Earthquakes – Page 91 – Iceland geology

February 12, 2016February 12, 2016

Minor earthquake swarm on the Reykjanes peninsula

Yesterday (11-February-2016) at 08:47 UTC an earthquake swarm started on the Reykjanes peninsula. This has so far been a small earthquake swarm and largest earthquake so far had the magnitude of 2,7 other earthquakes have been smaller in magnitude.

The earthquake swarm on the Reykjanes peninsula. This is at the moment a small earthquake swarm. Copyright of this image belongs to Iceland Met Office.

This is classic earthquake swarm pattern on the Reykjanes peninsula at the moment. It does appear that this earthquake swarm is over, but it might start again without warning. This earthquake swarm is not connected to a volcano activity in the area, but it is forming a rift valley in the area.

Article updated at 00:53 UTC.

February 11, 2016February 11, 2016

Update on Bárðarbunga volcano (Week 06/2016)

Short update on Bárðarbunga volcano.

Bárðarbunga volcano continues to inflate at the depth of 15 – 10 km. Making it hard to observe it on the surface. Earthquake activity continues to increase, with regular earthquake swarms with magnitude of 3,0 – 3,5 at the moment. The reason for this earthquake activity is the inflation currently taking place in Bárðarbunga volcano at depth of 10 – 15 km and at shallower depth. I expect that hydrothermal activity is going to continue to increase in Bárðarbunga volcano for the next few weeks and months as magma pushes up to shallower depths inside the volcano.

Magnitude 3,1 earthquake (if my memory is correct) in Bárðarbunga volcano on Monday 8-February-2016. Copyright of this image belongs to Iceland Met Office.

Today (11-February-2016) magnitude 3,3 earthquake in Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

No other changes have been observed in Bárðarbunga volcano. Current pattern of activity in Bárðarbunga volcano is going to continue for a really long time. There is at the moment no need for to write about all of it. Unless something changes in Bárðarbunga volcano. Rift episodes like the one that has started in eastern rift zone in Iceland take a long time, the longest one can go for up to 20 years and they happen slowly most of the time. The biggest risk now is a new dyke intrusion and eruption (or both). That might start without warning and only last for few hours to days at most.

Icelandic News about Bárðarbunga volcano

Hæg atburðarás undir Bárðarbungu (mbl.is, Icelandic) – Attempt Google Translate at own risk. It might bring trolls and elves into existence.

Noise on SIL stations

I did have a conversation about Icelandic Met Office about the strange tremor spikes I’ve been seeing on SIL stations around Bárðarbunga volcano over the past few weeks. It turns out that is connected to 3G (900Mhz) interference. It has two factors in it, the 3G stations loosing signal, creating a dropout in the data stream to Iceland Met Office and what I suspect a signal leak into the hardware that Iceland Met Office has (in the same was as I’m seeing on my Böðvarshólar geophone) when the quality of the 3G signal is poor due to ice and snow on the transmitters antenna, that forces the 3G hardware to boost it’s transmitter power up to 2W. This issue won’t go away until they move to 4G (maybe) or something else.

Other

I’ve decided that I’m first going to move to Denmark and then maybe I’m going to move to Germany. To the village of Andernach. The time frame on this plan is 10 to 15 years at the shortest. I don’t know if this plan is going to happen, it might do so and then it might not do so. I plan on to save up for a house in Germany, the reason for long preparation time is that I need to learn German and learn on the system in Germany. The town I’ve chosen is close to the West Eifel Volcanic Field. This is not the first time I’ve planned to move there (to Koblenz, but that town is too big I think), but those plans are now gone, replaced with this one. I don’t know yet if this plan is going to happen, it might do so in about 10 to 15 years if everything works out.

February 4, 2016

Magnitude 3,1 earthquake in Tjörnes fracture Zone (TFZ)

Today (04-February-2016) an magnitude 3,1 earthquake took place in south Tjörnes Fracture Zone. I don’t know if this earthquake was felt in nearby village of Kópasker.

The earthquake swarm on Tjörnes Fracture Zone, the green star is the magnitude 3,1 earthquake. Copyright of this image belongs to Iceland Met Office.

This earthquake swarm has now been going on for almost a month now and there doesn’t seems to be any sign of this earthquake swarm stopping any time soon. The activity drops at times, but always continues, even at low levels. Activity did increase after the magnitude 3,1 earthquake, but it has since dropped again into the same low it was before. I do expect this earthquake activity to continue.

February 3, 2016

Magnitude 3,9 earthquake in Reykjanes peninsula

Tonight at 19:50 UTC a magnitude 3,9 earthquake took place in Krýsuvík volcano. This earthquake is not volcano related, this is a tectonic earthquake and has started a minor earthquake swarm in Krýsuvík area. Other earthquakes so far have been small, with largest aftershock having the magnitude of 1,6. The magnitude 3,9 earthquake was felt in Hafnarfjörður and in the Reykjavík area (and nearby towns).

