Swarm – Page 92 – Iceland geology

May 11, 2014May 12, 2014

Magnitude 3,8 earthquake on the Reykjanes Ridge [Updated]

Today (11-May-2014) at 01:57 UTC a magnitude 3,6 earthquake took place in the Reykjanes volcano on the Reykjanes ridge. Depth of this earthquake was 11,6 km and there have not been any reports that this earthquake was felt.

The magnitude 3,6 earthquake is the green star closest to land on this map. Copyright of this image belongs to Icelandic Meteorological Office.

There has been constant earthquake activity in this part of the Reykjanes ridge for the past two weeks (about 17 days so far). This activity has however remained minimal with few earthquakes reaching the magnitude above 2,0. There has been increase and decrease in the during this time as expected. I reported an earthquake swarm in this area on 27-April-2014, on 13-April-2014 an minor earthquake swarm took place on the Reykjanes ridge (no earthquakes above 3,0), I wrote about it here.

Other dates of earthquake activity in this area are 4-April-2014 as can be seen here. There seems to have been close to continues earthquake activity on the Reykjanes ridge during the month of April and May. I am not sure why that it is, but this might be related to magma movements in this area, so far there is nothing to suggest an eruption is going to take place in this area. I expect earthquake activity to continue in this part of the Reykjanes ridge. All larger earthquakes are going to appear clearly on my geophone network, its website can be found here.

Update 1: New magnitude has been issued for the earthquake on the Reykjanes ridge that took place yesterday (11-May-2014). The new magnitude is 3,8 with the depth of 11,5 km. Two magnitude 3,1 earthquake also took place at the same time (01:55 and 01:59 UTC) at the same location.

The green stars show the magnitude 3,8 earthquake, along with the magnitude 3,1 earthquakes at the same location. Copyright of this image belongs to Icelandic Meteorological Office.

New earthquake activity has taken place at Reykjanes ridge today, so far no earthquake has the magnitude above 3,0 according to automatic results from Icelandic Meteorological Office. I am expecting more earthquake activity to take place at this location. Earthquake activity at this location is not continuous and has short and long breaks in them. Earthquakes larger than magnitude 2,5 appear clearly on my webicorders and can be viewed here.

Updated at 17:19 UTC.

May 9, 2014May 9, 2014

Update on earthquake swarm in Herðubreiðartögl on 9-May-2014

This is a short update for the earthquake swarm in Herðubreiðartögl on the 9-May-2014.

For the past 24 hours there has been drop in activity and no earthquake has been over magnitude 2,0. Activity continues but a lot lower levels then before. It does not look like it is over at this point, but the end of this soon to be seven day earthquake swarm in this area.

The earthquake swarm in Herðubreiðartögl as it was today. It can be seen that earthquake activity was at lot lower levels today then yesterday (08-May-2014) or the days before that. Copyright of this image belongs to Icelandic Meteorological Office.

This can also be seen in the tracer on Icelandic Meteorological Office website. Copyright of this image belongs to Icelandic Meteorological Office.

This drop in activity can also be seen in drop in the harmonic tremor plots in Askja. Fewer earthquakes means less earthquake related noise on the harmonic tremor plot (2-4Hz blue line). Not all of the activity that appears here is from Herðubreiðartögl, some of it is from SISZ and Reykjanes ridge activity. Copyright of this image belongs to Icelandic Meteorological Office.

The drumplot from Icelandic Meteorological Office also show this drop in activity. Some of the activity that appears is from Reykjanes Ridge. Copyright of this image belongs to Icelandic Meteorological Office.

None of this earthquake activity is strong enough to appear on my geophones. Since earthquakes at Herðubreiðartögl need to be at least magnitude 3,0 or larger to appear clearly on my geophones. My webicorders website can be found here, it shows all earthquakes that are taking place in Iceland and are large enough to appear on it. Its mostly earthquakes larger then magnitude 3,0 that are currently taking place (when this written).

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Updated at 20:11 UTC.

May 9, 2014

Earthquake swarm on the Reykjanes Ridge

The earthquake swarm that has been taking place on the Reykjanes Ridge for the past few days did increase today (09-May-2014). The largest earthquake had the magnitude of 3,6 with the depth of 15,6 km. So far around 70 earthquakes have been recorded in this area. The earthquake swarm is taking place in area considerable distance from land and next populated area, so it might not be felt at all.

The earthquake swarm on the Reykjanes Ridge. Green star marks the magnitude 3,6 earthquake. Copyright of this image belongs to Icelandic Meteorological Office.

