Swarm – Page 102 – Iceland geology

March 26, 2013March 26, 2013

Deep earthquakes in Askja volcano

Today (26.03.2013) at 08:09 UTC there where three deep earthquakes in Askja volcano. The most depth of this earthquake swarm was 25.5 km. None of the earthquake had the magnitude above 2.5. The strongest earthquake had the magnitude 2.1 with the depth of 20.4 km

Earthquakes in Askja volcano. Askja is located to the north of Vatnajökull glacier and the lake is round in shape on this map. Marked by the orange dots on it. Copyright of this image belongs to Icelandic Meteorological Office.

This activity is part of an progress that started in Askja volcano back in the year 2010. So far this has not lead to any eruption. But it has created some odd changes. Along one was that Askja lake was ice free last year (winter 2012). The reasons for that are still not known to me.

Blog post updated at 16:32 UTC on 26.03.2013.

March 20, 2013

Earthquake swarm on the Reykjanes ridge

Today (20.03.2013) at 10:51 UTC an earthquake swarm started on the Reykjanes ridge. This earthquake swarm was about 850 km away from Reykjavík so it was not felt. This also gives little information on what is happening in this location. Since the depth of the ocean at this location is around 2 to 3 km. The largest earthquake in this swarm had the magnitude of 4.8 according to automatic EMSC results. The range of magnitude that was detected is from 4.6 to 4.8. The estimated depth is around 10 km. But that might not be correct.

The location of the strongest earthquake in this swarm on the Reykjanes ridge. Copyright of this image belongs to EMSC.

More information on the strongest earthquake in this swarm can be found here, on the EMSC web site. I do not know if activity is going to continue in this place. This location is just too remote to know that for sure.

March 17, 2013

Earthquake activity intensifies in Skjaldbreið

The earthquake activity that started in Skjaldbreið yesterday continues. This earthquake activity has been picking up in number of earthquakes. But when this blog post is written no earthquake has been over magnitude 2.0. That however might change if this earthquake activity picks up more from the current activity level.

Earthquake activity in Skjaldbreið south of Langjökull glacier. Copyright of this image belongs to Icelandic Meteorological Office.

It is hard to know what is going to happen in this earthquake swarm. But earthquake activity in this area is often “slow”, in the terms it is slow to start and reaching its high point. If that is going to happen now is impossible to know. All that can be done is to watch and see how this earthquake swarm progresses and if any stronger earthquakes start to appear. Stronger earthquakes might not appear at all in this earthquake swarm. But they also cannot be ruled out.

March 17, 2013March 17, 2013

Three earthquakes in Hekla volcano

During the night there where three earthquakes in Hekla volcano. All of the earthquakes where small with the magnitude of 0.6 up to 0.9. Depth of this earthquakes was on the range of 10.7 and down to 11.8 km. No other activity has followed this earthquakes in Hekla volcano since this earthquakes took place.

The earthquakes in Hekla volcano. Copyright of this image belongs to Icelandic Meteorological Office.

Currently there are no signs of volcano eruptions in Hekla volcano. If that changes I am going to write about it. But for now Hekla volcano is as quiet as it has been since the year 2000. When last eruption took place.

March 16, 2013

Minor earthquake swarm in Skjaldbreið

During the night a small earthquake swarm started in Skjaldbreið south of Langjökull glacier (might be part of Presthnjúkar volcano). This earthquake swarm is minor. With largest earthquake only being magnitude 1.9. While this is an minor earthquake swarm there seems to be more activity taking place then appears on reviewed and automatic SIL map. The reason for that is the earthquakes in questions are small to be located by three or more SIL stations in the area. While this unseen earthquake activity does not appear on Icelandic Meteorological Office maps it can be seen on the SIL station closest to the earthquake locations.

Location of the earthquake swarm in Skjaldbreið. Copyright of this image belongs to Icelandic Meteorological Office.

Activity at the end of this tremor plot suggests more earthquakes are taking place. But they are not being located as they are not detected on three or more SIL stations. Copyright of this image belongs to Icelandic Meteorological Office.

Earthquake activity is common in this area. Since it is on the tectonic plate boundaries in Iceland. It is difficult to know how this earthquake swarm is going to behave in the next few hours. But so far it has stopped for few hours before continuing again.

March 10, 2013

Earthquake swarm in TFZ

During the night an earthquake swarm started in TFZ. The first earthquake had the magnitude of Mw3.8 according Icelandic Meteorological Office. This earthquake was felt clearly in the area it has been reported. Above 20 aftershocks have been recorded in this area following this earthquake.

Location of the magnitude 3.8 earthquake in TFZ. Copyright of this image belongs to Icelandic Meteorological Office.

Trace of the earthquake activity. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquake was well detected on my geophone in north Iceland. This image is released under CC Licence. Please see CC Licence page for more details.

It is possible to watch this earthquake activity on my geophone network page here. At the moment the earthquake activity has stopped. It is impossible to know if it is going to start again in this area or not. But this area is normally highly active in terms of earthquake activity during the year. So earthquakes swarms like this are not uncommon.

