PSN-L Email List Message
Subject: Re: Spring for AS-1 type vertical seismometer
From: Brett Nordgren brett3nt@.............
Date: Mon, 21 Nov 2011 08:50:59 -0500
Hi Dave,
I agree, Richard has made a very nice looking instrument.
Regarding noise, I think it's the other way around. Generally the
verticals are considerably less sensitive to local disturbances of
the ground (though much more sensitive to temperature and barometric
pressure changes). Here's a couple of traces captured from the
vertical channel (top trace) and one of the horizontal channels of a
Nanometrics Trillium Compact 120 three-axis instrument, operated by
Dave Nelson in
California. http://bnordgren.org/seismo/H_vs_V_-_Trillium_120.jpg
The wind was blowing that day and was shaking the ground quite a
bit. That's typical of what you would normally see.
Good verticals can be a lot harder to build, but they can perform
much better in the sorts of locations that are likely to be available.
Although his instruments are located very close to the
house http://bnordgren.org/seismo/IMG_1383s.jpg
Dave gets very good results with his verticals, whose
traces http://bnordgren.org/seismo/gif_images.htm
can look as good or better than the USGS helicorder
plots. http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/ANMO_24hr.html
As we continue to test new designs, it appears that his vertical
instruments' sensitivity, as determined by their internal noise, may
possibly be a little better than his Trillium. More testing in the works.
Regards,
Brett
At 04:48 AM 11/21/2011, you wrote:
>Hi Richard
> great looking sensor :)
> I have pondered the construction of a vertical sensor but have
> always thought they
> picked up too much local "people noise" to be really successful,
> particularly in
>suburbia. I wonder how you have found it ? maybe you have a reasonably quiet
>location.
> going by the seismograms it obviously works very well
>
> I would like to see some more information on how your pivot is
> assembled, if
>that is possible please :) I just couldnt quite make it all out in the pic.
>
>cheers
>Dave Nelson
>Sydney
__________________________________________________________
Public Seismic Network Mailing List (PSNLIST)
To leave this list email PSNLIST-REQUEST@.............. with
the body of the message (first line only): unsubscribe
See http://www.seismicnet.com/maillist.html for more information.
[ Top ]
[ Back ]
[ Home Page ]