When this is written around 00:36 UTC on 9. July 2011 the harmonic tremor levels on SIL stations around Katla volcano have continued to increase. The latest spike in harmonic tremor levels happened after an ML1.5 (automatic size) earthquake that took place at 22:13 UTC. There has been an small earthquake swarm in Katla volcano caldera yesterday. But the largest earthquake in that earthquake swarm had the size ML2.4.
The harmonic levels are getting so strong that they have started to appear on stations around Hekla and on my own geophone, even if it is located almost 60 km away from the source of the harmonic tremor. Currently there is little to suggests that this is slowing down at the moment. But that might yet happen. But it is impossible to know for sure at the moment.
The lack of earthquakes tells me that the magma has not yet reached the surface. When or if that might happen is an good question that I do not have the answer to. But this might take several more hours until something happens in terms of earthquakes or other activity in Katla volcano.
Harmonic tremor can clearly be seen on this SIL station at the end of the tremor chart. This is saved around 00:36 UTC 9. July 2011. Copyright of this picture belongs to Icelandic Met Office.
Harmonic tremor can clearly be seen on this SIL station at the end of the tremor chart. This is saved around 00:36 UTC 9. July 2011. Copyright of this picture belongs to Icelandic Met Office.
As sad before the harmonic tremor can now be seen on SIL stations far away from Katla volcano. But the maximum range so far is around 65 km or so at the moment.
This is the last update for tonight. I am going post an update tomorrow on what has happened during the night. Even just to say people that things have slowed down or gone back to normal. Whatever happens. I am going to post information about it tomorrow when I awake up.
Thanks, Jon.
This is like someone close to you going into labour and you wish you could stay awake till the end but you know you won’t manage it and you drift off to sleep wondering whether there will be new baby in the morning or whether it’ll have been a false alarm. 😀
This is bad news.
Katla might be indeed close to an eruption. I never thought the tremor would rise so quick without large earthquakes. If this is so, then magma is rising up now, and it might break surface. Whether it could be an eruption similar to 1999 (very minor) or 1918 (large), that is the big question.
Tremor is decreasing now…
The tremor is indeed dropping. But I am not sure how long that is going to last. As earthquakes are still taking place. They are small most of them. But they are increasing at an alarming rate.
I also got two new ones just now. Both of them where extremely low period earthquakes.
I can see them, Jón.
I’ll be watching from here.
It’ only 11 p.m in Rio.
ufff look at now:
http://hraun.vedur.is/ja/Katla/god_trem.gif
Jón: harmonic tremor on your geophone is crystal clear.
Tremors increased again reaching their highest so far, on several stations around Katla
New blog post is up. An small glacier flood has started from Mýrdalsjökull glacier.
So that I understand the “likely” sequence of things correctly, if the tremors continue strong and consistent and the eruption is starting, we should see at the same time dozens of quakes moving upward along with some large quakes 4-5+, then once the eruption breaks the surface, we have about 2-12 hours of jökulhlaup and then we can see the eruption on the web cams, correct? The duration of this sequence of events leading up to the sub glacial eruption, is anyones guess from what I gather, but could take place over a period of hours to several days, but could drag on for weeks?
Eyjafjallajökull had high seismic activity starting in Dec 2009, but then on 2/26/10, it started back with high seismic and inflation and ground deformation for 1 month before it erupted on March 20. I get the feeling Katla would not take that long as it is very sick and ate way too much bad food.
Hi jon. how do i get on to your new blog. new activity now. do you think that there is going to be an eruption? evacuation has been cancelled????
I am not following your question. Just click on the newest blog post to see the comments and the full blog post.
Thanks for the reply:)
Some of us benefit from this. We live in the flight path of an airport, and the silence when the planes cannot fly is wonderful. Can hear the bird sing, not woken up with the mail planes at 2am. Life before we had all these noisy planes. Peace is such a lovely word when you get it.