Earthquake in Brennisteinsfjöll volcano

On 24-May-2021 at 21:36 UTC an earthquake took place in Brennisteinfjöll volcano. The magnitude of this earthquake was Mw3,6 and this earthquake was felt in Reykjavík area.

Green star in the middle of the image of Reykjanes peninsula showing the location of the earthquake that was felt in Reykjavík.
The location of the earthquake in Brennisteinfjöll volcano. Copyright of this image belongs to Icelandic Met Office.

There have been few smaller earthquakes in this area since the largest earthquake, but other than that it has been quiet. This earthquake is believed to have happened because of stress changes on the Reykjanes peninsula because of the eruption in Fagradalsfjall mountain.

New information about the situation in Fagradalsfjall volcano

This is a short article about the new information published today (8-March-2021) by Icelandic Met Office and Department of Civil Protection and Emergency Management.

New measurements of the situation in Fagradalsfjall volcano show that the dyke intrusion continues to grow and as at its shallowest point at 1 km depth. Possible eruption is expected at the south end of the dyke intrusion (closest to Fagradalsfjall mountain). Earthquakes are going to happen at the south-west end of the dyke and north-east of the dyke because of the inflation the magma is creating in the area.

The dyke shown with dotted line and circle shows the most effective area. Gray areas at both ends shows earthquake effected area
The earthquake areas at the ends of the dyke intrusion, shown in gray areas on this map. The dyke is shown within the line with dot lines. Copyright of this image belongs to Icelandic Met Office.

There are going to be quiet times between high period of activity according to the news about this activity. There is also ongoing risk of a earthquake with magnitude of Mw6,5 in Brennisteinsfjöll volcano and according to Icelandic Met Office that risk has not been reduced in recent days. Outside of the Fagradalsfjall volcano magma dyke, no magma movement has been detected in Reykjanes (Svartsengi?) volcano and in Krýsuvík volcano.

Sources (Icelandic)

Áfram má búast við að virknin á Reykjanesskaga verði kaflaskipt (Iceland, English, Polish, Almannavarnir.is)
Kvikan er á kílómetra dýpi (Rúv.is, Icelandic)

Earthquake swarm in Reykjanes volcano and deep earthquake activity in Brennisteinsfjöll volcano

Today (10-December-2020) at 00:08 an earthquake with the magnitude of Mw3,5 took place in the volcano Reykjanes. This earthquake was felt in nearby area. Since then there has been a minor earthquake swarm going on in the area of Reykjanestá.


Green star shows the earthquake activity in Reykjanes volcano. Copyright of this image belongs to Icelandic Met Office.

Brennisteinsfjöll volcano

Today (10-December-2020) an deep earthquake swarm took place in Brennisteinsfjöll volcano. All earthquakes that took place where small in magnitude but depth was from around 5km to 12 km depth. It is not known at the writing of this article if this suggests an magma movement inside Brennisteinsfjöll volcano.


Orange dots to east of Krýsuvík volcano show the activity in Brennisteinsfjöll volcano. Copyright of this image belongs to Icelandic Met Office.

I am expecting more earthquake activity in Brennisteinsfjöll volcano in next few months. It is going to take few weeks to months to see if anything more is going on there.

Earthquake activity slowly reducing since Mw5,6 earthquake yesterday (20-October-2020)

Since yesterday (20-October-2020) the earthquake activity on the Reykjanes peninsula in the volcano Reykjanes or Krýsuvík volcano has been slowly getting down after the Mw5,6 earthquake. There have been at the writing of this article 30 earthquakes with magnitude that are larger than Mw3,0 in this area, some of those earthquakes have been felt in nearby populated areas.


The earthquake activity slightly more than 1 day later on the Reykjanes peninsula. Copyright of this image belongs to Icelandic Met Office.

At the writing of this article the number of detected earthquakes in this swarm is getting close to 2000 earthquakes. The risk of stronger earthquake both west and east of the Mw5,6 earthquake that took place yesterday. Strongest possible earthquake in this part of Iceland can reach magnitude Mw6,5 to Mw6,7 depending on location and that is only east of current earthquake activity in Brennisteinsfjöll volcano area.

According to the news, the first injury because of the Mw5,6 earthquake has been reported along with damage to a viewing place in the mountain close the location of the earthquake yesterday.

Rotaðist þegar jörðin kippt­ist und­an (mbl.is, pictures, Icelandic)

I am going to post updates soon as possible if anything more happens in this activity on Reykjanes peninsula. At the writing of this article there has not been any sign of magma movement or any sign that an eruption has taken place in this area.

Medium sized earthquake swarm in Brennisteinsfjöll volcano

Today (21-August-2017) during the night an earthquake swarm took place just east of Brennisteinsfjöll volcano. The area in question is in part inside Brennisteinsfjöll volcano fissure swarm. Part of the area is outside any known volcano. The last night earthquake swarm had some magma signature but was mostly tectonic in nature as to be expected.


The earthquake swarm as it currently appears on Icelandic Met Office earthquake map. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had the magnitude of 2,9 and other earthquakes are smaller in magnitude. Not every earthquake has been reviewed so far due to how many earthquakes happened. Around 210 earthquakes happened in this swarm. Around 07:00 UTC the earthquake activity mostly stopped and it has been like this for several hours. It is difficult to know for sure if a new earthquake swarm is going to start in this area soon. There is nothing suggesting that an eruption is imminent, even if magma is pushing around in the ground at the moment.

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Earthquake activity in Breinnisteinsfjöll volcano

Since the weekend there has been a earthquake swarm ongoing in Breinnisteinsfjöll volcano (Wikipedia link). This earthquake swarm has not been strong in magnitude of the earthquakes happening, with largest magnitude just at 2,8 and all other earthquakes being smaller in magnitude. Close to 130 earthquakes have happened so far.


