大震前后尾波Q值变化的又一震例

本文根据Ａｋｉ的尾波散射理论，利用澜沧－耿马７．６、７．２级大震前后近１２年的时间，对大震区域及外围的７个地震台３０００多张地震记录图的尾波进行了测量，计算出尾波Ｑ值随时间的变化。结果表明：澜沧、耿马大震前有３～５年左右的低Ｑ值异常；在大震前一年左右，Ｑ值处于回升阶段；大震后多数台Ｑ值明显增大。在对两次大震震中和两次强震震中的不同距离的台站测出的Ｑ值，确定存在主震前低Ｑ值或高Ｑ值，主震后高Ｑ值或低     

大震前后尾波Q值变化的又一震例／

本文根据Ａｋｉ的尾波散射理论，利用澜沧—耿马７．６、７．２级大震前后近１２年的时间，对大震区域及外围的７个地震台３０００多张地震记录图的尾波进行了测量，计算出尾波Ｑ值随时间的变化。结果表明：澜沧、耿马大震前有３～５年左右的低Ｑ值异常；在大震前一年左右，Ｑ值处于回升阶段；大震后多数台Ｑ值明显增大。在对两次大震震中和两次强震震中的不同距离的台站测出的Ｑ值，确实存在主震前低Ｑ值或高Ｑ值，主震后高Ｑ值或低Ｑ值的两种相互矛盾的现象。并得出地震强度与Ｑ值异常幅度无关，与Ｑ值异常的持续时间成正比。     

丽江大震前长—中—短—临地震学异常的演化过程

本通过丽江大震前地震学各项异常的动态追踪，研究了长－中－短－临异常伴随大震孕育、发生的演化过程，结果表明：在强震的缺震、强震的重复、中强震密集、诱发地震、相关地震等多项长期异常的背景上，出现了中小地震活跃、调制小震频繁、复发周期降低、震源深度加深和震级差增大、地震序列ｈ值下降等同步的中期异常，而１９９５年中小地震活跃后的平静、低复发周期的回升、震源深度为２５公里和震级差在１．０－１．１级的地震次     

丽江7.0级地震前地震波特征的时空演化过程

本论述了１９９６年２月３日丽江７．０级地震前洱源、腾冲两个地震台的多项地震波运动学和动力学异常及滇西北多台波速比异常的特征，探讨了其时空演化的动态变化过程。得出：在时间进程上，多项地震波突变特征均在震前一年左右的时间出现。其中，波速比在大震前的单点突变异常幅度为中强震的５倍之多；振幅比突变异常幅度约为中强震的３－５倍；尾波持续时间比则是在震前一年左右出现持续性的低值，时间尺度约为中强震异常时间的     

极限时间法分析2003年中强地震前h′值异常变化过程

选择2003年2月24日巴楚-伽师6．8级地震和2003年2月14日石河子4．9、5．4级地震震前、震后序列，分析其h'值在中强地震前的异常变化过程，统计其h'值的异常峰值出现时间与发震时间的优势时段。算例结果显示，中强地震发生前h'值确实存在异常波动变化，地震越大异常变化幅度越显著。不同地区因为地震活动性强度不同，h'值的绝对量级也不尽相同，但一般来说中强地震前h’值存在高值突变，可将其作为短临预报参考依据之一。     

新疆大震前b值时空动态变化特征

研究了１９７０年以来新疆及各地震在大震前ｂ值时空扫描动态变化。根据异常分布特征，结合新疆近几年ｂ值时空扫描图象分析，给出了未来几年新疆ｂ值异常分布区。最后对ｂ异常特征进行了可能的物理解释。     

大地震前后平均断错的时空变化

本文讨论了唐山、永善、中甸、邢台、海城大地震前后平均断错的时间和空间变化.结果表明,大地震前,中等地震和小地震的波谱异常变化的时间和空间都与主震震级有关.其趋势是主震震级越大,异常时间越长,异常区域越大.唐山M_s=7.8级地震的F值异常时间为52个月,异常区域范围为400公里;中甸M_s=6.4级地震F值异常时间为8个月,异常区域范围为110公里.这些结果对探讨大震孕育过程有一定参考意义.     

