Category: Earthquakes

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Earthquake swarm in Katla volcano, Kolbeinsey ridge, Hveravellir geothermal area

It has been a bit busy day earthquake wise in Iceland. But there has been more activity today then in past few weeks in Iceland. But it has been really quiet for a long time now in Iceland. But let’s start with the largest earthquake of the day.

Kolbeinsey Ridge

Today at 11:11 UTC there was an earthquake with the magnitude of ML3.65. This earthquake was not felt since it was more then 100 km away from nearest human population in Iceland. The earthquake took place on Kolbeinsey Ridge. It last erupted in the year 1755. No known eruption is known in this area since then. My geophone network did record this earthquake properly. The signal was strongest at my Hvammstangi geophone station. But it was also recorded on my Heklubyggð geophone station. On other geophone stations. The signal was too weak to be properly detected by my geophone.


The ML3.65 magnitude earthquake as it was recorded on my Hvammstangi geophone. This image is released under Creative Commons licence. Please see the CC Licence page for more details.


The ML3.65 magnitude earthquake as it was recorded on my Heklubyggð geophone. It is filtered at 1Hz. This image is released under Creative Commons licence. Please see the CC Licence page for more details.


The location of the earthquake. Copyright of this picture belongs to Iceland Meteorological Office.

Hveravellir geothermal area

There is an earthquake swarm ongoing (or it might be over. I have no good way to know that currently) at Hveravellir geothermal area. I only know there is an earthquake swarm there because of the tremor recording on Hveravellir geothermal area. But only two earthquakes have been large enough to appear on earthquake map on IMO web page.


The two earthquakes that did appear on IMO earthquake map. Copyright of this picture belongs to Iceland Meteorological Office.


However, Hveravellir SIL station did show that more was going on then did appear on the earthquake map. Most of this earthquakes are too small to appear automatic on the earthquake list. Some might even be too weak to be properly located by the SIL network. Copyright of this picture belongs to Iceland Meteorological Office.


Some of this activity did also appear on Skrokkalda SIL station I think. Copyright of this picture belongs to Iceland Meteorological Office.

Katla volcano

Katla volcano did have an new earthquake swarm during the night. This earthquake swarm had around 30 or so earthquakes. Most of them where located almost in the central caldrea. This type of swarm activity has now been ongoing since end of April, when it started rather sharply with an earthquake swarm. Since then it has had many earthquake swarm. But the current rate of earthquake swarm is around 1 to 3 earthquake swarm pr. Week. Normally they are in an new area inside the Katla volcano caldera.

My geophone station at Skeiðflöt records most of the earthquakes if the background noise is not too high during that time.


The earthquake activity in Katla volcano last night. Copyright of this picture belongs to Iceland Meteorological Office.

So far. This is just normal earthquake activity. It does not signal any chance of eruption activity so far. But this earthquake pattern is interesting. What it means is a different matter. So far, nobody knows for sure at this point in time. This activity seems to change hydrothermal activity inside Katla volcano caldera. This has also created minor glacier floods from Katla volcano caldera. But the flood have been seen on instruments that record water conditions in Múlakvíls glacier river. Glacier floods are marked by higher conductivity of the water, darker color and stronger sulfur smell (rotten egg smell). What happens next in Katla volcano is anyone guess. As Katla volcano has proven to be unpredictable volcano.

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New earthquake swarm in Katla volcano on 11. June 2012

Today from 04:00 to around 08:00 UTC this morning. There was an earthquake swarm in Katla volcano. This earthquake swarm was not large in the magnitude of the earthquakes. With the largest earthquakes being around ML2.0 in magnitude. There has been slight increase in conductivity in Múlakvísl river following this earthquake swarm. That suggests water is now leaking from hydro-thermal vents in Mýrdalsjökull glacier. So far no change in harmonic tremor has been seen. So for now, this are just earthquakes taking place inside Katla volcano caldera.


The earthquake swarm in Katla volcano this morning. Copyright of this picture belongs to Iceland Meteorological Office.

It is difficult to know what happens next in Katla volcano. As it is bit unclear what is exactly taking place in Katla volcano. With the lack of harmonic tremor following this earthquake swarms. This simply might just be normal summer earthquake swarms taking place. But Katla volcano is well known for that type of behavior during the summer in Iceland. With the most earthquake activity taking place in July and August.

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Earthquake swarm in Katla volcano yesterday (07.June 2012)

Yesterday there was an earthquake swarm in Katla volcano. Over 50 earthquakes have been recorded so far. But this earthquake swarm stopped yesterday at 16:22 UTC. Most of the earthquakes where shallow, with depth less then 1 km. Largest earthquake had the magnitude of ML2.5. No harmonic tremor was detected following this earthquake swarm. But that is unlike what did happen last year, when a similar earthquake swarm took place in Katla volcano.


