Application of surface-wave tomography to mineral exploration: a case study from Siilinjärvi, Finland

In order to assess the feasibility and validity of surface-wave tomography as a toolfor mineral exploration, we present an active seismic three-dimensional case studyfrom the Siilinj ̈arvi mine in Eastern Finland. The aim of the survey is to identify theformation carrying the mineralization in an area south of the main pit, which will bemined in the future. Before acquiring the data, we performed an accurate survey designto maximize data coverage and minimize the time for deployment and recollectionof the equipment. We extract path-averaged Rayleigh-wave phase-velocity dispersioncurves by means of a two-station method. We invert them using a computationallyefficient tomographic code which does not require the computation of phase-velocitymaps and inverts directly for one-dimensional S-wave velocity models. The retrievedvelocities are in good agreement with the data from a borehole in the vicinity, and thepseudo three–dimensional S-wave velocity volume allows us to identify the geologicalcontact between the formation hosting most of the mineralization and the surroundingrock. We conclude that the proposed method is a valid tool, given the small amountof equipment used and the acceptable amount of time required to process the data.