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.

Something is going on in Grímsfjall volcano

This is a tricky thing to write about. Because nothing has started on the surface and might not start on the surface. It seems that something is going on in Grímsfjall volcano. Since the glacier flood is almost over or has finished the harmonic tremor level should have started dropping, it has not done so and I am not sure why that is. This might be boiling of the hydrothermal systems in Grímsfjall volcano when the pressure on the suddenly drops. Currently the harmonic tremor doesn’t look like it has reached eruption levels, that might change without warning.

Rising harmonic tremor, with a high top from storm noise on the 10/10. Colours are blue, green and purple that is barley visible at the end of the line.
Harmonic tremor in Grímsfjall volcano. Copyright of this image belongs to Icelandic Met Office.
One red dot in Grímsfjall volcano in middle of Vatnajökull glacier shown by white area on the map
Earthquake activity in Grímsfjall volcano. This is almost no earthquake activity. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know what is going on. Since there seems to have been a change in Grímsfjall volcano after the big eruption in May 2011. What that change is I don’t know. It seems to have slowed down Grímsfjall volcano eruption rate from what it was, its been 11 years since last eruption. It might continue if no eruption starts now following the small glacier flood that just ended.

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.

Small glacier flood from Grímsfjall volcano expected tomorrow (11. October 2022)

According to a news on Rúv. A small glacier flood is expected from Grímsfjall volcano tomorrow. This glacier flood is not expected to create any problems for roads or bridges. Last glacier flood took place in December 2021. The glacier flood is expected to appear in the glacier river Gígjukvísl.

Icelandic news and announcement of the glacier flood

Lítið hlaup úr Grímsvötnum (Icelandic, Icelandic Met Office)
Von á litlu hlaupi úr Grímsvötnum á morgun (Icelandic, Rúv.is)

Earthquake activity has started to increase in Fagradalsfjall and Reykjanes volcanoes

Since yesterday (06-October-2022) the earthquake activity has been increasing in the volcanoes Fagradalsfjall and Reykjanes volcanoes. Please note that Global Volcanism Program has updated the informations regarding Fagradalsfjall mountain and now classifies it as its own volcano, this is after a new report and information from Icelandic Met Office. From now on I am going to use that classification when updating on activity in Fagradalsfjall volcano. I’ll not update older articles (too much work), but this also applies to them as such.

This also means that Fagradalsfjall is a new volcano in Iceland.

Earthquake activity in Fagradalsfjall volcano, Krýsuvík-Trölladyngja and Reykjanes volcano. Shown with red, orange and blue dots
Earthquake activity in Fagradalsfjall volcano and Reykjanes volcano along with Krýsuvík-Trölladyngja volcano. Copyright of this image belongs to Icelandic Met Office.

Earthquake activity at start of an eruption cycle in Fagraldsfjall volcano are not large. They grow larger once magma has started to push into the crust, until then the earthquake activity only seems to happens with minor earthquake swarms.

Article updated with new information.

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Inflation from start of September in Krýsuvík-Trölladyngja volcano and in Reykjanes volcano

According to GPS data from Icelandi Met Office that can be viewed here for Krýsuvík-Trölladyngja volcano (Þorbjörn) and here for Reykjanes volcano. It seems that a inflation period, at least in Krýsuvík-Trölladyngja volcano started in early September and is ongoing at the writing of this article. Earthquake activity is low at the moment, but the area has already moved a lot in recent earthquake swarms and that might he dropped the crustal stress in the area. It might also explain some of the GPS movements. I have some, but limited understanding of reading GPS data so my assessment might be off, wrong or both.

There also seems to be inflation going on, without many earthquakes in Reykjanes volcano. That seems to be have been going on since start of August. There have not been any eruption in Reykjanes volcano even after repeated inflation and deflation cycles in the volcano. Inflation cycles often have earthquake swarm activity if dyke activity follows an inflation event. That does not seem have happened this time around.

If this inflation continues, in either one or both volcanoes. It is clear a new period of high earthquake activity is about to start on Reykjanes peninsula. When that earthquake activity is going to start is impossible to know. Since recent earthquake and volcano activity has changed how the crust works in the parts of the Reykjanes peninsula where magma has been active. Since hot magma slowly softens the hard rock in the crust at depth and that lowers the earthquake activity. Rather then at the start of an volcano activity, when the crust is cold and brittle, resulting in high earthquake activity before an eruption.

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Strong earthquake swarm on the edge of Reykjanes ridge

This earthquake swarm is around 1330 km away from Reykjavík and in the North Atlantic ocean. What is going on here is unclear, but this is probably an earthquake swarm before an eruption or during an eruption in that area. The ocean depth at this location is between 3 to 4 km so nothing is going to appear on the surface.

Earthquake Zoom - LAT: 50 - 60 ; LON: -44 - 34 ; Red dots and orange dots show the earthquake swarm on the edge of Reykjanes ridge
Earthquake activity on the edge of Reykjanes ridge. Screenshot from EMSC website.

Total of 61 earthquakes have been recorded since 26-September-2022 when this activity started. Largest earthquake so far had a magnitude of Mw5,7 but several earthquakes with magnitude of Mw5,0 appears to have taken place. Because how remote this area is only the largest earthquakes are being recorded. It is possible to monitor the earthquake swarm here on EMSC website.

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Update on the earthquake swarm east of Grímsey island (12-September-2022)

This is a short update on the earthquake swarm that is ongoing east of Grímsey island.

The earthquake swarm that started on 8-September-2022 east of Grímsey island is ongoing. Over 6000 earthquakes have been recorded at the writing of this article. Largest earthquakes in recent days have had a magnitude Mw4,2 and have been felt over a wide area. People living in Grímsey island and tourists in Grímsey island feel this earthquake swarm clearly.

Green stars and red dots in line east of Grímsey island in the ocean. Green star is also close to Húsavík, but that might be an error in recording
Earthquake activity in Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Met Office.

There are no signs of an eruption is about to start. That might change without warning, but I don’t know likely an eruption is in this location because there’s no good data on possibility of an eruption. There’s also no clear reading from any nearby GPS station. This most likely is just an earthquake swarm. The risk of a magnitude 6 to 7 earthquake in this area remains high and such earthquakes can happen without warning.

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Magnitude Mw4,9 earthquake east of Grímsey island (Tjörnes Fracture Zone)

During the night of 8-September-2022 at 04:01 UTC an earthquake with magnitude of Mw4,9 took place east of Grímsey island. According to news reports this earthquake did wake up people in Grímsey island and was felt over a wide area in north-eastern Iceland. Over 22 earthquakes with magnitude above Mw3,0 have taken place since this earthquake swarm started. Over 700 earthquakes have been recorded at the writing of this article. This earthquake swarm is ongoing and number of earthquakes and possible stronger earthquakes might happen after this article is published.

A lot of green stars showing earthquakes over magnitude 3,0 east of Grímsey island and more red and orange dots showing smaller earthquakes. The map is brown for land mass and blue for ocean area, were the earthquake swarm is taking place
Earthquake activity east of Grímsey island. Copyright of this image belongs to Icelandic Met Office.

Earthquake swarms like this are common in this part of Tjörnes Fracture Zone and happen every 2 to 3 years, it is longer between large earthquakes in the magnitude range of 6,0 to 7,0, but they do happen. This area has an volcano, but there are no signs that is currently active and remains dormant.

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