Abstract Primary and secondary microseisms are generated by ocean wave interactions, with the latter occasionally split into short‐ and long‐period bands in some regions. The short‐period secondary microseism (SPSM) sources have traditionally been associated with nearby coastal segments, suggesting a more uniform distribution across shorelines. Here, we challenge this assumption by combining polarization analysis, source mechanism modeling and attenuation assessment in the Mediterranean Sea. This region offers an optimal setting, as we reveal that the primary and long‐period secondary microseisms originate in the North Atlantic Ocean, whereas the SPSM arise within the Mediterranean Sea, allowing these sources to be clearly isolated. We find that SPSM sources are well‐constrained, spatially localized and highly dynamic. Our results reveal that bathymetry strongly controls the spatial distribution of these sources.