A comparison between long-period Q models and those derived from short-period data
Rahman, Kamarudin Abdul
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The Q-depth relation in the earth's mantle has been estimated for short period P waves from a Southern Alaskan earthquake and a Novaya Zemlya nuclear explosion. The power spectra of P waves obtained from a network of 17 stations have been used to measure the effects of attenuation over the whole mantle. These power spectra were computed using the Maximum Likelihood Method (MLM). Estimating a Q model on the basis of power spectra ratios between these stations has been unsuccessful. However, an indirect method was successful in which the short- period t* (travel time/quality factor Q) from the stations is obtained and compared to the t* values from an existing Q model. The probable Q models obtained are consistent with a high-Q upper and middle mantle, and a low Q region near the core-mantle boundary. The short-period Q values are much higher than Q values at longer periods. The result of this investigation suggests that Q increases with frequency.