From: Jim ODonnell 
To: psnlist 
Sent: Thu, 10 Oct 2013 1:00
Subject: Re: Please review these SAC

Tiago- I call it a seismometer Burp (hiccup is good too)- happens with=20
the 1 Hz phones, although I think all seismometers do it, but not as=20
much. =C2=A0I use 1 Hz phones in the desert for field work & in the summer=
=20
they did this a lot, until I painted them with a white epoxy paint.
You need another sensor recording nearby to see if the ground actually=20
moved............ =C2=A0 =C2=A0Jim

Hi Jim,

     Do you have any idea what is happening, please ? Maybe the top=20
spring is expanding out of step with the bottom spring and buckling ?=20
Are the geophones in direct sun light ? Are they the old type geophones=20
or the redesigned newer ones ? White epoxy paint should reduce the=20
amount of radiation absorbed, but it could also seal the unit=20
completely. Have you tried wrapping them in Al foil to reduce absorbed=20
radiation ? How about mounting them inside a Copper tube to slow down /=20
prevent differential heating ?

    Regards,

    Chris Chapman





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