A method which uses observed frequency spectral ratios of seismic plane waves for exploration of ore bodies is now available. The new method is based on the numerical solution of the response of a two-dimensional shallow structural anomaly to an upward-moving seismic wave from a distant earthquake or explosion. Finite-element analysis is used for both P- and S-waves. Solutions to the direct problem for bodies of arbitrary shape have not previously been available. Results in the time and frequency domains are discussed here for a salt ridge and for a massive sulfide body. For the inverse problem, interpretation using contours of spectral ratios along a surface profile is suggested.