Shear velocity structure in the Aegean area obtained by inversion of Rayleigh waves   总被引：2，自引：0，他引：2  

E. E. Karagianni  C. B. Papazachos  D. G. Panagiotopoulos  P. Suhadolc  A. Vuan  G. F. Panza 《Geophysical Journal International》2005,160(1):127-143

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An attempt to estimate isotropic and anisotropic lateral structure of the Earth by spectral inversion incorporating mixed coupling   总被引：2，自引：0，他引：2  

Hitoshi Oda 《Geophysical Journal International》2005,160(2):667-682

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Linearized 2.5-dimensional parameter imaging inversion in anisotropic elastic media     

Stig-Kyrre Foss  Maarten V. de Hoop  Bjørn Ursin 《Geophysical Journal International》2005,161(3):722-738

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Shallow seismic trapping structure in the San Jacinto fault zone near Anza, California   总被引：3，自引：0，他引：3  

M. A. Lewis  Z. Peng †  Y. Ben-Zion  F. L. Vernon 《Geophysical Journal International》2005,162(3):867-881

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Two-dimensional inversion of direct current resistivity data using a parallel, multi-objective genetic algorithm   总被引：2，自引：0，他引：2  

Christoph Schwarzbach  Ralph-Uwe Börner  Klaus Spitzer 《Geophysical Journal International》2005,162(3):685-695

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Characterization of dispersive surface waves using continuous wavelet transforms   总被引：1，自引：0，他引：1  

M. Holschneider  M. S. Diallo  M. Kulesh  M. Ohrnberger  E. Lück  F. Scherbaum 《Geophysical Journal International》2005,163(2):463-478

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Primary Ore Mineral Assemblage and Fluid Inclusion Study of the Batu Hijau Porphyry Cu-Au Deposit, Sumbawa, Indonesia   总被引：3，自引：0，他引：3  

Akira Imai  Satoshi Ohno 《Resource Geology》2005,55(3):239-248

Abstract. The Batu Hijau porphyry Cu‐Au deposit, Sumbawa Island, Indonesia, is associated with a tonalitic intrusive complex. The temperature‐pressure condition of mineralization at the Batu Hijau deposit is discussed on the basis of fluid inclusion microthermometry. Then, the initial Cu‐Fe sulfide mineral assemblage is discussed. Bornite and chalcopyrite are major copper ore minerals associated with quartz veinlets. The quartz veinlets have been classified into ‘A’ veinlets associated with bornite, digenite, chalcocite and chalcopyrite, ‘B’ veinlets having chalcopyrite bornite along vuggy center‐line, rare ‘C’ chalcopyrite‐quartz veinlets, and late ‘D’ veinlets consisting of massive pyrite and quartz (Clode et al., 1999). Copper and gold mineralization is associated with abundant ‘A’ quartz veinlets. Abundant fluid inclusions are found in veinlet quartz consisting mainly of gas‐rich inclusions and polyphase inclusions throughout the veinlet types. The hydrothermal activity occurred in temperature‐pressure conditions of aqueous fluid immiscibility into hypersaline brine and dilute vapor. The halite dissolution (Tm[halite]) and liquid‐vapor homogenization (Th) temperatures of the polyphase inclusions in veinlet quartz range from 270 to 472d?C and from 280 to 454d?C, respectively. The estimated salinity ranges from 36 to 47 wt% (NaCl equiv.). The apparent pressures lower than 300 bars are estimated to have been along the liquid‐vapor‐halite curve for the fluid inclusions having the Th lower than the Tm that trapped the brine saturated with halite, or at slightly higher pressure relative to liquid‐vapor‐halite curve for the fluid inclusions having the Th higher than the Tm that trapped the brine unsaturated with halite. The actual temperature and pressure during the hydrothermal activity at the Batu Hijau deposit are estimated to have been around 300d?C and 50 bars. At such temperature‐pressure conditions, the principal and initial Cu‐Fe sulfide mineral assemblages are thought to be chalcopyrite + bornite solid solution (bnss) for the chalcopyrite‐bearing assemblage, and chalcocite‐digenite solid solution and bnss for the chalcopyrite‐free assemblage.  相似文献   

Analysis of earth dams affected by the 2001 Bhuj Earthquake   总被引：3，自引：0，他引：3  

Raghvendra Singh  Debasis Roy  Sudhir K. Jain   《Engineering Geology》2005,80(3-4):282-291

