Crustal Structure Beneath Botswana from Ambient Seismic Noise Tomography

Botswana is situated in central Southern Africa and is characterized by diverse geology, including prominent cratons such as the Congo and Kalahari cratons, as well as two sedimentary basins. Previous studies of the crustal structure beneath Botswana have primarily relied on traditional regional and teleseismic earthquake tomography. In this study, we use ambient seismic noise tomography to image the crustal structure of Botswana and its surrounding region. Using two years of seismic data (2019–2020) from 40 broadband stations including stations from the Botswana Seismological Network (BSN) and neighbouring regions, cross-correlation functions (CCFs) are computed and used to reconstruct surface waves propagating between station pairs. Dispersions of the surface waves are extracted and used in a 2-D inversion to produce Rayleigh-wave group velocity maps of the region. Here, we present results including 2-D group-velocity maps across multiple periods and 1-D inversion results in the form of shear-velocity depth profiles derived from the dispersion measurements. We discuss these results and their implications for imaging crustal structure in this region and for developing detailed 3-D velocity models of Botswana's crust, providing new insights into the region's subsurface structure and geodynamics.