Full-waveform inversion

Full waveform inversion (FWI) methods are among the most recent techniques for geotechnical site characterization, and are still under continuous development. The method is fairly general, and is capable of imaging the arbitrarily heterogeneous compressional and shear wave velocity profiles of the soil.^[1]

Elastic waves are used to probe the site under investigation, by placing seismic vibrators on the ground surface. These waves propagate through the soil, and due to the heterogeneous geological structure of the site under investigation, multiple reflections and refractions occur. The response of the site to the seismic vibrator is measured by sensors (geophones), also placed on the ground surface. Two key-components are required for the profiling based on full-waveform inversion. These components are: a) a computer model for the simulation of elastic waves in semi-infinite domains;^[2] and b) an optimization framework, through which the computed response is matched to the measured response, via iteratively updating an initially assumed material distribution for the soil.

References

↑ Kallivokas, L.F.; Fathi, A.; Kucukcoban, S.; Stokoe II, K.H.; Bielak, J.; Ghattas, O. (2013). "Site characterization using full waveform inversion". Soil Dynamics and Earthquake Engineering 47: 62–82. doi:10.1016/j.soildyn.2012.12.012.
↑ Fathi, Arash; Poursartip, Babak; Kallivokas, Loukas (2015). "Time‐domain hybrid formulations for wave simulations in three‐dimensional PML‐truncated heterogeneous media". International Journal for Numerical Methods in Engineering 101: 165–198. doi:10.1002/nme.4780.