Large-scale floodplain modelling     

D. Michael Gee  Malcolm G. Anderson  Laura Baird 《地球表面变化过程与地形》1990,15(6):513-523

A two-dimensional horizontal finite element numerical model (RMA-2) was applied to a 24 km river channel-floodplain reach in West Germany. Initial results indicate that finite element schemes may successfully estimate inundation in large-scale floodplain applications. Potentially, the resulting detailed velocity vector distributions and identification of inundation zones throughout storm events could provide an insight into the present day sedimentary environment on the floodplain.  相似文献   

Two observations about low-frequency signals on accelerograms from the october 15, 1979 imperial valley,california earthquake     

John G. Anderson 《地震工程与结构动力学》1985,13(1):97-108

Accelerograms from the Imperial Valley have been integrated and baseline corrected by a simple procedure which keeps track of the signal that is removed at long periods. Specifically, acceleration is integrated once to obtain velocity, a linear baseline is subtracted from velocity, the velocity is integrated to displacement, and low order terms of a trigonometric expansion of displacement are subtracted. It is observed that even though this procedure is not suitable for routine processing, one obtains displacement traces which usually resemble the results obtained by standard methods. It is also observed that amplitudes of the trigonometric series expansions are consistent with a simple earthquake source theory for frequencies greater than 1/12 Hz, suggesting that the records are dominated by signal at those frequencies.  相似文献   

Book reviews     

Keith L. Bildstein  Franz E. Anderson 《Estuaries and Coasts》1985,8(4):396-397

  相似文献   

Anisotropic models of the upper mantle     

Janice Regan  Don L. Anderson 《Physics of the Earth and Planetary Interiors》1984,35(4):227-263

Long period Rayleigh wave and Love wave dispersion data, particularly for oceanic areas, have not been simultaneously satisfied by an isotropic structure. In this paper available phase and group velocity data are inverted by a procedure which includes the effects of transverse anisotropy, anelastic dispersion, sphericity, and gravity. We assume that the surface wave data represents an azimuthal average of actual velocities. Thus, we can treat the mantle as transversely isotropic. The resulting models for average Earth, average ocean, and oceanic regions divided according to the age of the ocean floor, are quite different from previous results which ignore the above effects. The models show a low-velocity zone with age dependent anisotropy and velocities higher than derived in previous surface wave studies. The correspondence between the anisotropy variation with age and a physical model based on flow aligned olivine is suggestive. For most of the Earth SH > SV in the vicinity of the low-velocity zone. Neat the East Pacific Rise, however, SV > SH at depth, consistent with ascending flow. Anisotropy is as important as temperature in causing radial and lateral variations in velocity. The models have a high velocity nearly isotropic layer at the top of the mantle that thickens with age. This layer defines the LID, or seismic lithosphere. In the Pacific, the LID thickens with age to a maximum thickness of ～50 km. This thickness is comparable to the thickness of the elastic lithosphere. The LID thickness is thinner than derived using isotropic or pseudo-isotropic procedures. A new model for average Earth is obtained which includes a thin LID. This model extends the fit of a PREM, type model to shorter period surface waves.  相似文献   

Volatiles H2O,CO2, and Cl in a subduction related basalt     

David M. Harris  Alfred T. Anderson Jr. 《Contributions to Mineralogy and Petrology》1984,87(2):120-128

The products of the 1974 eruption of Fuego, a subduction zone volcano in Guatemala, have been investigated through study of silicate melt inclusions in olivine. The melt inclusions sampled liquids in regions where olivine, plagioclase, magnetite, and augite were precipitating. Comparisons of the erupted ash, groundmass, and melt inclusion compositions suggest that the inclusions represent samples of liquids present in a thermal boundary layer of the magma body. The concentrations of H₂O and CO₂ in glass inclusions were determined by a vacuum fusion manometric technique using individual olivine crystals (Fo77 to Fo71) with glass inclusion compositions that ranged from high-alumina basalt to basaltic andesite. Water, Cl, and K₂O concentrations increased by a factor of two as the olivine crystals became more iron-rich (Fo77 to Fo71) and as the glass inclusions increased in SiO₂ from 51 to 54 wt.% SiO₂. The concentration of H₂O in the melt increased from 1.6 wt.% in the least differentiated liquid to about 3.5% in a more differentiated liquid. Carbon dioxide is about an order of magnitude less abundant than H₂O in these inclusions. The gas saturation pressures for pure H₂O in equilibrium with the melt inclusions, which were calculated from the glass inclusion compositions using the solubility model of Burnham (1979), are given approximately by P(H₂O)(Pa)=(SiO₂−48.5 wt.%) × 1.45 × 10⁷. The concentrations of water in the melt and the gas saturation pressures increased from about 1.5% to 3.5% and from 300 to 850 bars, respectively, during pre-eruption crystallization.  相似文献   

