Thank you everyone to all your comments. I just want to keep it simple. Instead of calculating the gradients (e.g. 1stVD, 1stHD in EW, etc.) using any available software, I would like to measure it. I am interested in the total magnetic field intensity as a scalar, hence in just the strength of the total field, not in its direction. However RtP transformations are always preferred. So, the inclination should be 90 degrees.
So, grad TMI, nabla TMI, partial d TMI / partial d space, etc. is my interest. This can be approximated by two simultaneous (or almost simultaneous) measurements of TMI and by a set distance. I have tried single gradients in airborne and ground platforms, with VTEM as offered by Geotech (horizontal gradient perpendicular to flight direction) and by GEM Systems (vertical gradient measured with two GSM-19). Results are always impressive. Besides improving S/N, it delivers measured gradients, not calculated ones. The horizontal gradient worked very well e.g. in a known porphyry near Copiapo, Chile. We were about to rename the porphyry to Donut, because of the shape of the gradient and the exact mapping of contacts. It works well with other geological geometries. I was wondering who was offering a full gradient system on a ground platform. I already have the answer. By the way, I have nothing to do with the search of the missed aircraft. Regards On Fri, May 3, 2019 at 11:59 AM Ed Cunion via SEGMIN < [email protected]> wrote: > The 2 cents understanding here while having lunch, > > Having been involved on surveys using triaxial airborne gradiometer and > 3-axis fluxgate vector magnetometers- > > Measured gradiometer surveys usually use scalar sensors -alkali vapor- > etc. to measure the difference between cross-axis sensors, cross wing, > cross tail, cross fuselage, say for a fixed wing. The sensors measure the > scalar total field. The gradient across the scalar sensors is then > determined. > > Fluxgates, the 3-axis type, Bartington is one manufacturer, there are > several even chip scale now, alternatively, measure the three vectors of > the magnetic field and return the three vector readings. The fluxgate can > either be aligned in some way with the 3D earth field, say like might be > seen at an observatory like in Boulder, or not, like out on some sort of > field survey for example, UXO, Archeology, whatever, why limit yourself? As > the fluxgate provides the 3D vectors, a bonus is these can be combined to > get a total field reading too. > > Taking this one step further, vector magnetometers can be used instead of > scalars, in 2D or 3D gradient arrays. As might be expected this produces a > wealth of magnetic field data to process and interpret. > > Fluxgates can also be used in EM, Smartems been around for a while, MT too? > > Cheers, > > Ed > > Red Rocks Geophysical > Mobile 001 720 300 3641 > > Sent from my T-Mobile Android device > > > > On Fri, May 3, 2019, 8:44 AM S E Geoscience and Exploration via SEGMIN < > [email protected]> wrote: > >> Joel, >> >> can you please expand on that ("the gradient of the total field is not >> the same as the gradient of the field")? >> >> A gradient is a spatial derivative, changes of a value in space. So, what >> is the difference between the value "(magnetic) total field" and the value >> "(magnetic) field"? >> >> Thanks >> >> >> On Thu, May 2, 2019 at 10:08 AM Jansen, Joel via SEGMIN < >> [email protected]> wrote: >> >>> Peter has brought up a good point: that the gradient of the total field >>> is not the same as the gradient of the field. The former can be collected >>> with proton or Cs/K-vapour magnetometers, while the latter requires >>> fluxgates or SQUIDS. >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> * Joel Jansen D +1 604 696 3511 M +1 604 218 3887 From: >>> SEGMIN <[email protected] >>> <[email protected]>> On Behalf Of Peter Annan via SEGMIN >>> Sent: May 1, 2019 7:52 PM To: [email protected] >>> <[email protected]> Cc: Peter Annan <[email protected] >>> <[email protected]>> Subject: Re: [SEGMIN] full gradient mag surveys This >>> message originated outside Anglo American ------------------------------ >>> Hi Richard: From my understanding and talking to many in the archeo >>> field, these are primarily single axis gradiometers or arrays of these >>> devices and not triaxial gradiometers. Someone may have a more advanced >>> version since there are lot of people playing but have not see a triaxial >>> unit. More likely to find the triaxial solution in the UXO area if there >>> is one.. Regards Peter From: SEGMIN <[email protected] >>> <[email protected]>> On Behalf Of Richard Smith via SEGMIN >>> Sent: Wednesday, May 1, 2019 10:33 PM To: [email protected] >>> <[email protected]> Cc: Richard Smith <[email protected] >>> <[email protected]>> Subject: Re: [SEGMIN] full gradient mag surveys >>> There are lots of archeological groups doing multisensory mag for Greek and >>> Roman ruins, Stonehenge etc. There was someone from Flinders University in >>> South Australia written up recently in Preview. These systems are >>> generally towed by a quadbike or similar and are designed for open spaces >>> like fields. Regards Richard Smith -----Original Message----- From: >>> Roger Henderson via SEGMIN <[email protected] >>> <[email protected]>> To: segmin <[email protected] >>> <[email protected]>> Cc: