Day: September 6, 2011

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Earthquake swarm in Krýsuvík volcano

Earlier today a earthquake swarm did start in Krýsvík volcano. This earthquake appears tectonic in nature from what I can tell on my geophone. This type of earthquake swarm is common in this area in Krýsuvík volcano. It does not mean that a eruption is about to start. But this area is a rift zone and it has many earthquake swarms during the year. This is just one of them so far. It is impossible to know how large this earthquake swarm is going to be or how long it is going to last.

The first earthquake swarm did start at 15:42 UTC, the second earthquake swarm did start at 21:53 UTC. That earthquake swarm is currently ongoing with several earthquakes every 2 min or so.

The current area of activity is a lake named Kleifarvatn lake. But that lake is on top of Krísuvík volcano.


Current activity in Krýsuvík volcano. This is a tectonic earthquake activity, not volcanic. Copyright of this picture belongs to Iceland Met Office.

I think that this earthquake activity is going to continue something into the night and next few days at the longest.

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Most likely water creating harmonic tremors in Katla volcano (for the moment)

In the news from Rúv at 22:00 UTC it was sad that water is the most likely source of the harmonic tremors in Katla volcano. But it seems that hydrothermal activity in Katla volcano is increasing and melting the glacier. But for the past few hours there have been signs of hydrothermal melt water getting into Múlakvísl glacier river, making the river have more water then normal and increasing conductivity in it. This is not glacier flood as such. The cauldrons that formed in July have not changed according to this news, but it was not reported if they had actually gotten deeper or larger.

Due to cloud cover it was not possible to explore the north part of Mýrdalsjökull glacier. Just the south part. According to the news on Rúv at 22:00 new small cauldron have formed in the south part of Mýrdalsjökull glacier. They are shallow at present time and may have taken few weeks for form to present size (not sure how big they are), but among this cauldrons is a cauldron that has not been seen for past seven to eight years, cracks have formed around the cauldron and he has gotten deeper and water has collected in the cauldron. But with more earthquake activity and increased hydrothermal activity under the glacier. So more monitoring is needed on Katla volcano according to Magnús Tumi Guðmundsson volcanologist at University of Iceland.

Note: When I wrote this blog post. It seems that new earthquake swarm is about to start in Katla volcano. At least I think so.

News about this events in Icelandic. Use Google translate if you want to insult the Easter-bunny.

Telja að vatn valdi óróa (Rúv.is)
Engin augljós skýring á óróa (mbl.is)
Jarðhiti aukist mjög mikið undir Kötlu – dæmigerð einkenni að menn eigi að búa sig undir gos (Vísir.is)

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Strong harmonic tremor pulse starting in Katla volcano

There seems to be a strong harmonic tremor pulse starting in Katla volcano. I do not think that this is anything else for the moment. I do not have any more details at the moment. But I am going to post updates when I know more.

Start of the harmonic tremor pulse on the SIL stations that he appears best on.


Slysaalda, north of Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Rjúpnafell, South-west of Katla volcano. Copyright of this picture belongs to Iceland Met Office.


Lágu Hvolar SIL station. Copyright of this picture belongs to Iceland Met Office.


Álftagröf SIL station. South of Katla volcano. Copyright of this picture belongs to Iceland Met Office.

The start of the harmonic tremor event can be seen on the end of harmonic tremor chart. It stands out as it above the background noise on the SIL station. Next update on the SIL stations (10 or 20 min until it happens) is going to show more how big event this is going to be.

More updates when I know more on what is taking place in Katla volcano.

Update 1: The Public Civil Emergency Authority (Almannavarnir) in Iceland has increased monitoring with Katla volcano. But they have not declared any emergency level yet. Announcement about that in Icelandic can be found here. But scientists where flown over Mýrdalsjökull glacier at 18:00 UTC today (6. September 2011).

According to the news there has been increase in conductivity in Múlakvísl river. But for the moment the water level has not increased. There has been speculation that the tremor was created by water on the move. But that is unclear at the moment, however it is quite possible that more water is on the move under Mýrdalsjökull glacier.

Currently the harmonic tremor in Katla volcano has dropped back to normal levels. For the moment everything is quiet in Katla volcano. But that can change at any time without any warning.

News about this in Icelandic.

Órói undir Mýrdalsjökli (Rúv.is)
Fylgjast með aukinni virkni í Kötlu (Vísir.is)
Eftirlit aukið með Kötlu (mbl.is)
Flogið yfir Kötlu (mbl.is)

Update 2: It seems that a new harmonic tremor episode is about to start in Katla volcano. So far it has remained small. But it is impossible to know if that is going to change suddenly or not. Update 2b: There is also some wind noise on the seismometers around Katla volcano. This wind is increasing background noise. It often look like a tremor increase, while in reality it is not.

Blog post updated at 18:37 UTC.
Blog post updated at 18:46 UTC.
Blog post updated at 20:03 UTC.
Blog post updated at 20:29 UTC.

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Growing harmonic tremor spike in Katla volcano

It seems that Katla volcano is going to keep me busy for coming days and weeks.

At this moment it seems that there is a growing harmonic tremor in Katla volcano. This harmonic tremor started today after the earthquake swarm that took place earlier today. After it stopped a spikes of small harmonic tremor spikes did start to appear. During the past few hours they have been growing in size. But it seems that the harmonic tremor drops for few moments between spikes.


Earthquake swarm that took place yesterday in Katla volcano. Copyright of this picture belongs to Iceland Met Office.

This earthquake swarm was mostly small one. With largest earthquakes going up to around ML2.1.


Slysaalda SIL station. Harmonic tremor appears poorly on this SIL station. Copyright of this picture belongs to Iceland Met Office.


Rjúplafell SIL station. The harmonic tremor signal can be seen here clearly, even if it a small one. Copyright of this picture belongs to Iceland Met Office.


Lágu Hvolar SIL station. The harmonic tremor signal can be seen poorly on this SIL station. But it signalled with minor change in the background noise on this SIL station. Copyright of this picture belongs to Iceland Met Office.


Álftagröf SIL station. The harmonic tremor spike can be seen most clearly here, as it goes clearly above background noise. Copyright of this picture belongs to Iceland Met Office.

From what I can tell this harmonic tremor signal is growing every few hours or so. It is possible that this is a repeat of what did happen in July. But for the moment it is too early to know that for sure at the moment. But for the moment there is no eruption about to start in Katla volcano.

When I was writing this blog post, it seems that a new earthquake swarm is about to start in Katla volcano. But the earthquake swarms in Katla volcano often start slowly with few earthquakes, but they seems to grow with time.