An earthquake of magnitude of 7.6 (M_w 7.6) occurred in Bhuj, India on January 26, 2001. This event inflicted damages of varying extents to a large number of small to moderate size multi-zone earth dams in the vicinity of the epicenter. Some of the distress was due to the liquefaction of saturated alluvium in foundation. Liquefaction was relatively localized for the majority of these dams because the earthquake struck in the middle of a prolonged dry season when the reservoirs behind these dams were nearly empty and shallow alluvium soils underneath the downstream portions of the dams were partly dry. Otherwise, liquefaction of foundation soils would have been more extensive and damage to these dams more significant. Six such dams have been examined in this paper. Four of these facilities, Chang, Shivlakha, Suvi, and Tapar were within the 50 km of epicenter region. These dams underwent free-field ground motion with peak ground accelerations between 0.28g to 0.52g. Of these Chang Dam underwent severe slumping, whereas Shivlakha, Suvi, and Tapar Dams were affected severely especially over the upstream sections. Fatehgadh Dam and Kaswati Dam were affected relatively less severely. Foundation conditions underneath these dams were first examined for assessing liquefaction potential. A limited amount of subsurface information available from investigations undertaken prior to the earthquake indicates that, although the foundation soils within the top 2.0 to 2.5 m underneath these dams were susceptible to liquefaction, Bhuj Earthquake did not trigger liquefaction because of lack of saturation of these layers underneath the downstream portions of these dams. These dams were then analyzed using a simple sliding block procedure using appropriate estimates of undrained soil strength parameters. The results of this analysis for these structures were found to be in general agreement with the observed deformation patterns.  相似文献   

Influence of tectonic structures on the Hope Slide, British Columbia, Canada     

Marc-Andr  Brideau  Doug Stead  Derek Kinakin  Karin Fecova 《Engineering Geology》2005,80(3-4):242-259

The Hope Slide, which occurred on January 9, 1965, involved an estimated 47-Mm³ of meta-volcanics and intrusive rocks. Previous workers reported the presence of tectonic structures (faults and shear zones) along the failure surface at the Hope Slide. These tectonic features were investigated in detail to assess their effects on rock-mass quality and the related implications for slope stability. This paper integrates basic field and laboratory concepts from structural and engineering geology. Subdividing the failure area into structural domains allowed distinct discontinuity sets to be associated with specific tectonic structures. The Geological Strength Index (GSI) was used to estimate the rock-mass damage related to the tectonic structures. Low GSI values were seen to outline tectonic damage zones. Point-load tests were used to characterise the compressive strength of rocks adjacent to the tectonic structures. Strength anisotropy, tentatively attributed to damage caused by a large shear zone, was observed in greenstone samples. Seepage zones along the failure surface were observed preferentially along shallow discontinuities that dipped downslope and in rock masses of good quality (GSI > 40). An alternative morphology of the slope failure is proposed by distinguishing between the extent of the surficial damage due to the rock-slope failure and the zone of failed material (depletion zone). For the first time, a kinematic mechanism for the Hope Slide is proposed, based on a preliminary 3-dimensional block model. A pre-1965 DEM was produced from estimates of material lost and gained as reported by previous workers. The pre-1965 DEM revealed that the tectonic structures recognised during fieldwork bounded the material that failed in the 1965 event.  相似文献   

Slope stability evaluation using Back Propagation Neural Networks   总被引：4，自引：0，他引：4  

H.B. Wang  W.Y. Xu  R.C. Xu 《Engineering Geology》2005,80(3-4):302-315

The Yudonghe landslide, located in western Hubei Province of China, consists of eastern and western subunits as well as a main landslide mass with upper and lower slip surfaces. As an important landslide close to Shuibuya Dam on the Qing River, its stability is crucial, as the slide might reactivate because of a change in ground-water level caused by filling of the Shuibuya Reservoir. Existing weakness zones, growth of ruptures, the downslope attitude of geologic strata, and water infiltration, which reduced the strength of rocks and soils, have been found to be the most important factors contributing to the Yudonghe landslide. With regard to the landslide processes, it can be noted that the original large-scale slide activity was due to erosion by the Qing River, the second sliding resulted from the fall of blocks from the head scarp, and the final activity was the growth of the eastern and western secondary slides. A base failure was the main type of slope movement, however, it was obvious that more than one sliding event occurred, as inferred from striations and fractures detected by microstructure analysis of soils along the failure surfaces. Slope instability was evaluated by the method of Back Propagation Neural Networks (BPNN), in which a four-layer BPNN model with five input nodes, two hidden layers, and two output nodes was constructed using a training data set of landslide samples throughout the Qing River area. The predicted results of this analysis showed that the factor of safety was 1.10, which indicates that the Yudonghe landslide is currently in a marginally stable condition.  相似文献