Roger Henderson <[email protected] >>> <[email protected]>> Sent: Wed, May 1, 2019 8:07 pm Subject: Re: [SEGMIN] >>> full gradient mag surveys Yes, Sergio did say GROUND and he gets offered >>> helicopter systems. Hasn’t any one watched the British TV show “Time team” >>> using triaxial mags for archaeology? I think they were fluxgates made by >>> Bartington. Anyway plenty of others . Geometrics? Peter Annan Chief >>> Executive Officer Sensors & Software Inc. 1040 Stacey Court, Mississauga, >>> Ontario, Canada L4W 2X8 [email protected] <[email protected]> | +1 905 624 >>> 8909 >>> www.sensoft.ca <http://www.sensoft.ca/index.html> This transmission may >>> contain PRIVILEGED OR CONFIDENTIAL INFORMATION. Unauthorized disclosure is >>> strictly prohibited. On 2 May 2019, at 5:17 am, Stephen Reford via >>> SEGMIN <[email protected] <[email protected]>> wrote: Here >>> is another one: http://www.shageophysics.com/heli-gt.html >>> <http://www.shageophysics.com/heli-gt.html> No doubt there are a few >>> other heliborne triaxial gradiometers out there. However, I see that >>> Sergio is asking for a ground triaxial gradiometer. From: SEGMIN >>> <[email protected] <[email protected]>> On >>> Behalf Of Pierre Bérubé via SEGMIN Sent: May 1, 2019 3:12 PM >>> To: [email protected] <[email protected]> Cc: Pierre Bérubé >>> <[email protected] <[email protected]>> Subject: Re: [SEGMIN] >>> full gradient mag surveys Never had any problems with these guys, they >>> should be able to deliver what you want. >>> https://www.facebook.com/Airborne-Geophysics-Eagle-K8aranda-Geophysics-133062360111477/about/ >>> <https://www.facebook.com/Airborne-Geophysics-Eagle-K8aranda-Geophysics-133062360111477/about/> >>> Pierre <image001.jpg> Pierre Bérubé, ing. / Eng. Président / >>> President _______________________________________________ >>> tel.: 1.819.874.8800 #201 fax: 1.819.874.8801 1740 chemin >>> Sullivan suite 1400, Val-d’Or (QC) Canada J9P 7H1 www.ageophysics.com >>> <http://www.ageophysics.com/> <image002.jpg> From: SEGMIN >>> <[email protected] <[email protected]>> On >>> Behalf Of S E Geoscience and Exploration via SEGMIN Sent: May 1, 2019 9:12 >>> AM To: [email protected] <[email protected]> Cc: S E >>> Geoscience and Exploration <[email protected] >>> <[email protected]>> Subject: [SEGMIN] full gradient >>> mag surveys Dear all, is there a ground geophysical contractor offering >>> full gradient mag surveys? (horizontal gradient perpendicular to profile >>> direction + vertical gradient). Thanks -- Sergio Espinosa, Ph.D., >>> P.Geo Director, Geophysics S E Geoscience & Exploration >>> ----------------------- SEGMIN community mailing list service >>> ([email protected] <[email protected]>). Change your personal >>> options >>> here: https://lists.geosoft.com/mailman/options/segmin/rogah%40tpg.com.au >>> <https://lists.geosoft.com/mailman/options/segmin/rogah%40tpg.com.au> >>> Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin >>> <https://lists.geosoft.com/mailman/listinfo/segmin> >>> Archives: https://lists.geosoft.com/mailman/private/segmin/ >>> <https://lists.geosoft.com/mailman/private/segmin/> NOTE that <Reply> will >>> reply to all members of the list. ----------------------- SEGMIN >>> community mailing list service ([email protected] >>> <[email protected]>). 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Change your personal >>> options here: >>> https://lists.geosoft.com/mailman/options/segmin/se.geoscience.and.exploration%40gmail.com >>> <https://lists.geosoft.com/mailman/options/segmin/se.geoscience.and.exploration%40gmail.com> >>> Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin >>> <https://lists.geosoft.com/mailman/listinfo/segmin> Archives: >>> https://lists.geosoft.com/mailman/private/segmin/ >>> <https://lists.geosoft.com/mailman/private/segmin/> NOTE that <Reply> will >>> reply to all members of the list. * >> >> >> >> >> *-- Sergio Espinosa, Ph.D., P.GeoDirector, GeophysicsS E Geoscience >> & Exploration* >> >> >> >> >> >> >> * ----------------------- SEGMIN community mailing list service >> ([email protected] <[email protected]>). Change your personal >> options here: >> https://lists.geosoft.com/mailman/options/segmin/ed.cunion%40gmail.com >> <https://lists.geosoft.com/mailman/options/segmin/ed.cunion%40gmail.com> >> Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin >> <https://lists.geosoft.com/mailman/listinfo/segmin> Archives: >> https://lists.geosoft.com/mailman/private/segmin/ >> <https://lists.geosoft.com/mailman/private/segmin/> NOTE that <Reply> will >> reply to all members of the list. * > > > > > > > > * ----------------------- SEGMIN community mailing list service > ([email protected] <[email protected]>). Change your personal > options here: > https://lists.geosoft.com/mailman/options/segmin/se.geoscience.and.exploration%40gmail.com > <https://lists.geosoft.com/mailman/options/segmin/se.geoscience.and.exploration%40gmail.com> > Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin > <https://lists.geosoft.com/mailman/listinfo/segmin> Archives: > https://lists.geosoft.com/mailman/private/segmin/ > <https://lists.geosoft.com/mailman/private/segmin/> NOTE that <Reply> will > reply to all members of the list. * *-- Sergio Espinosa, Ph.D., P.GeoDirector, GeophysicsS E Geoscience & Exploration*
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