Spatial distribution of radon and thoron in the soil around active faults as a contribution to the elevated indoor radon

我们分析了在富根达克火山(U1)附近首次测量的数据。氡浓度低于预期，水平分布和垂直分布变化较小。因此，我们选择了另一个活动断裂点，在高山市(T1)附近具有不同的地质结构。用有源装置测量了土壤气体中氡(Rn)和钍(Tn)的浓度，以及氡析出率、土壤通透性和CO2。用HPGe探测器对采集的土壤样品中的Ra和Th进行了测定。测定了土样的容重和孔隙度。利用地球物理方法，结合标准岩土工程圆锥贯入仪，识别该地区的地质构造和土体特征，并确定预测的断层位置和路线。获得的数据被准备作为氡扩散-对流传输模型的输入。

We analysed the data from the first measurements taken near the Fugendake volcano (U1). The radon concentration was lower than expected with low variation of horizonal nor vertical distribution. We therefore chose another active fault site, with a different geological structure near Takayama city (T1). Radon (Rn) and thoron (Tn) concentrations in soil gas with an active device together with radon exhalation rate, soil permeability and CO2 were measured. Measurements of Ra and Th in the collected soil samples were carried out using HPGe detector. Bulk density and porosity of soil samples were determined. Geophysical methods combined with the standard geotechnical cone penetrometer were used to recognize the geological structure and soil characteristics of the area and locate the predicted faults positions and routes. Obtained data were prepared as an input for the radon diffusion-convection transport model.