Swarm – Page 71 – Iceland geology

September 7, 2016

New earthquake activity in Katla volcano

Early this morning (7-September-2016) an earthquake with the magnitude of 3,5 took place in Katla volcano. There was little earthquake activity before the main earthquake and after it, since this morning activity has remained low.

Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity is in the same area of the magnitude 4,9 earthquake two weeks ago. No harmonic tremor has been detected following this earthquake. I don’t know if anything more is going to happen. All that can be done is to wait and see what happens next.

August 30, 2016

Earthquake swarm in Bárðarbunga volcano

Today (30-August-2016) an earthquake swarm started in Bárðarbunga volcano. The earthquake swarm took place in the caldera of Bárðarbunga volcano, as has been the case for the past few months. Nothing suggests that magma is on the move or that eruption is imminent, this seems to be tectonic or tectonic related activity in Bárðarbunga volcano after the eruption in 2014, that ended in February 2015.

The earthquakes in Bárðarbunga volcano. Green stars are earthquakes larger then magnitude 3,0. Copyright of this image belongs to Iceland Met Office.

Largest earthquakes so far have the magnitude of 3,8 (at 13:33 UTC) and 3,4 (at 16:58 UTC), other earthquakes have been smaller in magnitude. The reason for this earthquakes is inflow of magma at depth (more than 10 km) into Bárðarbunga volcano. This is creating stress changes higher up in the crust, resulting in earthquake swarms. More earthquakes can be expected from Bárðarbunga volcano in next few hours to days. This type of earthquake activity almost happens weekly at the moment and that has been the activity pattern since September-2015. I’m not expecting any change in this activity pattern for next few months.

August 29, 2016August 29, 2016

Katla volcano earthquake activity update

This is not going to be a too long update about the activity in Katla volcano. Since I fear that this article might become outdated rather quickly.

Currently there is no eruption in Katla volcano. At the moment only earthquake activity has happened. Latest information shows that hydrothermal water has entered Múlakvísl glacier river from Mýrdalsjökull glacier and that is making the air nearby possibly toxic and dangerous. The two largest earthquakes had the magnitude of 4,5. One earthquake had the depth of 3,8 km while the one that happened 20 seconds later had the depth of 0,1 km. Other earthquakes had magnitude around 3,0 and above and below.

Green star show where earthquakes with magnitude above 3,0 took place in Katla volcano. Copyright of this image belongs to Iceland Met Office.

It is not know how and eruption starts in Katla volcano, since no historical recordings exist when last eruption took place in the year 1918. Making ideas on how an eruption in Katla volcano start mostly guesswork. Current earthquake activity is the strongest since 1977, in 1955 there was some strong earthquake activity but magnitude of those earthquakes is not known. It is my idea that Katla volcano erupts when a rift zone activity takes place in this area, since it is on the eastern volcano zone (EVZ) in Iceland, it is currently expanding south of Vestmanneyjar and American plate and Euroasian plate is around 1cm/year.

The main 4,5 earthquake in Katla volcano. This image clearly shows a long period earthquake. This is my station in Heklubyggð. This image is under CC Licence, please see CC Licence page for more details.

The main 4,5 earthquake as it appeared on my geophone in Böðvarshólar. The earthquake signal is clear. This image is under CC Licence, please see CC Licence page for more details.

It is difficult to know what happens now. The signs are not good, but Katla is an active volcano with regular eruption cycles so this is only matter of time now. As mentioned above, the reason is lack of data on how the eruption process starts in Katla volcano. All that can be done now is to wait and see what happens next.

August 29, 2016

Earthquake activity in Katla volcano

This article is going to be updated in the next 24 hours if needed. Details are few at this moment.

A magnitude 3,6 earthquake (automatic magnitude estimate) has happened in Katla volcano. Few other earthquakes happened before the largest earthquake and few minor earthquakes took place after it. At the moment activity has dropped down (as it appears on my geophone) to nothing. That might change without warning.

Earthquake activity in Katla volcano. This image does not have the magnitude 3,6 (automatic magnitude estimate) in it. Copyright of this image belongs to Iceland Met Office.

At the moment no harmonic tremor has appeared on the SIL stations around Katla volcano. This means that eruption has not started. Until an harmonic tremor appears, this is just an earthquake activity.

This article is going to be updated if needed in few hours (around 16:00 GMT/UTC due to my current day plan).

August 26, 2016

Minor earthquake swarm on Tjörnes Fracture Zone (TFZ)

Today (26-August-2016) a minor earthquake swarm started on TFZ. This is currently not a large earthquake swarm and only around 50 earthquakes have happened so far. More earthquakes might happen if this earthquake swarm continues.

