Interrelationships Between Topography,Quaternary Vertical Displacement,Active Faults and Short-term Horizontal Crustal Strain in Honshu,Japan

Regional and local characteristics of active fault patterns and elevation variation throughout Honshu, Japan are characterized in terms of their fractal dimensions; this allows variation in these complex variables to be compared directly to the scalar properties of net Quaternary vertical displacement, elevation and 10- and 110-year horizontal strains. The comparisons reveal that, throughout Honshu as a whole, there is significant correlation (r=0.75) between Quaternary vertical displacement, elevation, and its fractal properties. There is poor correlation, however, of elevation and its fractal properties to horizontal crustal strain, and also between Quaternary vertical displacement and horizontal crustal strain. A slight negative correlation is observed between the fractal properties of the active fault system and horizontal crustal strain measured over 10- and 110-year time periods (–0.43 and –0.26, respectively). The correlation between the 10-year (1985–1994) and 110-year (1883–1994) area strains, 0.48, reveals the occurrence of considerable change in the distribution of regional strain over these short time frames. Local computations of the correlation between data sets made for overlapping 160 km length windows of data spaced every 20 km along analysis lines reveal internal fluctuations in the correlation between variables. The local correlation between Quaternary vertical displacement and elevation is highest through central Japan and the Kinki Triangle. There is weak negative correlation between area strain and fractal dimensions of the active fault network. The local correlation between the fractal dimensions of active faults and horizontal area strain over the recent 10-year time period averages about –0.6 through central Japan in an area that extends across the Kinki Triangle through the northern part of central Honshu and northeast across the Itoigawa Shizuoka Tectonic Line. In general, regions of greatest complexity in the active fault network are associated with persistent negative area or compressional strain. Sparsely faulted areas in general coincide with areas of positive or roughly zero area strain. The presence of negative correlation through central Japan and the Kinki Triangle area in the recent 10-year period results from a decrease of area strain within an increasingly complex active fault system that reaches maximum negative values concentrated in the Kinki Triangle during the 1985–1994 time period.     

保山水汞异常与中强震关系研究

对云南保山滇14井1992—2004年水汞观测资料与其周围400km范围内发生的所有Ms≥95．0地震进行了研究。结果表明：在中强地震发生前,滇14井水汞存在短临异常,且异常特征清晰,异常幅度明显;所提取的短临预报指标对应地震效果较好,但对应范围受区域地质构造控制,主要对应云南西部地区及缅甸弧型构造带中的中强地震。     

Relation Between Seismicity and Geothermal Structure of the Lithosphere in Yunnan Province,China

The isoline map of the heat flow has been drawn by using the measured and estimated values of the heat flow in Yunnan Province and its adjacent region. The contrast studies of the heat flow and epicenters of the strong earthquakes (886 ～ 1998), the distribution of the geotemperature and high accurate data of focal depth (1983 ～ 1997 ) show that the strong earthquakes take place along the geothermal gradient zone in which the thermal stress is concentrated, and that the foci are generally located between 100°and 600° isogeotherms corresponding to the depths of 3～ 25km and densely distribute between 200° and 450° isogeotherms, i.e. the depths of 5 ～20km. The distribution range of the focal depths is probably related to the crustal brittle to ductile transition which mainly results from the geotemperatures.     

泾县凤村井水位异常与地震关系分析

系统分析和整理了安徽泾县凤村井水位在(超远)距离强震前出现的异常变化及其特征。映震分析结果显示:该井对远大震响应较为灵敏,尤其是东南沿海、西太平洋、南太平洋的大震活动。希望研究结果有利于泾县凤村井后续水位异常的判别,增强其预测能力。     

The Effect of Varying Damage History in Crystalline Rocks on the P- and S-Wave Velocity under Hydrostatic Confining Pressure

