The source spectrum of small-moderate earthquake can be represented by theoretical "Brune" model, the geometric attenuation factor of whole path can be represented by three-segment geometric model.
中小地震的震源谱可以用“布龙”理论模型表示，传播路径中的几何衰减因子可以用三段几何衰减模型表示。
The spectrum of small shocks also changed obviously before and after the Datong earthquake.
大同地震前后小震波谱有明显变化。
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