Refraction anomalies determined from meteorological sounding measurements

Summary The paper outlines some new approaches to discovering refraction anomalies using available meteorological data which characterize the vertical condition of the atmosphere in the neighbourhood of an observatory. Due to the limited number of data and the methods of processing, the resultant refraction anomalies refer to only a part of the atmosphere, approximately 10 km in height.     

长期性前兆异常的探讨

对长期性前兆异常进行研究的结果表明:①长期性前兆异常的开始和结束及其发展变化一般与地震活动幕的起止和强震活动有关;②近年出现的长期性前兆异常的开始时间一般是先东后西,呈现出一定程度的有序性,与强震依次由东向西发生一致。长期性前兆异常展示了区域应力场的演化、扩展、转移的图像,以及地震间的相联系和相互影响,并有可能判定地震幕的起止和预测后续地震。 因此,该结果为研究和判定地震趋势提出了一种可能的途径。     

滇川地下水异常时空转移特征研究

分析研究川滇及邻区地下水异常在中期— 短期— 临震孕震阶段认为, 异常时空转移是地震短临跟踪的一种有效方法。根据中期— 短期— 临震异常井孔数量少— 增多— 减少( 密集) 等变化, 判定地震孕育所处阶段。并用有无区域性异常时空转移等特征预测强震和非强震;用异常时空转移的方向大致估计可能的发震地区;用短临孕震阶段时空转移的明显程度预测发震时间。     

泉州四至井水氡异常及中国台湾东南部(包括附近海域)地震的对应关系

对泉州四至井2006年1月至2008年12月水氡观测数据进行分析与处理,依据2倍中误差、短期阶升突跳、短期和中长期趋势异常等多种判别法,对其水氡异常进行判别。结果表明:泉州四至井水氡氡值基本保持春夏高、秋冬低的弓形年变化动态图像,出现的水氡异常对中国台湾东南部及附近海域有较好的对应关系,并对2006年7月28日花莲6.0级、2006年12月26日恒春7.2级、2007年9月7日台东6.3级地震进行案例分析,有关研究结果对寻求泉州四至井水氡异常对中国台湾地区某些敏感对应点的映震能力具有一定的现实意义。     

山西地区视应力时空变化特征分析

利用2001~2011年ML≥2.0地震波形资料计算得到山西地区的视应力,结合山西地区2001年以来5次M4.5以上地震探讨地震前后视应力时空变化特征后发现,在5次4.5级以上地震前1年均出现过视应力高值,地震发生在高值异常下降的过程中,且这5次中等地震发生在视应力高值异常区域内或附近。结果表明视应力高值异常区对中强震的震中预测具有一定的指示作用,可以作为地震危险性判定的参考依据。     

Ozone concentration at meteor heights determined from forward-scatter radar echoes

The ozone concentration has been measured in the meteor zone using a method of radar echo duration distribution suggested by Jones and Šimek (1995). Data obtained by the forward-scatter system during the Lyrid meteor shower period in five consecutive years 1992–1996 agree with the Solar Mesosphere Explorer results for the same heights of 95 km. The mean value of the ozone concentration [O₃]=(1.56±0.05)×10¹⁴ m⁻³ has been derived from a total of 6596 radar meteor echoes with duration ≥1 s. The results for individual years indicating a possible decrease in [O₃] are discussed.     

水位、水氡小波分析中期异常提取方法

利用小波分析方法在时间域和频率域都有较高分辨率的特性,建立了水位、水氡的小波中期异常提取的方法.该体系包括研究（预测）目标地震的确定、 井（泉）和测项的初选、小波异常的提取及异常性质的鉴定等7个步骤.采用小波异常提取方法,研究了华北、四川及邻区、海南多年积累的震例资料,分析了水位、水氡小波异常与地震活动之间的关系,给出了上述3个地区中期小波异常的时间分布特征.小波异常的超前时间,可作为发震时间的预测指标,为这3个区域的实际震情判定提供依据.     

