<p>Surface wave amplification in sedimentary basins arises from a combination of geometric effects and source characteristics. However, the relative contributions of source depth, radiation pattern, and basin configuration to surface wave development remain incompletely understood. In this study, the influence of source depth and focal mechanism on surface wave development is examined through high-resolution three-dimensional numerical simulations. Surface waves are extracted from the computed ground motions using the Normalized Inner Product (NIP) method, which enables single-station identification and characterization in terms of polarization amplitude, central frequency, and azimuth. A range of basin geometries and sediment shear-wave velocities is considered. The results indicate that shallow sources with low incidence angles tend to generate stronger, lower-frequency surface waves concentrated near basin edges, while deeper sources lead to more symmetric amplification patterns. The radiation characteristics of the source influence the spatial distribution of wave energy and the orientation of motion, particularly in relation to basin boundaries. Surface responses across the basin are analyzed using a directional zoning framework, allowing for systematic comparison across models. The findings demonstrate that both the depth and orientation of the seismic source, together with the mechanical properties and geometry of the basin, significantly affect the nature and spatial variability of surface wave amplification.</p>