Seismic wave velocities in the lower mantle — Part II

Summary In an earlier paper the author developed mathematical expressions for the longitudinal and transverse wave velocities in the lower mantle in the form of power functions of the radius. In the present paper we shall instead develop the velocities as power series or polynomials of the radius. The two procedures are compared with regard to accuracy and convenience in applications. The power series expansion can permit higher accuracy in the representation of the velocities, but often entails greater complications in applications.     

Surface-wave magnitude corrections for intermediate and deep earthquakes

The small amplitudes of surface waves for intermediate and deep-focus earthquakes lead to too low values of the surface-wave magnitudes. On the basis of available material, average magnitude corrections are deduced, which increase with focal depth and amount to 0.1–0.5 for focal depths of 50 100 km and to 0.5–0.7 for depths of 100–700 km.     

A method for mapping seismic intensities applied to Sweden

Based on a combination of instrumental and macroseismic data, a method for calculating maximum seismic intensities is developed and applied to Sweden for the period 1951–1976. The method is particularly useful for areas with a low seismicity and a sparse population. Tectonophysical and engineering aspects on the resulting map are discussed.     

Continental dispersion of seismic surface waves

Summary Continental dispersion curves for Love and Rayleigh waves have been determined by means of the Uppsala seismograph records for three earthquakes near the south coast of Turkey in April, 1957. To the authors' knowledge this is the first time dispersion curves have been determined for a relatively homogenous path across the whole of continental Europe and covering a good range of periods, namely from 3 to 86 sec for Love waves and from 5 to 61 sec for Rayleigh waves. The dispersion curves obtained are relevant to determinations of the average structure along the path traversed in particular, and to determinations of crustal structure of the European continent in general.

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Zusammenfassung Kontinentale Dispersionskurven für Love-und Rayleigh-Wellen wurden vermittels Registrierungen an der Station Uppsala von drei Erdbeben in der Nähe der Südküste der Türkei im April 1957 bestimmt. Soweit es den Autoren bekannt ist, wurden damit erstmalig Dispersionskurven für einen relativ homogenen Weg über das gesamte kontinentale Europa mit einem beträchtlichen Periodenbereich, der 3 bis 86 Sek für Love-Wellen und 5 bis 61 Sek für Rayleigh-Wellen umfasst, ausgearbeitet. Die erhaltenen Dispersionskurven haben ihre Bedeutung in der Festlegung der mittleren Krustenstruktur entlang dem durchlaufenen Wellenweg und überhaupt in der Festlegung der Krustenstruktur im Bereich des europäischen Kontinents.

     

Seasonal variations of zinc in a eutrophic lake

Depth profiles of dissolved zinc were measured monthly over one year in Lake Greifen, a eutrophic lake. The concentrations are in the range 10–40 nM and show systematic variations over time and depth. Due to the increased binding to particles and subsequent settling, concentrations of zinc in the epilimnion decrease during summer stagnation. Clear correlations between Zn and major nutrients (P, Si) are, however, not observed in the water column. No accumulation of Zn occurs in the anoxic hypolimnion. The Zn sedimentation is related to the sedimentation of algae and of manganese oxide. A mass-balance calculation shows that 87% of the Zn input is retained in the sediments of Lake Greifen.     

Dating of soil layers in a young floodplain using iron oxide crystallinity

Dating of fluvial deposits is essential for a more quantitative understanding of landscape evolution and soil development in floodplain environments. We collected soil layers in defined depth intervals down to 60 cm along a substrate age gradient in a floodplain of the Danube River near Vienna, Austria. Depth profiles of fallout ¹³⁷Cs were used to assess short-term sedimentation, and optically stimulated luminescence (OSL) dating was used to attribute sediment deposits to time periods between the early last millennium BC and the 18th century AD. In the studied soils, the ratio of oxalate- to dithionite-extractable iron (Fe_o/Fe_d), which indicates the degree of iron oxide crystallinity, progressively decreased from ratios greater than 0.5 to values less than 0.2 with increasing soil age and proved to be a reliable indicator of soil maturity. We linked the observed Fe_o/Fe_d ratios to the radiometric and OSL ages in a chronofunction, which allows to approximately date soil layers that lack an independent age control. The soil ages calculated with this chronofunction accurately reflected their geomorphological position, resulted in consistent age trends with depth, and highlighted the active morphodynamics of the studied floodplain. The chronofunction was further validated by dating a soil profile near the studied chronosequence that contained an archaeological find dated to the La Tène period (5th to 1st century BC).     

Coupling the Xinanjiang model to a kinematic flow model based on digital drainage networks for flood forecasting

The Xinanjiang model, which is a conceptual rainfall‐runoff model and has been successfully and widely applied in humid and semi‐humid regions in China, is coupled by the physically based kinematic wave method based on a digital drainage network. The kinematic wave Xinanjiang model (KWXAJ) uses topography and land use data to simulate runoff and overland flow routing. For the modelling, the catchment is subdivided into numerous hillslopes and consists of a raster grid of flow vectors that define the water flow directions. The Xinanjiang model simulates the runoff yield in each grid cell, and the kinematic wave approach is then applied to a ranked raster network. The grid‐based rainfall‐runoff model was applied to simulate basin‐scale water discharge from an 805‐km² catchment of the Huaihe River, China. Rainfall and discharge records were available for the years 1984, 1985, 1987, 1998 and 1999. Eight flood events were used to calibrate the model's parameters and three other flood events were used to validate the grid‐based rainfall‐runoff model. A Manning's roughness via a linear flood depth relationship was suggested in this paper for improving flood forecasting. The calibration and validation results show that this model works well. A sensitivity analysis was further performed to evaluate the variation of topography (hillslopes) and land use parameters on catchment discharge. Copyright © 2009 John Wiley & Sons, Ltd.