Dyke intrusions – Page 43 – Iceland geology

November 27, 2013November 27, 2013

Harmonic tremor detected in Þórðarhyrna volcano

On the 21-November-2013 there was an earthquake swarm in Þórðarhyrna volcano (part of Grímsfjall volcano). This was not large earthquake swarm or a strong one. With the largest earthquake just having the magnitude of 1,9. While I did just suspect it I did not have it confirmed until today that following this earthquake swarm was an harmonic tremor pulse. This harmonic tremor lasted from 03:30 to 06:10 UTC. Based on nearby SIL station this was not a strong harmonic tremor, but this is important because it suggests that something is taking place in Þórðarhyrna volcano. If this is going to lead to an eruption is unknown at current time. This might be a dike intrusion into the volcano at depth, but that has not been confirmed.

The harmonic tremor pulse can be seen at 21-November date on this tremor plot from Icelandic Meteorological Office. Copyright of this image belongs to Icelandic Meteorological Office.

The harmonic tremor pulse as it did appear from Grímsfjall SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

Harmonic tremor pulse as it did appear on Jökulsel SIL station. Copyright of this image belongs to Icelandic Meteorological Office.

This activity might not lead to an eruption, but given the past history of this area and the eruption in Grímsfjall volcano in the spring of 2011 I find it to be highly likely outcome that eruption is going to take place in Þórðarhyrna volcano in near future, it is not possible to know when such eruption might take place. Last eruption took place in Þórðarhyrna volcano in the year 1902, it is not known if any later eruptions have taken place in Þórðarhyrna volcano.

Blog post updated at 14:47 UTC.

November 24, 2013November 24, 2013

Earthquake swarm in Tungnafellsjökull volcano

There is currently ongoing interesting earthquake swarm activity in Tungnafellsjökull volcano. This earthquake activity appears to be taking place due to magma injection at depth into the volcano. Currently the earthquake activity doesn’t appear so clearly on the Icelandic Meteorological Office earthquake maps. I am not sure why that is, the largest earthquake so far has had the magnitude of 2,3 at the depth of 0,5 km so activity is already rather shallow, deepest activity had the depth of 17,5 km. Earthquake activity started in Tungnafellsjökull volcano in the year 2012, before that earthquake activity had taken place in Tungnafellsjökull volcano following an eruption in Bárðarbunga / Grímsfjall volcano in the year 1996 [map here of Week 41 – 1996]. Current earthquake activity is not based on any such event.

Earthquake activity in Tungnafellsjökull volcano. Copyright of this image belongs to Icelandic Meteorological Office.

Tremor activity showing minor earthquakes taking place in Tungnafellsjökull volcano (most likely) over the past few hours. Copyright of this image belongs to Icelandic Meteorological Office.

I am not sure yet what is happening in Tungnafellsjökull volcano. But data in mounting and suggesting that magma is about to start flowing into the volcano at faster rates then before (via dike intrusions). Tungnafellsjökull volcano has not erupted in historical times (at least no eruption is documented) so it is impossible to know for sure what happens next in this volcano. If an eruption where to take place it would be mostly basalt based on post sub-glacier eruptions (when they erupted is not known). Current earthquake activity might die down as it did in the year 2012 when (and earlier this year [2013] also) this swarm like activity at depth (15+ km) started to happen.

Blog post updated at 04:36 UTC.
Blog post updated at 04:46 UTC.

November 17, 2013November 17, 2013

Minor earthquake swarm in south-east of Katla volcano

Today (17-November-2013) a minor earthquake swarm took place in Katla volcano at 06:21 UTC and it lasted to 07:09 UTC. The largest earthquake has the automatic magnitude of 1,8 with the depth of 18 km. This earthquake swarm took place under an former island in the area called Hjörleifshöfði (in Deutsch, English is not available). It is possible that this former island has it’s origin is in an volcano activity in the area, while I do not have it confirmed it is at least an idea. The deepest earthquake in this area had the depth around 22 km according to automatic results from Icelandic Meteorological Office.

131117_1815 — The earthquake activity in the east part of Katla volcano system. *Copyright of this image belongs to Icelandic Meteorological Office*.

Based on the depth of this earthquake swarm, the origin of this earthquake swarm was in magma movement or dike intrusion. It is not a tectonic activity, since such earthquakes are not so common in this part of Iceland, but they do happen. I am not sure what this means for activity in Katla volcano since I have not seen this before as it appeared now. This area of Iceland can be viewed in Google Maps and with Street View here.

October 11, 2013October 12, 2013

Source of the glacier flood in Hofsjökull volcano found

In August-2013 there was an glacier flood from Hofsjökull volcano, this glacier flood was minor and did not cause any damage. The source of this glacier flood has now been found according to Icelandic Meteorological Office. A new glacier cauldron has been found in Hofsjökull glacier, where none was before. The cauldron is around 700 meters long and about 30 – 50 meters deep. The glacier is cracked a lot around the cauldron and it’s dangerous to travel to this area because of that. The hight of this cauldron is around 1700 meters above sea level.