Earthquake activity in Katla volcano yesterday (07. June. 2012). The main areas appear clearly on this map. The small dot SE on the caldera rim is an area that became active after last years minor eruption. What is taking place there is still an mystery. Copyright of this picture belongs to Iceland Meteorological Office.

This activity appears to be similar to what happened around 9th July, 2011. But no harmonic tremors are taking place in Katla volcano following this earthquake swarm.


Earthquake activity in Katla volcano on 9. July 2011. This good to compare the earthquake activity yesterday (image above this one). Copyright of this picture belongs to Iceland Meteorological Office.


The ML2.98 magnitude earthquake that happened in Katla volcano yesterday (07. June. 2012). This is the earthquake as it was recorded on Skeiðflöt geophone station. This image is released under Creative Commons License. See License page for more details.


Same earthquake as above. But filtered at 1Hz and this is how the earthquake appeared in Heklubyggð geophone station. This image is released under Creative Commons License. See License page for more details.

So far this is just an earthquake swarm. As there are no harmonic tremor signal taking place as the earthquake swarm is taking place. I do not know if there has been any glacier flood following this earthquake swarm. But if there was. It would mean that hydrothermal vents under Mýrdalsjökull glacier have been emptying out. It happens regularly in glacier such as Mýrdalsjökull glacier.

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Minor earthquake swarm in Katla volcano

Today (28.05.2012) at 11:22 UTC an small earthquake swarm did start in Katla volcano. This earthquake swarm did end at 12:28 UTC. This is small earthquake swarm, both in numbers of earthquakes and in the magnitude of the earthquakes in the swarm. With the largest earthquake having the magnitude of ML1.4. The depth of this earthquake swarm was around 0.1 km, but that gives the depth around 100 meters or so. Following this earthquake there has been some minor disturbance at Álftagróf SIL station. But because it only appears on one SIL station. This change might have its origin in something else. Like human traffic, local wind etc. For the moment I cannot rule that out.


The change in tremor at Álftagróf SIL station. This change in tremor might not be because of Katla volcano. But something else. Please keep that in mind. Copyright of this picture belongs to Iceland Meteorological Office.

If the tremor changes at Álftagróf SIL station where from Katla volcano. They where highly local and did not show up on other SIL stations for some unknown reason. That has happened before, but the SIL network was not as dense around Katla volcano back then.


Image of the active area in Katla volcano. Copyright of this picture belongs to Iceland Meteorological Office.

I find it most likely reason for this earthquake swarm where some changes in hydrothermal areas inside Katla volcano caldera. All hydrotheraml areas in Katla volcano are under high pressure due to the glacier that is on top of them. So changes might not happen without some earthquake activity as did happen few hours ago. This is also not in any way a sign that Katla volcano might be about to erupt. This is far too low earthquake activity for such event to be starting. There is an chance of small glacier flood following this earthquake swarm in next 8 to 24 hours. But it is far from certain that is going to happen.

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Earthquake activity in Herðubreið is not volcanic in nature

The earthquake activity in Herðubreið during past few days is not volcanic in nature, or magnetic in nature. It is purely tectonic in nature. But the faults that have been moving are vertical, not horizontal as so many earthquake faults. Earthquakes are common in this area, as it on the eastern rift zone. The fault lines in this area of Iceland are highly active at times. Iceland Metorlogical Office has released this interesting information about the earthquake activity in this area during the past few years.


The first fault plane in Herðubreið. This one has the direction of N41°A. Copyright of this image belongs to Iceland Meteorological Office.


The second fault plane in Herðubreið. This second fault has the direction of N221°A (49°). Copyright of this image belongs to Iceland Meteorological Office.

Most of the earthquakes are on the depth of 5 to 6 km according to IMO.


The earthquake activity in Herðubreið the days 14 to 17 of May 2012. Copyright of this image belongs to Iceland Meteorological Office.


Earthquake activity in Herðubreið during the years 2005 to 2006. Copyright of this image belongs to Iceland Meteorological Office.


Total amount of earthquakes in Herðubreið from the years 2005 to 2012. This clearly shows that activity in this area has been rather constant during this period. Copyright of this image belongs to Iceland Meteorological Office.

The area in question is outside Askja volcano main fissure swarm. It is also outside Kverkjföll volcano main fissure swarm. So this earthquakes are tectonic in nature. But even so this area has erupted in the past. But for now. It is just earthquakes and not magma on the move, or breaking its path up to the surface as was case in Upptyppingar tuff mountain. The images are from Week 20 overview (what is up about it) at IMO web site.