The minor earthquake swarm is shown by the cluster of red dots. Copyright of this image belongs to Iceland Met Office.

This area has seen several earthquake swarm since July and is a high chance earthquake activity is going to continue in this area for the next few days to weeks. Earthquakes with magnitude above 3,0 cannot be ruled out.

August 19, 2016

Earthquake activity in Katla volcano

Today (19-August-2016) a magnitude 3,5 earthquake took place in Katla volcano. It was followed by several earthquakes, both before the strongest earthquakes and after it.

The earthquake activity in Katla volcano. The green star shows the location of the magnitude 3,5 earthquake. Copyright of this image belongs to Iceland Met Office.

This doesn’t seems to be an activity connected directly to magma movements. This might however be a gas under pressure breaking rock, since clues this summer suggests that heat is now increasing in the caldera. At least for now, it might cool down again in coming months. The most common months for Katla volcano to erupt are from July until November, eruptions in other months are less common, they do happen every few hundred years.

The magnitude 3,5 earthquake as it appeared on my geophone in Heklubyggð. This image is under Creative Commons licence. Please see the CC Licence page (above) for more details.

June 25, 2016

Strong earthquake swarm deep on the Reykjanes ridge

Few days ago an earthquake swarm started deep on the Reykjanes Ridge, this is as far as the Reykjanes ridge extends at the end of it. After that the north Atlantic ridge starts. It is close to impossible to know for sure what is going at this location, however the data suggests that an eruption is taking place there and it appears to be a big one. How big I don’t know and I’m not willing to guess it due to lack of data.

The earthquake activity has been interesting, with the largest earthquake having a magnitude 5,5 (EMSC info). Other earthquake magnitudes are 4,9 (EMSC info), magnitude 5,0 (EMSC Info), magnitude 4,9 (EMSC Info).

This earthquake activity is currently ongoing, since the distance from land is ~1100 km it is impossible to know for sure what is going on. There is also around 4 km deep ocean at this location. If an eruption is taking place at this location, it is not going to show in the surface of the ocean. I’m sure a lot of smaller earthquakes are taking place, they are just not being recorded by any seismic detecting network due to distance.

June 25, 2016

Something is going on in Bárðarbunga volcano

This is little short on details as of yet. There is clearly something going on in Bárðarbunga volcano. I don’t know what at the moment, several earthquakes have appeared, the strongest one with the magnitude of 4,0 so far. I’ll post more updates soon as I know more.

The earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

No volcanic harmonic tremor has been seen as of yet. That means no eruption for the moment.

June 21, 2016

Minor earthquake swarm on the Reykjanes peninsula

Today (21-June-2016) a minor earthquake swarm took place on Reykjanes Peninsula, this earthquake swarm was located close to a mountain called Keilir. This was not a large earthquake swarm, around 20 earthquakes took place.

The earthquake swarm on the Reykjanes peninsula. The earthquakes are the red dots. Copyright of this image belongs to Iceland Met Office.

None of the earthquakes that took place was strong, with the largest earthquake only having the magnitude of 2,2. Other earthquakes that took place had smaller magnitude. This earthquake activity appears to have died out (for now at least).

June 9, 2016June 9, 2016

Earthquake swarm close to Hveravellir (Langjökull north)

I don’t know a lot about this earthquake swarm close to Hveravellir (Langjökull north), due the lack of information. What I do know is that an earthquake swarm is taking place there and the largest earthquakes so far have the magnitude around 2,1. Largest reviewed earthquake had the magnitude of 2,1 at 2,1 km depth. Other than this information I don’t know for sure what is going on in this area.

The few earthquakes that Iceland Met Office has been able to locate with some certainty in Hveravellir. Copyright of this image belongs to Iceland Met Office.

This earthquake swarm is appearing clearly on nearby SIL station and only this one SIL station. Copyright of this image belongs to Iceland Met Office.

The drumplot of that SIL station also shows this earthquake swarm clearly. Copyright of this image belongs to Iceland Met Office.

I’m currently guessing that around 50 – 100 earthquakes have taken place so far, but without accurate data its difficult to know. The magnitude in this earthquake swarm is from 0,0 – ~2,1 so far. Larger earthquakes can’t be ruled out, but as the magnitude grows, so improves the SIL network ability to locate the earthquake magnitude and depth properly. For the smaller earthquakes, they are only going to appear on one to two SIL stations and that is not enough data to properly locate them or figure out exact magnitude.

I’m going to post updates to this earthquake swarm as it happens if needed.

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