Monitoring – Page 95 – Iceland geology

January 21, 2016January 21, 2016

Update 3 on Tjörnes Fracture Zone earthquake swarm

Today (21-January-2016) the earthquake swarm on Tjörnes Fracture Zone continued after a little stop. This time it was the earthquake swarm on the south end (next to Kópasker village) that started to increase. The change happened around 02:30 UTC this morning and in the beginning a magnitude 3,1 and 3,6 earthquake took place. Total of three earthquakes took place with magnitude 3,0 or larger. The earthquake swarm was most active until around 06:00 UTC when it started to slow down. The earthquake swarm continues at this moment, but it appears to be slowing down. The largest earthquake was felt in Kópasker.

The earthquake swarm on the south end of Tjörnes Fracture Zone. Copyright of this image belongs to Iceland Met Office.

Earthquake swarms in this area of TFZ are common and often there are several taking place over the year. I expect this earthquake swarm to continue for next few days. The risk of more magnitude 3,0 or stronger remains high. It is also a question if this activity starts earthquake swarm on nearby faults on TFZ. This activity is not connected to any volcano, this only tectonic earthquakes due to stress related changes (continental drift) in the area.

If any new development happens. I’m going to update this article.

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Website

I’ve been doing few changes to this website. It’s now possible to see latest comments posted. That can be found above the calendar. Now it’s also possible to go directly to my webicorder (geophones) website if anything happens when it comes to earthquakes.

January 20, 2016January 21, 2016

Earthquake swarm in Bárðarbunga volcano (Week 03/2016)

Today (20-January-2016) at 13:05 UTC an earthquake swarm started in Bárðarbunga volcano. This earthquake swarm was not a surprise to me, since I had seen clues it would happen on 17 and 18 of January-2016 (more details later in this article). I wasn’t sure if it would happen.

The earthquake swarm in Bárðarbunga volcano today. Copyright of this image belongs to Iceland Met Office.

The largest earthquake in this swarm had the magnitude of 3,6 and that is a increase in magnitude from last earthquake swarm taking place at this location two weeks ago. This earthquake appears to have been created by a magma breaking rock under pressure (low frequency element present in it).

The harmonic tremor plot from Vonarskarð SIL station, next to Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

I have noticed and I told Icelandic Met Office about this few days ago. There is a change in the harmonic tremor plot at 2-4Hz few days before an earthquake swarm starts in Bárðarbunga volcano. This has happened several times. Last time this happened is on 17 and 18 January-2016. Why this happens I don’t know for sure. One idea is that magma is over-pressuring once it enters the magma chamber and this might be gas release in the magma at the same time. If that is the reality, it is creating a magma foam at the top of the magma chamber that would erupt rather explosively when the pressure breaks the magma chamber currently holding it (see here, I’m not sure what this is called in science). This is only a idea that I have, but I find it the most likely explanation on what is going on in Bárðarbunga volcano. This might be wrong, but only time is going to tell what happens in Bárðarbunga volcano.

The time period between earthquake swarms is getting slightly shorter, now it’s around half a week from a whole week as was last month (December-2015). This change of phase suggests that more magma is flowing into the magma chamber and possibly in greater volume. The path the magma flows into the magma chamber is clear of all blockage, that means no earthquakes are created at that location. Current evidence suggest that only one magma chamber is being filled up with magma at the moment, but that magma chamber might be big and with some room left, but that might be quickly running out as is suggested by current earthquake swarms. The earthquake activity would be considerably higher if an eruption was about to start.

If anything more happens in Bárðarbunga volcano this week I’m going to update this article. Unless an eruption starts, then I’ll write a new one.

Update 1

A minor dyke intrusion took place in Bárðarbunga volcano caldera today (21-January-2016). The strongest earthquake in this dyke intrusion had the magnitude of 2,8 and depth of 2,5 km. This was a small and short event that took place.

The dyke intrusion in Bárðarbunga volcano took place in SW part of the caldera. Copyright of this image belongs to Iceland Met Office.

It’s difficult to know for sure what this means. What is clear is that magma is trying to break a path to the surface and it might have found a weak spot in the crust inside the caldera. If this starts to be a regular feature it means problems. This is the second weak spot to form in the caldera, the first one being in North-east part of the caldera, creating weekly earthquakes since September-2015.

