Long-lasting patterns of radon in groundwater at Panzhihua, China: Results from DFA, fractal dimensions and residual radon concentration
Long-lasting patterns of radon in groundwater at Panzhihua, China: Results from DFA, fractal dimensions and residual radon concentration
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中国攀枝花地下水氡的持久模式：DFA、分形维数和残余氡浓度的结果
DOI：
10.2343/geochemj.2.0571
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发表时间：
2019-01-01
影响因子：
0.8
通讯作者：
Nikolopoulos, Dimitrios
中科院分区：
文献类型：
--
作者：
Alam, Aftab;Wang, Nanping;Nikolopoulos, Dimitrios
本文报道了2012年至2017年间四川攀枝花中国地下水中氡(Rn-222)变化所隐藏的混沌和长记忆趋势。分析使用了滑动窗口(A)去趋势波动分析(DFA)，(B)Higuchi，Katz和Sevcik方法的分维分析和(C)残余氡浓度(RRC)。发现了几个具有高可预测性的分数布朗运动(FBM)持续时间序列段，DFA斜率高于1.5，而分维低于1.5。许多七天分段显示RRC超出了+/-2西格玛限制，具有值得注意的前兆价值。通过一种新的两阶段计算方法，将持续的震前FBM地震足迹段与低可预测性段分开。发现了几个具有分形性和长记忆性的动力学复杂性的组合片段。对于这些区段，试图将研究期间发生在中国和邻近国家边境地区的6级大地震与之联系起来。在这一时期的17次地震中，有4次地震是通过所有方法的组合来识别的，而其余的地震至少是通过三种方法的组合来识别的。对长记忆的发展趋势进行了识别和讨论。这一发现与地震发生的分形学和SOC末期相一致。最后对潜在的地质源进行了讨论和分析。
This paper reports chaos and long-memory trends hidden in radon (Rn-222) variations in the groundwater of Panzhihua, Sichuan Province, China, between 2012 and 2017. The analysis is performed using sliding-window (a) detrended fluctuation analysis (DFA), (b) fractal dimension analysis with the methods of Higuchi, Katz and Sevcik and (c) residual radon concentration (RRC). Several fractional Brownian motion (fBm) persistent time series segments of high predictability are found, with DFA slopes above 1.5 and fractal dimensions, below 1.5. Numerous seven-day segments exhibit RRC out of the +/- 2 sigma limits and are of noteworthy precursory value. Through a novel two-stage computational approach, the persistent pre-seismic fBm earthquake footprint segments are separated from the low-predictability ones. Several combined segments of dynamical complexity are found with fractal and long-memory behaviour. For these segments, associations are attempted with major (M-w >= 6.0) earthquakes occurred in China and border areas of near countries during the period of study. Out of seventeen earthquakes of the period, four earthquakes are identified with all combinations of methods, whereas the remaining earthquakes, with the combination of at least three methods. Trends of long-memory are identified and discussed. The findings are compatible with fractal, and SOC final phases of generation of earthquakes. Finally, potential geological sources are discussed and analysed.