Jan.  I believe your system is in the "ball-park" in performance.  I =
don't know what design you are working with, or your exact location.  =
With our experience with a long-period cantilever (l8 sec) period, we =
generally read 3.0 events --here in Virginia, some quarry blasts, not =
many natural events here!.  Anything Mag. 5 and above in the U.S. =
Alaska, and much of Central and South America.  Anything Mag.. 6 or more =
worldwide.   Of course events in South Pacific outnumbered the rest of =
the World for us.  The ideal was when we ran two identical sensors =
broadside N-S and E-W.  We generally let microseisms decide the =
amplitude setting.  In our summertime here in VA. the microseisms are =
lower (for whatever reasons??) and we could crank up the daily gains, =
and for a two month summer recording with two sensors we received our =
record of 62 events in 60 days.  That was years ago, and I haven't tried =
a repeat.
         Best wishes,    Jim Lehman
  ----- Original Message -----=20
  From: Jan Froom=20
  To: psn-l@.................
  Sent: Thursday, October 11, 2007 3:35 PM
  Subject: seismometer/site sensitivity


  I'm curious how many of you have come up with a "rule of thumb" for =
the general sensitivity of your seismometers.

  For instance I have sensed a 3.0 sixty miles out from my seismometer, =
and have seen 5s within 300 miles.
  And I understand we should be able to sense a 7 anywhere in the world.
  But just now, I did not see a 1.3  seven miles out.
  So my question.... is this good, bad, average?=20
  I'm sure there are lots of variables such as type of instrument, =
orientation, ambient noise, etc..=20
  but still, shouldn't there be a general feeling or rule of thumb.

  Jan in Gilroy








Jan.  I believe your system is in =
the=20
"ball-park" in performance.  I don't know what design you are =
working with,=20
or your exact location.  With our experience with a long-period =
cantilever=20
(l8 sec) period, we generally read 3.0 events --here in Virginia, some =
quarry=20
blasts, not many natural events here!.  Anything Mag. 5 and above =
in the=20
U.S. Alaska, and much of Central and South America.  =
Anything=20
Mag.. 6 or more worldwide.   Of course events in South Pacific =

outnumbered the rest of the World for us.  The ideal was when =
we=20
ran two identical sensors broadside N-S and E-W.  We generally =
let=20
microseisms decide the amplitude setting.  In our summertime here =
in VA.=20
the microseisms are lower (for whatever reasons??) and we could crank up =
the=20
daily gains, and for a two month summer recording with two sensors we =
received=20
our record of 62 events in 60 days.  That was years ago, and I =
haven't=20
tried a repeat.
        =20
Best wishes,    Jim Lehman

  
----- Original Message ----- 
  From:=20
  Jan=20
  Froom 
  
To: psn-l@.............. 
  
Sent: Thursday, October 11, =
2007 3:35=20
  PM
  
Subject: seismometer/site=20
  sensitivity
  

I'm curious how many =
of you=20
  have come up with a "rule of thumb" for the general sensitivity of =
your=20
  seismometers.

For instance I have sensed a 3.0 sixty miles out =
from my=20
  seismometer, and have seen 5s within 300 miles.
And I understand we =
should=20
  be able to sense a 7 anywhere in the world.
But just now, I did not =
see a=20
  1.3  seven miles out.
So my question.... is this good, bad, =
average?=20
  
I'm sure there are lots of variables such as type of instrument,=20
  orientation, ambient noise, etc.. 
but still, shouldn't there be a =
general=20
  feeling or rule of thumb.

Jan in=20
Gilroy