GNGTS 2023 - Atti del 41° Convegno Nazionale

Session 3.3 ______ ___ GNGTS 2023 We can see in Figure 2 that both straight-ray and curved-ray SWT have reconstructed the location and the value of the high-velocity anomaly accurately. The model from the curved-ray method is slightly better at the vicinity of the high-velocity anomaly (Figures 2d and 2f). The low-velocity anomaly has been modelled better by the curved-ray approach (Figure 2e). From the quantitative point of view, the curved-ray method has slightly decreased the model misfit but at the cost of tripling the computational time. Even though the final model misfit is slightly lower (0.14 %) in the curved-ray approach, not only has the run time increased, also the memory has increased by 35 %. Conclusions We have shown that SWT can be used successfully to build VS models in complex near-surface structures. We evaluated the straight-ray and curved-ray SWT approaches in a 3D numerical example and showed that they produced similar results. The obtained model from curved-ray SWT has improved the accuracy but it has considerably increased the computational cost. Figure 1. True VS model. (a) 3D view of the model together with the acquisition geometry. The red arrows and letters represent the location of 2D slices in subplots (b-d). (b) Horizontal slice at 2.5 m depth, (c) vertical slice at Y=18 m, (d) vertical slice at X=18 m. The boundaries of the low- and high-velocity anomalies are superimposed in blue and red, respectively. (Karimpour et al., 2022).