张北6.2级地震前廊坊地区地下流体异常特征

廊坊地区所属的安头屯井、浅牛6井是静水位观测井,文安井由文安地震台进行多年的水氡观测。这3口井始测时间为20世纪80年代,资料连续可靠。资料清理过程中发现在1998年1月10日张北6．2级地震前以及强余震活动中均有明显的异常显示。本文探讨了张北震例的综合异常特征。     

Geoid anomalies across fracture zones and the thickness of the lithosphere

Recent advances in the measurement and interpretation of geoid height anomalies provide a new way to estimate the thickness of the oceanic lithosphere as a function of crustal age. GEOS-III satellite altimetry measurements show abrupt changes in sea level across fracture zones which separate areas of lithosphere with different ages. These changes have the correct location, amplitude, and wavelength to be caused by the combined gravitational attraction of the relief across the fracture zone and the isostatic support of this relief. Eight profiles of geoid height and bathymetry across the Mendocino fracture zone are inverted to determine the depth of the isostatic compensation, assuming that the compensation occurs in a single layer. These depths are then interpreted with a thermal boundary layer model of lithospheric growth. To explain satisfactorily the geoid measurements, the thermal diffusivity of the upper mantle must be 3.3 × 10^?3 cm² s^?1 and the thickness of the lithosphere, defined as the depth at which the geotherm reaches 95% of its maximum value, must be9.1km m.y.^?1/2 × t^1/2, where t is lithospheric age.     

Research on the perturbation phenomenon while tracing the radon concentration in real time

Generally, researchers are interested in time averaged radon concentration levels. However when we study the migration and adsorption characteristics of radon, the measurement of radon concentration in real time is important. Radon monitors based on electrostatic collection method cannot follow the rapid changes in radon concentration. The main reason for this is that a sufficient decay time is needed in order for the radon concentration in the internal cell of radon monitor to come to equilibrium with the ²¹⁸Po. We propose a novel algorithm for determining the actual radon concentration versus time, derived from the data provided by the radon monitor. However there is a distinct ‘perturbation’ phenomenon associated with this procedure when the measurement cycle time is short. In this paper we will also analyze the source of this perturbation phenomenon and provide an improved process model, based upon a faster convergence method that enables reduction of this perturbation to acceptable limits. This model can be used to improve the measurements for any radon monitor like Rad7 based on electrostatic collection for tracing the radon concentration on short measurement cycles.     

活断层上覆盖层中土壤氡浓度分布的数值模拟

本文利用实测地质剖面建立了活断层上覆盖层中氡迁移的地质-物理模型,根据氡的迁移机理建立了活断层上氡迁移的数学模型,采用有限差分方法求解氡迁移的二维微分方程的数值解,得到了直立活断层,倾斜活断层,地堑活断层,活动断裂带或破碎带上覆盖层中氡浓度的二维断面等值图和横切断层的剖面曲线,分析了氡浓度分布的二维断面特征和剖面曲线特征,它们与氡的迁移机制及活断层调查的实测剖面曲线相符,这些为活断层的调查和进一步反演奠定了理论基础.     

A theoretical model for change of shape of spring-water radon anomalies with epicentral distance

A model for radon anomalies before earthquakes, with a relatively fast increase in radon concentration at the beginning of the anomaly, is postulated. A calculation based on this model shows that a parameter can be deduced from the form of the radon anomalies, which depends on the epicentral distance of the measurement point. After adjustment of some parameters the model calculation is in good agreement with observed earthquake precursor anomalies.     

数字化形变观测提取的地震短临异常特征

数字化形变资料由于采样率的大幅度提高, 丰富了潮汐观测的震前变化信息, 使研究震前短临的异常信息成为可能。通过对2001年10月27日永胜6. 0级地震以及2001年11月14日昆仑山口西8. 1级地震前后若干倾斜、重力数字化观测的结果进行计算分析, 初步获得了两次地震前形变异常的阈值及临震异常特征图像。对临近地震前形变异常时间、空间上的特征进行总结。依据固体潮汐观测模型计算潮汐、非潮汐参数与日异常频次、日差分异常频次, 将各参数综合考虑, 有可能对未来发震的时间及地点给出预估计。     

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.     

