PSN-L Email List Message
Subject: Re: Please review these SAC
From: Jim ODonnell geophysics.jim@.........
Date: Wed, 9 Oct 2013 22:05:57 -0700
Tiago- I looked at your 3 records in both time series & PS(FFT) and indeed
they have a 2.5 Hz peak. This is probably not a burp because there is so
much other high frequency activity around it....
Since I work in the desert with temp's going over 100F during the day the
Aluminum case get so hot you can not touch them, and they start to Burp.
By painting them white, it keeps them cooler and keeps burps to a minimum.
I sometime deploy a line of phones (30 at 100m spacings) & record for 24
hrs, to measure microseisms, Rayleigh waves, (~40 to 1 Hz) to get a Vs
under the line.
<<<< Jim
On Wed, Oct 9, 2013 at 6:40 PM, Tiago A. wrote:
> Thanks for the answer Jim.
>
> I suspected also that it was something to do with the geophone, but how
> does the epoxy help? Tomorrow i can check a 10km distance station to check
> if it also record something (which i dont believe).
>
> Netherless i forgot to post the link of the SAC files, they can be
> downloaded here:
> https://dl.dropboxusercontent.com/u/15802004/sac.zip
>
> Chris, in my case the geophone (1996 one) is inside a house, covered with
> styrofoam.
>
>
> 2013/10/10
>
> 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
>> the 1 Hz phones, although I think all seismometers do it, but not as much.
>> I use 1 Hz phones in the desert for field work & in the summer 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
>> moved............ Jim
>>
>> Hi Jim,
>>
>> Do you have any idea what is happening, please ? Maybe the top spring
>> is expanding out of step with the bottom spring and buckling ? Are the
>> geophones in direct sun light ? Are they the old type geophones or the
>> redesigned newer ones ? White epoxy paint should reduce the amount of
>> radiation absorbed, but it could also seal the unit completely. Have you
>> tried wrapping them in Al foil to reduce absorbed radiation ? How about
>> mounting them inside a Copper tube to slow down / prevent differential
>> heating ?
>>
>> Regards,
>>
>> Chris Chapman
>>
>>
>>
>>
>>
>> ______________________________**____________________________
>>
>> 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.htmlfor more information.
>>
>
>
Tiago- I looked at your 3 records in both time series=
& PS(FFT) and indeed they have a 2.5 Hz peak.=A0 This is probably not =
a burp because there is so much other high frequency activity around it....=
Since I work in the desert with temp's going over 100F during the d=
ay the Aluminum case get so hot you can not touch them, and they start to B=
urp.=A0 By painting them white, it keeps them cooler and keeps burps to a m=
inimum.=A0 I sometime deploy a line of phones (30 at 100m spacings) & r=
ecord for 24 hrs, to measure microseisms,=A0Rayleigh waves, (~40 to 1 Hz) t=
o get a Vs under the line.
<<<<=A0=A0=A0 Jim
On Wed, Oct 9, 2013 at 6:40 PM,=
Tiago A.
<tiagoagre@.........> wrote:
Thanks for the answer =
Jim.
I suspected also that it was something to do with th=
e geophone, but how does the epoxy help? Tomorrow i can check a 10km distan=
ce station to check if it also record something (which i dont believe).
Chris, in my case the geophone (1996 one) is inside a =
house, covered with styrofoam.
[ Top ]
[ Back ]
[ Home Page ]