Category: Earthquakes

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Warning of man made earthquakes in Hengill volcano

Almannavarnir put out a warning yesterday (19-May-2015) about increased risk of man made earthquakes in Hengill volcano. This happens when a water is pumped down into the ground it changes the pressure in the rock and creating earthquakes as a consequence. There is a risk of earthquakes with magnitudes up to 4,5 or larger. The first pumping down of this leftover water is expected to end by 19-June-2015.

Icelandic News about this

Vara við jarðskjálftum á Hengilssvæðinu (Rúv.is, Icelandic)
Niðurdæling vegna hitamengunar að hefjast (Rúv.is, Icelandic)

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Earthquake activity in Askja volcano

During the week there has been a swarm of minor earthquakes in Askja volcano. All of the earthquakes have been small and none have reached magnitude 2,0 far as I know.

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Askja volcano is the volcano most south on this image (the volcano on the end). Copyright of this image belongs to Icelandic Met Office.

There is nothing suggesting that current earthquake swarms are due to magma movements at shallow depths. This is rather hydrothermal activity changes in the volcano due the it being warmed up by new magma entering it and warming up groundwater inside the volcano. That has happened before in earlier eruptions and is documented, the time scale of such changes is not documented far as I know.

Askja volcano started for prepare for an eruption phase in 2010, so far nothing suggest that an eruption is imminent, but it remains a question if the push from Bárðarbunga volcano has changed anything in Askja volcano.

Article updated at 18:56 UTC.

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New dyke intrusion in Katla volcano

Yesterday (01-May-2015) a minor dyke intrusion took place in Katla volcano. This dyke had depth down to 26,9 km and up to 18,5 km. This is the second dyke intrusion in this are in short space of time. Largest earthquake in the following earthquake swarm had the magnitude of 2,0.

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Dyke intrusion in Katla volcano (dense cluster of earthquakes). Copyright of this image belongs to Icelandic Met Office.

While this doesn’t signal imminent eruption in Katla volcano this activity does have me concerned due to past experience with activity in Katla volcano. This might die out, but there is no way to know for sure. All that can be done is to wait and see what happens next in Katla volcano.

Notice on Grímsfjall volcano

There has been a slight increase in earthquakes in Grímsfjall volcano. This suggest that the volcano is about to be ready for its next eruption. Earlier eruptions took place 2011, 2004, 1998 … etc. It is impossible to know when or how big next eruption in Grímsfjall volcano is going to be.

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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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