Category: Earthquakes

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Earthquake activity continues in Katla volcano

Even if it is December and Mýrdalsjökull glacier has added around 6 meters of snow on top of it self. It seems that the earthquake activity in Katla volcano is rather strong, even if it winter already in Iceland.


Earthquake activity in Katla volcano past 48 hours. Some of this earthquakes might be frost-quakes due the freezing weather in Iceland for the past few days. Copyright of this picture belongs to Iceland Met Office.

The earthquake activity in Katla volcano is resistant in the Katla volcano caldera and has been that for several weeks already. I cannot interpreted this earthquake activity other then Katla volcano is preparing for an eruption. But when I am not sure at this moment. There is an pattern of earthquakes in Katla volcano caldera, this pattern has been in place since Week 27, but that is the week when the minor eruption took place in Katla volcano caldera last summer (summer 2011).

It is clear that this earthquake activity in Katla volcano is going to continue. I am assuming that this earthquake activity is going to continue until a eruption takes place in Katla volcano. But there is also the chance of the year 1999 event. When a small eruption took also place and earthquake activity remained high for several weeks after that. But after some time the earthquake activity started to drop. For the moment I find that to be unlikely outcome given how long the earthquake activity has remained high in Katla volcano after the minor eruption this summer.

Donations: I am going to try and setup the geophones in Eyrarbakki village and the geophone close to Katla volcano in December. But that trip is going to cost me some money (I pay for the car benzine), but the cost might go as high €157, 1169 DKK, $210, 25.000 ISK (current exchange rates) just for gas (on an car) for that trip. So if anyone can help with this cost it would be welcomed. Thanks for the support! 🙂

Update 1: I am most likely going with the bus. But that also costs some money, around 3900 ISK, 182 DKK, 24€. $32, 20GBP (Current exchange rates).

Blog post updated at 13:12 UTC on 12 December, 2011.

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Earthquake activity in Katla volcano

Even if there is December and Katla volcano is supposed to have less earthquake activity during this time of year. It seems to be that currently that is not the case. But the earthquake activity is less then it was this summer after the minor eruption in July 2011. No major earthquake swarm has been taking place in Katla volcano for the past few weeks. But there is a lot of earthquakes taking place, without it being a earthquake swarm at one single location inside Katla volcano.


Current earthquake activity in Katla volcano. Copyright of this image belongs to Iceland Met Office.

Many people might ask if this earthquake activity is something to worry about. The answer is no. Katla volcano is unlikely to start an eruption in December. But if this pattern of earthquake activity it is clear that Katla volcano is going to erupt sooner rather then later. But the question after the mini-eruption last summer (July 2011), if there are going to be around 10 years until next eruption takes place in Katla volcano. For the moment nobody knows for sure.

Other: I want to remind people about the forum. It can be used to ask questions, chat, share pictures and so on.

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Harmonic tremor in El Hierro volcano drops

There was a change in the eruption in El Hierro volcano last night. The harmonic tremor started to drop of slowly. This drop in harmonic tremor comes several days after a drop in earthquake activity happened. But it might be possible that this drop in earthquake activity in north El Hierro volcano might be because a erupting vent did open up in north El Hierro volcano. But at such depth that the eruption was not noticed on the surface on the ocean. At least that might be the reason. But without any data, this is just a speculation. But at any rate, the earthquake activity in north part of El Hierro volcano has dropped down to almost zero in few days time.


The harmonic tremor yesterday (5 December, 2011). The drop in harmonic tremor can clearly be seen here. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor today at 08:15 UTC. The harmonic tremor continues to drop during the past few hours. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The harmonic tremor drop is something that has happened before in El Hierro volcano. Just before a new fissure did open up in El Hierro volcano eruption. I am unsure if that is the case now. But it should become clear in about two to three days. But it is also a possibility that this eruption is coming to a end. But it has been erupting now for close to three months now. So this eruption might just ending. But we might have to wait a bit until that is confirmed. But at the moment the harmonic tremor is dropping and that means the eruption is smaller for the moment.

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Growing earthquake swarm in Krísuvík volcano

There seems to be a growing earthquake swarm in Krísuvík volcano on the Reykjanes peninsula. The strongest earthquake so far is a ML2.2 according to the automatic size estimate. Some ghost earthquakes appear to be outside a town called Akranes and Reykjavík to the north. But that are earthquakes that are in fact nothing but errors. This earthquake swarm is tectonic in nature, not volcanic. So there is not going to be a eruption in Krísuvík volcano from what I can tell at current moment.


The earthquake swarm in Krísuvík volcano. Copyright of this picture belongs to Iceland Met Office.

It is hard to know how this earthquake swarm is going to develop. But this earthquake swarm looks growing. For that it is going to peak in activity sometimes in the next few hours. But when exactly is hard to know for sure. I am going to update this blog post if something major happens. The strongest earthquakes appears on my geophone and can be viewed here.

