Continental rifts commonly develop in orogenic belts and avoid cratons as cratonic crust agedness and cooler geotherms inhibit strain localization. Recent earthquakes in Eastern Botswana unveil an active incipient rift zone within the Kalahari Craton featuring ~80-km long fault scarps of the Khurutshe Graben. Here, we investigate the rift structure, syn-rift stratigraphic architecture and long-term evolution, to understand the timing and rift initiation mechanisms. We utilize 2-D DC-resistivity imaging, borehole logs, and field observations in excavations of the Khurutshe Fault (KF) scarps to delineate its fine-scale structure and relationships with subsurface stratigraphy. Borehole-constrained resistivity tomography reveals four geoelectrical layers: a shallow ~10-m thick resistive wedge unit representing the Holocene Kalahari Formation which thickens towards and terminates on the KF, overlying ~100-m thick highly-discontinuous moderate-to-very high resistivity Jurassic (Karoo) basalts and siliciclastics which also thicken towards the KF, and basal highly-resistive Precambrian crystalline basement. Borehole isopach maps confirm a ubiquitous pattern of stratigraphic thickening on the KF hanging walls. Excavations of the fault zone reveal highly cemented Karoo sandstones hosting slickensided calcite-altered slip surfaces. These observations indicate: 1) concurrent fluid-involved normal faulting with syn-tectonic deposition of the Jurassic sequences, providing for the first time, evidence of Karoo extension in southeast Botswana, and 2) that the Phanerozoic cratonic rift initiation was first accommodated by magmatic diking and normal faulting. We propose that this ancient, failed rift zone constitutes a mechanical weakness in the cratonic lithosphere that is now being reactivated again by the lithospheric buoyancy tectonic forces of the African Superplume.