Category: Swarm

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Continued earthquake activity in Öræfajökull volcano

Earthquake activity continues in Öræfajökull volcano. There is a small drop in earthquake activity every few hours just before it increases again. This seems to be normal for earthquake like Öræfajökull volcano. The magma in Öræfajökull volcano is expected to be rhyolitic in nature. That explains the nature of the earthquakes swarms that are now taking place.


The earthquake activity in Öræfajökull volcano for the last 48 hours. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in last 48 hours had the magnitude of 1,7. At the moment larger earthquakes have not yet happened in last few weeks (since the magnitude 3,5 earthquake took place). The earthquakes at the outline and some distance from Öræfajökull volcano seems to be fault lines that move as Öræfajökull volcano continues to inflate. There is some risk of earthquakes at those locations, it is my view that risk is mostly minimal for now at least. I don’t know how the development has been for the cauldron in Öræfajökull volcano caldera since I haven’t seen any news about the development of that area.

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Slow increase in earthquake activity in Öræfajökull volcano

There seems to be a slow increase in earthquake activity in Öræfajökull volcano. For the last 48 hours the number seems to be rising. This is how it looks on this graph from Icelandic Met Office.


Earthquake activity in Öræfajökull volcano from 2005 – today. Copyright of this image belongs to Icelandic Met Office.

This increase in earthquake activity suggest that more magma is pushing up the volcano at faster rate. The main idea now is that the magma that is pushing up Öræfajökull volcano is rhyolite in nature and that seems to be confirmed to an extent by the earthquake activity as it now appearing.


Last 48 hours of earthquake activity in Öræfajökull volcano. The volcano is located in south part of Vatnajökull glacier. Copyright of this image belongs to Icelandic Met Office.

How this develops is a big question due to lack of accurate historical accounts. What is known about the eruption in 1362 was written down up to two centuries later and when that happens lack of accuracy is passed into the written record. The written record for the eruption in 1727 – 1728 is slightly better but is far from being accurate.

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Magma movement in Askja volcano (Dyngjufjöll)

For the past few days there has been a earthquake activity in Askja volcano. All of the earthquakes so far have been small in magnitude and only few have reached magnitude above 1,0. This earthquake activity is due to magma movements and its the first time I have seen it reported at this shallow depth (above 10 km depth).


Earthquake activity in Askja volcano. North of Vatnajökull glacier. There is also activity in Herðubreið to the east, but that’s an unrelated activity and is due to tectonic forces in the area. Copyright of this image belongs to Icelandic Met Office.

There are no clear signs that an eruption is about to happen in Askja volcano or in Dyngjufjöll as this area is also called. If an eruption starts in this area outside of any major water area its only going to erupt lava with minimal risk. Explosive eruption due to water is also a possibility but those are impossible to predict.

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Two magnitude 3,9 earthquakes in Bárðarbunga volcano

Today (21-November-2017) at 13:53 and 13:55 UTC two magnitude 3,9 earthquakes happened in Bárðarbunga volcano. This earthquake activity was in the regular area in the north-east part of the Báðarbunga volcano caldera. It remains to be seen if there is any change in conductivity in Jökulsá á Fjöllum following this earthquake swarm.


Earthquake activity in Bárðarbunga volcano today (green stars, red dots). Öræfajökull volcano is quiet today (maybe due to extremely bad weather in this part of Iceland at the moment). Copyright of this image belongs to Icelandic Met Office.

The aftershocks form a interesting line that goes east to west in the caldera. I’ve not seen that form before and it’s interesting to see it. I don’t know yet if it means anything besides a possible fault in the volcano. It takes the glacier water 9 hours to reach the monitoring station at Jökulsá á Fjöllum, Grímsstaðir from the one at Upptyppingar. I don’t know how long it takes the water to reach Upptyppingar from the glacier, it is at least several hours.

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Please note that with current high activity I’m getting a bit stressed out with the workload when a lot of things are happening in short period of time.

Current list of unrest volcanoes is this.