Cracks play a very important role in many geotechnical issues and in a number of processes in the Earth’s crust. Elastic waves can be used as a remote sensing tool for determining crack density. The effect of varying crack density in crystalline rock on the P- and S-wave velocity and dynamic elastic properties under confining pressure has been quantified. The evolution of P- and S-wave velocity were monitored as a suite of dry Westerly granite samples were taken to 60, 70, 80 and 90 % of the unconfined uniaxial strength of the sample. The damaged samples were then subjected to hydrostatic confining pressure from 2 MPa to 200 MPa to quantify the effect of varying crack density on the P- and S-wave velocity and elastic properties under confining pressure. The opening and propagation of microcracks predominantly parallel to the loading direction during uniaxial loading caused a 0.5 and 6.3 % decrease in the P- and S-wave velocity, respectively. During hydrostatic loading, microcracks are closed at 130 MPa confining pressure. At lower pressures the amount of crack damage in the samples has a small but measureable effect. We observed a systematic 6 and 4 % reduction in P- and S-wave velocity, respectively, due to an increase in the fracture density at 2 MPa confining pressure. The overall reduction in the P- and S-wave velocity decreased to 2 and 1 %, respectively, at 50 MPa. The elastic wave velocities of samples that have a greater amount of microcrack damage are more sensitive to pressure. Effective medium modelling was used to invert elastic wave velocities and infer crack density evolution. Comparing the crack density results with experimental data on Westerly granite samples shows that the effective medium modelling used gave interpretable and reasonable results. Changes in crack density can be interpreted as closure or opening of cracks and crack growth.     

Preliminary Research on Relation Between Field and Source in Earthquake Preparation

The "field" and "source" are two important branches in seismology and earthquake research.In this paper,we use a computer model to study the relation between the field and the source in earthquake activity.In our modeling,a network of nonlinear elements is used to simulate seismic activity of seismic zones in a seismotectonic block.Constant strain rate is enforced on the boundary of the model,cyclic seismic activity,quasi-periodic variation of stress field intensity,and strain energy are observed with high and low fluctuations.There is a main seismicity area in seismic cycles,and the main seismicity area shows the spatial migration during different seismic cycles.If the precursory area is related to high element stress,it is found that the development of precursors in our model is quite complicated.No certain relation between the precursors and earthquakes has been discovered.Anomalies show different characteristics in the seismic quiet period and active period.All of the seismic zones in the system hav     

云南思茅大寨井与大理月溪井水位同震响应对比分析

云南思茅大寨井和大理月溪井分别位于云南西南和西北部,是云南地区主要地震流体观测井.通过水位观测数据分析,思茅大寨井水位和大理月溪井水位同震响应差异明显.思茅大寨井水位同震响应能力较好,主要表现为阶升,阶变幅度达10 cm以上的有16次,最大可达57.1 cm.大理月溪井水位同震响应能力较弱,阶变幅度小,主要表现为阶降....     

林县深浅构造与小震活动的关系

叙述了林县的小震活动,区域地球物理场与深浅构造特征、小震区的重力变化,得出林县小震活动受该区深浅构造控制的结论。     

山西夏县热水井逸出He异常与地下水开采关系的研究

山西夏县疗1号井处于山西南部中条山北麓的山前断裂带上,位于中条山山前断裂与北西西向隐伏断裂交汇处热水区内,成井于1975年,井深140 m,水温38 ℃.     

水动力条件下底泥中氮磷释放通量

在环形水槽内模拟了水动力条件下底泥的起动规律,分析了底泥运动的不同状态。该环形水槽内水体流速基本均匀,水槽转速与槽内水体流速能够精确的相互转换,实验中通过改变水槽转速模拟了不同扰动强度下底泥悬浮和释放的规律．以太湖底泥为例,通过上覆水中TN、TP浓度的变化,建立了底泥中TN、TP的释放通量(y)与水流(x)的关系,其表达式为TN：y=137．88e^0.06x(R^2=0．94);TP：y=36．78e^0.56x(R^2=0．97);并将该实验结果应用在太湖的水量水质模型中,取得了比较满意的效果．     

Hydrochemical Relation Between Shallow Groundwater with Elevated Fluoride and Groundwater in Underlying Carbonates

