I seem to be able to see distant quakes down to
about 6 although my Lehman sits on
a carpeted basement slab in a noisy environment.

Note that I am still debugging my system, and 
I use Amaseis and WinQuake software.  Amaseis
seems to screw up some of the file headers
passed to Winquake

1/1/01 MINDANDAO, PHILIPPINES 7.2Ms
daily Amaseis display with 0.08 LP Hz
http://www.infiltec.com/seismo/010101.jpg
Winquake LP @ 0.08 Hz
http://www.infiltec.com/seismo/010101C.jpg

1/1/02 MINDANDAO, PHILIPPINES 6.2Ms
daily Amaseis display with LP @ 0.08 Hz
http://www.infiltec.com/seismo/010102.jgp
Winquake LP @ 0.08 Hz
http://www.infiltec.com/seismo/010102D.jpg 
Winquake with no LP (analog 4 hz LP)
http://www.infiltec.com/seismo/010102C.jpg

As you can see there is a lot of slab tilting going on
during the day when the building is occupied, and
the 6 sec noise is pretty high recently so I get
a lot better seismic signal with a LP @ 0.08 Hz.  And
lucky for me all big quakes occur at night!

Ciao,

Dave Saum  

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