Although hypocenters of earthquakes on the island of Hawaii are now routinely assigned to within 5 km, depth was a poorly determined parameter until the early 1960's. However, the 1950--1960 period was very active both in volcanic eruptions and large earthquakes. Source depths for the 12 largest Hawaiian earthquakes (Magnitude 6 or greater) since 1940 are estimated from the ratios of body and surface wave amplitudes recorded at Pasadena, California. Excitation functions for Rayleigh waves are calculated as a function of source depth for the two dominant periods in the Pasadena records, 8 s and 20 s. Theoretical body wave amplitudes are determined from synthetic seismograms. Calculated ratios are very sensitive to source depth; for example, amplitudes of 8 s Rayleigh waves diminish by a factor of 300 between depths of 10 km and 50 km. This a is much larger effect than the fault geometry, which we estimate to be a factor of 4 between representative focal mechanisms. Estimated depths for post-1960 earthquakes agree fairly well with the instrumental depths. In general, large earthquakes near the volcanic flanks and fault systems are shallow (≤20 km). Two earthquakes of magnitude 6 occurred under the volcanoes Mauna Loa (in 1950) and Kilauea (in 1951); they preceded major eruptions by 3 days and 14 months, respectively, and had the largest depth estimates at 40-55 km and 35-50 km. MS values assigned from global amplitudes are compared with those assigned from Pasadena amplitudes alone, for 70 events in 1973-1974 with 5.1≤MS≤6.0. The global values are only slightly larger (0.05 magnitude units) than the Pasadena values, indicating that Pasadena amplitudes are on the average representative of the event magnitude.