Tectonics and seismicity of the Gulf of Aden: contributions of edge detection filters applied to potential field data

Abstract

Several studies have applied edge detection filters based on potential field derivatives, ratios and statistical-based tools to evaluate structures and provide interpretations. These edge filters provide different responses that may lead to false interpretations, making the selection of an effective filter that can provide optimum response difficult for users. Evaluating the reliability of the edge filters and avoiding false interpretations of the geologic structures requires simultaneous evaluation of filters applied to the same set of theoretical models. By using 2.5D models of gravity and magnetic synthetic data, we evaluate the performance of 21 edge detection filters based on different scenarios. The outcome of the various tests shows that filters of the third class give best results, with reference to the second and first class, and present good to moderate resolution in gravity and magnetic models. This comparison provides a means of inferring the tectono-structural styles, having generated multiple results from different filters and screening for artefacts (i.e., false impressions). Thereafter, we applied the edge enhancement filters to the magnetic and free-air gravity data of Aden Rift. Boundaries corresponding to seafloor spreading, divergent plate and transform faults were identified. The boundaries correlate well with the source locations of earthquakes at shallow depths. In addition to the dominant extensional tectonic regime, we suggest that the local fault system influenced by the Afar plume provides insights to the complex interaction between magmatic, sedimentary, and tectonic forces, shaping the geology of the Arabian-Nubian triple junction and contributes to the dynamics of the Gulf of Aden. The occurrence of earthquake activities along normal and transform fault zones which correlates with identified structural boundaries resulting from the application of edge detection filters provides a novel application to the study of rifting processes by multiple observation techniques.