The magnitude 3,6 earthquake on the Reykjanes Ridge as it did appear on my Heklubyggð geophone. This image is released under Creative Commons Licence. Please see CC Licence page for more details.

It is difficult to know for sure what is taking place on the Reykjanes Ridge. There are clues this might be due to magma movement at depth, possibly dike intrusion. So far there are no signs of eruption taking place at this location at current point in time. It is possible to see any earthquake that takes place (at least large one) here on my webicorder website. It is also possible to see earthquake activity in Iceland at Icelandic Meteorological Office website.

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May 9, 2014May 9, 2014

Magnitude 3,9 earthquake in SISZ last night

Yesterday (8-May-2014) a magnitude 3,9 earthquake took place in SISZ (South Icelandic Seismic Zone). This earthquake was felt over all of south Iceland, no damage took place following this earthquake. This earthquake appears to have been on N-S fault in SISZ. Only few minor aftershocks took place following this earthquake. I don’t know why that is and this lack of aftershocks is interesting.

The star marks the magnitude 3,9 earthquake in SISZ. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake in SISZ as it appeared on my geophone station in Heklubyggð. This image is released under Creative Commons licence. Please see CC Licence page for more details.

It is possible to see any future earthquake activity here on my geophone station at Heklubyggð. The geophone station at Böðvarshólar is not updating due to failed 3G transmitter the area that I use to connect that geophone station to the internet. I hope it gets fixed soon. People can also used the website of Icelandic Meteorological Office to watch for any future earthquake activity in SISZ.

Update 1: According to Icelandic Meteorological Office this earthquake took place on a fault that had a magnitude 7,0 earthquake in the year 1784, on 14-August that year. More details can be found here, the text is in Icelandic.

Updated at 12:43 UTC on 9-May-2014.
Updated at 12:56 UTC on 9-May-2014.

May 9, 2014

Strong earthquake in South Iceland (SISZ)

Today (9-May-2014) at 23:15 UTC a strong earthquake took place in SISZ. Exact magnitude is not clear at this moment, but the magnitude of 4,0 is wrong in my view based on how this earthquake appeared on my geophone. This earthquake was felt in south Iceland and in the capital area. I am going to post updates on this earthquake once I have the details.

The earthquake can be seen here along with all the aftershocks that are going to take place.

May 6, 2014May 6, 2014

Herðubreiðartögl earthquake swarm update 6-May-2014

This is an update on the earthquake swarm in Herðubreiðartögl on 6-May-2014. This information might go outdated quickly if the activity in this earthquake swarm changes suddenly.

For the past 24 hours the earthquake activity in Herðubreiðartögl has been dropping. This means fewer earthquakes overall, the magnitude of earthquakes taking place has also been getting lower, with strongest earthquakes just in the magnitude 2,5 to 2,9 range. In the past 24 hours no magnitude 3,0 or larger earthquake has taken place.

The earthquake activity in Herðubreiðartögl on 6-May-2014. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake tracer at Icelandic Meteorological Office website clearly shows the drop in activity. Copyright of this image belongs to Icelandic Meteorological Office.

My earthquake counter clearly shows this drop in earthquake activity. It is for all of Iceland, but majority of earthquakes over the past days are from Herðubreiðartögl. This image is released under Creative Commons Licence. Please see CC Licence page for more details.

I did discover today that Icelandic Meteorological Office has updated its drumplot website. So its now possible to see the earthquakes directly. The drumplot here above is from Askja SIL station, it clearly shows the earthquake activity in Herðubreiðartögl. The website with the drumplots can be found here (I have just found this website in Icelandic, there does not appear to be English version available). Copyright of this image belongs to Icelandic Meteorological Office.

It remains difficult to know for sure what is the source of this earthquake swarm. There is a slight chance it might be due to magma injection at depth, but that remains unproven as is. My geophone stations (I only got two running now) are going to show the largest earthquakes and they are going appear clearly. It can be viewed here.

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Article updated at 21:22 UTC on 6-May-2014.
Article updated at 21:37 UTC on 6-May-2014.

May 4, 2014May 4, 2014

Update on ongoing earthquake swarm in Herðubreiðartögl

The earthquake swarm that started yesterday (03-May-2014) in Herðubreiðartöl continues. Information about this earthquake swarm changes quickly so this article about it is going to get obsoleted quickly. The largest earthquake in past 24 hours had the magnitude 3,9. Since around midnight over 370 earthquakes have been recorded. This means the earthquake swarm is more powerful in terms of earthquakes today than it was at the same time yesterday.

