Category: Swarm

Posted on

Earthquake swarm on Reykjanes Ridge last night (16.09.2012)

Last night there was an earthquake swarm on Reykjanes Ridge. Possibly on one of the volcanoes that are in this area of Iceland. The earthquake swarm lasted for several hours. Strongest earthquakes in this swarm had the magnitude of 3.5. With the depth from 23 km and up to 0.3 km. Strongest earthquakes in this swarm where visible on my geophone network.


The earthquake swarm on the Reykjanes Ridge. Copyright of this image belongs to Icelandic Meteorological Office.

Last earthquake swarm in this area was on 8. February 2012. There was also earthquake activity deep on the Reykjanes Ridge. With two earthquakes that did get the magnitude 4.4 (EMSC) at 12:51 UTC. The second earthquake took place at 14:30 UTC and had the magnitude of 4.4 (EMSC). This earthquake activity is far enough from land that only the largest earthquakes are detected.

But there seems to be a lot of earthquake activity both south and north of Iceland (Jan Mayen earthquake activity). But this not connected activity as such. But it is known that activity on Reykjanes Ridge happens in jumps. It is an question if such time has come that an new activity episode is about to start on the Reykjanes Ridge. But last major episode in activity on the Reykjanes Ridge ended about 671 years ago. But there is one eruption documented off the coast in the year 1926 according to Global Volcanism Program. That activity did last for 4 days or so.

I am not sure what is going to happen next on the Reykjanes Ridge. But I am going to report it best to my ability. With the best information that I can get when the time comes.

Icelandic news about this earthquake activity

34 skjálftar frá miðnætti (mbl.is, Icelandic)

Blog post updated at 02:47 UTC on 17.09.2012

Posted on

Continued earthquake activity on Kolbeinsey Island ridge

In the past few days there has been considerable earthquake activity in Kolbeinsey Island ridge. Many of the earthquakes have been reaching the magnitude of at least 3.0. But some of it might be underestimation. As this earthquake activity is taking place far off Iceland coastline and far away from the SIL network. But that makes detection of earthquakes more difficult. Along with effects of weather and ocean waves that often prevent detection of smaller earthquakes in this area.


The location of the earthquake activity in Kolbeinsey Island ridge. Copyright of this image belongs to Icelandic Meteorological Office.

This is not the only activity in this area in the past few weeks. But the largest earthquake in this area was an magnitude 4.4 to 4.6 few weeks ago. So the activity in this area seems to be connected to something major. It is an question if this is due to volcano eruption currently taking place in this area now. But with depth of up to 4 km. It is impossible to know that for sure without actually going there on an ship. But given current weather. That is not going to happen any time soon. Maybe not for several years in fact.

Posted on

Ongoing earthquake swarm in Breinnisteinsfjöll volcano / SISZ

Since yesterday (02.09.2012) there has been ongoing earthquake swarm in Breinnisteinsfjöll volcano / SISZ (south iceland seismic zone). It is impossible to know how this earthquake swarm is going to proceed. But from what I can tell. It does not seem like it is going to be over any time soon. It is also an possibility that current earthquake swarm is part of an larger stress change in the area. But for now it is too early to know for sure what it means in the long term. Current earthquake activity is ongoing. With almost no breaks or stops. Most earthquakes have the magnitude of 0.1 and up to 2.0. But no larger earthquakes have been detected so far. The first earthquake in this earthquake swarm had the magnitude of ML4.4. Depth of this earthquakes is from 3 to 7 km (in that range).


The earthquake activity in Breinnisteinsfjöll volcano. The earthquakes align them self on an fault line that almost directly north-south direction. Copyright of this image belongs to Icelandic Meteorological Office.

It is impossible to know what is going to happen next in this earthquake swarm. But strong earthquake should not be ruled out for now. This might also activate nearby fault lines if the activity intensifies. As that sometimes happens in Iceland. Whatever happens next in this area. It is worth keeping an eye on the progress of this earthquake swarm.

Icelandic news about this earthquake swarm

Enn skelfur undir Bláfjöllum (mbl.is)
Enn skelfur í Bláfjöllum (Rúv.is)

Posted on

Magnitude 3.2 earthquake on the Reykjanes peninsula

Today (01.09.2012) at 16:33 UTC there was an earthquake with the magnitude of ML3.2. The depth was 7.6 km. Following this earthquake there was an swarm of smaller earthquakes following the first earthquake. None of those have been above magnitude 2.0. The earthquake took place in the Reykjanes volcano most likely. But it appears tectonic in nature. Rather then volcanic.


