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Title:: Spatial Distribution and Movement of Active Faults in Xiong'an New Area: Insights from Geochemical Soil Gas

作者:: 王江¹; 2; 陈志³; 张帆¹; 2; 张志相¹; 2; 刘兆飞³; 何鸿毅³; 唐杰¹; 2; 丁志华¹; 2; 张素欣¹; 2; (1.河北红山巨厚沉积与地震灾害国家野外科学观测研究站,河北邢台 054000; 2.河北省地震局,河北石家庄 050021; 3.中国地震局地震预测研究所地震预测重点实验室,北京 100036)

Author(s):: WANG Jiang¹; 2; CHEN Zhi³; ZHANG Fan¹; 2; ZHANG Zhixiang¹; 2; LIU Zhaofei³; HE Hongyi³; TANG Jie¹; 2; DING Zhihua¹; 2; ZHANG Suxin¹; 2; (1.Hebei Hongshan National Observatory on Thick Sediments and Seismic Hazards,Xingtai 054000,Hebei,China)(2.Hebei Earthquake Agency,Shijiazhuang 050021,Hebei,China)(3.Key Laboratory of Earthquake Prediction,Institute of Earthquake Forecasting,China Earthquake Administration,Beijing 100036,China)

Keywords:: Xiong'an New Area; soil gas; geochemistry; gas concentration; buried fault; fault activity

摘要:: 通过密集测点和跨断裂测线土壤气体地球化学野外流动观测,获取了雄安新区土壤气体Rn、CO₂和Hg浓度的区域背景场资料及跨断裂剖面分布特征。结合Q-Q图频率统计法和Kriging插值对雄安新区土壤气体地球化学背景进行综合分析发现,雄安新区断裂来源土壤气体Rn、CO₂和Hg的浓度高值呈串珠状聚集于牛东断裂、牛东分支断裂1、牛东分支断裂2、容城断裂和徐水—大城断裂沿线,表明这5条断裂可能是研究区较为活动的断裂带,根据气体浓度高值优势方向及城市活断层探测结果,进一步限定了各断裂的空间展布态势。各活动断裂不同段气体浓度相对强度的计算结果显示,新区断裂活动性由东南向西北方向递减,牛东分支断裂2的活动性最强,其Rn浓度相对强度高于首都圈地区的18条主要活动断裂。由于观测范围的局限性,各活动断裂不同段土壤气体浓度相对强度并无明显差异。

Abstract:: The geochemical observation of the soil gas in the fault zone is one of the most important means of detecting buried faults and analyzing fault activity.The spatial distribution of the concentration of soil gases Rn,CO₂,and Hg are obtained by field measurement at 542 equispaced points and on 6 profiles across 5 active faults in Xiong'an New Area.Clustered distribution of the soil gas Rn,CO₂,and Hg with high concentration along the Niudong fault,Branch 1 of the Niudong fault,Branch 2 of the Niudong fault,Rongcheng fault and Xushui-dacheng fault are presented in the geochemical background using Kriging interpolation.This indicates that the five faults are more active.The fault outlines are further delineated according to the distribution of the soil gas concentration and the results from urban active fault detection.In addition,the relative intensity of the soil gas concentration in the 5 active faults decreases from the southeast to the northwest in Xiong'an New Area,suggesting the weakening of faults' activity from the southeast to the northwest,and the Niudong fault in the southeast of Xiong'an New Area could be the most active; the relative-intensity value of Rn concentration in this fault is higher than those in the other 18 major active faults in the Capital area.There is little difference between the movement of the sections of the 5 active faults in Xiong'an New Area.