We investigate the trapping of oblique water-waves by horizontal cylinders in a two-layer liquid. Two cases depending on a small parameter are studied: first, the liquid densities are close to each other, and second, the density of the upper layer is small in comparison with that of the lower layer. We give sufficient conditions for wave trapping for appropriate limit problems. The main results involve asymptotic formulas for the surface and interfacial trapped mode frequencies. In addition, we prove comparison principles and sufficient conditions for the existence of trapped modes in various situations.

CEMAT - Center for Computational and Stochastic Mathematics