The magnitude ML3.2 earthquake on the Reykjanes peninsula. Copyright of this image belongs to Icelandic Meteorological Office.

It is hard to know for sure if this activity is going to continue. But since this earthquakes. Activity in this area has stopped. But it might resume at later time.

Icelandic news about this earthquake

Jarðskjálfti á Reykjanesskaga (Rúv.is)
3,2 stiga skjálfti við Grindavík (mbl.is)

Posted on

Earthquake swarm on Kolbeinsey Ridge yesterday (30.08.2012)

Yesterday (30.08.2012) there was an earthquake swarm on Kolbeinsey Ridge. But earthquakes have been taking place there for several weeks already. This earthquake activity seems to be growing in number of earthquakes swarms taking place. In the year 1999 there might have been an dike intrusion or submarine eruption south of Spar Fracture Zone (more details here). Last earthquake swarm that was noticed by the SIL network was exacly two months ago (30.06.2012). My coverage of that can be found here. But it was not in the same place. But that earthquake swarm was south of Kolbeinsey Island, not north of it as was the case yesterday.


The earthquake area in question are the yellow dots north of Iceland on this map from IMO. Copyright of this image belongs to Icelandic Meteorological Office.

What happens next in this area in terms of earthquake activity, or possible volcano activity is hard to impossible to know. As it is really hard to monitor volcanoes and rift zones that are under 2 km deep ocean and good distance from the coast line. However if there is any major earthquake activity in this area. It is going to appear clearly on my geophone network and IMO SIL network in Iceland.

Posted on

Glacier flood confirmed from western Skaftárkatli cauldron

Today (30.08.2012) an glacier flood was confirmed from the western Skaftárkatli cauldron. This glacier flood is small as expected. But it did take several days longer to appear from Vatnajökull glacier then expected. Some hydro-thermal activity in Hamarinn volcano (Bárðarbunga volcano) seems to be currently taking place at the moment. But some harmonic tremor spikes have been taking place in the past two hours.


Harmonic tremor pulse can be seen at the end of this tremor plot from IMO. It only lasted for about 30 to 60 min. Copyright of this image belongs to Icelandic Meteorological Office.


Harmonic tremor pulse can be seen at the end of this tremor plot from IMO. It only lasted for about 30 to 60 min. Copyright of this image belongs to Icelandic Meteorological Office.


Harmonic tremor pulse can be seen at the end of this tremor plot from IMO. It only lasted for about 30 to 60 min. Copyright of this image belongs to Icelandic Meteorological Office.

It might be that this harmonic tremor signals are coming from other volcano system then Hamarinn volcano. This type of activity has been seen before in Hamarinn volcano and follows glacier floods from it. Given the activity last year. I cannot rule out volcano activity taking place now in Hamarinn volcano. New episode of harmonic tremor is now starting in Hamarinn volcano. Based on early observations . It seems that current activity is behaving in similar manner as did happen in July 2011 when an minor eruption took place in Hamarinn volcano. If that is the case now remains to be seen. But it should be clear in few hours what is exactly going on in Hamarinn volcano following this glacier flood.

Icelandic news about this glacier flood

Skaftárhlaup kom úr katlinum – myndband (Rúv.is, video)
Hlaupið kom úr vestari katlinum (mbl.is)

Posted on

Two earthquakes in Jan Mayen today (30.08.2012)

Today (30.08.2012) Jan Mayen was hit by two earthquakes. The second earthquake was not an aftershock of the first one. But it remains an question if it was triggered by the first earthquake. The first earthquake had the magnitude of Mw6.6 according to EMSC web site. The second earthquake had the magnitude of Mb5.3 according to EMSC. Both earthquakes where felt by Norwegian military and science staff that resides on Jan Mayen.


Location of the Mw6.6 earthquake off the coast of Jan Mayen. As can be seen. This earthquake took place far out in the ocean. Copyright of this image belongs to EMSC.

The second earthquake was less in magnitude. But was closer to the Jan Mayen Island. For that reason it was possibly felt better the first earthquake.


Large view of the second Jan Mayen earthquake. This earthquake had the magnitude of Mb5.3. Copyright of this image belongs to EMSC.


Close up view of the second Jan Mayen earthquake. Copyright of this image belongs to EMSC.


The Mw6.6 earthquake that took place in Jan Mayen. This geophone station is the closest to the earthquake in Jan Mayen. This image is released under CC licence. Please see CC licence page for more details.


