Category: Swarm

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Strong earthquake swarm deep on the Reykjanes ridge

Yesterday (11-January-2018) at 09:46 and 09:50 UTC two strong earthquakes took place around 780 km deep south west of Iceland. The earlier earthquake had a magnitude of Mw5,4 (EMSC information here) and the second earthquake had a magnitude of mb4,9 (EMSC information here).


Earthquake activity deep south of Iceland (green stars). Copyright of this image belongs to Icelandic Met Office.

Icelandic Met Office reports in total 7 earthquakes, including the two largest ones that EMSC did record but with lower magnitude. The EMSC magnitude is the correct one. This earthquake swarm starts at 08:37 UTC with a magnitude 4,0 earthquake. It ends at 11:11 UTC with a magnitude 3,6 earthquake. The exact location of this swarm is difficult to know due to the distance it is from any earthquake monitoring network. It is also difficult to know for sure what is going on at this location but the earthquake data suggests that this was just a normal earthquake swarm and not connected to any volcano activity. At this distance smaller earthquakes are not detected (below magnitude of Mw3,6).

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Sharp increase in earthquakes in Katla volcano

Yesterday (05-January-2018) a warning was issued about higher conductivity in glacier rivers from Mýrdalsjökull glacier. This is due to increased activity in Katla volcano. At the moment the conductivity is around 613 µS/cm according to Icelandic Met Office (I can’t find that number on their website for unknown reasons). Volcano gas has also been registered at Láguhvolar SIL station (a gas measurement takes place there). Last time this happened was in November-2017 when a slightly larger glacier flood took place.


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

Following the glacier flood was a sharp increase in earthquake activity. It is unclear why that happened as glacier flood do not require special earthquake activity to happen. There are no clear sign of minor eruptions happening on SIL stations around Katla volcano. I have not seen any change in tremor plots from SIL stations around Katla volcano. As it now stands I am expecting more earthquake activity and more glacier flood activity if this follows earlier pattern. That might not happen and it is difficult to know for sure what is going to happen next. Largest earthquake in current activity had the magnitude of 2,1 and all other earthquakes have so far been smaller in magnitude. All earthquakes have depth shallower than 1 km.

Sorry if my English is bit off. I did travel for good 14 hours (start time at ~04:10 and got home at ~18:40) on 4th of January-2018. This is the time it takes me to travel home (Denmark) from Iceland. I was completely exhausted once I got home.

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Small earthquake swarm in Katla volcano

Today (30-December-2017) a small earthquake swarm took place in Katla volcano. This earthquake activity was a minor one and the largest earthquake only had a magnitude of 1,4 and all other earthquakes where smaller.


Earthquake activity in Katla volcano. Copyright of this image belongs to Icelandic Met Office.

It is difficult to know if more earthquake activity is going to happen in Katla volcano. Winter months are normally quiet when it comes to earthquake activity in Katla volcano.

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No changes in Öræfajökull volcano earthquake activity

Earthquake activity continues in Öræfajökull volcano as has been doing for past several months. Earthquake activity goes up and down a little, some days there are fewer earthquakes while in others there is more activity.


Latest earthquake activity in Öræfajökull volcano. Copyright of this image belongs to Icelandic Met Office.

Current earthquake activity is consistent with volcano of this type (stratovolcano with rhyolitic type of magma). Earthquake activity happens when the magma or gas connected to it moves inside the volcano. That movement changes during the day and is never constant and impossible to predict.

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Earthquake with magnitude 4,1 in Bárðarbunga volcano

On 23-December-2017 at 23:41 UT a magnitude 4,1 earthquake took place in Bárðarbunga volcano. At the moment no other earthquake activity has followed this earthquake.


Green star shows the location of the magnitude 4,1 earthquake. Copyright of this image belongs to Icelandic Met Office.

More earthquake activity cannot be ruled out in this area as the location is the normal north-east part of Bárðarbunga volcano caldera that has been seeing a lot of earthquake activity since September-2015.

