Category: Volcano

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Strong earthquake swarm in Krýsuvík volcano

Yesterday (29-May-2015) there was a strong earthquake swarm in Krýsuvík volcano. Largest earthquake had the magnitude of 4,0, a smaller magnitude 3,1 earthquake also took place.

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Green star shows the location of the magnitude 3,1 and 4,0 earthquakes. Copyright of this image belongs to Icelandic Meteorological Office.

Other earthquakes in this swarm where smaller, total of 97 earthquakes where recorded. Earthquakes swarms in this area are common, since the volcano has been inflating and deflating for the past few years. I don’t know if this earthquake swarm was related to such movements, since tectonic forces often create strong earthquake swarms in this area and along the Reykjanes peninsula and Reykjanes ridge.

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The earthquakes as they appeared on my geophone in Heklubyggð. This image is under Creative Commons licence. Please see CC Licence page for more details.

On the geophone shut-down

There has been some discussion about me turning off the geophone network in Iceland. There is one station renaming in Heklubyggð and that station is going to continue to run for some time now (it doesn’t use the 3G network in Iceland). When it turns off I do not know. Besides 3G connection costs that have been going up in Iceland for the past few years, it has also become more expensive for me to fix the computers if they fail, along with 3G signal leak and other issues. It is also time consuming to run a remote network. I do help people if asked on what to buy in terms of hardware if they want to start there own geophone or seismometer. I don’t plan on stop recording earthquakes, I just plan on doing that just from my home once I am back in Denmark.

As for sensitivity of such hardware, it depends on what type of hardware is being used. Geophones are good for local earthquakes but more sensitive hardware is needed to record earthquakes at longer distance, like the magnitude 6,8 earthquake in Alaska this morning. It can be viewed here for the next few hours on long period seismometer (the top one and few others).

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How Bárðarbunga volcano collapsed

There is a good article about how Bárðarbunga volcano collapsed during it’s six month long eruption in Holuhraun. The most recent data (the work on Bárðarbunga volcano is far from over even there is no eruption taking place currently) show that Bárðarbunga volcano did in fact collapse. This collapse was not marked by a big explosion, but rather slow subsidence of Bárðarbunga volcano over a large area. Holuhraun eruption is the largest eruption in Iceland for the past 230 years, both in magma and size of the eruption.

More details can be found here.

Iceland’s Bárðarbunga-Holuhraun: a remarkable volcanic eruption (blogs.egu.eu)

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Small glacier flood from Grímsfjall volcano caldera

Today (11-May-2015) a glacier flood started from Grísmfjall volcano caldera. This is not a dangerous glacier flood due to its small size. There is however a danger from sulphur gases and other gases that dissolve when the pressure is dropped on the water. If people get too close to the Gígukvísl glacier river where the flood comes from Vatnajökull glacier they risk a damage to there eyes and lungs due to burning effects from the gases in the air.

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Increased harmonic tremor from Grímsfjall volcano. Copyright of this image belongs to Icelandic Met Office.

There is now a increased harmonic tremor from Grímsfjall volcano. It is not clear why that is, it is either the glacier flood or hydrothermal vents boiling at the bottom of the lake due to the sudden pressure release on them. There is nothing suggesting that an eruption is going to follow this glacier flood from Grímsfjall volcano. Last glacier flood took place in 2014.

Icelandic News

Lítið hlaup í Gígjukvísl (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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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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Deflation has stopped in Bárðarbunga volcano

According to a short news today on Rúv it appears that Bárðarbunga volcano has stopped deflating and activity is slowing down in new hydrothermal vents that opened up during the most active period of Bárðarbunga volcano. The rift activity that has started in this region of Iceland is not over yet, even if there is nothing happening at current time.

It is impossible to know when next period of eruptions starts in this area. Until then it is going to remain mostly quiet.

Icelandic news

Sigið í Bárðarbungu er hætt (Rúv.is)

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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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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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