The earthquake swarm in Herðubreiðdartögl today. Copyright of this image belongs to Icelandic Meteorological Office.

The evolution of the earthquake swarm in Herðubreiðartögl today. As be seen here this earthquake swarm is heavy in number of earthquakes being detected. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake swarm in Herðubreiðartöl at Askja SIL station. As can be seen here this earthquake swarm is close to continuous. There is some minor drop in activity few hours ago before the earthquake activity picks up again. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake swarm seen on the SIL station at Mókollar. It is close to what is seen on Askja SIL stations and other SIL stations around this area. Copyright of this image belongs to Icelandic Meteorological Office.

My earthquake counter today showing all the activity. This gives me good comparison to how many earthquakes where recorded yesterday. This image is released under Creative Commons Licence. See CC Licence page for more details.

I am expecting more earthquake activity in Herðubreiðartögl next hours and even days. Since currently there are no signs of this earthquake swarm slowing down. The largest earthquakes (above magnitude 3,0) appear clearly on my geophone network website.

May 3, 2014May 3, 2014

Ongoing earthquake swarm north of Herðubreiðartögl

Today (03-May-2014) around midnight (00:02 UTC) a earthquake swarm started north of Herðubreiðartöglum (Global Volcanism Program link on Askja volcano can be found here), this area is an small mountain ridge that has built up with regular eruptions over some period of time. The largest earthquake in this swarm took place this morning at 05:49 UTC and had the magnitude of 3,5 with the depth of 7,6 km. After this earthquake took place the swarm increased with many minor earthquakes. So far over 265 earthquakes have been recorded today, this number gets obsoleted quickly since new earthquakes happens ever 1 to 3 minute when I am writing this text.

Tremor plot on nearby SIL stations show that a lot more earthquake activity is taking place than appears on IMO earthquake website. Reason for this is simple, the earthquakes cannot be located since they are only detected at one or two SIL stations, a minimal of three or four SIL station are required for location of each earthquake. The tremor plot in the area also show that no magma is erupting, but that does exclude the possibly that magma injection is responsible for this earthquake swarm. It has not reached the surface and currently there is no eruption taking place at this location. If an eruption takes place in this location, it is going to be Hawaiian eruption with large lava flows.

The earthquake swarm north of Herðubreiðartögl as they appear on Icelandic Meteorological Office maps. Copyright of this image belongs to Icelandic Meteorological Office.

The earthquake rate during this earthquake swarm. Copyright of this image belongs to Icelandic Meteorological Office.

The SIL station in Askja volcano. As can be seen the earthquake swarm is dense and highly active. Copyright of this image belongs to Icelandic Meteorological Office.

The SIL station south of Herðubreiðartögl, this SIL station is called Mókollar and the earthquake swarm appears clearly on it. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake swarms are common in this area and have been for a long time. Most of that earthquake activity has been contributed to normal tectonic activity in this region (plate tectonic movements). This area also has erupted in the past (last 12,000 years). I don’t think there have been any eruptions in this area in the past 1000 years, at least there are no such signs on the surface (crates, lavas). It is difficult to know what happens in this area for the next few hours to days, all that can be done is to continue monitor the activity that is now taking place. The largest earthquakes appears clearly on my Böðvarshólar geophone (link here), even if the distance is up to 200 km.

Donation note: Please remember to donate. Otherwise I am going to have a rather bad month of May in terms of being broke. Thanks for the support.

April 27, 2014May 3, 2014

Minor earthquake swarm in Bárðarbunga volcano

Yesterday (26-April-2014) and today (27-April-2014) an minor earthquake swarm took place in Bárðarbunga volcano. I am not sure if this earthquake activity is due to dike intrusion or normal tectonic activity.

Minor earthquake swarm in Bárðarbunga volcano. Copyright of this belongs to Icelandic Meteorological Office.

This area of Bárðarbunga volcano is well known for high earthquake activity. If this is an dike intrusion as is an possibility, it does not increase the risk of an eruption, since dike intrusion without starting an eruptions are a common feature in Icelandic volcanoes.

April 27, 2014April 27, 2014

Minor earthquake swarm on Tjörnes Fracture Zone (TFZ)

Yesterday (26-April-2014) and today (27-April-2014) an minor earthquake swarm took place on TFZ not far from an island named Flatey. This was a small earthquake swarm and largest earthquakes had an magnitude around 2,0.

The minor earthquake swarm on TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

It is difficult to know if this earthquake activity is going to continue. Earthquake activity at this location is only tectonic based, this area of Iceland is volcano free.

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