一个新的中矩期地震预报指标

通过对强震前数年一定震级档次内的地震活动进行分析,提出一个刻划地震孕育过程进入中短期阶段的指标－Ｃｒ值。它可以反映岩石本构关系曲线峰值点附近的状态。在对７次７级左右强震进行震例研究表明,震前Ｃｒ值出现明显高值异常。Ｃｒ值达最高值的时间超前地震发生１￣３ａ,多数是在１ａ左右,这对中短期地震预报有意义。     

河南及邻区中等地震前广义时间维的变化特征

应用广义时间分维理论，对河南省及邻区１９７０年以来发生的１２次ＭＬ≥４．７级地震前后的中小地震活动进行了时间扫描，分析其变化特征。结果表明，在研究区内发生的这１２次中等地震前１－２年内，震中区及其邻近地区的广义时间维Ｄｔ都存在一个较为明显的降维过程；地震大多发生在Ｄｔ下降后开始恢复的过程段内；其发震时间大约距Ｄｔ异常最低点２－２０个月；地震发生后Ｄｔ值常快速回升，并逐步恢复正常。     

云南地区近期强震重复发生时地震学的动态演化特征

通过地强震重复发生的滇西北、滇东北、滇西南澜沧江以西３个地震区多项地震活动性和地震波参数的动态追踪，发现在同一地震区重复发生的强震，震前的异常形态可以具有相惟性，反向变化的特征。如滇东北地区中小地震在１９８５年禄劝强震前的活跃和１９９５年武定强震前的平静；澜沧地震叶波速比月均值在１９８８年澜沧－－耿马大震前的低值异常和１９９５年孟连西中缅边境大震前的高值异常。本同时以ｂ值和波速比为例，讨论了强震     

用单台Z／H法研究陕西地区深部电导率

利用陕西地磁台站的磁静日资料和单台Ｚ／Ｈ磁测深法研究了陕西地区深部电导率状况。多年和多台的平均结果为：陕西地区电磁感应比例尺度Ｃｒ１约９００ｋｍ，高于磁场梯度法测定的华北地区结果，但接近单台Ｚ／Ｈ法测定的兰州地区值；Ｃｒ２为５００ｋｍ，和华北地区的结果接近；Ｃｉ－Ｔ曲线高于华北地区值；内外场之比｜Ｑ１｜、｜Ｑ２｜、｜Ｑ３｜约为０．４，和全球平均结果一致；σ＊－ｈ１曲线显示在２５０ｋｍ附近有一高电导层。     

改进R值评分方法的一点更正及其多种用法

具体介绍了改进的R值评分方法的一点小小的更正,并说明在不同震级预报、长期预报、短临预报、全国或局部区域的预报中的使用方法,以及如何客观评价预报方法的优劣等。从而说明了改进的R值评分方法科学严谨,用途广泛,使用方便。     

宁波台水氡、水位在汶川8．0、日本9．0级地震中异常现象分析

宁波台ZK03井水氡在汶川8．0和日本9．0级地震前后出现的异常,可能是这两次地震的前兆异常和震后效应,并且出现的异常有较多相似之处。从水氡五日均值曲线来看,震前11个月开始就出现了异常,五日均值最大异常量都出现在异常结束前5个月,形成了一个“V”字形的中短期低值异常形态。同井观测的动水位同震响应也较相似,说明这两次地震波传播中对该井的水动力作用基本相同,因此也可能会出现相似的水氡中短期异常现象。     

Humidity effects on gravitational settling and Brownian diffusion of atmospheric aerosol particles

