check out details here. This being a plate divergence margin complicates things. There will be another meeting soon.

March 20, 2020, 4:48 p.m., Pacific: I’m a couple days late with this, but GVP reports that the Iceland Met Office raised Reykjanes Volcano to aviation code yellow after the uplift, which had stopped, began again. There are a few large (M4 to M5) earthquakes in the ongoing seismic swarm, too.

Of note, as of this writing, the Iceland Met Office website linked below seems to have had a failure. (Edit: The Iceland Met Office site is back up now, with this notice about the activity.) Per this news report, volcanic activity doesn’t appear imminent, and the scientists are going to hold a meeting next week.

Update, March 11, 2020, 3:02 p.m., Pacific: Per the Iceland Met Office yesterday:

Seismic activity in the vicinity of SW-tip of Reykjanes peninsula has decreased since last week. Earthquakes are though still being detected there. Considerable earthquake activity has been in the area since the 15th of February.

Seismic activity near Grindavík

Earthquake activity near Thorbjorn has significantly decreased recently. Uplift is no longer being observed, which is likely due to the halt of magma inflow. The uncertainty phase that Civil Protections declared is still in force.
Written by a specialist at 10 Mar 10:59 GMT

Update, February 15, 2020, 11:56 a.m., Pacific: Per the Icelandic Met Office today (emphasis added):

The earthquake activity in the area has decreased but is still above average, but less than when it peaked in the end of January. The largest earthquake detected in last week was M3.2 on the 11th of February at 18:46 west of Thorbjorn.

Indications are that the crustal deformation has decreased but is still ongoing. Additional monitors have been installed around Thorbjorn with two new seismographs installed last week. Gas will be monitored regularly and scientists recommend the continuing monitoring of the area.

The most likely explanation of the uplift and earthquake activity is that a magmatic intrusion is located at 3 to 5 km depth just west of Þorbjörn. It is most likely that this activity will stop without an eruption. The next meeting of the scientific council of Civil Protection will, Thursday February 20th.

Back on February 7th, Eric Klemetti did a terrific article about this and about the general geologic situation in Iceland.

I hope no eruption does ensue, because it would probably trash that beautiful Blue Lagoon resort (see image at top of page, with swimmers in the warm water and people walking around the pool wearing winter gear!). And I’m also wondering what effect it would have had on the nearby geothermal power plant — the one in Puna during Kilauea’s 2018 eruption was a concern, and they sealed some wells to avoid explosions that would have polluted the regions; fortunately, though, the lava never reached those wells, though it was close.

Original post follows.

This post is from a volcanophile who keeps a close eye on Iceland. I had never heard of this volcano system before, and I think it’s fascinating that today’s technology can actually spot magma moving in before any surface activity gives away its presence. The Icelandic Met Office is the official source, and here is their page on Thorbjorn.

The volcano Reykjanes (Þorbjörn) information and history

The current inflation that is now happening on the Reykjanes peninsula below the tuff mountain called Þorbjörn is in a volcano system called Reykjanes in the Global Volcanism Program . . .


Here are a couple of videos made by someone I found in a YouTube search — I don’t know who he is or his background, but it is a very nice introduction to the area. Of note, it isn’t a “huge” amount of magma; per the Met Office, a relatively small amount is involved — just a tiny fraction of a cubic km.

Also, in the second video, it isn’t correct to say that any volcano is “due.” They do their own thing, regardless of humanity’s sense of timing.

But this YouTube coverage is very helpful to those of us who aren’t familiar with the area; for updates, the channel is here.

First video:

Second and most recent video to date:

Go to that video’s page to see the links mentioned — there’s a good selection of them, including one to Jon Frimann’s blog, but I can’t easily transfer them to this post.

Featured image: The Blue Lagoon geothermal resort near Mount Thorbjorn (which is in the background, I think), by Andrei!, CC BY-SA 2.0

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