Bárðarbunga (continued in September 2015 after the August 2014 – February 2015 eruption)
Öræfajökull
Katla
Askja (deep magma activity, not a major concern at the moment)

Other volcanoes are not a concern until they erupt without warning.

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Earthquake swarm in TFZ close to Kópasker village

Today (08-November-2017) a small earthquake swarm happened west of Kópasker village. Largest earthquake in this swarm had magnitude of 3,0 and the second largest magnitude was 2,2 (foreshock).


The earthquake activity in TFZ. The green star shows the location of this earthquake swarm.

This earthquake swarm seems to be over at the moment but there is always a lot of earthquake activity in TFZ. Earthquake activity at this location has been going on for some time now with quiet period between them. There is a good chance that pattern is going to repeat in next few weeks.

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Earthquake swarm in Öræfajökull volcano

For the last few hours there has been a earthquake swarm in Öræfajökull volcano. I’m not clear on how many earthquakes have so far happened in Öræfajökull volcano at the moment. Most of them have been smaller than 1,5 in magnitude and only few earthquakes with magnitude 2,0 and above have so far happened. This is a unusual earthquake swarm and possibly the largest one since the unrest started in Öræfajökull volcano few years ago.


The earthquake activity in Öræfajökull volcano at the south end of Vatnajökull glacier. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm is on a line that is almost north-south direction and that is interesting as it crosses the crater of Öræfajökull volcano. That type of pattern appeared last month during the earthquake swarms that took place then. Between now and then there has just been few earthquakes here and there in the volcano. Old history tells (from the eruption 1362) that before the main eruption at least two earthquakes are felt nearby. How accurate that documentation is questionable due its age and possible rewrite over history. Detailed report on Öræfajökull volcano can be found here (pdf) by Icelandic Met Office. Historical data shows that eruption from Öræfajökull volcano are powerful and can lost for a short time (1326 eruption), but they can also last for few months like the 1727 eruption that started in August 3rd and ended on May 1728 (+- 30 days error margin).

Notice on Esjufjöll volcano

There has also been a minor increase in earthquake activity in Esjufjöll volcano. This seems to be a side effects of the activity in Öræfajökull volcano. Why and how that works is unknown to me. I don’t expect any eruption to take place in Esjufjöll volcano. Last eruption was possibly in the year 1920 and was short lived (few hours?). I don’t know how long this earthquake activity has been going on in Esjufjöll volcano, but it is mentioned in a Icelandic Met Office report from 2002, that report can be read here (pdf).

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Strongest earthquakes in Bárðarbunga volcano since February 2015

Yesterday (26-October-2017) and today (27-10-2017) two strongest earthquake took place in Báðarbunga volcano since end of the eruption in February 2015. The magnitudes of earthquakes so far are two Mw4.7, One magnitude Mw3,9 and one Mw3,2 earthquake. So far other earthquakes have been smaller in magnitude. No harmonic tremor has been detected so far, but given the location an eruption might start in other part of the caldera without warning even if the earthquake swarm activity is happening in the northern part of the Bárðarbunga volcano caldera.


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


The magnitude 3,9 earthquake as it appeared on my geophone in Dellukot. This image is under Creative Commons Licence, please see CC licence for more details.


The magnitude 3,9 earthquake as it appeared on my geophone in Böðvarshólar. This image is under Creative Commons Licence, please see CC licence for more details.


The second magnitude 4,7 earthquake as it appeared on my geophone in Dellukot. For some unknown reason (maybe bad weather) I was unable to properly record the magnitude 4,7 earthquake at 23:26 UTC. This image is under Creative Commons Licence, please see CC licence for more details.


The second magnitude 4,7 earthquake as it appeared on my geophone in Böðvarshólar. For some unknown reason (maybe bad weather) I was unable to properly record the magnitude 4,7 earthquake at 23:26 UTC. This image is under Creative Commons Licence, please see CC licence for more details.