A universal thermal equation-of-state     

Orson L. Anderson 《Journal of Geodynamics》1984,1(2)

Evidence has steadily accumulated to show that at high temperatures (above the Debye temperature, θ) the thermal pressure, P_TH, of solids, is linear with T to a close approximation. This empirical finding yields a simple relationship between P, V, and T quite useful for the computation of the equation-of-state (EOS). For geophysical applications, the empirical data is, so far, limited to a few minerals, all of which are important to our geophysical models of the Earth. The same results have been found for a variety of types of solids, including alkali metals, noble gas solids, alkali halides and metals in addition to minerals. It is argued that the linearity between P_TH and T is a general high-temperature property of solids. This includes minerals. Thus it is proposed that there exists a common thermal EOS which transcends the chemical bonding type and crystallographic class.  相似文献   

Kolmogorov constants for CO2, wind velocity,air temperature,and humidity fluctuations over a crop surface     

Shashi B. Verma  Dean E. Anderson 《Boundary-Layer Meteorology》1984,28(1-2):161-167

The Kolmogorov constants for CO₂, wind velocity, air temperature, and humidity fluctuations were evaluated from measurements made over soybean and grain sorghum fields and found to be 0.78 ± 0.11, 0.49 ± 0.08, 0.70 ± 0.15, and 0.99 ± 0.16, respectively. These results are consistent with recent observations reported in the literature.Published as Paper No. 7255, Journal Series, Nebraska Agricultural Experiment Station. The work reported here was conducted under Regional Research Project 11-33 and Nebraska Agricultural Experiment Station Project 27-003.Associate Professor and Post Doctoral Research Associate, respectively, Center for Agricultural Meteorology and Climatology, Institute of Agriculture and Natural Resources, University of Nebraska, Lincoln, NE, U.S.A., 68583-0728.  相似文献   

Simulating 24-hour,all-slope surface temperatures during summer along a climatic-latitudinal transect     

Prof. W. H. Terjung  Patricia A. O’Rourke 《Theoretical and Applied Climatology》1984,34(1-2):49-63

  相似文献   

Partition of radiotracers between suspended particles and seawater     

Yuan-Hui Li  Linda Burkhardt  Marilyn Buchholtz  Patricia O&#x;Hara  Peter H Santschi 《Geochimica et cosmochimica acta》1984,48(10):2011-2019

Distinctive uptake mechanisms of different radiotracers by red clays in seawater are elucidated from the magnitude and change of distribution coefficients (K_d) for up to 17 γ-emitting radiotracers as functions of equilibration time, suspended particle concentration and compositions of solids and seawaters. The adsorption of ionic metals onto colloids and subsequent coagulation of colloids onto larger particles are the dominant removal processes of metals in the aquatic environments of low suspended particle concentration.  相似文献   

Suction-controlled triaxial testing: Laboratory procedures in relation to resistance envelope methods     

M. G. Anderson  M. J. Kemp 《地球表面变化过程与地形》1987,12(6):649-654

In certain tropical slopes it appears possible that soil suction may play a significant role in maintaining stability. This communication outlines a laboratory suction-controlled triaxial test that can be undertaken to validate the threshold suction predicted by resistance envelope methods. It is shown that for two sites examined in St. Lucia, West Indies, the results from such a test confirm results obtained by use of resistance envelopes.  相似文献