Application of microseismic multiplet analysis to the Basel geothermal reservoir stimulation events     

B.C. Dyer  U. Schanz  T. Spillmann  F. Ladner  M.O. Häring 《Geophysical Prospecting》2010,58(5):791-807

The stimulation of a geothermal well in Basel, Switzerland produced a distribution of microseismic event locations with an overall alignment in the direction of the maximum horizontal stress. Fault plane solutions of individual larger events indicated movements on fracture planes at an angle to the maximum horizontal stress that could not be reliably interpreted from the event locations. To obtain higher resolution images of the microseismic event locations, events with similar waveforms have been identified by multiplet analysis. A number of receivers were used in the multiplet processing to ensure each multiplet is represented by a unique group of waveforms. The location accuracy within each multiplet has been significantly improved using cross‐correlation to refine the shear‐wave traveltime picks. The distribution of events within each multiplet can be interpreted as being due to movements on a single fracture or a number of near parallel fractures. It is shown that whilst the overall distribution of events is around the direction of the maximum horizontal stress, the individual multiplets representing fracture planes have a variety of azimuths and dips.  相似文献   

Geology, Geochemistry and Chromite Mineralization Potential of the Amnay Ophiolitic Complex, Mindoro, Philippines     

Graciano P. Yumul Jr  Ferdinand T. Jumawan    Carla B. Dimalanta 《Resource Geology》2009,59(3):263-281

The Amnay Ophiolitic Complex in Mindoro, the Philippines, is considered an emplaced Cenozoic South China Sea oceanic lithosphere as a result of the collision between the Palawan microcontinental block and the Philippine mobile belt. Middle Oligocene sedimentary rocks intercalated with dominantly MORB-like pillow lavas and volcanic flows suggest the generation of this ophiolite complex in an intermediate spreading ridge within a back-arc basin setting. The volcanic rock suite geochemistry also manifests a slab component suggesting that it is a supra-subduction zone ophiolite. Petrography of the gabbros shows a plagioclase-clinopyroxene crystallization order consistent with a back-arc basin setting. Spinel and pyroxene geochemistry shows that the lherzolites and aluminous-spinel harzburgites are products of low degrees of partial melting. The chromitites hosted by the harzburgites could have not been associated with the MORB-like volcanic suites, gabbros, lherzolites and aluminous-spinel harzburgites. The chromitites are products of mantle sources that have undergone higher degrees of partial melting that would have involved the presence of water. The study of this ophiolitic complex gives us a glimpse of the characteristics of the South China Sea.  相似文献   

Biodiversity in the Benthic Diatom Community in the Upper River Töss Reflected in Water Quality Indices     

Lirika Kupe  Ferdinand Schanz  Reinhard Bachofen 《洁净——土壤、空气、水》2008,36(1):84-91

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Geomechanical assessment of the Corvara earthflow through numerical modelling and inverse analysis   总被引：1，自引：1，他引：0  

W. Schädler  L. Borgatti  A. Corsini  J. Meier  F. Ronchetti  T. Schanz 《Landslides》2015,12(3):495-510

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Statistical model of a smoke plume     

Ferdinand Hesek 《Studia Geophysica et Geodaetica》1969,13(3):308-320

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The effects of artificial ammonium enhancement on riverine periphytic diatom communities   总被引：2，自引：0，他引：2  

Joachim Hürlimann  Ferdinand Schanz 《Aquatic Sciences - Research Across Boundaries》1993,55(1):40-64

An experiment to ascertain the influence of artificially enhanced ammonium concentrations on riverine periphytic diatom communities was conducted during an 80 day period in winter 1988/89 (temperature: 5°C). During an initial 47 day enrichment phase, ammonium chloride at different concentrations was added to O₂-saturated river water in experimental channels. Compared to a control, the addition of 1.2 mg NH ₄ ⁺ -N·l^–1 resulted in only slight changes in the species composition of the diatom community. The addition of 5.1 mg NH ₄ ⁺ -N·l^–1 and more (60 µg NH₃-N·l^–1) resulted in a decrease in the biomass and a drastic change in the species composition. After the 42 day enrichment period, the diatom speciesFragilaria capucina var.vaucheriae, Navicula saprophila, Navicula atomus andGomphonema parvulum, all of which are known to be tolerant to organic pollution, were found with relative abundances of 44.8%, 35.6%, 2.3% and 1.5%, respectively. Changes in species composition of the periphytic diatom communities occurred within the first two weeks of the subsequent recovery phase. After a month of recovery, all periphytic diatom communities exhibited a high degree of structural similarity with the control.  相似文献   

