Due to the narrow width of continental rifts (30 – 50 km in the case of Rukwa Rift Basin), a 55 × 55 km window size was used in order to provide reliable estimates of the CPDs of less than 15 km. A 55 km window size is selected due to the fact that a window size greater than 55 km will incorporate anomalies from the neighbouring geological provinces, a contamination that may affects the basal depth estimation within the region/study area (Ross et al., 2006). As suggested by (Tanaka et al., 1999), a 50% overlap was used in each of the subregions/blocks in order to obtain a better lateral coverage and to minimize the ringing artefacts (fading signal) near the edges. The power spectrum of each block is computed using the fast Fourier transform (FFT) implemented in MAGMAP extension in Oasis Montaj software (Geosoft Inc., 2015), and a first-order trend is removed from each subregion/block, and grids are expanded by 10% in order to make the edges continuous.
The statistical error was calculated using the Linest Function in Excel based on the least squares best fit method (Chiozzi et al., 2005; Mousa et al., 2017).