Stacking for the frequencies and Qs of 0S0 and 1S0

Using nine IDA records for the Indonesian earthquake of 1977 August 19, we have formed an optimal linear combination of the records and have measured the frequency and Q</it> of <inf>0</inf>S</it><inf>0</inf> and <inf>1</inf>S</it><inf>0</inf>. The frequency was measured using the moment ratio method. The attenuation was measured by the minimum width method and by the time-lapse method. The frequency and attenuation were measured simultaneously by varying them to obtain a best fit to the data. A 2000-hr stack, the sum of nine individual records, for <inf>0</inf>S</it><inf>0</inf> gave a frequency of 0.814664 mHz±4 ppm. The values for the Q</it> of <inf>0</inf>S</it><inf>0</inf> for the three different methods of measurement were 5600,5833 and 5700, respectively. The error in the estimates of Q</it>-1 is about 5 per cent for the minimum power method. For <inf>1</inf>S</it><inf>0</inf> a 300-hr stack yielded a frequency of 1.63151 mHz±30 ppm. The values of Q</it> for this mode were 1960, 1800 and 1850, respectively, with an error in Q</it>-1 of about 12 per cent for the minimum power method.