In a message dated 26/01/2006, jonfr500@......... writes:

I also  have one question to ask this time. Does anyone know how the ocean
wave  appears on seismograph? Because I was doing some work on my
geophone early  this night and after that I saw wave top appear on my
seismographs  (preventing the geophone from moving by increase the
pressure on him with  plastic bags inside of the box that is on top of
him, also to minimise the  wind noise as I can), those tops are "smooth"
and don't look like wind  noise. I doubt that this is the plastic  bags
fault.



Hi Jon,
 
    The Atlantic ocean microseisms may be 0.5 to 15  microns with a period of 
6 to 7 seconds. I very much doubt if your geophones  will see this. The waves 
are usually short sections of rather rough sine form.  Since you are fairly 
close to the sea, you may pick up wave noise. You are  likely to see storm 
noise.
    If you have any air filled plastic bags in your  seismometer box, I 
suggest that you remove them immediatly. They are likely  to react quite strongly 
both to changes in atmospheric pressure and to  wind speed! 
    The accelerations that you normally observe should  not move a geophone 
case set on the ground. If you want to provide a more firm  fixing, I suggest 
that you get some children's 'plasticene' (like a non sticky  putty) and use 
this to 'join' the geophone case to  the concrete. 
    See _http://www.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf_ 
(http://www.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf)  I  can buy Blu-Tack and 
White-Tack adhesive putty from stationers. It is now  available in the US. See
_http://www.artech-electronics.com/us/products/accesso/blutack.html_ 
(http://www.artech-electronics.com/us/products/accesso/blutack.html)  It  is a semi 
elastic non drying adhesive mastic which hardens over a period of  weeks, but 
may be kneaded again by hand and re-used. Very useful for making  demountable 
seals, sticking posters to walls without damaging the finish  etc..
 
    Regards,
 
    Chris Chapman






In a message dated 26/01/2006, jonfr500@......... writes:
<=
FONT=20
  style=3D"BACKGROUND-COLOR: transparent" face=3DArial color=3D#000000 size=
=3D2>I also=20
  have one question to ask this time. Does anyone know how the ocean
wave=
=20
  appears on seismograph? Because I was doing some work on my
geophone ea=
rly=20
  this night and after that I saw wave top appear on my
seismographs=
=20
  (preventing the geophone from moving by increase the
pressure on him wi=
th=20
  plastic bags inside of the box that is on top of
him, also to minimise=20=
the=20
  wind noise as I can), those tops are "smooth"
and don't look like=20=
wind=20
  noise. I doubt that this is the plastic=20
bags
fault.


Hi Jon,
 
    The Atlantic ocean microseisms may be 0.5 to 15=
=20
microns with a period of 6 to 7 seconds. I very much doubt if your geophones=
=20
will see this. The waves are usually short sections of rather rough sine for=
m.=20
Since you are fairly close to the sea, you may pick up wave noise. You are=20
likely to see storm noise.
    If you have any air filled plastic bags in your=
=20
seismometer box, I suggest that you remove them immediatly. They are li=
kely=20
to react quite strongly both to changes in atmospheric pressure an=
d to=20
wind speed! 
    The accelerations that you normally observe sho=
uld=20
not move a geophone case set on the ground. If you want to provide a more fi=
rm=20
fixing, I suggest that you get some children's 'plasticene' (like a non stic=
ky=20
putty) and use this to 'join' the geophone case to=20
the concrete. 
    See http://w=
ww.bostik.com.au/pdf/datasheet/bostik_blu_tack.pdf I=20
can buy Blu-Tack and White-Tack adhesive putty from stationers. It is now=20
available in the US. See
=
http://www.artech-electronics.com/us/products/accesso/blutack.html =
It=20
is a semi elastic non drying adhesive mastic which hardens over a period of=20
weeks, but may be kneaded again by hand and re-used. Very useful for making=20
demountable seals, sticking posters to walls without damaging the finish=20
etc..
 
    Regards,
 
    Chris Chapman