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201.
202.
Seismic Hazard for Selected Sites in Greece: A Bayesian Estimate of Seismic Peak Ground Acceleration 总被引:1,自引:1,他引:1
A procedure for estimating maximum values of seismic peak ground accelerationat the examined site and quantiles of its probabilistic distribution in a future timeinterval of a given length is considered. The input information for the method areseismic catalog and regression relation between peak seismic acceleration at a givenpoint and magnitude and distance from the site to epicenter (seismic attenuation law).The method is based on Bayesian approach, which simply accounts for influenceof uncertainties of seismic acceleration values. The main assumptions for the method are Poissonian character of seismic events flow and distribution law of Gutenberg-Richter's type. The method is applied to seismic hazard estimation in six selected sitesin Greece. 相似文献
203.
An automated strategy for calculation of phase diagram sections and retrieval of rock properties as a function of physical conditions 总被引:9,自引:0,他引:9
We formulate an algorithm for the calculation of stable phase relations of a system with constrained bulk composition as a function of its environmental variables. The basis of this algorithm is the approximate representation of the free energy composition surfaces of solution phases by inscribed polyhedra. This representation leads to discretization of high variance phase fields into a continuous mesh of smaller polygonal fields within which the composition and physical properties of the phases are uniquely determined. The resulting phase diagram sections are useful for understanding the phase relations of complex metamorphic systems and for applications in which it is necessary to establish the variations in rock properties such as density, seismic velocities and volatile‐content through a metamorphic cycle. The algorithm has been implemented within a computer program that is general with respect to both the choice of variables and the number of components and phases possible in a system, and is independent of the structure of the equations of state used to describe the phases of the system. 相似文献
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Crack damage stress as a composite function of porosity and elastic matrix stiffness in dolomites and limestones 总被引:4,自引:0,他引:4
Twenty-five uniaxial compression tests were performed to determine stress at onset of dilation, referred to herein as “the crack damage stress,” in heterogeneous dolomites and limestones. A simplified model for crack damage stress (σcd) is developed here using porosity, elastic modulus, Poisson's ratio and three empirical coefficients. The model shows that when porosity decreases and elastic modulus increases, σcd rapidly increases and approaches its maximum value. On the other hand, when porosity increases and elastic modulus decreases, σcd rapidly decreases and approaches its minimum value. The proposed model is validated for six heterogeneous limestone and dolomite formations which are widely distributed in Israel. 相似文献
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Abstract. The Hishikari epithermal gold deposit consists of the Honko-Sanjin zone and Yamada zone. On the basis of observed crosscutting relationships of veins, vein system in the Hishikari deposit was classified into the early and late veins. They differ from orientation, width, control by unconformity, the amount of displacement and structural features, but have similarity in gold grade and Au/Ag ratios. K-Ar ages are presented for the classified veins to clarify timing of fracturing and duration of mineralization.
Age determination revealed that the early veins in the Honko-Sanjin zone range from 0.86 to 1.11 Ma and that the late veins range from 0.73 to 0. 84 Ma. The economically most important mineralization in the Hishikari deposit occurred around 0.90 Ma in a very short period (about 0.05 million years).
The distribution of mineralization age in the whole Hishikari deposit, occurrences of slickensides and ground water temperatures imply that mineralization lasted longer in the southern part of the deposit. As compared the early veins with late veins, structural changes including width, strike, dip and vein characteristics occurred at around 0.85 Ma. 相似文献
Age determination revealed that the early veins in the Honko-Sanjin zone range from 0.86 to 1.11 Ma and that the late veins range from 0.73 to 0. 84 Ma. The economically most important mineralization in the Hishikari deposit occurred around 0.90 Ma in a very short period (about 0.05 million years).
The distribution of mineralization age in the whole Hishikari deposit, occurrences of slickensides and ground water temperatures imply that mineralization lasted longer in the southern part of the deposit. As compared the early veins with late veins, structural changes including width, strike, dip and vein characteristics occurred at around 0.85 Ma. 相似文献
208.
Seismic profiles and well data from the Doukkala basin unravel the structure of the Palaeozoic basement and suggest that this coastal zone of western Morocco was affected by a compressive phase during the Frasnian. This resulted in the formation of upright, plurikilometric folds associated with reverse faults (North Doukkala), and of asymmetrical folds associated with mostly west verging ramps (South Doukkala). Folding involved all pre-Upper Frasnian formations and caused partial or total hiatus of Upper Frasnian–Strunian strata. This event can be correlated with the orogenic phase reported from more internal domains of the Morocco Hercynian belt, where it is referred to as the ‘Bretonne’ or ‘Eovariscan’ phase. To cite this article: H. Echarfaoui et al., C. R. Geoscience 334 (2002) 13–20 相似文献
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