Interpolation artifacts as a result of spatial aliasing: A case study of the airborne magnetic data set of southeastern Minas Gerais, Brazil

Abstract

<jats:p> Linear features at an acute angle with the flight direction are imaged as a series of aligned circular anomalies in the images of the Area 15 aeromagnetic survey, which covered part of the Brazilian southeastern region. These features are interpolation artifacts, a recurring problem found in airborne magnetic images that cause problems for qualitative and quantitative geophysical-geological interpretation. This imaging problem is attributed to spatial aliasing. By running simulations of magnetic data on a synthetic model, we physically proved that the interpolation artifacts from Area 15 are due to inappropriate survey design. Besides the most common expression of artifacts, we described a geologically non-coherent linear pattern as a new type of artifact. Supported by spectral analyses we shown that Area 15 aliased spectrum is similar to geological high-frequency magnetic features, which constitutes a motive for unearthing the correct geophysical signal. Thus, we made use of four techniques for removing the artifacts. The trend enforcement method was able to partially improve the images, while the inverse interpolation method was ineffective, apparently because Area 15 data are severely aliased. Both constrained coherence diffusion and multi-trend gridding methods were able to significantly reduce the presence of artifacts. Despite the high-frequency attenuation, these tools adequately enhanced the magnetic trends and minimized the artifacts. Therefore, the improved images are better suited for a reliable geological interpretation. </jats:p>

Sizing the carbon sink associated with Posidonia oceanica seagrass meadows using very high-resolution seismic reflection imaging

“…5c). Indeed, to increase the reliability of the estimation, additional ground-truthing or control points are needed to improve azimuthal control and perform accurate interpolation (Grohmann and Steiner, 2008;Morlighem et al, 2014;Majdanski, 2012;Fonte-Boa et al, 2020). Nevertheless, the vertical thickness of these deposits resulting from seismic data or spatial interpolation appeared to be highly consistent with values recorded throughout the Mediterranean (Molinier and Picard, 1952;Lo Iacono et al, 2008;Serrano et al, 2012Serrano et al, , 2014Serrano et al, , 2016a.…”

A multi‐parameter approach for recognition of anthropogenic noise in aeromagnetic data collected over populated areas: Erzgebirge, Germany

“…If not carefully monitored, this can lead to inappropriate interpretation of some features as anthropogenic 'source' anomalies, when in reality, they are a consequence of the gridding algorithm. Localized domes and basins are common artefacts produced by the standard minimum curvature gridding algorithm (Fonte-Boa et al, 2020). For this study, we used a 25 m grid cell for 100 m line spacing data, which represents the upper limit of commonly acceptable gridding practice.…”

“…This is a common problem with gridding algorithms like minimum curvature: they are not able to resolve elongated trends that are at an acute angle to the flight path, and thus produce several high-amplitude small circular features along this (usually geological) trend. As a result, we could end with a situation where the total field grid and associated sub-products show high amplitude, circular features of a size just under the survey line spacing, and therefore would resemble anthropogenic noise (Fonte-Boa et al, 2020). The multi-parameter approach we used in this study is based on the analysis of gridded data using a standard minimum curvature gridding algorithm.…”