Magnetic Inversion Method Example

Magnetic source depths or other parameters, can only be obtained at discrete locations above a suitable source (above the centre of narrow sources or over the edges of wide sources).  Furthermore, individual depth estimates, even from suitable anomalies, can easily be in error by 20% or more.  To map depth to basement, or depth to a magnetic source layer, it is necessary to interpolate sensibly between the depth solutions.  In many areas these solutions are sparse due to the scarcity of suitable anomalies.  FrOG Tech provides a superior and unique product in the interpretation of complete surfaces, incorporating structurally valid and consistent interpolation between depth estimates. 

Magnetic profiles can be modelled directly from survey line data, ship-track data or alternatively, the profile can be extracted from gridded magnetic data.  Modelling using the line data is preferred as the data has not been altered (or smoothed) during the gridding process.

Magnetic modelling based on geological cross-sections.

In the 2-dimensional example to the left, the top section indicates the match between the observed profile (Black: Mag) and modelled profile (Red: Mag_Mod). In order to produce a better fit between the observed and modelled results, the shape and magnetic properties of the bodies are progressively modified and iterated in ModelVision. A close curve match indicates a high quality model. The regional (Purple: Mag_Regional) is calculated as a second order polynomial from the data, and is kept flat in all the modelled profiles.

The bottom section presents a set of tabular model bodies, colour coded by susceptibility value with location and rock type based on published cross-sections.

All FrOG Tech magnetic models are built in 3-dimensional space and can be viewed and altered in cross-section, plan view and 3-dimensional formats.

Magnetic modelling in 3-dimensional view.Magnetic modelling in plan view.