Eine neue Darstellung der Seismizität unter Berücksichtigung des Herdvolumens     

Richard Maaz  Wolfgang Ullmann  Rezensent V. Kárník 《Studia Geophysica et Geodaetica》1972,16(3):221-229

Summary The projective seismicity of a single earthquake results from the local seismicity of the concerned quake. For the focal region a spherical and a cylindrical model are discussed. The volume of the focal region is identified with the focal volume. For calculation of the radius of both the sphere and the cylinder a common formula based on the Båth and Duda relation between the focal volume and the magnitude of an earthquake is used.

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Mitteilung Nr. 207 aus dem Zentralinstitut Physik der Erde der DAW zu Berlin, Institutsteil Jena.  相似文献   

Wind-generated internal waves and intertial-period motions     

Prof. Dr. Wolfgang Krauss 《Ocean Dynamics》1972,25(6):241-250

Summary The ocean is subdivided into a homogeneous upper layer (Ekman layer) and a continuously stratified lower layer. Horizontal velocities which in analogy to Fredholm's solution contain inertial oscillations, are generated in the upper layer by the tangential stress of the wind field varying both in space and time. The spatial structure of the wave field corresponds to that o the stress field. If the surface remains at rest (=0), vertical motions result from the horizontal oscillations. At the bottom of the Ekman layer the spatial structure of these vertical motions is proportional to divergence and rotation of the wind stress. Internal waves of the lower layer which primarily have periods approaching the inertial-period are generated by the vertical velocity field at the bottom of the Ekman layer (Ekman suction). Their structure is essentially more complicated than near the surface. Beats are a common phenomenon due to the superposition of internal modes.

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Windbedingte interne Wellen und Trägheitswellen

Zusammenfassung Das Meer wird in eine homogene Deckschicht (Ekmansche Reibungsschicht) und eine kontinuierlich geschichtete innere Region unterteilt. Die raum-zeitlich variable tangentiale Schubspannung erzeugt in der Deckschicht Horizontalgeschwindigkeiten, denen analog der Fredholmschen Lösung Trägheitswellen aufgeprägt sind. Ihre räumliche Struktur ist mit der des Schubspannungsfeldes identisch. Wenn keine Stauerscheinungen auftreten (=0), werden durch diese Horizontalbewegungen Vertikalbewegungen bedingt. An der Untergrenze der Ekman-Schicht ist deren räumliche Struktur der Divergenz und Rotation des Schubspannungsfeldes proportional. Das Vertikalgeschwindigkeitsfeld an der Untergrenze der Deckschicht erregt interne Wellen in der unteren Region, die vorwiegend Perioden in der Nähe der Trägheitsperiode aufweisen. Ihre Struktur ist wesentlich komplizierter als in der Deckschicht. Insbesondere zeigen sich Schwebungen.

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Ondulations internes dues au vent et mouvements dont la période dépend de l'inertie

Résumé L'Océan se divise en une couche supérieure homogène (couche d'Ekman) et une couche inférieure stratifiée d'une façon continue. Les vélocités horizontales, affectées, par analogie avec la solution de Fredholm, d'oscillations dues à l'inertie, prennent naissance dans la couche supérieure par suite de l'effort tangentiel du champ du vent, variable à la fois dans l'espace et dans le temps. La structure du champ du vent, dans l'espace, correspond à celle du champ de l'effort. Si la surface reste calme (-0) les mouvements verticaux sont dus aux oscillations horizontales. Au fond de la couche d'Ekman, la structure dans l'espace de ces mouvements verticaux est en rapport avec la divergence et la rotation de l'effort du vent. Les ondulations internes de la couche inférieure qui ont, à l'origine, des périodes proches de celle due à l'inertie, sont engendrées par le champ de la vitesse verticale au fond de la couche d'Ekman (succion d'Ekman). Leur structure est beaucoup plus compliquée que près de la surface. Les battements sont un phénomène commun du à la superposition de modes internes.

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The Influence of NaBr/NaCl Ratio on the Br--Catalysed Production of Halogenated Radicals     

Wolfgang Behnke  Manfred Elend  Ulrich Krüger  Cornelius Zetzsch 《Journal of Atmospheric Chemistry》1999,34(1):87-99

