Greg, I only have Grids (X, Y) of AppCond for the five pairs of frequency/geometry.
Regards On Sat, Nov 21, 2020 at 4:41 PM Greg Hodges <[email protected]> wrote: > I presume that is homogeneous-halfspace apparent resistivity. As long as > they didn't heavily filter it (and it is likely they did) then you can > forward model the apparent resistivity and height to get in-phase and > quadrature, subtract the host I and Q (assuming it is significant) and then > invert anomalies for a plate model. Rough, but better than nothing. > > Is there an apparent depth channel? That would indicate a pseudo-layer > (i.e. phase-amplitude) resistivity model, which would be better than an > amplitude-altitude model. If there is an apparent depth, add it to the > measured altitude when you forward model the apparent resistivity to I and > Q and it will do a better job of accommodating surface layers and/or > altitude error. > > I'd be interested to know if EMIT includes apparent resistivity forward > modeling in frequency domain. (Don't tell them I said this, but them > Australians don't do FDEM very well! [image: Emoji]) > > Greg Hodges > > > On Saturday, November 21, 2020, 03:08:00 p.m. EST, S E Geoscience and > Exploration <[email protected]> wrote: > > > Thank you, Greg. > > I should have asked that question in more simple words: I am working with > a dataset (5 frequency Hummingbird system) which contains only the > calculated apparent resistivity. Measured amplitudes (In-Phase and > Quadrature) are missing. Would that be enough to do plate (forward) > modeling? I guess it is. > > Perhaps it is best to contact EMIT to get an evaluation license. > > Regards > > On Sat, Nov 21, 2020 at 2:08 PM Greg Hodges <[email protected]> wrote: > > Hi, Sergio. > I'm not sure I understand the question - or the problem - so maybe others > don't either. > > If you're inverting (FDEM), the input is in-phase and quadrature > (normally) and apparent conductance (conductivity-thickness product, or > CTP) is a product along with the other plate parameters. > > If you're forward modeling, the conductivity is an input as part of the > CTP, and the EM response is the product, or output. From that EM we can > estimate a CTP (and then assign a thickness to get conductivity), but that > derived CTP depends on the plate model used. Changes in the size of the > plate (particularly the minimum dimension) change the phase angle (or decay > constant in TDEM) and therefore the estimated apparent CTP and > conductivity. > > Of course, when forward modeling you can use the size of the model plate > in your calculation of apparent conductance, but then you should get back > the initial model conductance (in the absence of other interfering factors, > like host response). > > So, what kind of model are you running, and what are you trying to get out > of it? > > Greg Hodges > > > On Friday, November 20, 2020, 05:17:12 p.m. EST, S E Geoscience and > Exploration via SEGMIN <[email protected]> wrote: > > > Re: Question about plate modeling with Maxwell > > Dear all, > > It has been a while since I worked last with Maxwell. > > Do you know whether we can model plates with just the calculated apparent > conductivity and without the in-phase and quadrature amplitudes? > > Regards > > -- > *Sergio Espinosa, Ph.D., P.Geo* > Director, Geophysics > *S E G*eoscience & *Ex*ploration > ----------------------- > SEGMIN community mailing list service ([email protected]). > Change your personal options here: > https://lists.geosoft.com/mailman/options/segmin/hodgesgreg%40ymail.com > Colleagues can join here: > https://lists.geosoft.com/mailman/listinfo/segmin > Archives: https://lists.geosoft.com/mailman/private/segmin/ > NOTE that <Reply> will reply to all members of the list. > > > > -- > *Sergio Espinosa, Ph.D., P.Geo* > Director, Geophysics > *S E G*eoscience & *Ex*ploration > -- *Sergio Espinosa, Ph.D., P.Geo* Director, Geophysics *S E G*eoscience & *Ex*ploration
----------------------- SEGMIN community mailing list service ([email protected]). Change your personal options here: https://lists.geosoft.com/mailman/options/segmin/archive%40mail-archive.com Colleagues can join here: https://lists.geosoft.com/mailman/listinfo/segmin Archives: https://lists.geosoft.com/mailman/private/segmin/ NOTE that <Reply> will reply to all members of the list.
