Static estimation of surface-wave tomography: a case study from Siilinjärvi, Finland

In this study, seismic surface wave (SW) tomography, usually applied at global or regional scale in global sesismology studies, is customized to be applied to 2D seismic exploration active data. The aim is to assess the feasibility of SW tomography for the estimation of near surface velocity model to be used for static correction of seismic reflection data for mineral exploration. The method is applied to a 2D seismic line acquired at the Siilinjarvi mine in Finland in the framework of the H2020 project Smart Exploration. The workflow starts by extracting path-averaged dispersion curves (DCs). The dispersion curves are picked by using two-station method. The picked path-averaged DCs are then inverted in a tomographic freamework to estimate 2D VS models. The 2D VS model are then transformed into the time-average VS (VSz) and the VSz is transformed into time average VP(VPz) by using apparent Poisson’s ratio values. The last step of the workflow is to calculate static shifts at each receiver position in term of one-way travel time at a given datum depth. Surface waves have good potential to be used directly from the exploration data and can be used to calculate statics, without any additional costs. The reliability of the result of tomography is checked by comparing the 2D VS model and inversion of VP estimation with the results obtained by other methods and by assessing the effect of the estimated velocity model during static application. SW tomography results to be an effective method for obtaining statics at mining exploration sites, typically characterized by high near-surface variability.