The dependency on relative humidity of the settling velocity of aerosol particles in stagnant air and of the diffusion coefficient due to Brownian motion of aerosol particles was computed for six aerosol types and different particles sizes in dry state. The computations are based (1) on mean bulk densities of dry aerosol particles obtained from measurements or from the knowledge of the chemical composition of the particles, (2) on micro-balance measurements of the water uptake per unit mass of dry aerosol substance versus water activity at thermodynamic equilibrium, and (3) on measurements of the equilibrium water activity of aqueous sea salt solutions. The results show a significant dependence of the settling velocity and Brownian diffusion of aerosol particles on relative humidity and on the particle's chemical composition.Nomenclature A surface parameter of a particle - B surface parameter of a particle - c _L velocity of sound in moist air - C 1+Kn[A+Qexp(–B/Kn]=slip correction - D diffusion coefficient of a particle - D ₁ D(=1)=diffusion coefficient of a spherical particle - f P _w /P _we (T,P)=relative humidity (f=0 dry air,f=1 saturated air) - g acceleration due to gravity - g |g| - k 1.3804×10^–16 erg/°K=Boltzmann constant - Kn _L /r=Knudsen number of a particle - Kn _{0 0L} /r ₀=Knudsen number of a dry particle - m 4r ³/3=mass of a particle - m _L 4r ³ _L /3=mass of the moist air displaced by a particle - M mobility of a particle - M ₀ molar mass of dry air - M _w molar mass of water - Ma |u–u _L |/c _L =Mach number of the particles motion relative to the ambient air - n particle number per unit volume of air - P P ₀+P _w =pressure of the moist air - P ₀ partial pressure of the dry air - P _w partial pressure of the water vapour - P _we P _we (T,P)=equilibrium partial water vapour pressure over a plane surface of water saturated with air - Q surface parameter of a particle - r equivalent radius of a particle (radius of a sphere with the particles volume) - r ₀ equivalent radius of a particle in dry state - R 1+0.13Re ^0.85=inertia correction - R ₀ specific gas constant of dry air - R _w specific gas constant of water - Re 2r _L u–u _L / _L =Reynolds number of the particles motion relative to the ambient air - t time - T absolute temperature - u velocity of a particle - u (amount of the) settling velocity of a particle in stagnant air - u ₁ u(=1)=(amount of the) settling velocity of a spherical particle in stagnant air - u _L velocity of the ambient moist air (far enough from the particle where the flow pattern remains undistorted) - W drag coefficient of a particles equivalent sphere - empirical parameter in equation (3.1) - dynamic viscosity of a particles liquid cover - _L dynamic viscosity of moist air - _0L dynamic viscosity of dry air (at the same pressure and temperature like the moist air) - celsius temperature - dynamic shape factor of a particle (=1 for a sphere) - ₀ dynamic shape factor of a dry particle - _L mean free path of the molecules in moist air - _0L mean free path of the molecules in dry air (at the same pressure and temperature like the moist air) - _Po mean free path of the molecules in dry air at the pressureP ₀ of the dry air and the temperature given - factor of solid to liquid change-over (=1 for a solid particle) - mean bulk density of a particle - _L density of the moist air - _0L density of the dry air at the same pressure and temperature like the moist air - ₀ mean bulk density of a dry particle - ₀ mean diameter of the molecules of dry air - _w diameter of water molecules - relaxation time of a particle - gradient operation - 3.141593     

中国西南和印缅地区8级地震活动特征及趋势

本分析了１９００年以来北纬１５°－３２°,东红８５°－１０５°,中国西南及印缅地区７级以上地震的时空特征,得出Ｍ≥７．５级地震有密集－平静现中活跃期持续时间长、短交替、印缅地区７级地震启动是８级地震的重要标志,８级地震发生在７级地震密集区附近。     