The activation of Br^- and Cl^- to atomic Br and Cl in sea-spray aerosol was investigated in smog-chamber experiments. In the presence of O₃, hydrocarbons and NaCl aerosol alone no activation was observed. By adding Br^- to the aerosol, the chain reaction: Br + O₃ BrO, BrO + HO₂ HOBr, HOBr HOBr(aq), HOBr(aq) + H⁺ + Br^- Br₂ (6), HOBr(aq) + H⁺ + Cl^- BrCl (7) was verified. The step from reaction (6) to (7) is accompanied by a decrease of the Br^-/Cl^- ratio from 1/600 to less than 1/2000. In the absence of sulphate, the chain is initiated by the reaction of OH(aq) with Br^-. The pH value decreases to less than 2 during the first minutes of the experiment and later on to almost 1 (in the absence of NO_x or SO₂). This is caused by the formation of oxalic acid from alkanes and toluene. In stopped flow experiments, the reduction of Br₂ by oxalic acid was observed to occur through a two-step mechanism: HC₂O₄ ^- + Br₂ Br^- + BrC₂O₄H (k₂₂, k_-22), BrC₂O₄H Br^- + H⁺ + 2 CO₂ (23) with the following rate constants and ratios of rate constants, k ± 2: k₂₂k_-23 / k_-22 = (2.9 ± 0.3) · 10^-4 s^-1, k_-22 / k_-23 = 7000 ± ₃₀₀₀ ¹³⁰⁰⁰ M^-1, k₂₂ = 2 ±_-1 ⁴ M^-1 s^-1, and k_-23 > 0.1 s^-1, k_-22 > 600 M^-1 s^-1. Oxalic acid may be responsible for the inhibition of the chain reaction observed at the end of the experiments.  相似文献   

Seismic anisotropy of the crystalline crust: what does it tell us?   总被引：2，自引：0，他引：2  

Wolfgang Rabbel  Walter D. Mooney 《地学学报》1996,8(1):16-21

The study of the directional dependence of seismic velocities (seismic anisotropy) promises more refined insight into mineral composition and physical properties of the crystalline crust than conventional deep seismic refraction or reflection profiles providing average values of P-and S-wave velocities. The alignment of specific minerals by ductile rock deformation, for instance, causes specific types of seismic anisotropy which can be identified by appropriate field measurements.
Vice versa , the determination of anisotropy can help to discriminate between different rock candidates in the deep crust. Seismic field measurements at the Continental Deep Drilling Site (KTB, S Germany) are shown as an example that anisotropy has to be considered in crustal studies. At the KTB, the dependence of seismic velocity on the direction of wave propagation in situ was found to be compatible with the texture, composition and fracture density of drilled crustal rocks.  相似文献   

On a scalar fixed altimetry—gravimetry boundary value problem     

Wolfgang Keller 《Journal of Geodesy》1996,70(8):459-469

For some years existence and uniqueness of the solution of a mixed altimetry — gravimetry boundary value problem is under investigation. Usually the size and the shape of the continental part of the Earth's surface is considered as unknown. This leads to a partly free and partly fixed mixed boundary value problem. A solution exists if the area of the continental part is sufficiently small. Obviously, this condition is not fulfilled in reality. Because the GPS is now fully operational, nowadays the size and the shape of the continental part of the Earth's surface can be considered as known, too. The aim of this article is to study the resulting fixed mixed boundary value problem and to prove the existence and uniqueness of its solution for an arbitrary distribution of land and sea at the Earth's surface.  相似文献   

Laudatio for Prof. Baarda     

Wolfgang Torge 《Journal of Geodesy》1996,70(12):876-877

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Auswirkungen des Extremhochwassers 1999 auf die Flächendynamik und Bestandsstruktur der Uferröhrichte des Bodensees     

Klaus Schmieder  Michael Dienst  Wolfgang Ostendorp 《Limnologica》2002,32(2)

In consequence of the extreme flood at Lake Constance in 1999 the reed belts showed a severe loss in vitality so that a permanent damage could be expected. The monitoring project presented here focuses the documentation of the damage following the disturbance event, the identification of co-factors, and is designed to find out significant stressors that may impede the recovery of the reeds. The monitoring is based on CIR aerial photo interpretation, quantitative GIS-analyses and field data. The design of the study implies the definition of five degrees of damage using the interpretation of CIR aerial photo series from July 2000. The aquatic reed beds were digitised and areal sums were calculated. These data were compared with the corresponding data from 1999 and 1993. Stand structural and biomass attributes were investigated in 50 randomly distributed permanent plots covering all site types and damage degrees. The results showed a loss of about 24 hectares of aquatic reeds at Lake Constance Untersee alone. The stands which had survived showed a great patchiness in terms of culm density, shoot population composition, culm architecture, and aboveground biomass production. Severely damaged stands were mainly composed of secondary shoots, whereas primary and insect infested shoots dominated in less damaged stands. One co-factor which explained the patchiness was the vertical position of the stand, i.e. the probability of being severely damaged increased with increasing distance below mean water level. The monitoring programme will be continued till 2003.  相似文献   

Pb/Pb age determinations on the Newania and Sevattur carbonatites of India: evidence for multi-stage histories     

Helmut Schleicher  Wolfgang Todt  Shrivinas G. Viladkar  Fatemeh Schmidt 《Chemical Geology》1997,140(3-4):261-273