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Special report: Magnitude Mw6.1 earthquake hit northern Italy, many aftershocks recorded

At 04:03 CEST (02:03 UTC) an earthquake with the magnitude of Mw6.1 did happen in north Italy. This earthquake was in an area that has seen a lot of earthquake activity during past several months now. But earthquake activity did start in this area late last year (2011). This earthquake did create a lot of damage in north Italy according to news reports. At least seven people have died from this earthquakes and well over 50 people have been injured because of this earthquake. Many historical sites have been damaged or completely ruined in this earthquake. I do not know what type of fault that did break. But data suggest that it was a slip fault that did break. I am unsure on directions of the fault that did break.


The earthquake in Italy as I did record it in Aabenraa, Denmark. There was a lot of surface waves following this earthquake. But those waves can be seen after the S-wave of the earthquake. This image is released under Creative Commons Licence. See CC Licence page for more details. Owner of this image is Jón Frímann Jónsson. Software used is WinQuake.


Local map of the Mw6.1 earthquake in North Italy. Copyright of this image belongs to EMSC.


The magnitude Mb5.2 earthquake in Northern Italy. I did not record this earthquake as clearly as the strongest one. This image is released under Creative Commons Licence. See CC Licence page for more details. Owner of this image is Jón Frímann Jónsson. Software used is WinQuake.


Local map of the Mb5.2 aftershock in North Italy. Copyright of this image belongs to EMSC.

What is most interesting about this earthquake is that it was had a pre-earthquake with the magnitude of ML4.2 about an hour to two hours before the main earthquake did happen. Web page of EMSC is not working properly at the moment. So I can’t check the time of the pre-earthquake at the moment. There have been more then dozen aftershocks less then Mb4.0 in size. But there have also been several earthquakes with the magnitude of Mb4.5. This aftershock activity continues at the moment.

Update 1: According to EMSC the pre-earthquake took place at 23:13 UTC on 19.05.2012.


Local map of the ML4.0 earthquake that took place at 23:13 UTC on 19.05.2012 in North Italy. This appears to be clearly pre-earthquake to the larger one. Copyright of this image belongs to EMSC.

I am going to update this blog post as more information are published.

English news about this earthquake.

At least 7 dead after quake rocks northern Italy (CNN.com)
Deadly northern Italy earthquake hits heritage sites (BBC News)
In pictures: Italy earthquake (BBC News)

Blog post updated at 15:44 UTC (17:44 CEST) on 20.05.2012.

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Earthquake swarm continues close to Herðubreið. Earthquake activity in Katla volcano

The earthquake swarm that started in Herðubreið two days ago continues. So far over 100 earthquakes have been recorded. Most of them are less then ML2.0 in magnitude. But this earthquake swarm continues at slow rate. This is not a big earthquake swarm. Based on number (in my system) of earthquakes pr hour. But in my system, a large earthquake swarm has tens to hundreds of earthquakes pr hour.


The earthquake swarm in Herðubreið. Copyright of this image belongs to Iceland Meteorological Office.


A bit higher resolution of the earthquake swarm in Herðubreið. Copyright of this image belongs to Iceland Meteorological Office.

Katla volcano

There is some earthquake activity in Katla volcano. But it is not high. There was one small earthquake this evening (it did appear on my Skeiðflöt geophone). But it has not been reviewed. So both size and depth are going to change.


Earthquake activity in Katla volcano during the past few days and until today. Copyright of this image belongs to Iceland Meteorological Office.

The earthquake activity in Katla volcano is also showing interesting pattern during this week (Week 20). It seems that earthquake activity is focusing on one point inside the caldera. It is hard to know for sure what this means at current time. But it is my opinion that it is not a good sign. But so far, nothing major has been happening inside Katla volcano caldera at this time. Until that happens, it is just best to keep watch and keep speculations within the amount of what is going on.


Earthquake activity in Katla volcano during Week 20 (current week). Copyright of this image belongs to Iceland Meteorological Office.

Beside this activity. It has been quiet in Iceland now for several weeks now. That is not un-common to happen during some years. While other years are often more active, some years are quiet. It is not clear yet if the year 2012 is going to be quiet year in Iceland or not.

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Earthquakes in Katla volcano. Earthquake swarm continues close to Herðubreið. Other earthquake activity

This morning there was a short earthquake swarm in Katla volcano caldera. This earthquake looks like a minor dike intrusion did take place this morning. Current series of events did start on 28. April 2012. With a small earthquake event and a small glacier flood that did follow it. Along with harmonic tremors coming from the glacier flood and possibly Katla volcano caldera (hydro-thermal activity boiling or something of that nature). I do not yet know if there was any glacier flood following the event this morning. But so far there is nothing that suggests a small glacier flood did take place following the earthquake swarm this morning.