Article updated at 01:52 UTC on 21-January-2016. Error fixed in date (it was not 10 and 11, it was 17 and 18th of January-2016).
Article updated at 20:56 UTC on 21-January-2016.

January 18, 2016

Update 2 on the earthquake swarm on Tjörnes Fracture Zone

The earthquake swarm on Tjörnes Fracture Zone (TFZ) that started on 12-Januar-2016 continues. The earthquake swarm is now smaller then in last few days, largest earthquake in past 48 hours had the magnitude of 3,3 with the depth of 17,8 km. Number of earthquakes in the last 48 hours is only 53 at the moment.

The earthquake swarm in TFZ for the past 48 hours. Copyright of this image belongs to Iceland Met Office.

It is difficult to know for how long this earthquake swarm is going to continue in Tjörnes Fracture Zone. This earthquake swarm might continue for next few days at most. It remains a question if new earthquake activity is going to start in Tjörnes Fracture Zone, that sometimes happens, but not always.

January 15, 2016January 15, 2016

Update 1 on Tjörnes Fracture Zone earthquake swarm

For the last 48 hours around 217 earthquakes have been detected in south Tjörnes Fracture Zone. Largest earthquake so far had the magnitude of 3,2 with depth of 6,2 km. Current depth of the earthquakes taking place shows that this are nothing more than tectonic earthquakes. This is not a volcano related activity so far. I doubt that is going to change for now.

Earthquake activity in Tjörnes Fracture Zone. Copyright of this image belongs to Iceland Met Office.

New earthquake swarm also started south of the earthquake swarm that started on 12-Januar-2016. So far that earthquake swarm has remained small, but dense in the number of detected earthquakes. Both earthquake swarms are minor at the moment. The fault area that is moving moves 20mm/year in right hand move, the rift in this area is also 5mm/year. This earthquake swarm is also small, compared to an earthquake swarm that took place in 2013 along the same fault (article about it can be read here. Article about start of that earthquake swarm in 2013 can be found here). It is not possible to know if this earthquake swarm is going to escalate or not. Current activity doesn’t rule it out.

Weather notice

There is a good chance that what remains of hurricane Alex to hit Iceland next week if it goes that path. The weather system might miss Iceland but I don’t know at this point if that is going to happen. If the remains of the hurricane get to Iceland I’m going to write a weather warning if the weather forecast gets really bad.

This article has been updated at 15:26 UTC.

January 11, 2016January 11, 2016

Fresh earthquake activity in Hekla volcano

During the night (11-January-2016) few minor earthquakes took place in Hekla volcano. None of the earthquakes did go over magnitude 2,0.

The earthquake activity in Hekla volcano (right). Copyright of this image belongs to Iceland Met Office.

No other activity has followed this earthquake activity. No change in harmonic tremor has been observed for the last 24 hours. At the moment this looks like a surface earthquakes due to some stress changes in the area of Hekla volcano.

January 10, 2016January 11, 2016

Bárðarbunga volcano earthquake swarm (Week 01 2016)

Current earthquake activity in Bárðarbunga volcano is going to be a regular feature until next eruption. Due to that I won’t write about all the earthquakes that happens, just when a magnitude 3,0 or larger earthquakes take place. The situation in Bárðarbunga volcano and nearby areas is getting more complex due to increasing magma activity at depth and surprising high number of them are creating pathways to the shallow crust. Since the eruption in Holuhraun ended there has been increase in earthquake activity in Bárðarbunga volcano, this is best seen by almost weekly magnitude 3,0 or stronger earthquakes. What has also been appearing over the past few weeks is deep activity in Trölladyngja, activity that started on 28 km depth and up to 20 km depth currently. That process only took around 1,5 – 2,5 months to happen (short amount of time). The activity in Trölladyngja is troubling in my view, since it’s my opinion that if the magma manages to create a pathway to the surface it is going to start an eruption in that area. Magma below Trölladyngja might also stop in it’s track, if it gets close enough to the surface without eruption it might create a new hill or new hydrothermal area while it’s cooling down. Whatever happens in the end is going to be interesting.

