Dear Mark:
What would you state as the noise level of your gradiometer, in terms of
SD of the mean, averaged over a particular time interval, with aircraft
tubulence envelope of a particular number of g's?
Harry Seigel
"Dransfield, Mark MH" wrote:
>
> Hello Peter,
>
> not a dumb question at all. While gravity gradiometers require essentially no free
>air or Bouguer slab correction, the terrain correction is very important and an
>accurate topographic model is required. My PhD thesis (Airborne Gravity Gradiometry,
>University of Western Australia, 1994) briefly mentions the topic giving rough
>estimates of the requirement. A paper by Chen and Macnae (Explor. Geophys., 1997,
>p21-25) looks at a particular example and there are older references in Geophys. (eg
>Chinnery, 196? and Hammer 19??).
>
> I can tell you that the BHP system deals with this problem very well!
>
> cheers
> Mark
>
> ===================================================================
> Dr Mark Dransfield ph. +61-3 9609 4478
> BHP Minerals Technology fax +61-3 9609 4489
> Discovery Technologies
> Level 17, 114 William Street, Melbourne
> GPO Box 86A, Melbourne, VIC, 3001
> AUSTRALIA [EMAIL PROTECTED]
> ===================================================================
>
> -----Original Message-----
> From: Peter Walker [mailto:[EMAIL PROTECTED]]
> Sent: Friday, 19 May 2000 23:28
> To: [EMAIL PROTECTED]
> Subject: Re: [SEGMIN]: BHP's Airborne Gravity Gradiometer System
>
> Hi Ken
>
> Perhaps this is a dumb question, but since a gradiomenter
> is essentially a shallow penetrating instrument (compared
> with the field), and since the largest effect has to be the
> contrast at the air-earth interface, won't the gradiomenter
> be inordinately sensitive to topography? Ie: to tease geologic
> signal from the data, will it not be necessary to have a very
> accurate topographic model?
>
> Peter
>
> ----- Original Message -----
> From: "Ken Witherly" <[EMAIL PROTECTED]>
> To: "Segmin@Lists. Geosoft. Com" <[EMAIL PROTECTED]>
> Sent: Thursday, May 18, 2000 7:37 PM
> Subject: [SEGMIN]: BHP's Airborne Gravity Gradiometer System
>
> > BHP announced yesterday that their airborne gravity gradiometer system is
> > flying. The attached JPEG is from a local (Melbourne) newspaper. The url
> > leads to the full talk (lots of other BHP bumf), there are some additional
> > images showing data from Ekati and Western Australia. Enjoy.
> >
> > Ken Witherly
> >
> > http://www.bhp.com.au/financials/brief/default.htm
> >
> >
> > Condor Consulting, Inc.
> > St. 206, 4860 Robb Street
> > Wheat Ridge CO 80033
> > Tel: 303-423-8475
> > Fax: 303-423-9729
> > www.condorconsult.com
> >
> >
> >
> > _______________________________________________________
> > List archive: http://www.mail-archive.com/[email protected]
> >
> >
> >
>
> _______________________________________________________
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> EOM
>
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