Swarm – Page 101 – Iceland geology

April 6, 2013April 6, 2013

Minor dike intrusion in Bárðarbunga volcano

Today (05.04.2013) a minor earthquake swarm took place in Bárðarbunga volcano. The depth of this earthquakes was around 18 – 26 km. Meaning this is magma, rather then tectonic creating this earthquakes. None of this earthquakes had magnitude above 1.0.

Earthquakes in Bárðarbunga volcano. They are the orange dots. Copyright of this image belongs to Icelandic Meteorological Office.

Dike intrusions happens sometimes in Bárðarbunga volcano without it meaning there is a eruption going to take place soon it. This appears to be one of those cases.

April 6, 2013April 6, 2013

Magnitude 3.6 earthquake in Hamarinn volcano

Last night (05.04.2013) at 01:50 UTC a magnitude 3.6 earthquake took place in Hamarinn volcano (no GVP profile yet!). This earthquake had the depth of 2.1 km. This seems to be a dike intrusion taking place in Hamarinn volcano. No clear signs of harmonic tremor have been detected based on tremor data from Icelandic Meteorological Office.

The Hamarinn volcano is where the green star is. But that is the location of the magnitude 3.6 earthquake that took place last night. Copyright of this image belongs to Icelandic Meteorological Office.

Harmonic tremor plot do not show any harmonic tremor pulse. The signal on this harmonic tremor plot is the earthquake swarm in TFZ for most parts. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake activity is due to minor dike intrusion. Rather then something else. It is not clear if this activity is just normal activity for Hamarinn volcano or signal about something else is about take place. But as before. Hamarinn volcano remains mostly quiet for the moment.

April 3, 2013April 4, 2013

Update on the TFZ earthquake swarm at 18:31 UTC

This is a short update on the TFZ earthquake swarm. There is no point in making a long update about what is taking place in TFZ at the moment. Since information gets outdated quickly during this earthquake swarm.

About 775 earthquakes have been recorded by Icelandic Meteorological Office since this earthquake swarm started on 2. April 2013 (about 48 hour period). This number is going to be outdated soon or already is outdated by the time this blog post gets published. Since there are about 40 – 60 earthquakes every 1 hour currently. The earthquake swarm however drops regularly in terms of activity. Over 80 magnitude 3.0 earthquakes have been recorded so far. This number is going to increase if this earthquake swarm continues as it has been doing for the past 48 hour period.

The earthquake activity in TFZ. The green stars show the earthquakes with larger magnitudes then 3.0. There is a second fault that has gone active since the earthquake activity started yesterday (02.04.2013). Copyright of this image belongs to Icelandic Meteorological Office.

As can be seen here. The earthquake swarm has been really powerful at times. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm is the largest one in the area for long time now. At the moment there are no sign about that this earthquake swarm is about to end any time soon.

Map showing the largest earthquakes in this swarm. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity as it appears on Grímsey SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity as it appears on Skrokkalda SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

Reviewed area of earthquake activity on TFZ. This map does not show the current earthquakes. It is few hours old also. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake swarm is complex and might last for a long time. There is a continued risk of a large earthquake in this area. But there has not been a earthquake larger then magnitude in this part of TFZ since 1910 at least. So this area has a lot of build up stress. Since there has not been a strong earthquake there for a long time. But the magnitude 5.5 earthquake and the following aftershocks have just released tiny amount of the stress that has build up in this area.

Map showing historical earthquake activity in TFZ. The image is from here. Copyright of this image belongs to Gunnar B. Gudmundsson, Pall Halldorsson, Ragnar Stefansson and other connected people.

For the moment. It is just best to keep watching the activity that is taking place in TFZ. It is impossible to know for sure what happens in TFZ during the next few hours to days.

Other news about this in Icelandic.

Um jarðskjálftana austur af Grímsey (IMO, Icelandic)
Jarðskjálftahrinan við Grímsey heldur áfram (IMO, Icelandic)

Update 1: Here is a focal depth of the earthquakes for the past 15 days.

This is the focal depth and number of earthquakes for the past 15 days in north Iceland. This might not show all earthquakes that have happened in this area. Copyright of this image belongs to Icelandic Meteorological Office.

Blog post is updated at 21:17 UTC.

April 2, 2013April 2, 2013

Information on the magnitude 5.5 earthquake in TFZ

This is a short blog post about the earthquake swarm in Tjörnes Fraction Zone.

The largest earthquake so far is a magnitude 5.5. The largest aftershocks so far are magnitude 4.4 that took place at 01:14 UTC and 4.7 that took place at 08:55 UTC this morning. This earthquake swarm is taking place on a complex fault area that is highly active. There is also big question what effect this earthquake swarm is going to have on other faults in the area. There is a risk that this earthquake swarm is going to start other earthquake swarms in nearby faults. Uncertainty level has been declared for area from Sauðárkrókur to Raufarhöfn at least. This is the largest earthquake in this area since the year 2002 and 2005. But both this years there was a magnitude 5.0 earthquakes in this area.

