Integration of geodetic and geotechnical deformation surveys in the geosciences

Ground movement studies can utilize information from conventional geodetic surveying, photogrammetry, and geotechnical measurements of strain, tilt, etc. Each method alone cannot yield a complete picture of the deformation. However, each is complemented by the others. Hence, their integration in a simultaneous analysis in space and in time is advocated. An integrated analysis is readily accommodated by a generalized method of deformation analysis devised by the authors. Any number of measurements of any type can be considered in any fashion of modelling with full statistical assessment of the modelling and of derived characteristics. Such an integration is illustrated using data from a coal mining area in rugged mountainous terrain of western Canada. Conventional terrestrial geodetic methods connected 15 stations. Displacements from an additional 29 points were obtained from aerial photogrammetry. Biaxial tiltmeters continuously measured ground tilts at 3 stations. A surface of subsidence for the whole area was modelled with the graphical depiction in three dimensions.     

Solution behavior of +4 cations in high silica melts: petrologic and geochemical implications

The saturation surfaces of rutile (TiO₂), zircon (ZrSiO₄), and hafnon (HfSiO₄) were determined in anhydrous, peraluminous, high silica liquids of the system SiO₂-Al₂O₃-Na₂O-K₂O as functions of silica concentration at 1,400° C in air. The saturation concentrations of TiO₂, ZrO₂, and HfO₂ in rutile, zircon, and hafnon-saturated liquids, respectively, decrease smoothly and gradually as functions of increasing silica concentration. Thermodynamic analyses of the data demonstrate that the activity coefficients of TiO₂, ZrO₂, and HfO₂ increase smoothly and gradually as silica concentration is increased from 67 wt-% to 80 wt-%, and that changes in SiO₂ of 1 or 2 wt-% result in small changes in the saturation concentrations and activity coefficients of +4 cations. Because the solution behavior of +4 cations in highly siliceous liquids (>75 wt-% SiO₂) is predictably different than in less siliceous liquids (70 to 75 wt-% SiO₂), classification of highly-siliceous igneous rocks on the basis of silica concentration alone should not be interpreted to mean that their solution chemistry differs significantly from that of less siliceous rocks. The results of this study are compared with other studies of +4 cation solution behavior. From this it is concluded that variations in liquid compositions observed in cogenetic suites of high silica rhyolites cannot cause the observed changes in +4 cation concentrations. Thus, even if a large change in solution behavior of +4 cations is inferred from the large variations in their concentrations, it cannot be due to changes in bulk composition of the parental liquid. In addition, the similarity in the solution behavior of Zr and Hf seen in this study suggests that their solution mechanisms are similar. It is thus unlikely that liquid-state processes can fractionate one with respect to another, and variations in Zr/Hf ratios in suites of extrusive rocks are likely due to crystal-liquid equilibria, e.g., zircon fractionation.     

Caution in the use of Niskin bottles for hydrocarbon samples

Niskin bottles may release into a water sample hydrocarbons that have a distribution very similar to a petroleum product.     

Anomalous induction in the Carpathians

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A substantial part of this paper was presented at the IAGA symposium Relations between External and Internal Magnetic Variations, XVI. IUGG General Assembly, August–September 1975, Grenoble.     

Demographic aspects of urbanization

Urban growth and urbanization can be defined, measured and studied in a variety of ways but there is little doubt that the demographic dimension is of paramount importance for both the general public and interested scholars. It seem appropriate that this aspect should be given a particular attention during the symposium organized during the International Geographical Congress as well as a special publication resulting therefrom. The present assay attempts to discuss the demographic issues at a very high level of generalization. The basic data used were derived from the latest UN estimates.     

Recognition of the zones of seismic hazard in Polish Coal mines by using a seismic method

In the Upper Silesian Coal Field the seismic hazard induced by mining operations in collieries is closely related to the rockburst hazard. A seismic method is used for premonitory recognition of the zones of seismic hazard. It takes advantage of the relationship between the velocity of propagation of seismic waves and the state of stress existing in the rock. It consists of the determination of the velocity field of artificially induced seismic waves in a studied fragment of the rock, and of locating the velocity anomaly. The position of the velocity anomaly zones and their intensity are the basis for estimating the seismic hazard in advance of mining works.