Category: Earthquakes

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Dyke intrusion in Bárðarbunga volcano

Today (30-April-2015) a minor dyke intrusion took place in Bárðarbunga volcano. This dyke intrusion was small and appears to be over for now. This does show that current activity in Bárðarbunga volcano is not over even if the eruption in Holuhraun has ended.

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The dyke intrusion in Bárðarbunga volcano is a small cluster of earthquakes, it can be found on this image as three orange dots and one red dot. Copyright of this image belongs to Icelandic Met Office.

Largest earthquake that appeared in the following earthquake swarm took place had the magnitude of 2,1. Depth of this earthquake swarm was around 17 km and going up to 5,3 km. Nothing suggest that at current time this dyke has reached the surface and no harmonic tremor was detected during the time this dyke intrusion took place in Bárðarbunga volcano. More dyke related activity should be expected in Bárðarbunga volcano in next few months to years. Other earthquakes in Bárðarbunga volcano are due to stress changes in the crust due to deflation the volcano came under during the eruption in Holuhraun, total subsidence of Bárðarbunga volcano during that eruption has been measured 62 meters. Current rifting activity is not over in this area even if no eruptions are taking place at the moment.

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Earthquake swarm on Tjörnes Fracture Zone (TFZ)

Since yesterday (27-April-2015) at least there has been earthquake swarm taking place in Tjörnes Fracture Zone (TFZ). This earthquake swarm had a peak in activity during the night. Total of 64 earthquakes have been recorded so far, it is unclear of this earthquake swarm is over at this moment.

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

Largest earthquakes in this swarm had the magnitude of 2,8 and 2,9. Depth of the earthquakes in this swarm was around 13 km. This does look like a tectonic activity and there is nothing suggesting this is a earthquake swarm of volcanic origin. Earthquake activity in this part of Iceland is common.

Article updated at 13:58 UTC.
Article updated at 16:12 UTC.
Article updated at 16:15 UTC.

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Deep earthquakes in Katla volcano

Yesterday (23-April-2015) there where deep earthquakes in Katla volcano. So far only six deep earthquakes have been recorded. The deepest earthquake had the depth of 26,6 km. The largest earthquakes in this swarm had the magnitude of 2,2.

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

Earthquake activity at this depth is rarely due to tectonic activity, it is mostly due to magma movements or pressure changes of the magma. It is impossible to know for sure what is going on. No harmonic tremor was detected following this earthquake activity and there is nothing suggesting anything else then just earthquake activity in Katla volcano at the moment.

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Article updated at 16:21 UTC.

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Minor earthquake swarm on Hekla – SISZ boundary

During the night of 9-April-2015 an earthquake swarm started on Hekla volcano – SISZ boundary. This has been for most part a minor earthquake swarm so far. With largest earthquake only having the magnitude of 2,8. This earthquake activity has appeared clearly on my Heklubyggð geophone.

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The earthquake swarm is located north of Mýrdalsjökull and Eyjafjallajökull. South of Hekla volcano. Copyright of this image belongs to Icelandic Met Office.

This earthquake swarm appears to be tectonic in nature. This means there is a higher chance it might be related to stress changes in SISZ (South Icelandic Seismic Zone), rather then any activity in Hekla volcano. There is little chance in my view that this activity is going to trigger any eruption in Hekla volcano, I just can’t rule it out at the moment. Currently it appears that this earthquake swarm is ongoing. This earthquake swarm doesn’t appear to be moving quickly at the moment, that might change but I am doubtful that is going to happen while minor earthquakes are just taking place. If stronger earthquakes start to happen this minor earthquake swarm might grow into a middle sized one or a big one. Largest known earthquakes in this area have reached magnitude Mw7,0. Such earthquake has not taken place in this part of SISZ for the past 103 years. Currently there is nothing indicating that earthquake with that type of magnitude is about to take place.

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Article updated at 00:20 UTC on 10-April-2015.

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Earthquake swarm in Krísuvík volcano

Today (31-March-2015) there has been a minor earthquake swarm in Krísuvík volcano. Total number of detected earthquakes was 27 so far.

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

Largest earthquake in this swarm had the magnitude of 2,6 according to reviewed results from Icelandic Met Office. Other earthquakes where smaller in magnitude. This is just tectonic activity at the moment. There has been inflation and deflation taking place in Krísuvík volcano for past several years and such activity is known to start strong earthquake activity in both deflation and inflation stage. At the moment there is nothing suggesting there is an eruption imminent in Krísuvík volcano.