Hofsjökull volcano and glacier. The new glacier cauldron is located at ~64°49,5‘N; 18°52‘W. Click on the image for full resolution. Image from NASA/USGS/Icelandic Meteorological Office/Geological Department of University of Iceland (Jarðvísindastofnun Háskólans).

According to Icelandic Meteorological Office this part of the glacier has not had any glacier cauldrons before that they know of. This cauldron has the volume of 1 million cubic meters (10⁶ m³) according to Icelandic Meteorological Office. This area now has highly active hydro-thermal area and hot-springs. What formed this glacier cauldron is unclear at the moment, it was not an eruption since no such signals have been recorded from Hofsjökull volcano before or after the glacier flood in August-2013. It is also unclear if this glacier cauldron is going to create new glacier flood in the future.

Icelandic Meteorological Office announcement

Hlaup úr Hofsjökli í ágúst 2013 (vedur.is, in Icelandic)

Icelandic News

Fundu sigketil á Hofsjökli (mbl.is, Icelandic)

Blog post updated at 21:02 UTC on 11-October-2013.
Blog post updated at 01:45 UTC on 12-October-2013.

October 3, 2013

Fewer earthquakes taking place on Tjörnes Fracture Zone at the moment

Donation note: I still need donations for October. I currently have no money for anything and that is rather bad. This bad situation that I am having is going to last for several months according to an excel document that I have set-up to figure out my total debt repayment. I can repay my debt (or buy replacement hardware if anything fails), but not buy food at the same time. The exchange rate of ISK to DKK is also bad at the moment. I hope for improvement but that won’t happen for next several months at least.

Activity in Tjörnes Fracture Zone continues as it has been doing for the past week. There is not a lot of other activity taking place in Iceland at the moment. The largest earthquake today (03-October-2013) had the magnitude of 3.5, a second earthquake with the magnitude of 3.1 also took place in TFZ today. Depth of this earthquake swarm remains the same, around 5 to 15 km at current time.

The largest earthquakes in this earthquake swarm in TFZ. Image in original context can be found here (Icelandic). Copyright of this image belongs to Icelandic Meteorological Office.

Today (03-October-2013) there were fewer earthquakes in this swarm than yesterday. The drop is currently around half of less activity than yesterday. I am not sure why this is as currently the earthquake swarm is ongoing. Even if there are fewer earthquakes taking place. This might just be a short time drop in earthquake activity, or this might signal an end of this earthquake swarm. Currently it’s too early to know for sure. The only thing that can be done is to wait and see what happens next in this earthquake swarm.

Earthquake activity today on Tjörnes Fracture Zone. Copyright of this image belongs to Icelandic Meteorological Office.

So far there are no signs of any magma having reached the surface, if that is the reason for this earthquake swarm in this area of Tjörnes Fracture Zone.

October 3, 2013October 3, 2013

Update on Tjörnes Fracture Zone earthquake swarm

Donation note: I still need donations to survive this month as any other months while I am just on social welfare from Iceland as I have explained here. This month I just have around 24 DKK (3.21€) for food this month after paying all the bills and my debt. I have already got some donation, but they just allow me to buy food for about one and half week if I am smart. Thanks for the help.

The earthquake swarm on Tjörnes Fracture Zone continues. The earthquakes are getting stronger, with the largest one today having the magnitude 3.8 (automatic results) and five other earthquakes with the magnitude 3.0 to 3.2. Currently the depth is around the same, it remains at 5 to 15 km and at the moment it doesn’t seems to be changing. Rate of earthquakes is around the same today (02-October-2013) as it was yesterday (01-October-2013), with no major changes in earthquake rate from what I can see currently taken place.

Earthquake activity in Tjörnes Fracture Zone. Green star show earthquakes larger than magnitude 3.0. Copyright of this image belongs to Icelandic Meteorological Office.

All earthquakes above magnitude 3.0 have been felt in Siglufjöður and Ólafsfjörður towns and other populated areas that are close to this earthquake swarm. There are no signs of this earthquake swarm slowing down as is. It still has not been confirmed if this earthquake activity is connected to magma injection at depth, or if this is just normal tectonic earthquake activity in this area. It’s going to remain difficult to confirm this idea until an eruption starts in this area and that simply might just not happen at all. The largest earthquakes appear on my webicorders website here, on the geophone station named Böðvarshólar.

Blog post updated at 22:33 UTC on 02-October-2013.
Blog post updated at 22:39 UTC on 02-October-2013.

October 1, 2013October 2, 2013

More earthquake activity in Tjörnes Fracture Zone

Donation note: Please donate. This month as past several months before that are difficult for me. Due to poor exchange range from ISK to DKK and the fact that I generally have low income. This website and writing on it is my job, along with other writing jobs that I attend to. Older posts on donations can be found here.

