From: http://pubs.usgs.gov/pinatubo/ramos/
HARMONIC TREMOR

The type of tremor with the narrowest frequency spectra is the 
harmonic tremor. Every event of this tremor is monochromatic, 
occurring with a very characteristic narrow frequency that remains 
constant throughout the duration of the events (fig. 10A,B). The 
dominant frequency may vary from event to event, but the range of 
frequency is still narrow, from 0.7 to 2.4 Hz.
****

I think that with the amplifier/filter that extends the range of the 
4.5 Hz sensor
to about 0.5 Hz, harmonic tremor will be recorded.

Cheers,
John


At 06:39 AM 12/30/2005, you wrote:
>In a message dated 30/12/2005, sismos@.............. writes:
>
>>http://earthquake.usgs.gov/image_glossary/harmonic_tremor.html
>
>
>Hi Angel,
>
>        Thanks. There seems to be no information on frequency, 
> period, or amplitude even on the volcano website.
>
>        See also 
> http://earthquake.usgs.gov/image_glossary/richter_scale.html
>
>        http://earthquake.usgs.gov/image_glossary/seismic_moment.html
>
> 
>http://earthquake.usgs.gov/image_glossary/magnitude.html 
>
>
>        Regards,
>
>        Chris


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