At the moment no eruption has been detected. But this strong and increasing earthquake activity suggest that magma pressure inside Bárðarbunga volcano might be reaching critical point. If it has not reached critical point already. For the next 24 – 36 hours really bad weather is forecasted in Iceland. With wind gusts forecasted up to 45m/s in the highland and in northern Iceland. This bad weather is going to cause problems in detecting earthquakes in Bárðarbunga volcano and elsewhere.

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Earthquake activity in south part of Bárðarbunga volcano caldera

Today (24-October-2017) at 14:18 UTC a magnitude 4,1 earthquake took place in south part of the Bárðarbunga volcano caldera. Few moments later at 14:54 UTC a magnitude 3,4 earthquake took place and few other earthquakes followed.


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

What is different now is that the earthquake activity is now happening in south part of the caldera. Close to the area where deep cauldrons have appeared due to shallow magma at this location. This makes the earthquake activity at this highly interesting and possibly highly dangerous if magma has now started to push it’s way up at this location. A small eruption at this location could result in a serious glacier flood, even if such an eruption only lasted for few hours.


The magnitude 4,1 earthquake as it appeared on my geophone in Dellukot. This image is under Creative Commons License, please see CC License for more details.


The magnitude 4,1 earthquake as it appeared on my geophone in Böðvarshólar. This trace has been filtered at 4Hz. This image is under Creative Commons License, please see CC License for more details.

It remains a question if an earthquake is going to happen in north-east part of the Báðarbunga volcano caldera in next few days. That seems to happen when a earthquakes takes place in south part of the caldera. I don’t know why that happens, it is just seems to do.

Article updated at 23:48 UTC. Text fixes.

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Strong earthquake swarm in south Iceland yesterday (20-October-2017) – minor damage reported

Yesterday (20-October-2017) a strong earthquake swarm happened in south Iceland on the SISZ fault zone. This earthquake swarm is currently ongoing and stronger earthquakes cannot be ruled out at this point.


The earthquake swarm as of the writing of this article. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake that has happened so far had the magnitude of 4,1 and four magnitude 2,9 earthquakes have happened at the writing of this article. During the strongest earthquake yesterday some minor damage has been reported, items falling out of shelves and breaking, picture frames getting skewed on walls. For a short time the village of Stokkseyri lost all line phone communication, I don’t know how long that outage lasted but phone service was restored quickly according to the news on Rúv. Largest earthquake was felt over a wide area, all the way to Reykjavík and up to Akranes village and east to Hella village.


The magnitude 4,1 earthquake as it appeared on my geophone in Dellukot. This image is under Creative Commons Licence, please see CC Licence page for more details.


The magnitude 4,1 earthquake as it appeared on my geophone in Böðvarshólar. This image is under Creative Commons Licence, please see CC Licence page for more details.

I don’t know if this earthquake activity signals a new period of earthquake swarm in SISZ. I have listed large history of earthquakes of the SISZ in a article from 2011 here.

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Strong earthquake swarm in Tjörnes Fracture Zone this morning (19-October-2017)

Today (18-October-2017) at 06:00 UTC (Icelandic time) people of Grímsey Island got a rude awaking when a magnitude 3,8 to 3,9 earthquake took place. At 05:01 UTC a magnitude 2,9 earthquake had taken place. For the past 48 hours total of 105 earthquakes have taken place in the Tjörnes Fracture Zone. The largest earthquake took place in what seems to be north part of Grímsey Island, there is no population in that part of Grímsey Island but the population lives only few hundred meters away.


The earthquake activity in Tjörnes Fracture Zone in Grímsey Island. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity started in this part of the Tjörnes Fracture Zone on 05-October-2017 as I wrote about here. Since then it is has been continuously ongoing, for a time it looked it was slowly stopping but the earthquake this morning increased the activity again. Since around 19:00 UTC this earthquake swarm seems to have slowed down a bit again, but the earthquake swarm is still ongoing as of writing of this article. More strong earthquakes in this area cannot be ruled out.

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