Volcano and earthquake activity in Iceland
I see this morning that there are intraplate earthquakes north of Hveravellir. Intraplate earthquakes sometimes happen in Iceland, they also happen in earthquake swarms that can grow quite big. Both in size and numbers.
Intraplate earthquakes in Iceland happens on old fault lines or in old volcano areas.
Few moments ago (around 20:15 UTC) a strong earthquake swarm started on Reykjanes Ridge. This earthquake swarm is deep on the Reykjanes Ridge. Strongest earthquakes so far are ML3,1 on Reykjanes Ridge.
I am going to post updates as the swarm progresses. Some of the earthquakes can be seen on my webicoders here. But the distance is great so only strongest earthquakes are going to appear there.
Update at 21:06 UTC.
EMSC reports that the strongest earthquake was Mb4.8 while USGS is reporting that earthquake at Mb4.9 in size. The earthquake activity in this area is ongoing when this is written.
There is always surprises in Iceland once in a while when it comes to volcanoes. This evening there was one. This time for a little known volcano named Esjufjöll. But since the year 2002 there have been regular earthquake swarms in Esjufjöll volcano since that year. But this indicates that magma is pushing up the volcano. But it is quite hard to know if that is going to lead to a eruption. It might happen. But so far nothing indicates that it is going to do so at present time.
Here (Week 43 also) are details of the earthquakes in Esjufjöll in the year 2002. But this earthquake activity in 2002 lasted until week 45 (a small earthquake swarm was also in Week 51) before it stopped completely.
So far this are the years that earthquake swarms have happened in Esjufjöll volcano. The year 2002 (swarms, see links above), 2006 (minor swarm, see here), 2008 (small swarm, see here), 2009 (small swarm, see here), 2010 (small swarm ?). Currently the only thing to do now is to wait and see what happens with the 2010 earthquakes in Esjufjöll. But this is unlikely to lead to a eruption. But with volcanoes with rather unknown eruption history it is hard to know for sure.
Last suspected eruption in Esjufjöll took place in 1927 on 5th of September (+- 5 days). But that is unclear eruption as it was not seen and did only create a minor glacier flood. This information is from Global Volcanism Program and can be found in the link at the top.
There is a web camera online that points to Esjufjöll, it can be viewed here.
Yesterday (18th October 2010) at 03:34 UTC there was a deep earthquake under Katla volcano. This earthquake was on a 14,8 km depth and had the size of ML0.7 according to reviewed earthquake data from IMO (this is too small for my Hekla geophone to detect at this distance). This was a single earthquake and does not indicate anything special at current time. However this earthquake might possibility signal a change inside Katla volcano and might be a start of a longer process that is in the end going to lead to a eruption in Katla some time in the future.
Currently it is unclear how the path to volcano eruption starts in Katla. But in 1918 there where no instruments to record that eruption.
This type of deep earthquake have sometimes created harmonic tremor signals in Katla volcano. But that happens due to dike event inside the volcano. This has happened regularly over the last few years. But has not been big enough to start a eruption.
Picture of the earthquake as it appears on IMO web site in the “EWIS (Icelandic)” that IMO has. Currently this earthquake is not on the weekly reviewed charts.
This is not the only earthquake that has been happening in Katla volcano over the past few weeks.
Week 41 earthquakes in Mýrdalsjökull and Eyjafjallajökull volcanoes.
The wait for Katla eruption is going to end one day. But that day is not today far as I know so far.
Many people don’t know how to spot a earthquakes on my helicorders web site (you can view it here). Here is a quick how-to. The earthquake used is a Mw6.3 earthquake that did happen in 2008 in Iceland.
The second the earthquake did hit the sensor. The green line is when the power did go down in my apartment, just moment before the earthquake. Before that you can see background noise. That is people, cards and stuff like that. The earthquake is the big black-red line on the helicorder. After that you see smaller earthquakes happening (mag 3+ in size). This Hvammstangi geophone
Same earthquake, different location. This station actually was low-gain at the time of the earthquake. But meant that it was less sensitive to smaller earthquakes then larger. But the aftershock can be seen clearly on the helicorder at the time.
