Dyke intrusions – Page 28 – Iceland geology

September 12, 2015September 12, 2015

Something is going on in Hamarinn (Bárðarbunga) and Tungnafellsjökull volcanoes

Today (11-September-2015) an earthquake swarm started in Hamarinn volcano (no GVP profile, see Bárðarbunga volcano). This is a volcano that is inside Bárðarbunga volcano fissure swarm and might be connected to it, that connection is unclear, but historical data suggests that once Bárðarbunga volcano gets erupting sometimes Hamarinn volcano does too. There is a similar pattern in Grímsfjall volcano and Þórðarhyrna volcano (no GVP profile) as an another example.

Current sequence of earthquakes in Hamarinn volcano started with a small earthquake at 22,5 km depth. Few shallower earthquakes happened before that event, those earthquakes however might be connected to changes in hydrothermal systems in the volcano, rather then something else. The deep earthquake that took place started a series of smaller earthquakes at shallower depth, suggesting that pressure is already high inside the volcano, how close it might be to erupting is impossible to know, but the clues that I’m not seeing do not look good. This might die out, but I think the chance of that are small. Last eruption in Hamarinn volcano took place in July-2011, I wrote about it here, here and here.

Current area of activity in Hamarinn volcano. This area is covered with a thick glacier up to 300 – 400 meters. Copyright of this image belongs to Iceland Met Office.

Harmonic tremor data is showing that current earthquake activity are low and long period earthquakes (green and red spikes). I also noted that on this image a harmonic tremor spike can be seen on the green band. It does not appear visible on the red and blue bands. I’m unclear on why this is. Copyright of this image belongs to Iceland Met Office.

The harmonic tremor spike does not appear on the SIL station Skrokkalda. I don’t know why that is. Earthquake activity appears clearly on it (spikes). Copyright of this image belongs to Iceland Met Office.

Activity in Tungafellsjökull volcano

There has been interesting earthquake activity in Tungafellsjökull volcano today. Today earthquake swarm started with the depth of 12,3 km and it mostly stayed there. Suggesting that magma dyke injections are taking place in the volcano at the moment. If and when this might lead to an eruption is impossible to know. Magma might be at shallower depth already due to high activity during the eruption in Bárðarbunga volcano.

The earthquake activity in Tungafellsjökull volcano, it’s located north of both Bárðarbunga and Hamarinn volcano (NE of Hamarinn). Current activity is a small cluster of earthquakes in north-east part of Tungafellsjökull volcano. Copyright of this image belongs to Iceland Met Office.

Largest earthquake in this swarm so far had the magnitude of 1,9. It was also the shallowest earthquake in this swarm. So far no change on the surface of Tungnafellsjökull volcano, meaning that no hydrothermal vents have appeared so far. That might not happen since formation of hydrothermal vents does not always happen before an eruption.

July 22, 2015July 22, 2015

Increased ground heat measured in Surtsey island

It was in the news yesterday (21-July-2015) that scientists have measured higher ground heat in Surtsey Island. The change is 10 degrees (Celsius) from measurements taken some two to three years ago. The theory is that the ground in Surtsey island started to warm up after an earthquake that happened last spring (2015). There have been few earthquakes in Vestmanneyjar volcano system during the past few years, no major swarms have taken place so far.

It is clear by the increased ground heat that magma is on the move in Vestmanneyjar volcano system. It’s too early to know if an eruption is going to take place in next few years. At the moment there is nothing imminent suggesting that is the case, volcanoes often warm up at the surface just too cool down. The largest risk now in Surtsey island are possible steam explosions. They are only risk to local bird and plant life in the summer time.

Icelandic News – in Icelandic

Nýjar tegundir finnast í Surtsey (Rúv.is)

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July 11, 2015July 11, 2015

Earthquake swarm in Tungnafellsjökull volcano

On Thursday 9-July-2015 an earthquake swarm started in Tungnafellsjökull volcano. So far around 50 earthquakes have been recorded in Tungnafellsjökull volcano, the earthquake swarm is currently ongoing. None of the earthquakes that have happened so far have reached magnitude 2,0 or stronger.

Earthquake activity in Tungnafellsjökull volcano. The yellow dots show older earthquakes. Copyright of this image belongs to Iceland Meteorological Office.

It is my view that Tungnafellsjökull volcano is now preparing for eruption regardless of what Bárðarbunga volcano is going to do (it’s not over there, even if it is on a break at the moment). There is also problem with amount of time when this all started. It is clear that earthquake activity started to increase in Tungnafellsjökull volcano in the year 2012 and it has been increasing since that year. It is clear that with the eruption in Bárðarbunga volcano it seems to have given Tungnafellsjökull volcano more energy and increased it’s activity, why and what the connection between the volcanoes remains unclear at the moment.

Current earthquake activity suggest that this is going to develop in similar way the weeks before the eruption in Eyjafjallajökull volcano. It is not going to be exactly the same, it is going to be close and a lot of earthquakes are going to take place once Tungnafellsjökull volcano starts to heat up for real. When that happens I do not know, this might be take several more years at the longest. There is also a good chance that nothing is going to happen at all.

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June 29, 2015June 30, 2015

Deep earthquakes in Bárðarbunga and Tungnafellsjökull volcanoes

Even if the eruption in Holuhraun and Bárðarbunga volcano is over, there is no shortage of activity in Bárðarbunga volcano. With deepest earthquake in past 48 hours having the depth of 28,6 km and earthquakes don’t get a lot deeper than this in Bárðarbunga volcano. At this depth earthquake activity happens due to magma movements rather than tectonic stresses.

Earthquake activity in Bárðarbunga volcano (red dots). Copyright of this image belongs to Iceland Meteorological Office.

Earthquake activity in Tungnafellsjökull volcano

Since the end of the eruption and any major activity in Bárðarbunga volcano. Earthquake activity in Tungafellsjökull volcano has not stopped as expected. The earthquake activity continues at low levels and at great depth. With deepest earthquake in last 48 hours at 26,2 km.

Earthquake activity in Tungnafellsjökull volcano (yellow / orange dots). Copyright of this image belongs to Iceland Meteorological Office.

It is unclear what is going on in Tungnafellsjökull volcano, it is clear that dyke intrusion is taking place at depth, if and when that might result in a eruption is not clear at this moment. This might lead to an eruption or it might not. It is impossible to know at this moment since Tungnafellsjökull volcano has no recorded or documented history of volcano eruptions in historical times.

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May 20, 2015May 20, 2015

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.

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.

May 2, 2015

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.

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.

April 30, 2015

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.

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.

April 24, 2015April 24, 2015

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.

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.

March 28, 2015

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.

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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March 27, 2015

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.

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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