The Mw6.6 Jan Mayen earthquake as it was seen on Heklubyggð geophone station. This image is released under CC licence. Please see CC licence page for more details.


The Mw6.6 Jan Mayen earthquake as it was seen on Eyrarbakki geophone station. This image is released under CC licence. Please see CC licence page for more details.


The Mw6.6 Jan Mayen earthquake as it was seen on Skeiðflöt geophone station. The P-wave goes trough something that speeds up it’s arrival. Something that the software that I use cannot account for. That is why the P-wave is in the wrong location. As model vs reality do not match in this case. This happen frequently with my location data. This image is released under CC licence. Please see CC licence page for more details.


I did also record this earthquake in Denmark. Where I now live. This is the most distance that I did record this earthquake. But the distance was around 2000 km. The signal did appear. But I did not record any surface waves as I did in Iceland. Background noise is also higher here in Denmark then in most location in Iceland and it is more constant. This image is released under CC licence. Please see CC licence page for more details.

I did not record the Mb5.3 earthquakes on my geophones. It was just too small for my hardware to detect it. The waveform from the second earthquake was also lost in the surface waves from the first earthquake during this time period. At least when it comes to my hardware as it currently is.

Icelandic news about this earthquake

Jarðskjálfti við Jan Mayen – 6.6 stig (Vísir.is)
Almannavarnir: Ekki miklar líkur á flóðbylgju (Vísir.is)
Jarðskjálfti upp á 6,6 stig (mbl.is)

Norwegian and danish news about this earthquake

Kraftig jordskjelv utenfor Jan Mayen (NRK.no)
Skælv på 6,6 ryster Grønlands østkyst (DR.dk)

Posted on

Earthquake in Brennisteinsfjöll volcano / SISZ earthquake zone

Today (30.08.2012) at 11:59 UTC there was an earthquake with the magnitude of ML3.8 (4.2Mw) in Brennisteinsfjöll volcano / SISZ. But SISZ overlaps this area to some extend. So large earthquakes do happen in this area of Iceland on regular basis. This earthquake was felt in Reykjavík area, south Iceland and some part of western Iceland.


The earthquake location and the following aftershocks. Copyright of this image belongs to Icelandic Meteorological Office.

In around 30 aftershocks have been detected in the area. More aftershock activity in this area cannot be ruled out. This earthquake did appear clearly on my geophones all over Iceland.


The earthquake at Eyrarbakki geophone station. This geophone is the closest to the earthquake. The most movement in this earthquake was on an N-S and E-W fault according to my geophones. This picture is released under CC Licence. See licence page for more details.


This is the earthquake as it was recorded on Heklubyggð geophone. It is the second closest geophone station to this earthquake. This picture is released under CC Licence. See licence page for more details.


Here is the earthquake as it did appear on Skeiðflöt geophone. This picture is released under CC Licence. See licence page for more details.


Here is the earthquake as it did appear on Hvammstangi geophone. This picture is released under CC Licence. See licence page for more details.

It is impossible to know for sure what this earthquake activity means. But earthquake activity in this area of Brennisteinsfjöll volcano did stop around 15:49 UTC. No aftershocks did go above 2.0 in magnitude. More earthquakes in this area should not be ruled out in the next few days to weeks.

Icelandic News about this earthquake

Alltaf von á eftirskjálftum (Rúv.is)
Skjálftinn á enda stórs misgengis (Rúv.is)
Verra ef safnið hefði skemmst (Rúv.is)
Skjálftinn hápunktur – ekki fyrirboði (Rúv.is)
Jörð skalf í dag (Rúv.is. Afternoon radio show about this earthquake in Icelandic)
Jarðskjálftasvæðið undir smásjá sérfræðinga (Vísir.is)
Má búast við nokkrum eftirskjálftum (Vísir.is)
Fólk hljóp á dyr í Litlu Kaffistofunni (Vísir.is)
Jarðskjálftinn var 4,6 stig (Vísir.is)
Á þriðja tug eftirskjálfta hefur mælst (mbl.is)
Jarðskjálfti upp á 4,6 stig (mbl.is)
Snarpur jarðskjálfti á höfuðborgarsvæðinu – Stærsti skjálftinn í 3 ár (Pressan.is)
Jarðskjálftafræðingur: Ekki búið að losa um neina spennu að ráði (Pressan.is)

Posted on

Glacier flood has started from west Skaftárketill cauldron in Vatnajökull glacier

Yesterday an glacier flood started form west Skaftárketill cauldron. But that is an hydro-thermal area inside Hamarinn volcano (Bárðarbunga volcano system). The glacier flood is expected to be small. Last year in July there was also an glacier flood from this area of Vatnajökull glacier. But that was due to minor eruption in this area (it was poorly documented by scientists. I do not know why that is). But now it is melt-water from hydro-thermal area that is causing this glacier flood.