The ages of Indian carbonatites are still controversial. Most of the earlier datings were done by K/Ar methods. We therefore analysed Pb/Pb ratios in carbonatites from carbonatite-alkalic complexes of Newania (NW India, Rajasthan State) and Sevattur (SW India, Tamil Nadu State) to constrain the age and geological history of these rocks. Newania carbonatites are intrusive into Precambrian Untala granite-gneiss and mainly dolomitic in composition (rauhaugite) followed by a later phase of ankerite carbonatite, while thin calcite carbonatite (sövite) dykelets are the youngest in the sequence. The analysed whole-rock samples are characterised by ²⁰⁶Pb/²⁰⁴Pb ratios between 60 and 176 and ²⁰⁷Pb/²⁰⁴Pb ratios between 22 and 40, which are extremely high in comparison to common igneous rocks and even for carbonatite compositions. One sample, New 37, shows the extreme ratios of ²⁰⁶Pb/²⁰⁴Pb = 574 and ²⁰⁷Pb/²⁰⁴Pb = 73. This requires a μ-value of about 2000 for the last 1550 Ma. If the samples are classified according to their petrographic/geochemical characteristics this results in an isochron age of 1551 ± 46 Ma for the ankerite carbonatites (six samples). The dolomites (6 samples) yield an isochron age of 2.27 Ga. Although these results fit quite well into the geological evolution scheme of the area, the extreme long age hiatus between dolomite carbonatite and ferrocarbonatite formation events raises severe problems for their petrologic interpretation.

The Proterozoic Sevattur carbonatite complex (SCC, Tamil Nadu) was emplaced contemporaneously with a large number of carbonatite complexes within the Precambrian gneissic terrane of the Eastern Ghats Mobile Belt. The main mass is composed of dolomite carbonatite (rauhaugite) with a few dikes of calcite carbonatite (sövite) and ankerite carbonatite within it. All eight samples together yield an isochron of 805 ± 10 Ma. This isochron is mainly determined on ankerite carbonatites with μ-values up to 1900 for the last 800 Ma. Taking only ankerite carbonatites into account, the resulting age is 801 ± 11 Ma. The ²⁰⁶Pb/²⁰⁴Pb and ²⁰⁷Pb/²⁰⁴Pb ratios of these samples are similar to the main group of Newania and far beyond the isotopic composition of common igneous rocks.

Our investigations show that in carbonatitic rock systems extremely high lead isotopic ratios can be established due to the crystallization of uranium-rich mineral phases. In both cases the observed high to extremely high initial Pb isotope ratios require the residence of the lead in intermediate high-μ reservoirs either within the upper mantle or the crust prior to the carbonatite formation. A high-temperature event, which completely reset the Rb/Sr and K/Ar isotopic systems of Nevania carbonatites, seems to have no influence on the lead isotopic systematics.  相似文献   

Phanerozoic magmatic activity in the northwestern part of the Trans-European Suture Zone     

Wolfgang Kramer 《Studia Geophysica et Geodaetica》1995,39(3):320-329

Summary Indicators of magmatism in the northwestern part of the Trans-European Suture Zone are outlined. The igneous rocks are predominantly mafic and of mantle origin. The changing character of the magma geochemistry of the Permosilesian volcanic series (rhyolitic-andesitic and MORB-type/continental tholeiites), via Uckermark and Rügen to Skåne, is consistent with the changing crustal thickness along the border of Baltica. Some features of Early Palaeozoic volcaniclastic sediments hint at Early Palaeozoic oceanic development (ophiolite association ?) in a suture zone, whereas the Permo-Carboniferous to Eocene volcanic associations are related to rift structures and deep-seated structural elements within the Tornquist-Teisseyre Zone (TTZ).  相似文献   

Discovery of the high-field polar RX J1724.0+4114     

Jochen Greiner  Robert Schwarz  & Wolfgang Wenzel 《Monthly notices of the Royal Astronomical Society》1998,296(2):437-441

We report the discovery of a new AM Herculis binary (polar) as the optical counterpart of the soft X-ray source RX J1724.0+4114 detected during the ROSAT all-sky survey. The magnetic nature of this V  ∼ 17 mag object is confirmed by low-resolution spectroscopy showing strong Balmer and He  II emission lines superimposed on a blue continuum, which is deeply modulated by cyclotron humps. The inferred magnetic field strength is 50 ± 4 MG (or possibly even ≈ 70 MG). Photometric observations spanning ∼ 3 yr reveal a period of 119.9 min, directly below the period gap. The morphology of the optical and X-ray light curves, which do not show eclipses by the secondary star, suggests a self-eclipsing geometry. We derive a lower limit on the distance of d  ≳ 250 pc.  相似文献