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Earthquake swarm 14 km to the east of Akureyri town

At 19:22 UTC a small earthquake swarm started 14 km east of Akureyri town. The earthquake swarm started with a earthquake with the size of ML3.11 at the depth of 9 km. The area of activity is unusual, but there are none known fault lines in this area that I am aware of. This area is also a bit off TFZ fault zone. This area normally does not have any earthquakes. I am not sure yet if this are intra-plate earthquakes or not, as this area is close to the NVZ (North Volcanic Zone).

This earthquake was felt in Akureyri town by the local people. How well I do not know.


The area where the earthquake swarm is taking place. Copyright of this picture belongs to Iceland Met Office.

I did record the strongest earthquake on enough geophone to be able to make a plot map from my own software from software called WinQuake that I use to plot earthquakes time, location and depth information with data from Iceland Meteorological Office.


Here is the earthquake location according to my geophones with location data from IMO. This picture is released under Creative Commons licence. See top bar for more information.

Here are the wave form data that where recorded on my geophones (they can be viewed online here). The Sauðárkrókur geophone is a testing geophone that I am currently running. But it is going to be turned off now in December.


The earthquake as it was recorded on the Heklubyggð geophone. This picture is released under Creative Commons licence. See top bar for more information.


The earthquake on Hvammstangi geophone. This picture is released under Creative Commons licence. See top bar for more information.


The test geophone at Sauðárkrókur village. This geophone is noisy. This picture is released under Creative Commons licence. See top bar for more information.


The strongest aftershock that I did record on my Hvammstangi geophone. The wave form data on Sauðárkrókur geophone where not good for some reason. So I do not display them here. This picture is released under Creative Commons licence. See top bar for more information.

The wave form outside the earthquake are ocean waves. They are strong now and show clearly on my geophone. So they appear even more clearly on the SIL network as higher tremor levels. But that is nothing that looks like a volcanic harmonic tremor.

As for the earthquake swarm. It is hard to know what it means. But more aftershocks in this area for the next few days are not impossible. As has been seen before in areas that suddenly start to make earthquakes after a long break.

Icelandic News reports of this event. Please use Google Translate with care. It does not yet understand.

Jarðskjálfti við Akureyri (mbl.is)
Jarðskjálftar við Akureyri (Rúv.is)
Þrír jarðskjálftar nærri Akureyri (Vísir.is)

Blog post updated at 06:02 UTC on 3 December, 2011. Fixing errors in the text.

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Activity remains low in Iceland. Eruption continues in El Hierro volcano

At the present time the earthquake activity remains low in Iceland. This goes for both Katla volcano and other areas of Iceland. This is the regular quiet time in Iceland, as it happens sometimes. For the next days, there is a risk of frost-quakes as the ground freezes over in a cold snap.

El Hierro volcano, Canary Islands

The eruption in El Hierro volcano continues as before. New eruption vents have been opening up at random in the south part of El Hierro volcano. Earthquake activity to the north has dropped. While at the same time, the earthquake activity seems to have increased slightly to the west part of El Hierro volcano. I am not sure why that is yet.

In the tremor data. I have been seeing several explosions taking place. But they create a spikes in the tremor plot, that is different then what happens when a earthquake takes place.


The current harmonic tremor from El Hierro volcano. Explosions are the spike activity (30 November, 2011). Some of this however might be sudden increase in eruption activity. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

Other then that. The eruption in El Hierro volcano seems to be about the same for the moment as it has been for the past almost two months now. So far it is impossible to know when this eruptions ends. But eruption in La Palma volcano lasted about one month on average. Eruptions in Lanzarote volcano have lasted about three months (last eruption was in the year 1824). Based on this. This might be a eruption that lasts for about 3 to 5 months at the longest in my opinion. But what actually happens is just something that is a wait and see matter.

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Earthquake swarm in Grímsey Island (TFZ)

Today there has been a earthquake swarm in Grímsey Island. But this tiny Island is off the north coast of Iceland. Around 100 people live on the Grímsey Island. This earthquake swarm is small. But its location makes sure that it is felt. But it is directly under the village on the Grímsey Island. So far the strongest earthquake recorded is a ML3.3 in size with the depth of 9.1 km.


The earthquake swarm in Grímsey Island. The Island is located where the earthquake swarm is on this map. Copyright of this picture belongs to Iceland Met Office.

The largest earthquake so far was recorded on my Hvammstangi geophone clearly.


The earthquake as recorded on my Hvammstangi geophone. This trace is filtered at 4Hz. This picture is released under Creative Commons licence. See top bar for more information.

The earthquake swarm appears to be ongoing. I am sure that this earthquake swarm is felt in the village because it is directly under it. But depth of the earthquakes might however play a role in it how well the earthquakes are felt in the village. So far there have not been any news reports on this earthquake swarm in Icelandic Media.

