The major methods of measuring Q-value by the natural earthquakes are the ones of using the data of free vibration of earth, body wave, surface wave and coda.

利用天然地震波测量Q值的主要方法有：利用地球自由振荡资料、利用体波、利用面波和利用尾波来研究Q值。

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On the basis of the observational data, this paper also discusses the probable reasons causing the variation of the coda wave attenuation rate both before and after strong events.

由观测事实出发本文讨论了地震尾波衰减率在大地震前后发生变化的可能原因。

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