Latest earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

The second issue that is now starting to show it self is Loki-Fögrufjöll volcano, also known as Hamarinn. Today a magnitude 3,2 earthquake took place in it, not far from Skaftárkötlum cauldrons, the depth was 0,7 km. The earthquake today in Bárðarbunga volcano also had the magnitude of 3,2 with the depth of 0,1 km. Loki-Fögrufjöll volcano is a complex volcano with shallow magma chambers. After the last glacier flood it was clear that hydrothermal activity in Skaftárkatlar cauldrons is increasing the hydrothermal areas are growing in size. This means there is more energy flowing into the hydrothermal systems and the only way that happens if new hotter magma into the volcano. This development is troubling, both in short term and long term. This increases the risk of minor eruption in Loki-Fögrufjöll volcano considerable in my view. Risk of larger eruption in Loki-Fögrufjöll volcano has also gone up. Last eruption in Loki-Fögrufjöll volcano that was large took place in the year 1910 and lasted from June to October that year. Last minor eruption in my view took place in July 2011, lasting for few hours. That eruption has not been confirmed by geologists yet, I don’t know why that is. A glacier flood followed that eruption.

Other complexities in all of this are random fissures that might open up under unknown dykes, starting a eruption in areas that might not have seen a eruption in a long time. Along with new magma dykes going somewhere new. Whatever happens it is going to be interesting and this is going to take a long time. It takes Bárðarbunga volcano, since it starts it eruption cycle up to 20 years to finish once it’s started. The eruption cycle that started in 1862 did not end until 1910. A new eruption cycle started in 2014 and it’s ongoing. The longest eruption cycle I see in GVP data is a eruption cycle that started in 1697, it didn’t end until the year 1797.

Hekla volcano

A single earthquake with the magnitude of 1,7 took place in Hekla volcano today. Nothing else happened following this earthquake. This means Hekla volcano remains quiet.

Frost quakes

It’s cold now in Iceland. This means frost quakes have been appearing on Iceland Met Office SIL stations. This has also been increasing the noise levels on some SIL stations (the blue band when seeing harmonic tremor levels).

History of eruptions in Iceland

I’ve added a short link to a post that a made back in 2011 and I continue to update. This post has all of the eruptions in Iceland since the year ~900. This is good for people that want to check for historical eruptions in Iceland.

Article updated at 00:25 UTC on 11-January-2016. Updated for slight increase in clarity of wording.

January 4, 2016January 5, 2016

Fresh earthquake activity in Bárðarbunga volcano

Today (04-Januar-2016) a fresh earthquake activity took place in Bárðarbunga volcano. The largest earthquake had the magnitude of 3,3 and the smaller earthquake had a magnitude of 3,2. Other earthquakes in this earthquake swarm where smaller in magnitude.

The earthquakes in Bárðarbunga volcano. Green stars show the magnitude 3,3 and 3,2 earthquakes. Copyright of this image belongs to Iceland Met Office.

Deepest earthquake yesterday (03-January-2016) had the magnitude of 2,6 and depth of 21,5 km. Current earthquake activity in Bárðarbunga volcano has been connected to a inflation that is now taking place where the earthquakes are taking place. According to Kristín Jónsdóttir on Rúv News earlier today. It appears at least one magma chamber on 10 to 15 km depth inside Bárðarbunga volcano is filling up and that might result in an eruption in coming months. Where and when is impossible to know at this point in time.

Icelandic News

Kvikusöfnun skýri skjálftavirkni í Bárðarbungu (Rúv.is, Icelandic)

Update 1

New earthquake with the magnitude of 3,0 took place in Bárðarbunga volcano at 01:24 UTC on 05-January-2016. The earthquakes that have been taking place have been low period earthquakes based on the fact they are not recording properly with the SIL network (tectonic earthquakes almost always have correct magnitude).

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

This is a sharp increase in earthquake activity in Bárðarbunga volcano. Currently nothing suggests that eruption is about to start, due to lack of continuous earthquake swarm in Bárðarbunga volcano. This earthquake activity however suggests that magma pressure is increasing fast in a magma chamber that is located in north-east part of Bárðarbunga volcano caldera. When it might erupt is a question that does not have any clear answers at the moment. At the moment the only thing that can be done is to wait and see what happens next.

Article updated on 05-January-2016 at 11:41 UTC.

