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本文运用活动断裂剖面上的土壤氡气浓度测量,对大成都地区断裂的位置、范围和活动性进行监测,监测结果表明汶川地震对大成都地区断裂带有较大的影响。通过对北川断裂虹口剖面、彭灌断裂小渔洞剖面、彭灌断裂中坝剖面、彭灌断裂白鹿剖面以及新津-蒲江断裂剖面进行监测,从测量结果分析可知:断裂剖面土壤氡浓度背景高于无断裂带地区,且受地震影响较大,距汶川地震震中越近,断裂剖面土壤氡浓度值越高;断裂剖面氡浓度异常阈值与背景值之比均不大于3,最大值与背景值之比均小于5。结合测量地点的地形、表层土壤结构等地质条件,对大成都地区震后活动断裂的相对活动性的强弱进行科学评价,认为目前大成都地区并无活动性极强的断裂,且北川断裂与新津-蒲江断裂的活动性高于彭灌断裂。
In this paper, the location, range and activity of the fault in the Chengdu area are monitored by radon concentration measurement in the active fracture profile. The monitoring results show that the Wenchuan earthquake has a great influence on the fault area in the Greater Chengdu area. By analyzing the Hongkou section of Beichuan fault, the Xiaoyu cave profile of Peng irrigation fault, the dam profile of Peng irrigation fault, the Bailu profile of Peng irrigation fault and the Xinjin-Pujiang fault profile, it can be known from the measurement results that the radon background concentration in the soil profile is high In the area without fault zone, and affected by the earthquake, the closer to the epicenter of the Wenchuan earthquake, the higher the soil radon concentration in the fracture profile; the ratio of the anomalous threshold to the background value of radon concentration in the fracture section is no more than 3, and the maximum and background values The ratio of less than 5. According to the topography, topsoil structure and other geologic conditions at the measurement site, the paper makes a scientific assessment of the relative activity of active faults in the Greater Chengdu area after the quake. It is concluded that there is no active highly active fault in the large Chengdu area, and the Beichuan fault The Xinjin-Pujiang fault is more active than the Peng-Guan fault.