Abstract <p>A detailed study of the tsunami generated by the Moneron earthquake of September 5, 1971 (<i>M</i>_w 7.3) in the northern Sea of Japan was conducted. Records from 14 tide gauges located along the coasts of Sakhalin, Hokkaido, and Primorye were used, allowing us to refine the seismic source parameters and numerically simulate tsunami generation and propagation in the Strait of Tartary. Using a modified earthquake source allowed us to accurately reproduce the amplitude-frequency characteristics of sea level oscillations at most stations. Analysis revealed that discrepancies between the modeling results and in situ records are primarily due to technical features of the well tide gauges and inaccuracies in coastal bathymetry in the Strait of Tartary. The results clarify the geometry of the Moneron earthquake source and tsunami patterns in the northern Sea of Japan. The study is of great importance for reconstructing historical tsunamigenic events and assessing the potential tsunami hazard of coastal areas of the Russian Far East.</p>