Today (01-October-2013) there has been a lot of earthquake activity in Tjörnes Fracture Zone. Current area of activity is same as for the past week, what is now changing is the rate and magnitude of earthquakes. This morning an magnitude 3.2 earthquake took place in this area. That earthquake and at least two other smaller ones where felt in Ólafsfirði, the town closest to this earthquake swarm. Earthquake activity is currently ongoing and with no signs of stopping.

Earthquake activity in TFZ today. Copyright of this image belongs to Icelandic Meteorological Office.

It has been reported by Rúv and other news media in Iceland that this might be an dike intrusion in this area. This is what geologist at Icelandic Meteorological Office are theorising at the moment. I do not know if this is true or not. What I do know is that at this location there is no known volcano and if there is an volcano at this location it is currently unknown and not documented at all (such things happen). If this is magma and if it finds an path to the surface we are going to see an eruption. I do not know if that would create an new island if that was the case, such speculations have to wait until an eruption started. If it ever gets that far. If this is magma then it is still at great depth, since the depth of this earthquake swarm is at the moment around 5 to 15 km and does not seem to change that much at the moment.

It is possible to watch this earthquake activity here on my webicorder website. The closest geophone station that I have to this earthquake swarm is the one named “Böðvarshólar”. It is already showing many of the strongest earthquakes in this swarm clearly. It is located in the country side far from any major traffic source.

I am going to post updates about this earthquake swarm when needed.

Blog post updated at 20:26 UTC on 01-October-2013.
Blog post updated at 23:53 UTC on 01-October-2013.

September 6, 2013

Minor earthquake swarm in Esjufjöll volcano

Today (05-September-2013) an minor earthquake swarm took place in Esjufjöll volcano. Largest earthquake in this swarm had the magnitude of 2.2 and the depth of 4.9 km.

Earthquake swarm in Esjufjöll volcano. Esjufjöll volcano are located in south part of Vatnajökull glacier, just northeast of Öræfajökull volcano. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquakes in this area are because of magma movement it is believed. Now there are more SIL stations in the area, so more earthquakes are being recorded. Few years ago the lowest magnitude that Icelandic Meteorological Office was able to detect in Esjufjöll volcano was magnitude 1.5 and above.

September 5, 2013

Earthquake activity in several volcanoes

Today (04-September-2013) had some minor earthquake activity in several volcanoes in Vatnajökull glacier. All of this earthquakes were small and less than magnitude 3.0 in size.

Kverkfjöll volcano

The deepest earthquake activity was in Kverkfjöll, with earthquakes at 31 km depth and 24 km depth. This deep earthquake activity is possible connected to magma movements since tectonic earthquakes are unlikely to take place this deep in the crust.

Grímsfjall volcano

One earthquake was recorded in Grímsfjall volcano, it was minor and shallow. This might even just be a glacier quake, rather than normal earthquake.

Öræfajökull volcano

Öræfajökull volcano did see two earthquake today, at the depth of 4 to 5 km. Both were small and tectonic in nature from the looks of it. Earthquakes are not common in Öræfajökull volcano so I am not sure why this increase has now taken place. It is worth noticing that sil network is now more sensitive in this area than before since new stations have been added in this area. This means that smaller earthquakes are now being detected than before.

Esjufjöll volcano

Esjufjöll volcano had two earthquake, the third earthquake might be a ice-quake. I am not sure if it was an real earthquake or not. Esjufjöll volcano normally do not have any earthquake activity, but few years ago an earthquake activity started with earthquakes that had magnitude of 2.5 to 3.0 so there is something going on in this volcano. What that might be I am not sure of yet.

Earthquake activity in Kverkfjöll, Öræfajökull, Esjufjöll, Grímsfjall volcanoes. All small earthquakes. Copyright of this image belongs to Icelandic Meteorological Office.

I do not expect anything major to take place in Vatnajökull volcano. Since the current quiet period in Iceland just seems to be ongoing as is.

September 3, 2013September 3, 2013

Minor dike intrusion into Bárðarbunga – Hamarinn volcanoes

It seems that yesterday (02-September-2013) a minor dike intrusion took place in Bárðarbunga – Hamarinn volcanoes. This created an minor harmonic tremor yesterday on nearby sil stations. There were earthquakes following this events, the strongest one had the magnitude of 2.8 at the depth of 14 km. A second earthquake with the magnitude of 2.1 took place few moments later, it had the depth of 15.5 km. Only one smaller earthquake have seen taken place in this area of Bárðarbunga – Hamarinn volcanoes.

The earthquake activity in Báðarbunga – Hamarinn volcano area. Copyright of this image belongs to Icelandic Meteorological Office.

It is important to notice that dike intrusions are common in this area, often happen many times a year. How many takes place can vary between years. That dike intrusion took place does not mean an eruption is going to take place. It just means that magma moved, what that means for the future is unknown at present time.

Donations: It would be nice if people donated so that I can buy food this month. In other case I am going to have to eat really little this month and I am not happy about such things taking place.

Blog post updated at 21:43 UTC on 3-September-2013.

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