Seismo-meteo-electromagnetic phenomena observed during a 5-year interval around the 2011 Tohoku earthquake

The purpose of the paper is to try to find ULF electromagnetic precursors to the 2011 Tohoku earthquake (EQ), on the basis of extensive investigation of radiations in vertical component of the magnetic field or with a large ratio of the vertical to full horizontal component. Nighttime records have been analyzed of three Japanese fluxgate magnetometers located in a distance from 300 to 1300 km from the epicenter of the main shock, and the frequency range from 10 to 150 mHz was used for the analysis. We have applied wavelet analyses to improve the detection of pulsed signals. All obtained scalograms have been averaged over the nighttime interval from 01 h to 05 h JST and flattened by means of multiplication by square of frequency. The sequence of spectra thus obtained has been compared with the evolution of seismicity, which has resulted in that the radiation in the vertical component has been detected. It exhibits seasonal variations with winter maxima, but it increases further by approaching the moment of the EQ and decreases after that. This radiation seems to be correlated with atmospheric parameters – air humidity, temperature, vapor pressure and rainfall. So, we consider that this radiation cannot be caused by subsurface sources, but its possible sources can be atmospheric discharges. The evolution of this phenomenon can be explained by a seasonal variation of atmospheric parameters and also its variations under the influence of injection of gas from the focal zone of a forthcoming EQ.     

山西定襄奇村水氡观测短期异常分析

文章对山西定襄泉、奇村水化井中水氡含量的年变动态规律及其相关影响因素进行了全面的分析。针对2008年6月至8月两处出现的短期、高值突跳变化进行对比分析,得出,定襄水氡短期变化受短期降暴雨影响;奇村水氡则是周围冷水井抽水灌溉所致。     

德令哈6．6级地震及后期强余震序列前青海省水氡异常特征

2003年4月17日德令哈发生6．6级地震,2004年该震区相继发生了5次5级以上的中强地震,分析德令哈系列地震前青海省水氡资料,发现震前水氡异常较显著,并表现出不同的异常特征。     

Evaluation of the flushing rates of Apalachicola Bay, Florida via natural geochemical tracers

We used naturally occurring radium isotopes as tracers of water exchange in Apalachicola Bay, a shallow coastal-plain estuary in northwestern Florida. The bay receives fresh water and radium from the Apalachicola River, and mixes with Gulf of Mexico waters through four inlets. We deployed moored buoys with attached Mn-fibers at several stations throughout the estuary during two summer and two winter periods. After deployment for at least one tidal cycle we measured the ratio of the two short-lived radium isotopes ²²³Ra (half-life = 11 d) and ²²⁴Ra (3.6 d) to estimate “radium ages” of the water in the bay.During our four seasonal deployments the river discharge ranged from 338 to 1016 m³ s^− 1. According to our calculations the water turnover time in the bay during these samplings ranged from 6 to 12 days. Age contours in the bay showed that winds and tides as well as river discharge influence the water movement and the residence time of freshwater in the bay. We also calculated the mean age of river water in the bay which was between 5 to 9 days during the studied periods. We suggest that this approach can be used to quantify transport processes of dissolved substances in the bay. For example, soluble nutrient or pollutant transport rates from a point source could be examined. We conclude that the radium age technique is well suited for flushing rate calculations in river dominated shallow estuaries.     

带有多道相关的抛物线Radon变换法分离P-P、P-SV波

因为多波多分量地震勘探中P-P波和P-SV波通常混杂在一起,所以较好地分离P-P波和P-SV波能够提高数据处理和解释的质量.抛物线Radon变换法在分离P-P波和P-SV波时取得了一定效果,但是在离散叠加的计算过程中会带来假频,这些假频会干扰波场分离.本文针对这一问题,将多道相关算法引入抛物线Radon变换,发展了带有多道相关的抛物线Radon变换法.该方法利用叠加信号具有相似性的特点,依据多道相关中衡量多道信号相似性的能量比标准,对叠加过程加以控制,压制变换中出现的假频.本文用该方法对合成地震记录进行了波场分离,取得了较好的效果.     

地面氡及其子体测量在新疆汉水泉地区砂岩型铀矿找矿中的应用

介绍了氡气和γ能谱测量的基本原理,通过数据常规分析和相关分析其在新疆三塘湖盆地汉水泉地区的同点测量结果,常规分析未得出砂岩型铀矿成矿有利的氡浓度异常,而相关分析共提取了11个有利于铀成矿的氡浓度异常,说明氡气和γ能谱测量结果相关分析在砂岩型铀矿找矿中预测远景区是值得借鉴的方法.     

氡室中氡量变化规律的数学模型

本文建立了在稳定氡源的情况下，氡室中氡量变化规律的数学模型，并导出了氡室中氡量控制参数的三个计算公式．该数学模型为氡室的研制和氡量控制提供了理论依据，对环境的辐射监测与评价也有指导意义．     

煤田陷落柱氡气场的数值计算及空间形态分布特征

根据流体场的扩散理论和对流理论,建立了扩散系数与对 流速度为常量或变量情况下的氡气场三维状态方程;对于陷落柱柱体侧面有源氡气场和柱体 体内有源氡气场两种理论模型,给出了不同系数和边界条件下的数值解的形式. 针对模型的 特点及其边界条件用差分法分别进行了数值计算,结果表明陷落柱氡气场的空间形态 分布特征. 野外实测和模型试验的结果相互吻合.     

山东德州2号井水氡异常变化原因探讨

研究了山东德州2号井2004年9月11日水氡高值异常变化特点,对水氡高值异常的原因进行了系统的探讨。详细调查影响水氡变化的各种环境因素和人为因素,进行科学的数据分析、合理推断和试验验证。结果表明:该“异常”是由于临近水井抽水引起的干扰,不是地震异常。研究论证了开展流体氡前兆观测与分析预报的同时开展流体氡的动态变化及其影响因素研究的必要性。     

华清4#泉两次水化学观测试验研究

主要介绍了2001年11月-2002年10月、2006年8～9月期间,华清4^#泉水氡和气体总量的对比观测实验情况,结合观测点的实际情况,对上述两次实验结果进行了分析,探讨了影响水氡和气体总量观测的主要因素。