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Erosivity of intact clay: influence of the natural structure
GEOMECHANICS ABSTRACTS
875004 Three dimensional modeling of crustal stress and the s.eismicity of the east coast Mareschal. J C; Kuang, J; Long. L T Proc Third US National Conference on Earthquake Engineering, Charleston, 24-28 August 1986 ['1, Pl05115.Publ El Cerrito. Earthquake Engim'ermg Research Institute
Geology Tectonic processes and structural
geology
See also: 875132
875001 Construction of shear strain profiles across brittle-ductile shears Weijermars, R .-Inn Geoph.vs V5, Set B, N2, April 1987, P201-210 A new method is presented for construction of shear strain profiles across and along zones with brittle-ductile shear geometries. It is applied here to major wrench faults in Spain (Truchas and Palomares shears) and New Zealand (Alpine fault) but is equally applicable to other types of shear zone of any size and orientation, from plate tectonics to microscopic shear zones in cleavage fabrics.
Loading of the earth's lithosphere b.v the topography and by changes in crustal thickness induces horizontal stresses. Crustal stress has been modelled in three dinaensions for the case of an elastic layered slab on an inxiscid fluid. Surface and internal loadings are introduced as boundar.~ conditions. Results of preliminary calculations for the Charleston, South Carolina, area of the USA are presented, and suggestions are made for improvements of the assumed model. This work is to test the hypothesis that the superposition of local and regional stresses can increase the local stress field such that earthquakes are triggered.
Environmental effects, weathering and soil formation
875002 Analysis of seismic instability of the Vancouver Island lithoprobe transect Nyland, E; Li, Q Can J Earth Sci V23, NI2. Dec 1986, P2057-2067 Seismic reflection and refraction surveys and gravity measurements over Vancouver Island. British Columbia, Canada. can constrain a finite element model of the geodynamics of the subduction zone. Stress estimates obtained from this model have been combined with rock failure criteria to yield a probability measure of seismic risk that assumes seismic events start from a dilute distribution of Griffith cracks. The results are in aggreement with the observed seismicity and lead to the suggestion that the dominant mechanism of this oceanic plate subduction zone is gravitational ridge push and mantle convection. Auth.
875005 Rates and processes of soil development on Quaternary terraces in Cajon Pass, California McFadden, I.. D: Weldon, R J Bull Geol Soc Am V98, :V3, March 1987, P2,~¢0-293 Soils from I 1 well dated terraces in the Cajon Pass area have been studied in the field and in the laboratory, and morphology, chemistry and mineralogy examined. As initial conditions are similar on most surfaces, the rate at which soil properties have developed can be studied, and effects of soil-forming variables such as climatic changes and the incorporation of eolian dust. a primary source of silt. clay and some iron oxides, on rates of soil development can be evaluated.
875006 Erosivity of intact clay: influence of the natural structure Lefebvre. G; Rohan. K: Mitette, J P Can Geotech J V23, N4, Not" 1986, P427-434
875003 Origin of polygonal fractures in sand, uppermost Navajo and Page sandstones, Page, Arizona Kocurek, G; Hunter, G E J Sediment Petrol V56, N6, Noe 1986, P895-904 Polygonal fractures, largely rectangular and from I-6m across and up to 1.5m deep, are observed on the upper surface of the Navajo sandstone and along surfaces of the Page sandstones, Arizona, USA. They are caused by thermal contraction in a hot desert environment with a marked daily temperature range.
Erodibility drill hole tests were carried out on three Canadian clays on intact structured specimens, specimens destructured by consolidation, and remoulded and reconsolidated specimens. Destructuring drastically reduces resistance to erosion. with greatest falls for remoulded and reconstituted specimens. Effects vary from one clay to another. Pore water salinity appears to be an influential factor on the erosion of destructared clays.
~i~: 1987 Pergamon Journals Ltd. Reproduction not permitted 173A
875004 Three dimensional modeling of crustal stress and the s.eismicity of the east coast Mareschal. J C; Kuang, J; Long. L T Proc Third US National Conference on Earthquake Engineering, Charleston, 24-28 August 1986 ['1, Pl05115.Publ El Cerrito. Earthquake Engim'ermg Research Institute
Geology Tectonic processes and structural
geology
See also: 875132
875001 Construction of shear strain profiles across brittle-ductile shears Weijermars, R .-Inn Geoph.vs V5, Set B, N2, April 1987, P201-210 A new method is presented for construction of shear strain profiles across and along zones with brittle-ductile shear geometries. It is applied here to major wrench faults in Spain (Truchas and Palomares shears) and New Zealand (Alpine fault) but is equally applicable to other types of shear zone of any size and orientation, from plate tectonics to microscopic shear zones in cleavage fabrics.
Loading of the earth's lithosphere b.v the topography and by changes in crustal thickness induces horizontal stresses. Crustal stress has been modelled in three dinaensions for the case of an elastic layered slab on an inxiscid fluid. Surface and internal loadings are introduced as boundar.~ conditions. Results of preliminary calculations for the Charleston, South Carolina, area of the USA are presented, and suggestions are made for improvements of the assumed model. This work is to test the hypothesis that the superposition of local and regional stresses can increase the local stress field such that earthquakes are triggered.
Environmental effects, weathering and soil formation
875002 Analysis of seismic instability of the Vancouver Island lithoprobe transect Nyland, E; Li, Q Can J Earth Sci V23, NI2. Dec 1986, P2057-2067 Seismic reflection and refraction surveys and gravity measurements over Vancouver Island. British Columbia, Canada. can constrain a finite element model of the geodynamics of the subduction zone. Stress estimates obtained from this model have been combined with rock failure criteria to yield a probability measure of seismic risk that assumes seismic events start from a dilute distribution of Griffith cracks. The results are in aggreement with the observed seismicity and lead to the suggestion that the dominant mechanism of this oceanic plate subduction zone is gravitational ridge push and mantle convection. Auth.
875005 Rates and processes of soil development on Quaternary terraces in Cajon Pass, California McFadden, I.. D: Weldon, R J Bull Geol Soc Am V98, :V3, March 1987, P2,~¢0-293 Soils from I 1 well dated terraces in the Cajon Pass area have been studied in the field and in the laboratory, and morphology, chemistry and mineralogy examined. As initial conditions are similar on most surfaces, the rate at which soil properties have developed can be studied, and effects of soil-forming variables such as climatic changes and the incorporation of eolian dust. a primary source of silt. clay and some iron oxides, on rates of soil development can be evaluated.
875006 Erosivity of intact clay: influence of the natural structure Lefebvre. G; Rohan. K: Mitette, J P Can Geotech J V23, N4, Not" 1986, P427-434
875003 Origin of polygonal fractures in sand, uppermost Navajo and Page sandstones, Page, Arizona Kocurek, G; Hunter, G E J Sediment Petrol V56, N6, Noe 1986, P895-904 Polygonal fractures, largely rectangular and from I-6m across and up to 1.5m deep, are observed on the upper surface of the Navajo sandstone and along surfaces of the Page sandstones, Arizona, USA. They are caused by thermal contraction in a hot desert environment with a marked daily temperature range.
Erodibility drill hole tests were carried out on three Canadian clays on intact structured specimens, specimens destructured by consolidation, and remoulded and reconsolidated specimens. Destructuring drastically reduces resistance to erosion. with greatest falls for remoulded and reconstituted specimens. Effects vary from one clay to another. Pore water salinity appears to be an influential factor on the erosion of destructared clays.
~i~: 1987 Pergamon Journals Ltd. Reproduction not permitted 173A