Infinite elements in a poroelastodynamic FEM     

M. Nenning  M. Schanz 《国际地质力学数值与分析法杂志》2011,35(16):1774-1800

An infinite element is presented to treat wave propagation problems in unbounded saturated porous media. The porous media is modeled by Biot's theory. Conventional finite elements are used to model the near field, whereas infinite elements are used to represent the behavior of the far field. They are constructed in such a way that the Sommerfeld radiation condition is fulfilled, i.e. the waves decay with distance and are not reflected at infinity. To provide the wave information the infinite elements are formulated in Laplace domain. The time domain solution is obtained by using the convolution quadrature method as the inverse Laplace transformation. The temporal behavior of the near field is calculated using standard time integration schemes, e.g. the Newmark method. Finally, the near and far field are combined using a substructure technique for any time step. The accuracy as well as the necessity of the proposed infinite elements, when unbounded domains are considered, is demonstrated by different examples. Copyright © 2010 John Wiley & Sons, Ltd.  相似文献   

Review: Groundwater flow and transport modeling of karst aquifers, with particular reference to the North Coast Limestone aquifer system of Puerto Rico   总被引：7，自引：2，他引：5  

Reza Ghasemizadeh  Ferdinand Hellweger  Christoph Butscher  Ingrid Padilla  Dorothy Vesper  Malcolm Field  Akram Alshawabkeh 《Hydrogeology Journal》2012,20(8):1441-1461

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Proposed engineering of gypsiferous soil classification     

Moutaz A. Al-Dabbas  Tom Schanz  Mohammed J. Yassen 《Arabian Journal of Geosciences》2012,5(1):111-119

Proposed engineering of gypsiferous soil classification is given. This classification depends on soil texture, mineralogy, geochemistry and engineering properties. Study areas are located within the Mesopotamian plain and include four locations, namely, Najaf, Karbala, Falluja and Samarra which are located between latitudes 32° and 35° and longitudes 43° and 44° 30??. The study performed includes analyses of soil samples for their mineralogy and physical and engineering properties as well as the chemical analyses of soil water extracts. The results suggest that these soils consist of different percentages of sand, silt, clay and some gravel. Analysis also detected secondary gypsum, quartz, calcite, feldspar, different types of rock fragments and different types of heavy minerals in trace amount. Clay minerals are dominated by palygorskite. Hydrochemical analysis results of soil water extracts show that the calcium and sulphate ions are most common, followed by sodium, bicarbonate, chloride, magnesium and potassium. Bicarbonate and chloride show increased values in Karbala and Najaf areas. The highest gypsum content reached 67.5% in the Samarra area, while the lowest is in Karbala, which reached 28.9%.The physical and engineering properties of the studied soils were determined. Samples which were allowed to soak in water show a sudden drop in unconfined compressive strength, compression and shear values immediately after soaking and then decreased gradually. This classification of gypsiferous soils is composed of two classes: gypsiferous soil and highly gypsiferous soil, according to their gypsum content and initial void ratio, coefficient of curvature, coefficient of uniformity, the collapse potential, the compressive strength, cohesion, plasticity index, content of fines and the total dissolve solids of the soil water extracts. It is believed that this newly proposed classification for gypsiferous soils can be applied to other locations and therefore will be useful for other soil scientists and engineers as well because this classification depends on soil texture, mineralogy, geochemistry and engineering properties, while the other existing classifications deal with only one of these variables.  相似文献   

One-dimensional consolidation under haversine repeated loading with rest period     

Sabah S. Razouki  Tom Schanz 《Acta Geotechnica》2011,6(1):13-20

Presented in this paper is a study of the one-dimensional consolidation process under haversine repeated loading with and without rest period. The analysis was carried out using a hybrid coupled, analytical and numerical implicit finite difference technique. The rate of imposition of excess pore-water pressure was determined analytically, and the remaining part of the governing differential equation was solved numerically. The clay deposit considered was a homogeneous clay layer with permeable top and/or impermeable bottom hydraulic boundary conditions with constant coefficients of permeability and of consolidation. The study reveals that although the loading function is positive for all times, the excess pore-water pressure at the base of the clay deposit with permeable top and impermeable bottom oscillates with time reaching a ‘steady state’ after few cycles of loading depending on whether there is a rest period or not. An increase in the rest period causes a decrease in the number of cycles required to achieve the steady state. The paper shows also that the rest period in the haversine repeated loading decelerates the consolidation process. Similarly, the paper reveals that the effective stress at the bottom of the clay layer with permeable top and impermeable bottom increases with time but showing mild fluctuations that do not change the sign. The maximum positive effective stress achieved depends on the rest period of the haversine repeated loading. A haversine repeated loading without a rest period gives the highest value for the positive effective stress.  相似文献