We consider either an acoustic or an elastic wave with complex frequency incident on a plane crack of arbitrary shape in a three-dimensional space. Then we apply the variational boundary equation method to develop a numerical algorithm calculating the resonance poles in the scattering problem. Several tests are made in order to obtain a relation between these poles and the peaks of the scattering cross-section produced by incident waves with real frequencies.

CEMAT - Center for Computational and Stochastic Mathematics