Magnetics Processing/Enhancement Example

Examples of various magnetic enhancements from the Clarence-Morton Basin, NSW, Australia. To read the full report from which these images have been taken go to NSW DPI.

Levelling

Reprocessing the TMI and RTP grids has significantly improved the data levelling problem, evident by comparing the FrOG Tech reproduced TMI grid (right) with the original TMI grid (left).

Standard Filters

1VD of RTP after 50m Upward ContinuationThe first vertical derivative filter enhances near surface contrasts in magnetization.  The 1VD measures the rate at which field intensity varies with elevation. Shallow sources produce high amplitude vertical gradients, where deeper sources produce weaker vertical gradients.  Therefore, near surface features such as volcanics and intrasedimentary structures, as well as culture and geology noise are enhanced in this process. A 50m upward continuation filter has been used in order to reduce the high frequency noise level.

AS of RTP after 50m Upward ContinuationThe analytic signal calculates the total amplitude of the three directional derivatives (in EW, NS and vertical directions) of RTP.This enhancement filter highlights sources with a high magnetic susceptibility for remanent magnetic fields as well as induced magnetic fields.The amplitude of the filtered anomalies are all positive.The quiet or low amplitude values indicate areas with low magnetic susceptibility sources, or no sources.The high amplitude anomalies indicate the areas with strong magnetic strength bodies (either high susceptibility or high remanent magnetization sources).An upward continuation filter of 50m has been used in order to reduce the high frequency noise level.

Tilt Filter of RTP after 50m Upward Continuation

The tilt filter is defined as the arctangent of the ratio of the vertical derivative to the horizontal gradient magnitude of the field.  For isolated sources, the tilt angle is positive over the source, crosses through zero at or near the edge of a vertical sided source, and is negative outside the source region.  The tilt angle filter is excellent for highlighting structure in magnetic data.  It responds equally well to shallow and deep sources. An upward continuation filter of 50m has been used in order to reduce the high frequency noise level.

FrOG Tech proprietary Filters

Edgezone of RTP after 50m Upward ContinuationThe Edgezone filter is a FrOG Tech proprietary filter. It  was developed to increase the sharpness of anomalies used to map the edge of magnetic bodies.  The filter has compressed the amplitude range and responds equally well to shallow and deep sources.  The filter  provides significant curved lines which indicate source boundaries. An upward continuation filter of 50m has been used in order to reduce the high frequency noise level.

Block Filter of RTP after 50m Upward ContinuationThe Block filter is a FrOG Tech proprietary filter. It has the effect of transforming the magnetic data into “zones”, that segregate anomalous zones into apparent lithological categories.  The filter produces sharp edges and the amplitudes of original anomalies have been normalised and compressed into a reduced range. An upward continuation of 1km filter has been used in order to reduce the high frequency noise level. An upward continuation filter of 50m has been used in order to reduce the high frequency noise level.

FrOG Tech has many other proprietary filters. To find out how FrOG Tech can help you contact us.