Category: Earthquakes

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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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New swarm of deep earthquakes in Katla volcano

This morning (20-May-2015) a swarm of deep earthquakes took place in Katla volcano. This earthquake activity was at depth and it means that magma was moving or dyke intrusion taking place at depth.

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Earthquake activity in Katla volcano this morning. The earthquake swarm took place close to 1918 eruption site. Copyright of this image belongs to Icelandic Met Office.

Deepest earthquake in this swarm had the depth of 28,9 km. Shallowest depth was 17,3 km. At this depth there is only magma that can create earthquakes, since crust at this depth in Iceland almost never has earthquakes (it might happen, but is rare event) that is not related to magma movements. This activity is something that needs to be monitored since it might suggest that conditions inside Katla volcano might be changing. There is no way to confirm at this point that to be the case. At the moment there is nothing to suggest that eruption is imminent in Katla volcano at this point. This deep earthquake activity appears to be over for now.

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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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