Statistical estimation of a shock center: Slate Islands astrobleme

Statistical models are proposed for the distribution of directions in three dimensions that are thought to point toward a single source. These models are based on the Fisher distribution. The method of maximum likelihood is used to obtain an estimate of position of the source and to provide corre-sponding confidence regions. When applied to shatter cone data from the Slate Islands, northern Lake Superior, the method yields estimates comparable with those obtained by Stesky and Halls (1982), as well as statistically valid confidence regions.     

Frictional heat generation and seismic radiation in a foam rubber model of earthquakes

Results from a study of stick-slip particle motion at the interface between two stressed foam rubber blocks indicate that normal vibrations and interface separation are an important part of the stick-slip process in foam rubber. The dimension of the dynamic slip pulse is small compared to the dimension of the model (approximately 10 cm vs. 200 cm) consistent with the abrupt-locking slip pulse model ofBrune (1970, 1976), andHeaton (1990). A comparison of frictional heat generation between stable-sliding and stick-slip foam rubber models indicates a linear relation between the temperature increase on the fault surface (for a given distance of slip) and the driving shear force for the stable-sliding model, while for the stick-slip model there is essentially no variation in frictional heat generation with an increase in shear stress. We performed experiments to investigate the ratio of normal motion to shear motion at different levels of normal stress in the stick-slip foam rubber model. Preliminary result indicate that the normal component of the particle motion increases more rapidly with increasing normal stress than the shear component. The phenomenon of interface separation and normal vibrations may thus explain some of the most frustrating problems in earthquake mechanics, e.g., the heat flow paradox, the long-term weakness of major active faults, and anomalousP-wave radiation.     

清代移民屯田对新疆地名的影响

本文从移民地名、屯田地名、方位地名、方言地名等方面，论述了清代移民屯田对新疆的地名的影响。     

Observations of geomagnetic pulsations and variations with a new borehole magnetometer down to depths of 3000 m

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A triaxial magnetometer has been developed for investigating the in situ skin effect of horizontal geomagnetic pulsations and variations in deep boreholes. The observations were carried out in the pilot borehole of the Continental Deep Drilling Program of Germany (KTB) down to depths of 3000 m and up to temperature of 90 C. A weak skin effect, due to the known very low conductivity of the penetrated crystalline rocks, of 90 to 95 per cent in amplitude and -5 to -10 rotation in phase has been observed at periods of 10 s and magnetometer depth of 2400 m.
An essential prerequisite for all calculations is the accurate determination of the orientation of the downhole magnetometer. It is demonstrated how oriented record samples of temporal variations at depth correlate precisely with those from the surface.
Results from surface magnetotelluric (MT) investigations show strong local distortions of the telluric field. The distortion of the MT tensor response has been determined by means of newly introduced skin-effect transfer functions, which are assumed to be undistorted.     

苏北平原井下摆观测效果的讨论

文章以江苏省大丰台、盐城台、淮阴台、海安台，射阳台井下摆观测为例。比较它们的观测结果，分析认为井下摆的观测效果不仅与地面复盖层的厚度有关，而且与井下摆周围的环境干扰，观测用井的质量有关。为了提高井下摆观测效果，应尽量减少环境干扰，并注意井的垂直度和固井，文章还指出，沿海地区井下摆受海浪干扰相当显著的。     

Borehole pressure correction equation

Conclusion A method of calculation for borehole pressure has been developed and compared to measured data for PETN. The results show that by adjusting the ratio of the specific heats using an equation derived from a curve fit of a pressure as a function of decoupling ratio graph, the plot shifts to a position within the ranges of the measured data. Also, at this point the proper specific heat may be obtained for a given gaseous mixture. Although other mixtures have been considered the results are not yet conclusive, but preliminary values seem to hold for the methodology used.     

Investigation of electrical anisotropy in the deep borehole KTB

Information about electrical anisotropy in and around the deep borehole of the German Continental Deep Drilling Program (KTB) has been acquired using three different methods: (1) Under surface temperature and pressure conditions, the azimuthal dependence of resistivity has been measured in horizontal planes perpendicular to the axes of drill cores. (2) Simulated in-situ conditions (high temperature and pressure) have been applied to mini cores drilled at different orientations to structural features such as foliation. The resistivity was then measured in the direction of the mini cores' long axes. (3) Under quasi-in-situ (downhole) conditions, the azimuthal dependence of resistivity has been measured in horizontal planes using the Azimuthal Resistivity Imager (ARI), a down hole logging tool.These investigations have shown that electrical anisotropy is strongly related to structural features. The anisotropy of gneisses is the highest due to the strong foliation (averaged anisotropy factor 2.8). Lamprophyres are most isotropic (factor 1.2). Most rocks from KTB are amphibolites with intermediate anisotropies (factor 1.3). The anisotropies measured under surface temperature and pressure conditions and quasi-in-situ conditions on amphibolites are approximately the same, whereas anisotropies under simulated in-situ conditions are partially higher.Furthermore, the anisotropies measured on the cm to m scale using the various methods outlined above shall be compared with large scale anisotropies of the km scale measured around KTB using Magneto Tellurics.     

裂隙各向异性介质波场VSP多分量记录的数值模拟

从各向异性介质中最为普遍的裂隙各向异性介质出发，推导了同零井源距ＶＳＰ三分量观测方式相一致的一维三分量波动方程．为了更符合实际观测，引入了坐标旋转，可以模拟井中任意方位的多层各向异性介质的波场响应．用有限元方法进行了波场数值模拟，重点突出了获得凡Ｒ_３×３矩阵剖面的方法，同时对Ｒ_３×３，矩阵剖面进行了一般性的分析解释，事实证明，Ｒ_３×３矩阵剖面含有介质丰富的各向异性信息．     

局部重磁场源全方位成像理论概要(续)

作者近年来首创了"复杂条件下局部重磁场源全方位成像"理论体系。在本文中,概要阐述该理论体系中下延有限二度体复重磁场级数正演通式、复场模值全方位延拓和全方位反演等。