Note on the Eureka earthquake of June 6, 1932^† Available to Purchase

A rediscussion of the observations of the Eureka earthquake of June 6, 1932, gives for the waves P_7.0 and P_7.4 the velocities 7.15±0.065 and 7.53±0.073 km/sec., respectively. The errors quoted are standard errors, not probable errors. On the assumptions of Sparks's paper the thicknesses of the upper (granitic) and second layers come out as 12.6±2.5 km. and 12.2±1.9 km., in fairly good agreement with the values 16 km. and 14 km. given in the paper. The uncertainties arise mainly from the uncertainties in the constant terms in the linear formulae for the travel times T_7.8, T′_7.8, T″_7.8. In one respect the assumptions made in the previous discussion lead to an inconsistency among the data, and the need for and the value of further studies along the lines of Sparks's examination of the Eureka earthquake are stressed.