Blog post updated at 00:25 UTC on 25 November, 2011

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Rare earthquake close to Hvammstangi geophone

A rare earthquake took place yesterday close to my geophone in Hvammstangi village. But that village is located in north-west Iceland. This earthquake was small and I do not have location at moment, as I only have one geophone at this location for recording earthquakes.What I do know about this earthquake was around 25 km away from my geophone, with the default depth at 10 km. But this distance is a bit inaccurate due to default depth factors. So this is just a best effort guess. But what I do have is the wave form of this earthquake.


The vertical (Z) component of the earthquake. This picture is released under Creative Commons Licence. Please see the top bar for more information.


The North-South component of the earthquake. This picture is released under Creative Commons Licence. Please see the top bar for more information.


The East-West component of the earthquake. This picture is released under Creative Commons Licence. Please see the top bar for more information.

All the pictures here above show the 20 seconds wave form signal of the earthquake. I have marked the P and S wave of the earthquake in order to figure out the distance this earthquake took place from my geophone.

In this area I get around one to two earthquakes a year that are local and do not appear on the Iceland Met Office earthquake list. But that happens because there are few to none SIL seismometers in this area and IMO can only detect earthquakes that are larger then ML1.5 to 2.5 in size.

If I get a location on this earthquake, I am going to update this blog post.

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Update for the eruption in El Hierro volcano

As the eruption in El Hierro volcano moves closer to the second month. Information on what has been going on has gone bit hard to come by (for me anyway). As people settle with there new reality (erupting volcano). But that does not stop me from reporting on it.

The current status of the eruption is that nothing much has changed since last blog post. But yesterday there where reports of new vents opening up off the south coast of El Hierro volcano. But this is the area where current eruption has been taking place the past month and a half. It remains to be seen if that is going to change or not. But earthquake activity has continued in north part of El Hierro volcano. This earthquake activity seems to be a mixed one. But that means there are both earthquakes due to dike intrusions and local tectonic earthquakes. I now think that this earthquake activity is going to continue all the eruption. I am not sure why a eruption has not started in north part of El Hierro volcano yet. But for the moment it is just earthquakes. The strongest earthquakes in this area can go up to Mb5.0 in size. But I base that on what type of rock makes up the area, along with the thickness of the crust. But that is from 10 km thick.


The earthquake activity for the past 48 hours in El Hierro volcano (picture from 22 November, 2011). Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


Earthquake activity in El Hierro volcano for the past 4 days. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The earthquake activity from July 2011. This earthquake activity maps out well where the magma lies in the El Hierro volcano. But as the magma expands in the crust, it creates earthquake activity. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The harmonic tremor tells me what is going on in the eruption, when I lack all other visual data on what exactly is going on. But the harmonic tremor increases or drops depending on the strength of the eruption. But that aspect of the eruption is based on how many and how large fissures are open at the time.


The harmonic tremor as it is today (22 November, 2011) at 21:11 UTC. The eruption as can be seen is around the same level as before. But this is not the strongest the harmonic tremor has been. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).


The harmonic tremor when the eruption was more active then today. This can clearly be seen by how the harmonic tremor is stronger then the scale of the harmonic tremor plot. This happens when a new fissure opens up and its eruption is at the strongest. Copyright of this picture belongs to IGN (Instituto Geográfico Nacional).

The IGN web site on El Hierro volcano eruption can be found here. But it is in Spanish.

I am continuing to monitor this eruption. Even if it is a long term eruption, but that are eruptions that are longer then 1 month. As the for the eruption as a whole, little change has taken place in terms of strenght and location of the eruption. But that might change without warning as before.

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The weekend earthquake swarm deep out on the Reykjanes Ridge

During the weekend there was as earthquake swarm deep outside on the Reykjanes Ridge. It was about 700 km south of Reykjavík city. It was not felt on land and was only noticed on instruments. The last earthquake to be recorded was at 22:04 UTC, on 20 November 2011. It’s size was Mb4.4 according to EMSC. The largest earthquakes in this earthquake swarm had the size of Mb4.8, but there where several earthquakes recorded with this size.

Due to the location it is impossible to know if there was a eruption in this area or not. The ocean depth there is greater then 1 km (if my memory is correct). This means that if a eruption is taking place in this location. Nothing is going to appear on the surface of the ocean. So why this earthquakes are taking place are only speculation everything besides normal tectonic activity in this area. But the Reykjanes Ridge is a rift zone that often has earthquakes without any eruption taking place. There have however been several earthquake swarm during the year in this location. But what the actual reason remains a mystery due the location.

Other then this it is now quiet time in Iceland. This is the type of quiet time that I always worry about. But lets wait and see what is up with this lack of activity in Iceland.

Note: Update on the eruption in El Hierro volcano eruption is due tomorrow. This is now a long term eruption as explained few blog posts ago. So there are only updates on what is going on once in a while.