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Deep earthquake activity in Bárðarbunga and Öræfajökull volcano

Today (28-March-2015) there has been deep earthquake activity in Bárðarbunga volcano. This suggest that there is a fresh injection of magma into Bárðarbunga volcano system. If this is going to result in new eruption remains to be seen. It is not impossible at current time to happen. So far however nothing has happened. Deepest earthquake had depth of 21,1 km, others earthquakes are shallower.

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Earthquake activity in Vatnajökull glacier today. Copyright of this image belongs to Icelandic Met Office.

Öræfajökull volcano

Today (28-March-2015) there has also been deep earthquake activity in Öræfajökull volcano [Wikipedia link here]. This activity is not new and has been taking place every few months for the past 10 years or so. Quiet times are different in length. Each earthquake swarm that takes place is different in both magnitude and length, current activity appears to be deep, but mostly small earthquakes, less then magnitude 1,5 for most part. Deepest earthquake in this swarm had the depth of 25,0 km. This earthquake activity is only due to fresh magma entering Öræfajökull volcano system, not tectonic activity in this area due the depth of the earthquakes are taking place.

Based on historical accounts of earlier eruptions (1362 and 1728). It appears that eruptions in Öræfajökull start with powerful earthquake swarm (magnitude 4,0+ earthquakes). The following eruption is an ash cloud one with glacier floods taking place, with that phase lasting up to 48 hours. What happens after that is unclear, since it was not documented properly by historical records (at least not properly mentioned or lost due the old age of the historical records in question). Eruptions can last for up to 45 days, based on earlier documented eruptions. Current earthquake swarm is inside Öræfajökull volcano, since it is not round volcano, but goes a little to north where the earthquake swarm is taking place. There is no fissure swarm connected with Öræfajökull volcano, it does not rule out that one exist, it is at least not known at the moment. At the moment there are no clear sign that there is increased eruption risk from Öræfajökull volcano. That might change without warning, as is always the risk with volcanoes.

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Minor earthquake swarm in Hekla volcano

Since yesterday (26-March-2015) a minor earthquake swarm has been taking place in Hekla volcano. This has not been continuous earthquake swarm and there has not been huge number of earthquakes taking place. Largest earthquake had the magnitude of 1,4.

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

This earthquake activity took place deep inside Hekla volcano, with the deepest earthquake being on 17 km depth (mag 1,4). Other earthquakes took place on shallower depths, but all depths where greater then 10 km. What exactly is happening I do not know, at this depth it is possible the earthquake activity taking place is due to magma movement rather then tectonic changes. I don’t expect any eruption to take place in Hekla volcano at current time.

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Minor earthquake swarm close to Eldeyjardrangar on Reykjanes ridge

During the night (on 21-March-2015) a minor earthquake swarm took place close to Eldeyjardrangar on Reykjanes ridge. Largest earthquake in this swarm had the magnitude of 3,2. Total number of earthquakes in this swarm was around 30.

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Earthquake swarm close to Eldeyjardragnar. The green star shows the magnitude 3,2 earthquake. Copyright of this image belongs to Icelandic Met Office.

Earthquake swarms like this are common in this part of the Reykjanes ridge. It is difficult to know if more earthquake activity is going to take place soon.

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Article updated at 20:01 UTC.

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Minor earthquake swarm on the Reykjanes ridge

Today (19-March-2015) at 15:24 UTC a minor earthquake swarm started on the Reykjanes ridge. This earthquake swarm was minor, it however might be clue that more activity might happen soon in this part of the Reykjanes ridge.

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The earthquake activity on the Reykjanes ridge today (19-March-2015). Copyright of this image belongs to Icelandic Met Office.

Largest earthquake in this swarm had the magnitude of 3,5 and other earthquakes where smaller. Last earthquake swarm in this area took place on 3-March-2015 and I did write about it here.

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Minor earthquake swarm on the Reykjanes ridge

During the night (3-March-2015) there was a minor earthquake swarm on the Reykjanes ridge. Largest earthquake had the magnitude of 3,1. Other earthquakes where smaller.

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Earthquake activity on the Reykjanes ridge during the night. Copyright of this image belongs to Icelandic Met Office.

Most of this earthquake activity was deep, with most depth being at 16,0 km. This suggest that this earthquake swarm happened mostly due to magma movement at depth. There is nothing suggesting that eruption is imminent in this area. Depth of the ocean at this location is around 400 – 1000 meters, this means that any signs on the surface are going to be hard to detect or not detected at all.

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Article updated at 18:44 UTC.