December 26, 2015December 27, 2015

Fresh earthquake activity in Bárðarbunga volcano

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Last night (26-December-2015) two magnitude 3,3 earthquakes took place in Bárðarbunga volcano. This earthquake activity was followed by a change in activity on 2 – 4Hz band, I’m not sure why that is, it might signal a inflow of magma at depth into shallow parts of the crust. This is however only guess on my part, this change in signal and it’s origin.

The change in the SIL station can be seen between 25 and 26-December-2015 on the blue line. Copyright of this image belongs to Iceland Met Office.

It is my view that the risk of eruption in Bárðarbunga volcano is increasing fast and Bárðarbunga volcano might erupt without warning at any time. Iceland Met Office holds a different view and that is there is no major risk of eruption in Bárðarbunga volcano at the moment, even if magma continues to flow into Bárðarbunga volcano.

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

The magnitude 3,3 earthquake in north-east part of Bárðarbunga volcano caldera had the depth of 0,1 km. The magnitude 3,3 earthquake in south-east part of the caldera had the depth of 2,5 km. At 08:20 UTC this morning a magnitude 1,0 took place in Bárðarbunga volcano, that earthquake had the dept of 20,3 km and that suggest the magma inflow might be more than current ideas and models suggest (this earthquake is on the edge of the volcano, not far from Tungnafellsjökull volcano). I don’t know what is going to happen next in Bárðarbunga volcano. Since nobody knows for sure what is going to happen next in Bárðarbunga volcano.

Update 1

The earthquake activity in Bárðarbunga volcano has now created a half-circle of earthquakes in the caldera. Over the past 24 hours there has been slight increase in activity in Bárðarbunga volcano after the magnitude 3,3 earthquakes. There has also been some odd harmonic tremor spikes around Bárðarbunga volcano, the problem is that at the moment there is bad weather taking place at this location in Vatnajökull glacier area. So this might just be wind. I have to wait until the weather gets better in order to see if anything changes.

The earthquake activity in Bárðarbunga volcano at 27-December-2015. Copyright of this image belongs to Iceland Met Office.

I don’t know if any more activity is going to take place. This might die down, it is difficult to be sure about what happens next.

Article updated on 27-December-2015 at 17:56 UTC.

December 20, 2015December 20, 2015

Earthquake activity in Bárðarbunga volcano

Last night (20-December-2015) a earthquake activity took place in Bárðarbunga volcano. Largest earthquake in this short earthquake swarm had the magnitude of 3,5 and the second largest earthquake had the magnitude of 3,1. This earthquake activity is shallow and above above 10 km depth and it appears to be result of magma activity in north-eastern part of Bárðarbunga volcano caldera. The earthquakes that took place appear to be long period volcano earthquakes (details can be found here, under b-type earthquake).

Earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

There clearly is something going on in Bárðarbunga volcano, it is already known that inflation is taking place in Bárðarbunga volcano after the eruption in Holuhraun ended in February-2015. Along with increase in dyke intrusions this clearly suggest that magma pressure is increasing inside Bárðarbunga volcano. What worries me is not the risk of large eruption in Bárðarbunga volcano. The risk in my view is at the moment risk of small eruption taking place, if a small eruption takes place under a glacier it is going to mean glacier flood. Size depends on the eruption size, duration and other factors. Currently there are no signs of imminent eruption, but that might change without warning. The north-eastern part of the Bárðarbunga volcano caldera is in my view weakened structure due to all the earthquake activity for the past 15 (about) months.

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December 16, 2015

Minor dyke intrusion in Bárðarbunga volcano

From 20:10 to 20:14 UTC a minor dyke intrusion took place in Bárðarbunga volcano. This dyke intrusion was small, only lasting those few moments and the largest earthquake had the magnitude of 2,5. Other earthquakes are smaller. Depth was from 15,6 km to 23,2 km. Based on the location, this is clearly a dyke intrusion into Bárðarbunga volcano. It is too small to start an eruption, but suggest that magma processes in Bárðarbunga volcano are starting to increase again.

The dyke intrusion in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

There is also a change in the SIL station Vonarskarð. What is creating remains unknown. This might be a change in hydrothermal systems under the glacier, but is impossible to know for sure at this point in time. Copyright of this image belongs to Iceland Met Office.

I don’t know if any more earthquake activity is going to take place in Bárðarbunga volcano. Since it is impossible to know what magma does next inside a volcano. At the moment I’m not expecting a eruption in Bárðarbunga volcano.

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