Category: Harmonic tremors

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Second harmonic pulse seen on Grímsvötn SIL station

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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Possible Harmonic tremor pulse at Grímsfjall volcano

Today around 13:00 or 14:00 UTC (not sure exactly when) there was a possible minor harmonic tremor at Grímsfjall volcano. But earlier today I did write about the fast rise that is happening at Grímsfjall according to GPS data. It seems that things might get interesting soon if the current trend continues as it has for the past few weeks.

I do not believe that this is weather interference that I am currently seeing.


Possible harmonic tremor pulse seen at Grímsvötn SIL station on 2.October 2010. Image from IMO web site

Text updated at 16:25 UTC 2. October 2010.

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Quick note on harmonic tremor levels

There was a storm passing over Iceland. This has affected the tremor levels on IMO sensors. Mostly highland seismometers that get hit by stronger winds then those at lower altitude.

Volcano tremor appears differently at IMO sensors then wind noise and noise from ocean waves. But IMO sensors also pick those up at lower frequency bands (0.5 – 2Hz).