The earthquake activity in TFZ. Green stars are earthquakes that are larger then magnitude 3.0. Copyright of this image belongs to Icelandic Meteorological Office.

This trace shows how dense this earthquake swarm has been. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake is appearing clearly on my geophone network. This is Böðvarshólar geophone station. This image is released under Creative Commons licence. Please see the CC Licence page for more details.

The largest earthquakes as they did appear on Heklubyggð geophone station. This image is released under Creative Commons licence. Please see the CC Licence page for more details.

There have been over 500 earthquake recorded since this earthquake swarm did start. It is impossible to know for sure when this earthquake swarm is going to stop, or if it is going to pick up again. But the earthquake swarm is already starting to shown signs of dropping activity. But that might change again if there is new larger earthquake in this area, or swarm of larger earthquake.

I am going to post update of anything major happens in this earthquake swarm. It is possible to monitor the current status of this earthquake swarm here on my geophone web page.

Blog post updated at 15:23 UTC on 02.04.2013.
Blog post updated at 16:14 UTC on 02.04.2013.
Blog post updated at 16:26 UTC on 02.04.2013.

April 2, 2013

Image of the TFZ earthquake

Here are the images of the earthquake that took place at 01:00 UTC in TFZ. I do not have correct magnitude for this earthquakes yet. So it is missing at the moment.

The earthquake at Böðvarshólar geophone station. This image is relased under Creative Common licence. Please see the CC Licence page for more details.

The earthquake at Heklubyggð geophone station. This image is relased under Creative Common licence. Please see the CC Licence page for more details.

April 2, 2013April 2, 2013

Large earthquake in TFZ

Few moments ago a large earthquake did hit TFZ. Details pending. Webicorders show this earthquake clearly here. Details are pending. I am going to post them soon as I can do so.

March 31, 2013

Earthquake swarm east of Grímsey island (TFZ)

Today at 05:25 UTC a earthquake swarm started east of Grímsey island. But this island is located in the Tjörnes Fracture Zone. The largest earthquake today is a magnitude 2.8. No larger earthquakes have taken place so far.

Earthquake swarm in TFZ today. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity is common in this area of Iceland so this is nothing unusual. This earthquake swarm is not connected to any volcano activity that I know of. If anything major happens. I am going to write a blog post about it soon as I can do so.

March 31, 2013

Deep earthquakes in Askja and Kverkfjöll volcanoes

This is a update for both Askja and Kverkfjöll volcanoes. Since they both had deep earthquakes today. None of this earthquakes where larger then magnitude 1.0. There depth was around 22 to 24 km inside the volcanoes them self.

Earthquakes in Kverkfjöll and Askja volcanoes. There depth was around 22 to 25 km. Copyright of this image belongs to Icelandic Meteorological Office.

GVP Kverkfjöll volcano profile. GVP Askja volcano profile.

It is impossible to know for sure what this means in terms of future activity. But this are both active volcanoes and should be treated as such.

March 29, 2013

Magnitude 3.5 earthquake south of Langjökull glacier

Today at 17:24 UTC a magnitude 3.5 earthquake took place south of Langjökull glacier. This earthquake had pre-earthquakes with the magnitudes from 2.1 and up 2.8. There where also several smaller earthquakes at the same location. This earthquake did appear clearly on my geophones in south and north Iceland. My webicorders can be viewed here.

Langjökull earthquake activity today. Copyright of this picture belongs to Icelandic Meteorological Office.

This appears to be normal tectonic earthquake swarm that are common for this area. They are not related to any volcano activity at present time. But this area often has earthquake activity with it being connected to any volcano activity. The earthquake swarm is continuing when this blog post is published. This earthquake swarm might stop at any time, or pick up at any time without a warning. If that happens. I am going to write a new blog post about it soon as possible.

March 29, 2013March 29, 2013

Magnitude 4.4 earthquake north of Kolbeinsey Island

Today at 17:32 UTC there was a magnitude 4.4 earthquake north of Kolbeinsey Island. I do not know if this earthquake was tectonic or volcanic in nature. I do know that there where several aftershocks following this earthquake. Since I did register them on my geophone in north Iceland. The geophone web site can be viewed here. More information about the earthquake can be found here, on EMSC web page.

Regional view of the area where the earthquake took place. Copyright of this image belongs to EMSC.

Icelandic Meteorological Office did also detected many of this earthquakes that took place there. But detection from this location is difficult due to distance from the SIL network.

The earthquake swarm location according to Icelandic Meteorological Office. Copyright of this image belongs to Icelandic Meteorological Office.

For now this is just a earthquake swarm and nothing else. Regardless of what happens later. Earthquake activity has been common in this area of the rift zone for several months now. I do not know why that is. The ocean depth in this area is around 3 to 4 km where it is the deepest. So if an eruption takes place there it is not going to be noticed due to the depth of the ocean.

Cookie acceptance