The empirical Green’s function (egf) technique is frequently used to estimate the radiated seismic energy, ER, of an earthquake. An approximation of the moment-rate spectrum, 0(f), of the target earthquake is obtained from the ratio of the spectrum of the target earthquake to the spectrum of the egf earthquake, and the radiated seismic energy is computed by integrating graphic over frequency f. The choice of the upper limit of integration, fu, is critical. In this note we show that the optimum choice of fu for the ω2-source model is given by fu/fc1fc2/fc1, where fc1 and fc2 are the corner frequencies of the target and the egf earthquakes, respectively. This result provides a useful guide in the application of the egf technique to obtain a reliable estimate of the radiated seismic energy.

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