The earthquake swarm this morning took place on an location that did erupt on 8 and 9th of July 2011. So it is clear the area that erupted last year is picking up activity again. But there was an drop in activity from end of November 2011 until end of April 2012.


Earthquake activity in Katla volcano this morning. Copyright of this picture belongs to Icelandic Meteorological Office.

This earthquake activity did appear well on my geophone at Skeiðflöt farm.


Earthquake activity in Katla volcano caldera this morning on my Skeiðflöt geophone. There is a lot of noise on this geophone. But earthquake activity can still be seen on this. The earthquakes are marked by red (some noise is also marked by red). This picture is released under Creative Commons Licence. See CC Licence page for more details.

It is clear that Katla volcano seems to be warming up to an eruption. But it is impossible to know when such eruption might happen, or how big it is going to be.

Herðubreið

Earthquake activity continues south-west of Herðubreið. But almost all of the earthquakes have been less then ML2.0 in magnitude. Earthquake activity has been slowing down all day. At the moment, it appears this earthquake swarm is close to being over.


The earthquake activity close to Herðubreið mountain. Copyright of this picture belongs to Icelandic Meteorological Office.

This area is well known for for earthquake activity. So this is not something that is new in this area.

Reykjanes Ridge

According to EMSC and USGS there have been several earthquakes with the magnitude of Mb4.5 to Mb4.8 on the Reykjanes Ridge. Earthquake activity is common on the Reykjanes Ridge. But because of the location and depth (around 2km) it is impossible to know if there any volcano eruption taking place at this location. It might well be, or not.

Kolbeinsey Island

Over the past weeks there has been some earthquake activity close to or in Kolbeinsey Island. The largest earthquakes have had the magnitude around ML3.0, with some underestimates due to distance from the SIL network. At this moment it is impossible to know if this earthquake activity is related to possible eruption activity. But it believed that an eruption (or dike intrusion) took place on Kolbeinsey Ridge in the year 1999. It started off with a large earthquake swarm.

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Minor earthquake swarm close to Herðubreið

Today a small earthquake swarm started just south-west of Herðubreið. But Herðubreið is a volcano cone formation that erupted during last ice-age. But that eruption did break up trough the glacier. Explaining its shape.


The earthquake swarm off Herðubreið. Copyright of this picture belongs to Iceland Meteorological Office.

Largest earthquake so far had the size around ML3.1. But aftershocks have reached the size of ML2.5 according to IMO automatic magnitude estimate. This earthquake swarm is currently ongoing.

Icelandic news about this.

Grunnur skjálfti við Herðubreið (Vísir.is)
Jarðskjálfti nærri Herðubreið (Rúv.is)

Plus. Here are pictures from The Telegraph of Iceland volcanic nature.

Iceland from the air: aerial pictures of the country’s dramatic volcanic landscapes

Other: Donations help me running this blog (they also help me paying the bills, buy food and what comes with being a human being). Plus it appears that I need go the dentist. But as it is now. I can’t afford it properly. Thankfully this is not an emergency that I am dealing with in one of my tooth. But I need to get it fixed one way or the other soon. Thanks for the support! 🙂

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Katla volcano warming up for an eruption. Small glacier flood continues

This is going to be a short blog post. As I am going to be short of table and a cheer for few more days.

It seems that Katla volcano is warming up for a eruption. As I did mention in last blog post. But there is more to this. As the glacier flood that started on the 28. April 2012 continues according to a email that I got from an geologist working at Iceland Meteorological Office. But that suggests two things. That there is currently an ongoing melting of glacier taking place in Katla volcano, or there is a slow drainage taking place from some area in Mýrdalsjökull glacier. But given increased conductivity following this it is clear that this water has been in contact with magma. But that can be seen with the increased conductivity in the water.

There have not been many earthquakes following this events. But from the earthquakes that have happened. It seems that most likely source for current events is close to or the same area that erupted in July 2011. But at the moment this is just speculation based on limited data. It has not been confirmed so far.


The harmonic tremor that started on 28. April 2012. This is Lágu Hvolar SIL station. Copyright of this picture belongs to Iceland Meteorological Office. Used with written permission.

This plot shows clearly how the harmonic tremor starts and continues at same level for several days. I do not know if the harmonic tremor is ongoing. But I find it likely, if the small glacier flood is currently going on (that was my last information, but things might have changed during the day). But it is hard for me to know that for sure. But based on latest data from the water monitoring system around Katla volcano, the spike in this glacier flood is most likely over for now. But it impossible to know what happens next in Katla volcano. All that can be done is to wait and see what happens next.