But glacier floods like this happen every 1 to 3 years from this area. Following this glacier flood an swarm of glacier-quakes have been detected in this part of Vatnajökull glacier. Flood in western Skaftárkatli might trigger a glacier flood in the eastern skaftárkatli cauldron. But it is not known if that is actually going to happen this time. It is not expected that current glacier flood is going to be a large one. But there is an risk of Hydrogen sulfide poisoning if people are close the glacier river during the glacier flood. So it is not recommend to go close to the glacier river due to this risk. The glacier flood is expected to appear from under Vatnajökull glacier in the next 5 to 6 hours. It is expected to last around 2 to 3 days at most.


Glacier quakes in Vatnajökull glacier following this glacier flood. This glacier quakes are not strong and do not show up on automatic SIL system. Copyright of this picture belongs to Icelandic Meteorological Office.


Glacier quake activity as it appears on SIL seismometers around Vatnajökull glacier. Copyright of this picture belongs to Icelandic Meteorological Office.


Glacier quake activity as it appears on SIL seismometers around Vatnajökull glacier. Copyright of this picture belongs to Icelandic Meteorological Office.


Glacier quake activity as it appears on SIL seismometers around Vatnajökull glacier. Copyright of this picture belongs to Icelandic Meteorological Office.


Click on this image for full size. This plot here shows output from several SIL stations. This image was released by Icelandic Meteorological Office today. Copyright of this picture belongs to Icelandic Meteorological Office.

It is believed that sometimes following this type of glacier floods from this area in Vatnajökull glacier there are small eruptions, or steam events as the pressure on the hydro-thermal system drops . That in turns allows for some magma movement that is powering the hydro-thermal system in this area of Vatnajökull glacier. It is impossible to know for sure if that is going to happen now. But it is good idea to keep an eye-out for such events taking place in Hamarinn volcano. Given the minor eruption that took place there last year.

Here is an comparison of the events that took place last year compared to the events that are currently taking place in Hamarinn volcano.


Harmonic tremor subsiding from Hamarinn volcano on 13. July 2011. The following glacier flood appears clearly on this tremor plot from Icelandic Meteorological Office. Copyright of this picture belongs to Icelandic Meteorological Office.

I was seeing activity to November 2011 after the activity in July 2011.


One of the last harmonic tremor activity that I did see in Hamarinn volcano during the year 2011. But this took place on 7. November 2011. After this point it did go quiet. Copyright of this picture belongs to Icelandic Meteorological Office.

I do not expect any volcano eruption in Hamarinn volcano at this point. But such things are impossible to know for sure. As Hamarinn volcano has not been studied in details until after the year 2011 eruption.

Icelandic news about this glacier flood

Hlaup hafið í Skaftá (Rúv.is)
Verður væntanlega ekki mikið hlaup (Rúv.is)
Hlaup að hefjast í Skaftá (Vísir.is)
Aldrei verið jafnfljótir að sjá hlaupið (Vísir.is)
Skaftárhlaup hafið (mbl.is)

Posted on

New earthquake swarm in Katla volcano

This morning at 07:03 UTC on 21. August 2012 an earthquake swarm started in Katla volcano. This earthquake swarm lasted for few minutes with the last earthquake taking place at 07:50 UTC. No harmonic tremor was detected following this earthquake swarm in Katla volcano. Update 1: The largest earthquake in this earthquake swarm had the magnitude of 2.6 at the depth of 0.1 km.


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

It is impossible to know for sure what this activity means. But this might just be normal autumn activity in Katla volcano. I am expecting more earthquake activity in Katla volcano in next few days to weeks.

Icelandic news about this earthquake activity

Skjálfti í Mýrdalsjökli (Rúv.is, Icelandic)
Jarðskjálfti upp á 3,1 stig í Mýrdalsjökli (Vísir.is, Icelandic)
3,1 stigs skjálfti í Mýrdalsjökli (mbl.is, Icelandic)

Blog post updated at 15:18 UTC on 21.08.2012. I have not yet fully recovered from the heat wave. I forgot the important information about this swarm. They have now been added.