图35  共和7.0级地震前西宁水氡异常曲线

      （a）月均值曲线；（b）日测值指数窗速率曲线

Fig. 35  Curves of radon amomalies in groundwater before the M7.0

         Gonghe earthquake at Xining station

        （a）Curve of monthly mean value；

        （b）Velocity curve of daily observation exponential window