In the arid to semi-arid district of Chengcheng, Weinan City, in central Shaanxi Province, diminishing groundwater reserves in the shallow Quaternary (QLB) aquifer and elevated fluoride in the similarly shallow Permo-Triassic (PTF) aquifer, have promoted interest in the development of groundwater resources in the deep but poorly understood Cambrian-Ordovician carbonate aquifer system (COC). To investigate the origin of the COC groundwaters and the relationship between the deep and shallower systems, a hydrochemical study was undertaken involving 179 major and minor ion analyses, 39 stable isotope analyses (δD and δ¹⁸O), and 14 carbon isotope analyses (¹⁴C and δ¹³C). PHREEQC 3.0 was used to investigate mixing. Hydrochemical data support the presence of a well-connected regional flow system extending southwards from the more mountainous north. Stable isotope data indicate that the COC groundwaters originate as soil zone infiltration, under a much cooler regime than is found locally today. This is confirmed by ¹⁴C, which indicates the groundwater to be palaeowater recharged during the late Pleistocene (∼10–12 ka B.P.). The presence of nitrate in the COC groundwaters suggests leakage from overlying shallow aquifers currently provides an additional source of COC recharge, with major faults possibly providing the primary pathways for downward vertical flow.     

盘一井氢气异常与地震对应关系研究

对盘锦地震台盘一井溶解氢气观测数据的变化特征进行研究,对比分析1999年与2020年氢气异常特征与辽宁周边地球地震活动关系,分析井口周边300km范围内的地震活动与氢气的变化特征。结果表明,盘一井氢气在地震发生前能够较灵敏地反映出地震前兆变化,氢气异常幅度与震级呈正相关关系,与震中距呈负相关关系,异常多出现在震前三个月内。     

The Relation Between Humidity and Liquid Water Content in Fog: An Experimental Approach

Microphysical measurements of orographic fog were performed above a montane cloud forest in northeastern Taiwan (Chilan mountain site). The measured parameters include droplet size distribution (DSD), absolute humidity (AH), relative humidity (RH), air temperature, wind speed and direction, visibility, and solar short wave radiation. The scope of this work was to study the short term variations of DSD, temperature, and RH, with a temporal resolution of 3?Hz. The results show that orographic fog is randomly composed of various air volumes that are intrinsically rather homogeneous, but exhibit clear differences between each other with respect to their size, RH, LWC, and DSD. Three general types of air volumes have been identified via the recorded DSD. A statistical analysis of the characteristics of these volumes yielded large variabilities in persistence, RH, and LWC. Further, the data revealed an inverse relation between RH and LWC. In principle, this finding can be explained by the condensational growth theory for droplets containing soluble or insoluble material. Droplets with greater diameters can exist at lower ambient RH than smaller ones. However, condensational growth alone is not capable to explain the large observed differences in DSD and RH because the respective growth speeds are too slow to explain the observed phenomena. Other mechanisms play key roles as well. Possible processes leading to the large observed differences in RH and DSD include turbulence induced collision and coalescence, and heterogeneous mixing. More analyses including fog droplet chemistry and dynamic microphysical modeling are required to further study these processes. To our knowledge, this is the first experimental field observation of the anti-correlation between RH and LWC in fog.     

Approximate Relation Between the Ray Vector and the Wave Normal in Weakly Anisotropic Media

Determination of the ray vector (the unit vector specifying the direction of the group velocity vector) corresponding to a given wave normal (the unit vector parallel to the phase velocity vector or slowness vector) in an arbitrary anisotropic medium can be performed using the exact formula following from the ray tracing equations. The determination of the wave normal from the ray vector is, generally, a more complicated task, which is usually solved iteratively. We present a first-order perturbation formula for the approximate determination of the ray vector from a given wave normal and vice versa. The formula is applicable to qP as well as qS waves in directions, in which the waves can be dealt with separately (i.e. outside singular directions of qS waves). Performance of the approximate formulae is illustrated on models of transversely isotropic and orthorhombic symmetry. We show that the formula for the determination of the ray vector from the wave normal yields rather accurate results even for strong anisotropy. The formula for the determination of the wave normal from the ray vector works reasonably well in directions, in which the considered waves have convex slowness surfaces. Otherwise, it can yield, especially for stronger anisotropy, rather distorted results.