Category: Earthquakes

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Update on the activity over the Christmas

Here is a short update on what did go on in Iceland over the Christmas. In all there where few earthquakes in Iceland during Christmas. The main reason for this was a major storm that started in south Iceland on the 25th of December, it lasted until 27th of December in some parts of Iceland. The wind was topping 47m/s in strong winds. But the average wind speed was about 32m/s I think.

Around 17:02 UTC on the 25th of December there was a ML2.77 earthquake in Krísuvík volcano. Far as I can tell by the wave form this earthquake was mostly tectonic in nature. But it is impossible to know if the main source of this earthquake was the magma that is collecting in Krísuvík volcano or not. But activity continues in Krísuvík volcano as it has been doing in the last few weeks before. This earthquake was followed by 20 or so smaller earthquakes in the same area.

Due to the strong storm there where few to no earthquakes recorded on the late 25th to 27th of December. But the storm did simply hide all the minor earthquake that might have been taking place.

The ML2.77 earthquake in Krísuvík at 17:02 UTC at Heklubyggð geophone station. The storm noise almost drowns out the earthquake signal. This plot is filtered at 4Hz as a cut off frequency.

The ML2.77 earthquake in Krísuvík at 17:02 UTC at Hvammstangi geophone station. A normal level of noise can be seen both sides of the earthquake. No storm noise is presented in this plot, as it had not started in north of Iceland at this time.

A few deep earthquakes where seen in Eyjafjallajökull volcano over the same period. At current it is hard to know what they mean in the long term. But it is clear that Eyjafjallajökull volcano continues to make a little rumble and has not quieted down at current time.

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Last activity update before Christmas and Christmas stuff

Here is the last activity update before Christmas starts. As I did expect a deep earthquakes have started again under Eyjafjallajökull volcano. So far the main depth is about 10 to 15 km. So far nothing indicates a immanent eruption in Eyjafjallajökull volcano. But it is wise to keep watch on the deep earthquakes that have started to re-appear under Eyjafjallajökull volcano.

But Eyjafjallajökull volcano is not the only volcano making earthquakes. There are also earthquakes taking place in Grímsfjall volcano and in Esjufjöll volcano. The continues earthquake swarm in Krísuvík volcano. But this is the same that has been going on in previous weeks in that area.

There has also been some minor earthquake activity in Grímsfjall volcano. A signal that Grímsfjall volcano is getting ready for a eruption in the year 2011 maybe.

Non-volcanic earthquakes

There has been a lot of earthquakes in the Tjörnes Fracture Zone (TFZ). But the largest earthquakes in the last 24 hours did get the size ML3,0 according to the automatic SIL system that Icelandic Met Office runs. The size might be subject to a review later on.

But other then this it has been quiet in Iceland earthquake wise and volcano wise. But when the most frost was going on over Iceland there was a lot frost earthquakes taking place. But those events are false earthquakes and are due the fact that freezing water appears to crack the ground, sometimes with considerable force. The frost needed for this to happen has to be below -10C far as I understand.

Christmas stuff

I am going to take my Christmas break from 12:00 UTC on the 24th of December (2010) until the 27th of December (2010). While this break is on comments might be held longer in the moderation queue then normally. If anything major happens, I am going to post information about it when I can in this time. But unlike us humans nature doesn’t care about our days off. But I am hoping for a quiet Christmas in Iceland like everywhere else.

There is going to be special Christmas blog post tomorrow for all those Christmas greetings.

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Krísuvík volcano / Kleifarvatn lake static image

Here is a image from Icelandic Met Office about the earthquakes that have been taking place in Krísuvík volcano over the past few weeks. This plot shows the latest 15 days.

This image is from Icelandic Met Office. Copyright belongs to them. The original copy can be found here. Click on the image for full resolution.

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The Hekla volcano system earthquake last night

Here is a high resolution image of the Hekla volcano system earthquake yesterday. The earthquake was located in south-east part of the Hekla volcano system. But that area has been having earthquakes for few months now, starting few years ago. I am unclear on why this is happening in Hekla volcano system. But sometimes Hekla volcano erupts in fissures (crater row eruptions). But not from the main volcano.

