I see that many people think that Grímsfjall has started to deflate due to a drop in GPS measurements. But the “Up” part of the GPS measurements have been dropping over the past few days from about 85mm and down to about 65mm today.
As that may be true that the mountain has started to deflate from the top. It is not to say that deflation process has started at Grímsfjall. As the GPS data clearly shows that a inflation process has just moved from the top and to the south. But current GPS measurement clearly show that Grímsfjall is now inflating to the south (15mm today) with minor inflation to the east (about 15mm today). So it is clear that the magma is moving inside the volcano from one location to a other over the past few days. What that means is unclear at the moment. But it appears that the inflation to the south is speeding up at current time. This might get interesting soon in my opinion. Regardless if there is a eruption or not.
There is a sudden and sharp rise in harmonic tremors around Katla and Eyjafjallajökull volcano. I currently do not know what volcano is responsible for the spike in harmonic tremor. But this does not look like is a noise from the weather. But that can happen often this time of the year, as the wind forecast is good for all of Iceland at current time.
I will post more information if and when I get them.
SIL stations where the harmonic tremor rise can be seen.
According to GPS data from GPS station located on top of Grímsfjall the volcano continues to inflate. Now it is about 80mm and does not seems to go much higher then that for some reason. Since Grímsfjall has stopped to inflate up at the moment it is currently inflating in other directions. The automatic GPS data clearly shows that the inflation is now moving south but is interestingly is holding it east-west movement. I am not clear on why that is the case at the moment.
I am going to post some information when I have the time about volcanoes that you never hear about in the news. The volcanoes in Iceland that have finished there work and have now gone extinct and no longer make ash clouds or lava. Iceland is full of those volcanoes and they are part of Iceland. What they do is tell us the history of Icelandic volcanism and how the volcanoes them self evolved over time and what they did do in that time.
I don’t have any good pictures or maps of extinct volcanoes in Iceland at the moment. But lucky for me I currently live on top of one at the moment. Both where I am in school and at home. Here is a view to the top of the volcano at my home. Picture is taken in summer 2008.
For me this history is important, as we can learn from it about today volcanoes and how they might behave when erupting.
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 two days the GPS station on Grímsfjall has been reporting some interesting data on what is going on inside Grímsfjall. But it appears that Grímsfjall is inflating at really fast speed at the moment. The movement is mostly upwards, as the station is located on the top of the mountain.
Currently the GPS station at Grímsfjall is reporting about 85mm movement upwards and about 5mm movement north (moving south). At last the movement east is about 10mm. But that gives the expansion site close to the GPS station, I would estimate rather rudely about 5 to 10 km from the SIL and GPS location. But it might be closer or longer. This is just a badly educated guess that I am doing here.
It is clear that if Grímsfjall continues to inflate at the same rate and it has been doing for the past few days and weeks it is going to erupt real soon. When is a good question as always.
Over the past days there have been a quiet streak happening in Iceland geology. This regularly happens and doesn’t mean anything special. This quiet times can sometimes last for up to 10 to 20 days at the longest. The longest quiet time that I did see lasted something close to five weeks. But then activity started to pick up again slowly.
It also happens sometime that quiet period is end with a bang. Then with a ML/Mb 4.0 or 5.0 earthquake and following earthquake swarm. Even if quiet time happens in Iceland sometimes, it does not necessary mean that the year is going to be a quiet one. As we have already seen with Eyjafjallajökull eruption in 2010.
Earlier tonight a second harmonic pulse was seen on Grímsvötn SIL station. This time the harmonic pulse has lasted longer and is still ongoing when this is written. What is creating this harmonic pulse is unclear at this moment. But at current time Grímsvötn lake is full of water. It might well be that the water is on the move and is leaving the Grímsvötn lake. However it is not going to be clear if that is the case or not in the next few hours. I would not be surprised if it goes both ways. That is the water is on the move and that it might not be on the move at all.
The second harmonic tremor seen on SIL station run by the IMO. Picture credit, Icelandic Met Office.
Grímsvötn SIL station. Click here for the full list of SIL station run by Icelandic Met Office.
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