We explore the magnitude and slip distribution of the 1952 Kamchatka earthquake (Mw 8.8–9.0) using constraints from the 1952 Kamchatka tsunami. Our new field data provide more comprehensive coverage of the near-field tsunami than had been available to date. We examine the effects of internal slip distribution within complex earthquake ruptures on near-field tsunami runup and evaluate some of the limitations of this approach. Our approach compares tsunami-deposit distribution with simulated runup from tsunamis generated by different configurations of seafloor deformation from hypothetical earthquakes resembling that of the 1952 Kamchatka earthquake. We identify areas of high slip because different distributions of seafloor deformation result in variations in tsunami runup in the near field. Mapped deposits and local observations of the 1952 Kamchatka tsunami indicate that near-field runup in central Kamchatka was consistently less than 10 m (averaging 6 m), while south Kamchatka to the northern Kuril Islands had more variability and higher average runup (8 m runup in South Kamchatka and 10 m runup in the northern Kuril Islands). Our simulations show that in order to produce the distribution of runup indicated by tsunami deposits and historical observations, the 1952 earthquake had regions of high slip off the coast of southern Kamchatka, and the location of high slip is shallower in the subduction zone than previously interpreted.