汤阴地堑南部土壤Rn空间分布特征

为分析汤阴地堑南部土壤Rn空间分布特征,揭示其与断裂构造、岩性及沉积层厚度之间的联系,本文采用网格化布点野外流动观测方法测定了该地区380个点的土壤Rn浓度,结果表明：汤阴地堑土壤Rn浓度介于3.09—78.54 kBq/m³,背景均值为27.22 kBq/m³,异常阈值下限为48.40 kBq/m³。在空间分布上,研究区西部(以第四系等厚线50 m为界),受岩石单元和人类石料开采活动的影响,Rn浓度背景值高于东部。在西部高浓度背景影响下,Rn浓度高值异常点除沿汤西断裂带分布外,还沿断裂带外围呈斑块状分布,断裂带对气体释放的控制作用在一定程度上被掩盖。而东部地区,覆盖层较厚,Rn浓度背景值较低,部分高值异常点主要沿汤中和汤东断裂带分布,显示出构造对气体迁移的控制作用;另一部分高值异常点与第四系等厚线近似平行,呈条带分布,推测新乡—卫辉间存在一条规模较大的隐伏断裂。此外,研究区主要断裂带的Rn异常衬度表现为汤东断裂带高于汤西和汤中断裂带。结合灥研究扊区地质背景和深部孕震环境认为,该Rn异常衬度表现是汤阴地堑南部构造活动背景...     

丰满台水氡异常特征分析

对蚌埠地震台2020年4月15日以来出现的水氡数据转折下降—恢复上升的变化趋势进行分析,文章通过环境调查、气象因素对比、抽水取样化验后和研究得出：本次水氡变化与气温水温呈正相关关系,相关性显著,气温引起水温的变化,进而引起气体的溶解度和脱气率改变,从而引起水氡测值的变化。结合往年震例分析结果认为,气温可能不是引起水氡测值下降的单一因素,应该是环境干扰与地震前兆信息共同作用的结果,而水氡与气温之间的相关系数降低,与周边发生地震有一定的关联性。     

The spatial characteristic of the short-term and imminent anomalies of water radon before earthquake in the mainland of China

The changes of radon concentration in underground water (water radon) recorded at about 200 stations in 32 earthquakes occurred in the mainland of China are studied in this paper. The result shows that the spatial distribution of short-term and imminent anomalies of water radon before earthquake seems to be mainly related to the active master fault nearby the hypocenter of an earthquake and the earthquake-generating mechanism. Finally, some understandings on the mechanism of the anomalies and the imminent earthquake prediction are set forth.     

云南地区地壳磁异常与地质构造

根据美国地球物理数据中心的地磁场模型（NGDC-720）,研究云南地区地壳磁异常的空间变化,包括磁异常及其梯度的分布、磁异常随高度的衰减、不同波长成分对总体磁异常的贡献.比较磁异常与重力异常、大地热流、地震活动等地球物理信息的异同特征,探讨地壳磁异常与地质构造的关系.研究结果表明：丽江-小金河、红河断裂带以西的三江、滇西造山带的异常较弱,菱形地块的异常相对较强.研究区域的地壳磁异常主要是弱磁性基底背景下叠加的浅源磁性体产生.卫星磁异常显示滇中坳陷区具有清晰的偶极场特征.沿红河断裂带分布的正负磁异常带与断裂构造走向一致.围限菱形地块的丽江-小金河断裂、红河断裂、康定-奕良-水城断裂和弥勒-师宗-水城断裂带是磁异常的强弱过渡带.强烈地震发生的地点、大地热流值高的地区,地壳磁异常为负值或相对较弱.

     

Measurements of radon flux and soil-gas radon concentration along the Main Central Thrust, Garhwal Himalaya, using SRM and RAD7 detectors

Radon in the Earth’s crust or soil matrix is free to move only if its atoms find their way into pores or capillaries of the matrix. ²²²Rn atoms from solid mineral grains get into air, filling pores through emanation process. Then ²²²Rn enters into the atmosphere from air-filled pores by exhalation process. The estimation of radon flux from soil surface is an important parameter for determining the source term for radon concentration modeling. In the present investigation, radon fluxes and soil-gas radon concentration have been measured along and around the Main Central Thrust (MCT) in Uttarkashi district of Garhwal Himalaya, India, by using Scintillation Radon Monitor (SRM) and RAD7 devices, respectively. The soil radon gas concentration measured by RAD7 with soil probe at the constant depth was found to vary from 12 ± 3 to 2330 ± 48 Bq·m^?3 with geometrical mean value of 302 ± 84 Bq·m^?3. Th significance of this work is its usefulness from radiation protection point of view.     

地震前兆：电离层F2层异常

本文简述了目前提出的地震引起电离层异常扰动的物理机理，重点介绍了近几年国内外对震前F2层异常扰动的研究进展.大量的研究结果显示地震活动引起的电离层扰动不仅确实存在，而且在震级大于5级的地震发生前的几天到几个小时会发生电离层扰动.由于地震引起的电离层F2层变化具有独一无二的特性，这就意味着我们可以利用强震前的F2层异常变化作为地震短临预报的工具.