Presentation_Amplitude of the magnetic anomaly vector in low latitudes via equivalent layer.pdf (5.6 MB)
Presentation: Amplitude of the magnetic anomaly vector in low latitudes via equivalent layer.pdf
presentation
posted on 2019-09-25, 13:18 authored by Shayane GonzalezShayane Gonzalez, Valeria C. F. BarbosaValeria C. F. Barbosa, Felipe F. MeloFelipe F. Melo, Vanderlei C. Oliveira Jr.Vanderlei C. Oliveira Jr.Slides for the oral presentation given at the Sixteenth International Congress of the Brazilian Geophysical Society.
"The interpretation of total-field anomalies data presents
complexities due to dipolar characteristics of the
anomalies. Usually, the geophysicists apply some
transformations to the measured total-field anomaly to
assist the magnetic interpretation and inversion. However,
it can lead to an unstable transformed data at low latitude
regions. To transform the total-field anomaly into the
amplitude of the magnetic anomaly vector, we can use
the equivalent layer technique and the Fourier filtering.
These two methods are applied to synthetic magnetic
data simulated at high- and low-magnetic latitudes. At
high latitude, the computed amplitude of the magnetic
anomaly vector either by applying the Fourier filtering or
by employing the equivalent layer technique is equal to
the true one. However, at low latitudes, the computed
amplitude of the magnetic anomaly vector differs from the
true one either by applying the Fourier filtering or by
employing the equivalent layer technique. Both computed
amplitudes of the magnetic anomaly vector exhibit
striations in the direction of declination at low latitudes.
However, at low latitudes, the magnitudes of the
differences between the true and the computed amplitude
of the magnetic anomaly vector produced by employing
the equivalent layer technique are substantially smaller
than the ones produced by applying the Fourier filtering.
The better result produced by the equivalent layer
technique is because the stabilization imposed by the
Tikhonov regularization. We also applied the equivalent
layer technique and the Fourier filtering to real total-field
anomaly at a low latitude region encompassing the
Central Amazonian Province and the Carajás Mineral
Province, Brazil, aiming at computing the amplitude of the
magnetic anomaly vector. Likewise, both transformations
exhibit undesirable striations; however the one obtained
via the equivalent layer technique yields better result in
comparison with those obtained via the Fourier filtering."
complexities due to dipolar characteristics of the
anomalies. Usually, the geophysicists apply some
transformations to the measured total-field anomaly to
assist the magnetic interpretation and inversion. However,
it can lead to an unstable transformed data at low latitude
regions. To transform the total-field anomaly into the
amplitude of the magnetic anomaly vector, we can use
the equivalent layer technique and the Fourier filtering.
These two methods are applied to synthetic magnetic
data simulated at high- and low-magnetic latitudes. At
high latitude, the computed amplitude of the magnetic
anomaly vector either by applying the Fourier filtering or
by employing the equivalent layer technique is equal to
the true one. However, at low latitudes, the computed
amplitude of the magnetic anomaly vector differs from the
true one either by applying the Fourier filtering or by
employing the equivalent layer technique. Both computed
amplitudes of the magnetic anomaly vector exhibit
striations in the direction of declination at low latitudes.
However, at low latitudes, the magnitudes of the
differences between the true and the computed amplitude
of the magnetic anomaly vector produced by employing
the equivalent layer technique are substantially smaller
than the ones produced by applying the Fourier filtering.
The better result produced by the equivalent layer
technique is because the stabilization imposed by the
Tikhonov regularization. We also applied the equivalent
layer technique and the Fourier filtering to real total-field
anomaly at a low latitude region encompassing the
Central Amazonian Province and the Carajás Mineral
Province, Brazil, aiming at computing the amplitude of the
magnetic anomaly vector. Likewise, both transformations
exhibit undesirable striations; however the one obtained
via the equivalent layer technique yields better result in
comparison with those obtained via the Fourier filtering."