This earthquake was small like the earthquakes before him, registering only at ML2.43. The depth was 10 km. It was only 15.4 km away from my geophone. But that is the reason why it appear so clearly on my geophone.

Small weather news

Here is the view from my apartment in Hvammstangi earlier today. This is due to a storm that is coming from the north of Iceland. The winds are strong and the snow is on the move due that. The frost is only about -3C. But with the wind it goes down to -20 to -40C.

Click on both pictures to get full resolution.

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A ML3.9 earthquakes happens close to Grímey Island

According to the automatic SIL system that IMO runs there was a ML3.9 magnitude earthquake about 18.3 km north of the island Grímsey, this earthquake happened at 09:00 UTC. The automatic depth was 14.7 km. This numbers are expected to be changed as the earthquake get reviewed by seismologist at Icelandic Met Office.

No damage is expected from this earthquake. But there is a good chance that it might have been felt in Grímsey Island.

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Pictures of Kleifarvatn lake hot springs

I got this pictures in a email from a person how wants to remain nameless. Don’t ask me why, it is just a request that I got with the email and I see no reason not to grand it.

The hot springs at the south end of Kleifarvatn lake hot springs. The hot springs there are not new. But they do get lost when the water level rises in Kleifarvatn lake. When the water level dropped after the year 2000 years in the area this hot springs where for the first time visible to humans.

Click on all the pictures to get a full resolution.

The earthquakes swarm at Krísuvík (close to this area) continues with few breaks it seems.

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Earthquake wave forms from Krísuvík volcano earthquake swarm yesterday

I don’t have a lot to write about the earthquake swarm in Krísuvík volcano that took place there yesterday. But according to IMO the largest earthquake was felt in Hafnafjöður and in Reykjavík.

Here are the wave form data of the largest and the second largest earthquakes. There are no location data in this image. As I have not had time to put them into the wave form data.

From Hekubyggð. This is the ML2.8 earthquake.

From Hvammstangi. This is the ML2.8 earthquake. This one is low-pass filtered at 4Hz.

From Hekubyggð. This is the ML2.5 earthquake.

All pictures can be clicked to see the higher resolution of them.

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Two earthquakes yesterday and ground water heat map of Iceland

Here are two earthquakes that I did record yesterday. The earthquakes took place at Arnarvatns highland and in Krísuvík yesterday. The difference between the earthquakes is that one of them took place where the crust is old and carries the earthquake wave well. The second earthquake(s) took place where the crust is young, fractured and does not carry the earthquake wave that well most of the time. If a fracture area is not in-between the epicentre and the sensor in question.

The earthquake at Arnarvatns highland. The earthquake wave clearly shows what type of crust it has been going trough. In this case a old crust that carries the wave well in my direction. I cannot tell what way the crust fractured in this case, as I need a minimal of three geophones to do so.

The Krísuvík earthquakes. This is actually a string of many earthquakes. When this happens the SIL system that IMO has major issues with locating the earthquakes. As the S wave often get absorbed by the next P wave that follows the next earthquakes. Sometimes however the waves get separated at some distance. That often helps to figure out how many earthquakes happened at the same minute. What is also interesting about this earthquake is the fact that it is “noisy”. But a normal earthquakes has a clear P wave and clear S wave. But on Reykjanes and Reykjanes Ridge there are often noisy earthquakes. I do not know why that happens and I don’t think the reasons for noisy earthquakes are not at all understood (far as I know anyway).

This map here shows how warm the hot water is in Iceland. Where I live the hot water is about 66C warm. It is a deep magma that warms the ground water up to this levels. There is a good article on this process at Wikipedia here.

Text updated at 17:15 UTC on the 11th of December 2010. Spelling error fixed and minor text changes.