The earthquake activity in Breinnisteinsfjöll volcano. Copyright of this image belongs to Icelandic Met Office.

The signal from this earthquake swarm shows that some of the earthquakes happening are hybrid earthquakes. That means magma is creating some of them. While tectonic process is creating others. Last eruption in this volcano was in the year 1341 and I don’t have a lot of information about it. I don’t know if this is only magma that erupts or a mix eruption (magma and ash cloud). The earthquake swam is highly localized but has moved slightly to the south from the area where it started during the weekend. The earthquake swarm appears to be ongoing as is, there are however quiet period in it and currently that is what is happening.

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Earthquake warning for Reykjanes peninsula

Icelandic Meteorological Office and Almannavarnir have issued a warning about possible large earthquake on the Reykjanes peninsula. This warning is triggered by the earthquake swarm in Krísuvík on 30-May-2015 and a second earthquake swarm on the Reykjanes ridge on 11-June-2015.

Largest earthquakes in this earthquake sequence once it starts might reach magnitude of 6,5. There remains a hope that the stress on the Reykjanes peninsula and Reykjanes ridge is going to be released out slowly without large earthquake taking place. The warning only covers the populated part of the Reykjanes, from Kleifarvatn and east to Ölfus. It is my view that chance is small at best, it might work out that, I do think that is unlikely outcome of this. It is impossible to know when this earthquake activity might happen, but since the warning has been issued it might only be few weeks to month until something happens.

Last large earthquake in Bláfjöll mountains (Breinnisteinsfjöll volcano) took place in 1929 and 1968. Due to the area in question being less populated than it is today there was no or little damage. Current warning says the people should prepare to limit damage, since in past few years the populated areas have moved closer earthquake risk areas of the Reykjanes peninsula.

The warning (in Icelandic)

Skjálftavirkni á Reykjanesskaga (vedur.is, Icelandic Meteorological Office, Icelandic)
Fréttatilkynning vegna jarðskjálftavirkni að undanförnu á svæðinu frá Krísuvík austur í Ölfus (vedur.is, pdf, Icelandic)

Icelandic News

Vara við skjálfta til að draga úr slysahættu (Vísir.is, Icelandic, pictures)
Hætta á stórum skjálfta á Reykjavíkursvæðinu (Vísir.is, Icelandic)

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Article updated at 23:52 UTC.

Earthquake swarm on the Reykjanes

On Saturday (16-November-2013) an earthquake swarm started on the Reykjanes. This earthquake swarm started slowly with only few unnoticeable earthquakes for most of the time. There was also a second earthquake swarm taking place due to water being pumped back into the ground. That did hide the current earthquake swarm to start with. This earthquake swarm is taking place in Brennisteinsfjöll / Bláfjöll volcano area.

131118_1525
The earthquake swarm on the Reykjanes. Copyright of this image belongs to Icelandic Meteorological Office.

Largest earthquakes in the current earthquake swarm have so far just had the magnitude of 2,9. Stronger earthquakes cannot be ruled out at current time. At the moment there is nothing to suggest this activity is related to any magma movement at present time. Currently the earthquake swarm is ongoing and it is impossible to know if it is going to continue or just die out slowly. The strongest earthquakes appear clearly on my geophone website here.

Earthquake swarms in Brennisteinsfjöll volcano and TFZ

Over the past few days there has been continued earthquake activity in Breinnisteinsfjöll volcano. The largest earthquake in this swarm had the magnitude of ML2.5. It is possible that this earthquake swarms have there orgin in SISZ. Rather then Breinnisteinsfjöll volcano. But at current time is hard to be sure on this detail.


Earthquake activity in Breinnisteinsfjöll volcano during the past few days. Copyright of this image belongs to Icelandic Meteorological Office.

Tjörnes Fracture Zone

Earthquake activity has also been taking place east of Grímsey Island. This earthquake activity has mostly been small. But this are earthquake swarm did not have any earthquake that was above 3.0 in magnitude.


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

The largest earthquake in this swarm had the magnitude of ML2.8. More earthquake activity should be expected in this area. As this is one of most active areas in Iceland when it comes to earthquake swarm.

Magnitude 3.8 earthquake in Breinnisteinsfjöll volcano

Earthquake with the magnitude of 3.8 took place in Breinnisteinsfjöll volcano at 19:42 UTC. This earthquake was felt in Reykjavík and nearby area. Many aftershocks have followed this earthquake. Most of them are however below 2.0 in magnitude. There was also pre-earthquake activity before the magnitude 3.8 earthquake did take place. Most of those earthquakes where below 2.0 in magnitude. Last month an earthquake with the magnitude 4.3 took place in this same area. Earthquake activity is currently ongoing with smaller earthquakes for the time being.


Green star marks the place where the magnitude 3.8 earthquake took place. Copyright of this image belongs to Icelandic meteorological Office.

So far there is nothing to suggests that current earthquake activity is nothing but tectonic. But this area is a riftzone. So there are earthquake swarm often take place there without them being related to any volcano activity in this area. This earthquake swarm appears clearly on my geophone network in Iceland. I am going to continue to monitor this earthquake activity. As more strong earthquakes in this area can take place in the next few hours to days.

Icelandic news about this earthquake activity

Jarðskjálfti upp á 3,8 í Bláfjöllum (Rúv.is)
Jarðskjálftar við Bláfjöll (mbl.is)
Jarðskjálfti í Bláfjöllum (Vísir.is)
Skjálftinn var 3,8 stig (mbl.is)