Change in the earthquake activity in close to Herðubreið mountain

Sometime yesterday (24-October-2022) a change happened in the earthquake swarm close to Herðubreið mountain. I am not sure when that change happened and it probably took few hours to happen before I detected it. But the change seems to be that now the earthquake swarm is at two locations and not just one. The second change is that the earthquake swarm is now getting more intense. The earthquakes at the writing of this article are minor, only magnitude Mw0,0 to Mw2,7 at the strongest. Nothing above Mw3,0 so far, but that might change without warning. Depth of this earthquake swarm is around 2 to 3 km at the writing of this article.

Two swarms of red dots show the location of the earthquake swarm east of Askja volcano and south of Herðurbreiðartögl volcano. The earthquake swarm is now west and north of Herðubreið mountain
Earthquake activity close to Herðubreið mountain. Picture from Icelandic Met Office.

What is going to happen next is impossible to know. An eruption in this area has not happened for at least 12.000 years or even longer. I don’t know if stronger earthquake activity is required for this area for an eruption to happen. It already is rather fractured from older earthquake activity and rift activity, that makes it possible for magma to have easier paths to the surface without much earthquake activity. That is at least one idea on the situation in this area. I might be wrong on this, since I don’t have information on the finer details of the crust around Herðubreið mountain.

Earthquake swarm in west part of Fagradalsfjall volcano

This morning on 23-October-2022 an earthquake swarm took place in west part of Fagradalsfjall volcano. Largest earthquake in this swarm so far had a magnitude of Mw3,0.

Green star just west of main Fagradalsfjall volcano. Few blue, yellow and red dots on the map showing earthquakes in other nearby volcanoes
Earthquake activity west of Fagradalsfjall volcano. Picture from Icelandic Met Office.

This earthquake activity is the result of magma pushing up into the crust at around 5 km depth. This is not a large dyke intrusion and possibly won’t result in a eruption, unless there’s a sharp increase in earthquake activity and that has happened (the August 2022 eruption started this way). This is currently a situation that requires monitoring for changes. If anything is going to happen is impossible to know.

Earthquake swarm north of Herðubreið mountain

During the night of 23-October-2022 an earthquake swarm started north of Herðubreið mountain. This looks like a tectonic earthquake swarm, rather then a magma related activity. At the writing of this article, over 500 earthquakes have been recorded.

Earthquake swarm north of Herðubreið mountain, a lot of red dots and green stars on the map. Located east of Askja volcano and south of Herðubreiðartögl volcano
Earthquake activity north of Herðubreið mountain. Picture is from Icelandic Met Office.

Largest earthquake at the writing of this article had a magnitude Mw4,0 and one magnitude Mw3,1 earthquake took place. Second largest earthquake had a magnitude of Mw3,3. This earthquake swarm is ongoing at the writing of this article and there’s still a risk of larger earthquakes happening north of Herðubreið mountain. The largest earthquake was felt in Akureyri according to news reports.

Earthquake swarm in Brennisteinsfjöll volcano

Today (21-October-2022) an earthquake swarm took place in Brennisteinsfjöll volcano. Largest earthquake had a magnitude of Mw3,0 at 10:23 UTC. This earthquake swarm is possibly over, it is however difficult to be sure.

Red dots in Brennisteinsfjöll volcano on Reykjanes peninsula, located just south of Reykjavík city and east of Kleifarvatn lake. A lot of yellow and orange dots on the map in few volcanoes showing smaller earthquake activity
Earthquake activity in Brennisteinsfjöll volcano and other nearby volcanoes. Picture is from Icelandic Met Office.

This is probably just a tectonic earthquake activity. But it is worth noting that volcano activity as has been seen in Fagradalsfjall volcano (Iceland newest volcano) is going to move east on Reykjanes peninsula. How fast and how long that change is going to happen is not known because of lack of data and written records from 700 to 900 years ago are incomplete and vague on details at best.

Earthquake swarm north of Grímsey island

Today (19-October-2022) at 10:26 UTC an earthquake with magnitude of Mw3,8 took place and at 11:58 UTC an earthquake with magnitude of Mw3,3 took place at the same location. I don’t know if any of the larger earthquakes where felt. A swarm of smaller earthquakes took place and that activity is ongoing when this article is written.

Two green stars north of Grímsey island in Tjörnes Fracture Zone. This is out in the ocean far from land and populated areas.
Earthquake activity north of Grímsey island. Picture is from Icelandic Met Office.

