Yasuoka Y, Shinogi M
Health Phys. 1997 May;72(5):759-61. doi: 10.1097/00004032-199705000-00012.
Clear seismic-related anomalies in the radon (222Rn) concentration of the atmosphere were observed prior to the Kobe earthquake (magnitude 7.2) on 17 January 1995. The radon anomalies were observed at a monitoring station in Kobe, which is located about 20 km away from the epicenter. The means of radon concentration in the atmosphere for each day were calculated using the data observed between April 1984 and March 1994, in order to obtain the normal radon variation. The difference between the smoothed radon concentration and the smoothed mean radon concentration is the residual value. Using the weekly averages of residual values in the historical period, the weekly residual value in the validation period were predicted. The historical period was from April 1984 to March 1994. The validation period was from April 1994 to January 1996. The seismic-related radon anomaly higher than the 99% confidence limit of the residual value of radon concentration in the atmosphere was observed beginning about 2 mo before the earthquake.
1995年1月17日神户地震（7.2级）之前，观测到大气中氡（222Rn）浓度存在与地震相关的明显异常。在距离震中约20公里的神户一个监测站观测到了氡异常。利用1984年4月至1994年3月期间观测的数据计算出每天大气中氡浓度的平均值，以获得正常的氡变化情况。平滑后的氡浓度与平滑后的平均氡浓度之差即为残差值。利用历史时期残差值的周平均值，预测验证期的周残差值。历史时期为1984年4月至1994年3月。验证期为1994年4月至1996年1月。在地震前约2个月开始观测到与地震相关的氡异常，其高于大气中氡浓度残差值的99%置信限。
