Seismo-acoustic signatures of the shallow-entry Nqweba meteorite fall of 25 August 2024, Eastern Cape, South Africa

On 25 August 2024 (08:51 local time), a bright fireball was observed across the southwestern coastal region of the Eastern Cape Province, South Africa, and was linked to a confirmed meteorite fall near Nqweba. The meteoroid, estimated by NASA’s Center for Near-Earth Object Studies (CNEOS) to be ~1 m in diameter with an entry speed of 20.1 km.s-1, an energy release equivalent to 92 tons of TNT, and a disruption altitude of 38.2 km, produced visual and acoustic signatures detectable over hundreds of kilometres. We have analysed records from one infrasound station (I47ZA) and three seismic stations (SVILL, BUFB, and BFKLF) to characterise atmospheric and ground-coupled signals from the event. Infrasound data show multiple clearly separated arrivals generated by distinct acoustic sources, corresponding to ballistic shockwaves associated with the Mach cone and fragmentation episodes, with backazimuth variations consistent with a near-linear, approximately constant-velocity trajectory, in agreement with video observations. Seismic recordings likewise exhibit source-dependent variability, confirming both direct airwave coupling and ground-coupled Rayleigh waves, with the strongest and most complex signals at SVILL reflecting a shallow entry angle and station proximity to the trajectory. In contrast, weaker and simpler signals at BUFB and BFKLF highlight the influence of local geology on the meteoroid-generated seismic signal. Despite limited station coverage, the combined infrasound and seismic observations constrain the timing, geometry, and source characteristics of the event and demonstrate the value of integrated seismo-acoustic monitoring for characterising meteoroid atmospheric entries and meteorite falls.