This earthquake activity probably is continuation of an large earthquake swarm that started in that area in September. I don’t know if this is going to result in more stronger earthquakes, but that is a possibility.

Strong earthquake swarm on Reykjanes ridge close to Geirfugladrangur and Eldeyjarboða

This evening on 16-October-2022 an strong earthquake swarm started close to Geirfugladrangur and Eldeyjarboða on the Reykjanes ridge. At the writing of this article the strongest earthquake had a magnitude of Mw4,4 but that might change without warning.

Red dots and green stars on the Reykjanes ridge out on the ocean. Reykjanes peninsula on the left side of the image
Earthquake activity close to Geirfugladrangur and Eldeyjarboða on the Reykjanes ridge. Image from Icelandic Met Office.

It is difficult to know how this earthquake swarm is going to evolve but there are clues in this activity that this might be a large earthquake swarm. However, activity in this area is also known to just stop without warning.

People advised not go to Mýrdalsjökull glacier

The police and Icelandic Met Office have now advised people not to go to Mýrdalsjökull glacier. This is after the earthquake swarm earlier today. According to Icelandic Met Office this earthquake swarm is similar to what happened before the minor eruption in Katla volcano in July 2011 that resulted in a glacier flood down Mýrdalssand and destroyed the bridge over the glacier river in that area. All trips to see ice caves in Mýrdalsjökull glacier have been temporarily forbidden by the Icelandic Police.

Two green stars and few red dots in Katla volcano caldera on the east side of the volcano under Mýrdalsjökull glacier
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

In July 2011 it took around 24 hours from the start of the earthquake activity then until something happened. If that is going to be case now I don’t know. That this activity is similar to July 2011 eruption is worrying. The eruption in July 2011 was minor and didn’t break the glacier, but it resulted in damage in that area from the glacier flood.

Largest earthquakes now have the magnitude of Mw3,8 and Mw3,0 (few of them). Other earthquakes have been smaller in magnitude but that might change without warning.

Earthquake swarm in Katla volcano

Today (16-October-2022) an earthquake swarm started in Katla volcano in Mýrdalsjökull glacier. Largest earthquake at the writing of this article had a magnitude of Mw3,8. I don’t know if it was felt in nearby towns and farms. Second largest earthquake had a magnitude of Mw3,0.

Green star and red dots in Katla volcano caldera that is covered with Mýrdalsjökull glacier.
Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm is ongoing at the writing of this article and the situation can change quickly. This might be a normal earthquake swarm and nothing more might happen. This type of earthquake swarm is not uncommon and I am not sure what is required for an eruption to start in Katla volcano.

Earthquake swarm south and east of Grímsey island

Yesterday (12-October-2022) an earthquake swarm started south and east of Grímsey island. This is in the same area as an earthquake swarm took place few weeks ago. Largest earthquakes so far in this swarm had a magnitude of Mw3,5. Larger earthquakes remain a possibility. Largest earthquakes have been felt in nearby populated areas.

Red dots east and south of Grímsey island along with two green stars that show the largest earthquakes. On a blue background and the coastline is fjords and small peninsuals in north-eastern Iceland.
Earthquake activity south of Grímsey island. Copyright of this image belongs to Icelandic Met Office.

This area has frequent earthquakes. This earthquake swarm might grow as sometimes happens. It might also equally just stop, since that is also something that earthquake swarm in this area do.

Magnitude Mw3,5 earthquake in Krýsuvík-Trölladyngja volcano

Today (12-October-2022) at 14:18 UTC an earthquake with magnitude of Mw3,5 took place in Krýsuvík-Trölladyngja volcano. This earthquake was followed by few smaller aftershocks. This earthquake seems to be happening because of a inflation that is taking place in Fagradalsfjall volcano and this strongly suggests that inflation in Fagradalsfjall volcano is slowly reaching critical levels. There is no eruption expected from Krýsuvík-Trölladyngja volcano as is.

Green star with few red dots just west of Kleifarvatn lake, showing increase in activity in Krýsuvík-Trölladyngja volcano
Earthquake activity in Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity suggests that more stronger earthquake activity is possibly on the way. When it might start is difficult to know for sure. This has been the pattern in recent months. Earthquake activity starts to appears like this and then one day a major earthquake swarm starts. What happens now is a wait and see as before.