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

This earthquake swarm is currently ongoing, but it doesn’t appear to be a strong or a highly active earthquake swarm at the moment. It’s unclear if that is going to change since it’s impossible to predict how this earthquake swarms behave.

February 3, 2016February 3, 2016

Short update on Bárðarbunga volcano activity (Week 05/2016)

The activity in Bárðarbunga volcano continues to slowly increase, at the moment there seems to be a small lowdown in the activity but that might change without warning. There has been some change in the activity inside the caldera and that is important. There appears that two spots are forming inside the south part of the caldera, suggesting that magma has found a weak spot in the crust plug. The space between them is not big, at most 800 meters to 2 km. The weak spots might not erupt, the magma that is pushing up at this location might fail breaking trough the crust if the pressure is high enough to break trough the crust.

The green star marks the second weak spot in the caldera of Bárðarbunga volcano. Copyright of this image belongs to Iceland Met Office.

Yesterday (02-Februar-2016) signal appeared on the SIL stations around Bárðarbunga volcano. This signal was seen good distance from Bárðarbunga volcano, this does not appear to any type of failure in the SIL network, I’ve been looking for such and not found any. What this signal means is unclear and why it happens is unknown.

The strange signal starts around midnight at 02-February-2016 and continues until at least 05:00 UTC. It is not known why it happens. Copyright of this image belongs to Iceland Met Office.

The largest earthquake in past 48 hours had a magnitude 3,0 and was in the newly formed weak spot in the north-east part of the Bárðarbunga volcano caldera. Both weak spots in the Bárðarbunga volcano caldera have been having earthquakes this week and past week, in most of the caldera there has been some earthquake activity taking place. In late August-2014 the north-east caldera rim did leak some magma, creating a row of cauldrons above it. Both above the dyke and on the cauldron rim. I did try to find pictures of the cauldron in question, but I didn’t have any luck doing so.

Magma pressure inside Bárðarbunga volcano seems to be increasing faster then I expected. Something might have changed inside the volcano, or deep underneath it allowing for magma going inside the volcano at higher rate then before. It is not possible to know when next eruption in Bárðarbunga volcano happens, the time frame (based on historical data) is from 1 year and up to 10 years when a eruption cycle is going on.

January 29, 2016January 29, 2016

10 years of recording earthquakes

In 2006 I started recording earthquakes in Iceland for the first time. At the time I was living in Hvammstangi, Iceland (currently I am doing so now, but that won’t be for much longer). The first hardware that I got was a short period seismometer with amplifier and digitizer (turns analog signals into digital signals). That hardware continues to be in used today at Heklubyggð geophone station. The second hardware that I got also included three long period channels for seismometers like Lehman seismometer. I don’t know if I ever get any of this type of seismometers since I’ve been developing my standard over the last 10 years. I do plan on buying Volksmeter II seismometer when I’m back in Denmark and have the money to buy them. One for N-S direction and a second one for E-W direction. Vertical is not a option for this type of seismometer. Unlike the geophone I currently use, this are long period devices and they go down to 0.1Hz, giving me a excellent option in monitoring earthquakes at long range and down to magnitude 4,0 at the distance of 400 km (at the most).

I don’t know for sure how many earthquakes I’ve recorded over the past 10 years, but the numbers are somewhere over 10.000 – 20.000 earthquakes. In this time I’ve recorded earthquakes from two eruptions (Eyjafjallajökull (2010) and Bárðarbunga volcanoes (2014 – 2015). I did not record many earthquakes from Grímsfjall volcano eruption in 2011 or the minor eruption in Katla volcano in 2011 (that was an eruption in my view, even if the official word is that no such event happened).

The largest earthquake I’ve recorded since 2006 was the magnitude 9,0 earthquake in Japan in 2012. The second largest earthquake was a magnitude 8,3 close to Alaska, I don’t recall exact location. I’ve seen all types of earthquakes, all types of earthquake swarms over the past 10 years on my instruments.

Next 10 years

While I’m going to continue to record earthquakes. I don’t know how long I can continue to record earthquakes in Iceland. Since doing so is a difficult task and effort when it comes keeping everything up and running. Having 3G connection also costs me a little big of money each month. Changes also happen and with time it is going to be impossible for me to keep the two remaining geophones going in Iceland. At the peak of my network I had four active geophones, now I’m down to two geophones in Iceland. I’m going to turn on one geophone in Denmark once I move back there. In few years time I hope to add the Volksmeter II seismometers to my measuring tools in Denmark.

I’m going to continue to record earthquakes, even if I stop recording earthquakes in Iceland due to changes that I have no control over. Changes happens and I don’t know what next 10 years are going to have in store.

Current status

Currently my main earthquake computer is off-line and it’s going to remain off-line until I move back to Denmark. It has been off-line since I haven’t been able to get an apartment for the 1 year + 2 months I’ve been living in Iceland at the moment.

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.

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