The basic principles of surface wave dispersion have been known for decades.
Tomography. Sisprobe has developed techniques, and workflows to treat massive amounts of data recorded in month-long surveys by large surface arrays (100 to >2000 sensors). This produces 3D tomographic images of the subsurface.
Monitoring. By recording continuously for several months, or by making regular measurements, subtle changes in sub-surface stiffness and/or staturation can be detected. This allows Sisprobe to monitor the evolution of oil or gas reservoirs, weakness and leaks in dam walls, or changes during excavation of structures in urban settings (e.g. metro tunnels)
Both techniques have been successfully applied for imaging the crust (Shapiro et al. 2005) and monitoring fault zones (Brenguier et al. 2019a).
It also allows imaging and monitoring the subsurface for industrial applications including oil & gas (Chmiel et al, 2019; Brenguier et al, 2019b) mine safety (Olivier et al. 2015) and mineral exploration (Dales et al, 2020)