Near-Surface Explosion Localization in a Built Environment Using Ground-Coupled Airwaves

The preservation of target signatures over long distances can be effectively achieved using low-frequency seismic and acoustic sensing. Seismic sensing minimizes clutter caused by the multipath environment often experienced by acoustic waves in urban areas. While subsurface features such as basements, sewers, and building foundations may clutter the environment, they do not create multipath conditions for seismic waves, which primarily propagate through solid ground. This results in less pronounced scattering and reflections compared to airborne acoustic waves from above-ground structures Sheriff et al. 1995. Furthermore, seismic waves have longer wavelengths relative to many subsurface features, making them less sensitive to small-scale clutter, unlike acoustic waves, which are more easily scattered by similar-sized objects Aki et al. 2002, Aki et al. 2003. This study investigates seismic signatures from an airborne near-surface detonation of an explosive charge in a complex environment using an array of seismic sensors. We aim to accurately estimate the explosion's location amid various clutter signatures. We recorded both seismic waves and ground-coupled airwaves, with the seismic waves arriving earlier. By employing filtering and least-square estimation techniques, we located the explosion source with an average error of ±25 meters and determined the average velocity of the ground-coupled airwaves to be 342 m/s. These findings highlight the effectiveness of seismic sensing in locating airborne explosion sources within urban environments. Future work could optimize sensor placement and explore advanced signal processing methods or integrate data from multiple sensor types to further improve precision.