Oturere

[Suezy]

This looks pretty busy tonight David. Maybe you could fill me in on it please with not being so familar with these .http://www.geonet.org.nz/images/volcano/drums/ch/otvz/10/drum.png

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[TokWW]

I think they describe volcanic earth movements as a lot of rumbling but not actual earthquakes, not of any break and slip action, so they can appear "noisy" with more thermal activity which may be indicative of something new happening or a change I guess.  Oturere is near Ngauruhoe Volcano.  This may mean something is getting busy there. Interesting to see it. Thanks.

Looking down the interpretation page:

http://www.geonet.org.nz/volcano/monitoring-methods/seismic.html

Nothing there lines up with what is being seen...

[Suezy]

Thanks Graeme - have forgotten what I learnt from these.

[TokWW]

Just doing some more research...

http://www.geonet.org.nz/volcano/our-volcanoes/ngauruhoe.html

In January 1973, Ngauruhoe discharged red-hot blocks of lava, and periodic activity continued throughout the year. In 1974 and 1975 there were explosive eruptions of ash, and blocks of lava were thrown as far as 3 km away. During the last violent eruption, gases streamed from the crater for several hours, producing a churning plume of ash that towered up to 13 km above the crater. This column then collapsed and formed ash and scoria avalanches that swept down the sides of Ngauruhoe, leaving trails of rubble in their wake.

[TokWW]

I also note that Ruapehu is also noisy in the same period...


and Rotorua and Okataina to a lesser extent... oh, and Mt Tarawera as well.

I hope it is nothing sinister.

[TokWW]

The Oturere drum has quietened too like Ruapehu.  It had a similar noise level 11 days ago.  Worth watching though

[TokWW]

Oturere - Noisier again the last last 7hrs...  Mt Tarawera last 14hrs, but not as noisy.

http://www.geonet.org.nz/images/volcano/drums/ch/otvz/10/drum.png   Oturere

http://www.geonet.org.nz/images/volcano/drums/rt/tarz/10/drum.png  Tarawera

[David]

Hi Suezy, it is not volcanic noise, it's other noise - most likely wind. Considering elevation and the current conditions the wind speeds will be very high at this site.

The key is in the "RSAM/SSAM" plots. With volcanic unrest, we expect noise in the 1-5 Hz frequencies. An example showing volcanic noise is the White Island plot attached (look at the red rectangle).

On the Ngauruhoe plot, the noise extends up to 20 Hz, usually this is caused by strong winds.
Another clue that this is wind noise is that a lot of the drums are recording more noise than usual.

[Suezy]

Thanks for that Graeme as had not noticed with being out for most of the afternoon - nothing to worry about - hopefully. That would be the last straw.

[Suezy]

Thanks for that David appreciated.  Did learn about them awhile back but all forgotten now.  I know that one of them also has a "Gardens" somewhere near one of them too and the people and cars going there makes more noise on one of them  and recorded on the graphs but don't know which one it is now.  But understandable with the wind that you have had up there.

[TokWW]

Thanks David, was wondering about the wind myself, but your scientific breakdown was helpful.  Had looked at the Seismic Amplitude and the Spectrum Analysis charts as well, but needed that explanation.