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The earthquake swarm at Arnarvatns highlands

The earthquake swarm that started two days ago at Arnarvatns highlands continues in similar manner as was seen in the earthquake swarm that took place under Blöndulón lake few weeks ago.This earthquake swarm is taking place in a fracture zone known as West Iceland Fracture Zone (WIFZ). But that fracture zone sits between East Iceland Rift Zone and Snæfellsnes volcano zone. This area is known for strong earthquakes, but in the year 1974 there was a magnitude earthquake that had the size Mb5.5 to Mw6.1 (I am not sure on the exact size of this earthquake). According to news there is speculation that this earthquake swarm is somehow connected to the earthquake swarm that did happen under Blöndulón lake few weeks ago. This area is unpopulated and several tens of km to next farm in this area.


Click on the picture of better resolution. Picture is taken from here (Icelandic).

Explanation for the numbers in the picture. The number account for the fracture direction in the area. 1: Northwest-Southwest fracture. 2: West-East fracture. 3: North-South fracture. 4: Northeast-Southwest fracture.

Where the earthquakes are currently taking place are on the west-east fractures in the area. There are no active volcano where the earthquakes take place that I know of. The active volcanoes are south and west (Snæfellsnes volcanoes) of the current location of the earthquakes.

Currently is unclear if this activity did trigger earthquakes in the rift zone. That is Thingvellir and nearby areas that show earthquakes on IMO maps. This might just be poor locations from the SIL system. It is also a question if this earthquake activity is the reason for earthquakes close to Geysir (volcano) geothermal area.


Click on the picture for a full resolution. Picture is from Icelandic Met Office web site.

The earthquake swarm at 13:10 on the 6th of December 2010. Picture is from the IMO web site.

At current time is remains unclear if this earthquake activity is a pre-events before a bigger earthquake in this area. But about ten years ago there was a earthquake swarm south of this location with many earthquakes reaching ML4.0+ in size. But in any case it is worth keeping tab in this earthquake activity, as it might signal more interesting times ahead in this area. But that is just speculation on my part. Earthquake activity might fall down to nothing (normal for this area) in a short time span.

Due to how fractured this area appears to be. I am not recording the earthquakes in this area properly, as the energy of the earthquake wave appears to vanish rather quickly due to the fractures that are between me and the earthquakes that take place (the wave energy that goes north in this case). But this was not the case with earthquake swarm that took place in Blöndulón lake.

Icelandic News of this earthquake swarm. Use Google Translate at own risk.

Skjálftahrina stendur enn yfir (Rúv.is)
Skjálftavirkni á Arnarvatnsheiði (mbl.is)

Text updated at 13:57 UTC on 6th of December 2010. Minor error fixed.
Text updated at 08:33 UTC on 9th of December 2010. Error fixed.

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British Geological Survey costs the set-up of six seismometers around Eyjafjallajökull and Katla

According to Rúv it appears that British Geological Survey did pay for the set-up of six seismometers around Eyjafjallajökull and Katla volcanoes. This seismometers are able to detect lower frequencies better then current seismometers around Eyjafjallajökull and Katla. This type of sensors are normally called broadband seismometers and have frequency range down to 0.001Hz and up to 60Hz. I do not know how far the sensors that BSG did cost. But I am going to assume that they go down a bit farther then IMO sensors in the area. According to Rúv the sensors are already up and where on-line earlier this year.

They are located at following location.
Mælifellssandi not far from Slysaöldu, Rjúpnafell east of Mýrdalsjökul, two are located both sides of Eyjafjallajökull on Ásólfsskálaheiði at south and Smjörgili at north not far from Gígjökli glacier. Fifth sensor is going to be set-up in Pétursey in Mýrdal. The location of the six sensors has not been decided yet.

The cost of this project is about 100.000 pound according to Rúv.

The reason for this is that authorities in UK (and Europe) want to get more warning if there is a big eruption in Katla volcano. Mostly to prevent the air chaos that took place when Eyjafjallajökull erupted earlier this year.

Five sensors where in the area before. The sensor net is going to be really sensitive when the new sensors go on-line at IMO headquarters in Reykjavík. But more sensors give more accurate location of earthquakes, both in depth and location.

The news from Rúv in Icelandic. Use Google Translate at own risk.

Bretar setja upp jarðskjálftamæla (Rúv.is)