The effect of water on stress relaxation of faulted and unfaulted sandstone

A series of stress relaxation experiments have been carried out on faulted and intact Tennessee sandstone to explore the influence of pore water on strength at different strain rates. Temperatures employed were 20, 300 and 400°C, effective confining pressure was 1.5 kb and strain rates as low as 10^–10 sec^–1 were achieved. Most samples were prefaulted at 2.5 kb confining pressure and room temperature. This is thought to have secured a reproducible initial microstructure.The strength of the dry rock was almost totally insensitive to strain rate in the range 10^–4 to 10^–10 sec^–1. In contrast, the strength of the wet rock decreased rapidly with strain rate at rates less than 10^–6 sec^–1. Brittle fracture of the quartz grains which constitute this rock is the most characteristic mode of failure under the test conditions used.The experimental data are discussed in terms of the possible deformation rate controlling processes, and it is suggested that in the wet experiments at intermediate to high strain rates (10^–7 to 10^–4 sec^–1) the observed deformation rate is controlled by the kinetics of water assisted stress corrosion, whilst deformation at low strain rates (ca. 10^–9 sec^–1) is controlled by a pressure solution process.The results have implications for the rheology of fault rocks at depths of perhaps 10 to 15 km in sialic crust.     

EXPERIMENTAL STUDY ON DENSITY CURRENT WITH HYPERCONCENTRATION OF SEDIMENT

1. INTRODUCTIONSince 1960's, density curent with hyperconcentration of sediment have been observed andrecorded at over 10 reservoirs of the Heisonlin, Hengsban, Hongshan, Bajiazui, etc.Data from prototype observation and measurements were analysed. It is found that thecharacteristics of density current with hyperconcentrahon of sediment are quite different fromthat with low sediment concentration as had been described in available literatures. Densitycurrent with hyperconccntrahon of sed…     

Statistics on the vertical structure of rainshowers

A large sample of summertime data from the McGill Radar Weather Observatory was analyzed to determine the variation with altitude of the horizontal extent of individual rainshowers. For echoes defined by a reflectivity factor of 39 dBz (equivalent to a rainfall rate of about 10 mm/h) it was found that the mean area of the total population of echoes decreases linearly with altitude from approximately 20 km² at 2 km to 11 km² at 8 km. Subsets of the total population were investigated, consisting of only the echoes penetrating the altitudes of 6, 7, and 8 km. On the average these relatively tall echoes are much greater in horizontal extent than the total population. Whereas the sizes of the total population of echoes at any altitude are distributed approximately exponentially in terms of the square root of area, the sizes of the “survivors” that extend to high altitudes may be described by the gamma distribution with a mean value decreasing approximately linearly with height above 3 km and a dispersion of 0.55. Some characteristics are also reported for echoes defined by reflectivities of 31 dBz and 47 dBz. Estimates are given of the fraction of the total area in a horizontal plane that contains echoes in each of these categories.     

新疆3次6级强震前的短期前兆异常

分析了新疆3次6级强震前的短期前兆异常动态演化图像特征。这3次地震前兆异常的共性是地震前半年都出现了不同程度的短期前兆异常变化,且在震前2个月,短期异常均超过8项。但是3次6级强震发生前前半年的短期前兆异常变化不一致,有向震中迁移的,有包围震中的,还有前兆异常逐渐减少的。这些前兆异常现象同通常认为的越临近地震前兆异常数目越多是不一致的。     

倾斜裂隙介质反透射系数研究

自然界的裂隙排列并非都是直立的,在复杂地壳应力作用下裂隙排列很可能是倾斜的.本文从各向异性弹性动力学基本方程出发,在特征矩阵方法基础上提出了计算任意倾斜裂隙介质水平界面上的反射、透射系数的简单方法,并利用该方法计算了倾斜裂隙介质P-P波、P-SV波和P-SH波的反透射系数.结果表明,P-P波、P-SV波和P-SH波的反透射系数与倾斜裂隙的倾角、测线方位以及偏移距这些物理参数之间存在一定的依赖关系.此外我们计算了C波的零入射相角时的反射系数,发现该反射系数跟裂隙倾角、裂隙的方位角有着明显的对应规律,且各向异性越强时,该反射系数越大.这些研究对于深入了解倾斜裂隙的动力学特征具有一定的意义.