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Earthquake activity increasing again in Öræfajökull volcano

After quiet two weeks in Öræfajökull volcano earthquake activity has started in increase again. As before the magnitude of earthquakes happening remains small with only few earthquakes reaching magnitudes above 1,5.


Earthquake activity in Öræfajökull volcano. Copyright of this image belongs to Icelandic Met Office.

Largest earthquakes today (23-December-2017) had magnitude of 1,4 and 1,1. All other earthquakes that happened where smaller in magnitude. It is at the moment difficult to know if this current trend continues and earthquake activity continues to increase in Öræfajökull volcano or is going to start dropping off again. Based on earlier pattern in October and November the earthquake activity is going to continue to increase, reach a peak and then start to drop off again. The fact remains is that nothing is certain when it comes to volcanoes and it is close to impossible to predict and know what is going on in Öræfajökull volcano.

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Earthquake swarm in Hengill volcano

At 05:36 UTC a earthquake swarm started in Hengill volcano. Several dozen earthquakes took place and the largest earthquake had the magnitude of 3,4 and the second largest had a magnitude of 3,0. All other earthquakes where smaller in magnitude.


The earthquake swarm in Hengill volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm appears to have been tectonic in nature and ended at 05:57 UTC. The largest earthquake was felt in Reykjavík, Hveragerði and Selfoss.

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Minor earthquake swarm on TFZ (Tjörnes Fracture Zone)

During the night of 22-December-2017 a minor earthquake swarm took place south-east of Flatey Island on TFZ (Tjörnes Fracture Zone). This was not a large earthquake swarm.


The earthquake swarm south-east of Flatey Island on TFZ. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had the magnitude of 1,9 and the second largest had the magnitude of 1,5. All other earthquakes where smaller in magnitude.

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Two strong earthquakes in Bárðarbunga volcano

During the night of 20-December-2017 an earthquake swarm started in Bárðarbunga volcano. This earthquake swarm started at 02:17 UTC with a magnitude 1,4 earthquake. The first magnitude 4,1 earthquake took place at 04:57 UTC and the second large earthquake took place at 05:29 UTC and had the magnitude of 4,4. All other earthquakes where smaller in magnitude and around 40 to 48 earthquakes happened.


Earthquake activity in Bárðarbunga volcano. Green stars show the location of the earthquake activity in Bárðarbunga volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake activity was in the usual north-east part of the caldera of Bárðarbunga volcano. Currently hydrothermal activity is high and remains high in Bárðarbunga volcano. That means there is serious amount of magma inside Bárðarbunga volcano at shallow depth. That has not resulted in any small eruptions at the moment but that might change without warning (watch out for small magnitude focused earthquake activity).

Deep earthquake activity continues south-east of Bárðarbunga volcano (red dot on the image). That is magma movement but that activity doesn’t appear to be getting any shallower at the moment. That activity is focused in one location and might be high risk for an eruption in the future.

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Strong earthquake swarm ongoing in Skjaldbreið shield volcano

Yesterday (10-12-2017) a earthquake swarm started in Skjaldbreið shield volcano (in Global Volcanism program this area is under Presthnjúkar area). Currently the earthquake swarm is ongoing. This activity started on Friday with few earthquakes and started in full force when the magnitude 3,5 earthquake happened. Largest earthquake so far had the magnitude of 3,8 and was felt as was the first earthquake that happened.


Earthquake activity in Skjaldbreið shield volcano. Copyright of this image belongs to Icelandic Met Office.

At the moment the number of earthquakes recorded is at 100 and that number is going to increase as this earthquake swarm continues, number of earthquakes happening has dropped considerably for the last few hours. This is the first large earthquake swarm in Skjaldbreið since 1992 according to Icelandic Met Office records (it goes back to 1706 can be viewed here (Icelandic only), locations are not accurate until late 20th century). This earthquake activity appears to be only tectonic in nature and there are no signs of magma movements at the moment.

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