This is how my earthquake computer screen looked like at the time. The top line is currently not in use, as it is for a long period seismometers and I was just testing it at the time (it is also unclear on the signals as can be seen). The second and the third line in use is my geophone. But it clearly showed the earthquake and all it’s waves.
The Mosfellsbær station. That I had connection to at the time. But this is rather crazy view, as this is earthquakes and it is a lot of earthquakes in short space of time. I soon gave up trying to collect them.
This is how I finally work out the earthquakes. I put in location and depth from IMO data, as I can’t plot them my self.
I hope that this examples help people to see when there is a earthquake on my helicorder and just noise from human movement. Harmonic tremors are different and so far I have not been able to get any good example of it. But during the Eyjafjallajökull eruption a wind was problematic and I was unsure if I was recording wind into the harmonic tremors of that eruption or not. So that is going to have to wait a better time.
There was a small earthquake at 23:50 UTC in the Torfafjökull volcano. The earthquake it self was only ML1.7 in size, but the depth was 15 km. But that depth indicates that the earthquake was started by magma rather then tectonic process in the area. This would mean that a dike intrusion was starting in Torfajökull volcano at present time.
I did record this earthquake on my geophone, but this earthquake had a magma looking signature in it. But it was not clear and hard to see due to a minor weather effect in the area. Torfajökull volcano is not monitored with GPS instruments at the moment.
This is unlikely to be a pre-event to a eruption in the area. But dike intrusions appears to be a common events in Torfajökull volcano.
A earthquake swarm on Reykjanes Ridge is currently under way. At this time is it quite impossible to know how big and how long this earthquake swarm is going to be or if happens at all. But the biggest chance is that this earthquake swarm is going to be a small one, and is only going to last for a few more hours. But this earthquake swam started today with a small earthquake at 13:09 UTC close to Geirfuglasker. Over the past few hours the earthquakes have been getting more dense and growing slighty in size at the same time. A common feature for a earthquake swarm in Iceland.
The location of the earthquake swarm as it is now (19:49 UTC 17th of October 2010). Image is from Icelandic Met Office web page.
The best way to monitor this earthquake swarm is on IMO web page. They can also be seen on my helicorders. But they show clearly up on the Hekla helicorders.
One of Vatnajökull volcanoes named Kverkfjöll is starting to show again signs of activity. But few years (Week 31 2005, Week 35 2005, more data here) ago Kverkfjöll broke few decades of silence with a swarm of earthquakes. But most of them where small earthquakes and not many of them did reach ML3.0 in size.
In last week (Week 39 2010) there where few earthquakes in Kverkfjöll. But those where just few earthquakes, not a real swarm of earthquakes. Over the years there have been earthquakes (Week 7, 2003) in Kverkfjöll so this might not be so uncommon happening. But for the most part, Kverkfjöll normally don’t show much activity besides hot springs and boiled soil.
Last eruption in Kverkfjöll did happen in the year 1968 and in the year 1959 according to Global Volcanism Program.
I do not believe that Kverkfjöll are going to erupt soon. But things might get interesting in Kverkfjöll in 5 to 10 years from now. But it might take longer or shorter, the wait for Kverkfjöll however has started.
Over the past weeks there have been deep earthquakes happening under Eyjafjallajökull. The deepest earthquake so far that has happened was on 21 km depth. The latest earthquake that happened was on close to 15 km depth. Currently it is impossible to know if there is new magma pushing up.
If it is, then the amount of magma that is rising up trough Eyjafjallajökull is not great and is unlikely to start a new eruption any time soon. It is however worth noticing that this might change with a short notice. But the eruption in March to May 2010 did show that magma can rise fast up trough Eyjafjallajökull and appears to be followed by earthquake activity.
Around midnight tonight there where earthquakes deep south of Iceland. They where located on Reykjanes Ridge, by the far south end of it. At this distances it is hard to know if the earthquakes are related to tectonic activity or a volcanic one. But at this location there are volcanoes, but volcanoes do cover Reykjanes Ridge. But I am not sure how far south that actually goes. But I am assuming all the way down the end of it.
The details of the earthquakes can be found at EMSC web page. Just click on the earthquake of interest to get the scientific data on it.
There have been done studies on the volcanism on Reykjanes Ridge. But I do not know how detailed they are.