March 3, 2013

Deep earthquake swarm in Tungafellsjökull volcano

Today (03.03.2013) between 13:19 UTC and to 13:21 UTC a deep earthquake swarm took place in a volcano named Tungnafellsjökull. This was a minor earthquake swarm, with the largest earthquake having magnitude 1.4. But it is the depth that is important here. The depth was most at 28 km, with the shallowest earthquake having the depth 18.7 km. This suggest magma intrusion into the volcano at depth. A pattern that was seen during the Eyjafjallajökull volcano eruption as an example.

For the past few months. Tungnafellsjökull volcano has been having swarms of earthquakes. All of them small, but many of them above 2.0 in magnitude. But so far none above magnitude 3.0. While earthquake activity has remained low in Tungnafellsjökull volcano I find that events are speeding up there in the past few months. With the terms that more earthquakes are being detected in this volcano and now at more depth. I find this worrying and also interesting. This volcano is far from any populated area, so any damage resulting for an eruption in it should be minimal. It also has no glacier to speak of. There is going to be a bad weather in Iceland until Friday (according to the weather forecast at the moment), so detecting any small earthquakes in this area might be limited by it.

The red dots show the earthquake activity in Tungnafellsjökull volcano. Copyright of this image belongs to Icelandic Meteorological Office.

It is too early to know what happens in Tungafellsjökull volcano. It is also important to note that Tungnafelljökull volcano has never erupted in historical times. This makes figuring out what happens next in it more difficult then ever. This activity might not mean an eruption is imminent. But at the moment I cannot rule one out just yet. It is clear that more activity is going to be needed before the picture of what is taking place in Tungnafellsjökull volcano gets clearer.

March 2, 2013March 2, 2013

Interesting earthquake swarm in Katla volcano

There is a interesting earthquake activity taking place in south part of Katla volcano south caldera rim. This activity has been ongoing since in July 2011 after the minor eruption that year. The most logical reason for this earthquake activity is that in this location is a magma dike on the move. If that is actually the case is impossible to know for now. But this activity remains interesting for many reasons.

Earthquake activity in south Katla volcano caldera rim. This earthquakes are all small earthquakes. Copyright of this image belongs to Icelandic Meteorological Office.

This earthquakes are small. Most of them are on the magnitude range of 0.0 to 0.5. There depth is around 1 km up to 0.1 km (around 100 meters). So whatever is creating this earthquake activity is already shallow up in the crust. I do not know if there is going to be a eruption in this area. That is just a wait and see as always with volcanoes. But it is my estimate that (based on older data) this might mean there is more activity going to take place in Katla volcano soon. But that might fail. Since volcanoes are by nature unpredictable. So there are no assurances about what is going to happen next in Katla volcano.

February 28, 2013February 28, 2013

Earthquake swarm east of Grímsey (TFZ) and in Grímsfjall volcano fissure swarm

Currently there is a minor earthquake swarm east of Grímsey Island in the Tjörnes Fracture Zone. So far the largest earthquake has had the magnitude of 2.9 according to Icelandic Meteorological Office reviewed earthquake overview. Earthquake swarms are common in this area of TFZ.

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

Grímsfjall and Hamarinn volcanoes

Some internesting earthquake activity is now taking place in Grímsfjall volcano (outside the main volcano). This earthquake activity is in the fissure swarm that extents away from Grímsfjall volcano in the direction of Katla volcano fissure swarm. There has also been interesting earthquake activity taking place in Hamarinn volcano (no GVP page). But Hamarinn volcano last had a minor eruption in July of the year 2011. So far nothing suggests anything of volcanic nature is about to take place.

Earthquake activity in Grímsfjall volcano system today. Along with earthquake activity in Hamarinn volcano. Copyright of this image belongs to Icelandic Meteorological Office.

At the moment it appears that nothing besides earthquakes is going to take place in Grímsfjall volcano. But it hard to be sure given how often Grímsfjall volcano erupts. I do not yet have enough data on what is happening in Hamarinn volcano to say what is taking place there. So for now. It must just be observed.

February 16, 2013February 16, 2013

Earthquake swarm in Torfajökull volcano

Today (16.02.2013) at 15:11 UTC an earthquake swarm started in Torfajökull volcano. This is so far small earthquake swarm. With largest earthquake only having magnitude 2.6 (automatic result). Depth of this earthquake swarm is around 2 to 4 km. This earthquake swarm is taking place inside the volcano. So they might be magma related. But it is hard to know that for sure at the moment. This might just be normal tectonic earthquakes in this area. Earthquakes are common in this volcano. But major swarm activity does not seem to be for some reason.

Earthquake activity in Torfajökull volcano. The earthquakes are the red dots on this image. Copyright of this image belongs to Icelandic Meteorological Office.

It is hard to know exactly what happens next. But most often the earthquake activity in Torfajökull volcano stops after few hours. Last documented eruption in Torfajökull volcano took place in the year 1477 according to Global volcanism program (GVP). This earthquake activity appears clearly on my Heklubyggð geophone and Skeiðflöt geophone. The web site for my webicorders can be found here.

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