Analysis of the weightiness of site effects on reinforced concrete (RC) building seismic behaviour: The Adra town example (SE Spain)

The damage distribution in Adra town (south‐eastern Spain) during the 1993 and 1994 Adra earthquakes (5.0 magnitude), that reached a maximum intensity degree of VII (European Macroseismic Scale (EMS scale)), was concentrated mainly in the south‐east zone of the town and the most relevant damage occurred in reinforced concrete (RC) buildings with four or five storeys. In order to evaluate the influence of ground condition on RC building behaviour, geological, geomorphological and geophysical surveys were carried out, and a detailed map of ground surface structure was obtained. Short‐period microtremor observations were performed in 160 sites on a 100m × 100m dimension grid and Nakamura's method was applied in order to determine a distribution map of soil predominant periods. Shorter predominant periods (0.1–0.3 s) were found in mountainous and neighbouring zones and larger periods (greater than 0.5 s) in thicker Holocene alluvial fans. A relationship T = (0.049 ± 0.001)N, where T is the natural period of swaying motion and N is the number of storeys, has been empirically obtained by using microtremor measurements at the top of 38 RC buildings (ranging from 2 to 9 storeys). 1‐D simulation of strong motion on different soil conditions and for several typical RC buildings were computed, using the acceleration record in Adra town of the 1993 earthquake. It is noteworthy that all the aforementioned results show the influence of site effects in the degree and distribution of observed building damage. Copyright © 2007 John Wiley & Sons, Ltd.     

Origin of magnetic minerals and natural remanent magnetization of basaltic rocks from Lower Silesia,Poland

Summary Two groups of basaltic rocks with normal and reversed NRM were examined. It was found that in both groups the primary NRM, synchronous with the period of rock formation, is preserved. Relations of the primary NRM to the origin and the degree of oxidation of magnetic minerals were considered in detail.     

Petrography, chemistry and origin of early diagenetic concretions in the Lower Carboniferous of the Isle of Man

Three silicified limestone horizons of D1 age from the Visean of the Isle of Man contain calcitic concretions with peripheral silica crusts, occasionally surrounded by a further calcitic layer. Components of the original sediment include carbonate skeletons, carbonaceous grains, sponge spicules and muscovite. Diagenetic products include calcite, dolomite, pyrite, sphalerite, clays, feldspar and quartz. The concretions are composed of neomorphic calcite. The time of recrystallization and the identity of the neomorphic precurosor are both unknown. Displacive, fibrous calcite is chemically similar to neomorphic calcite and both are of early diagenetic age. Granular and rhombic ferroan calcites are of late diagenetic age and were precipitated from pore-waters with Sr/Ca, Mg/Ca and Fe/Ca ratios unlike those of seawater. The difference between early silicification which produced silica crusts and later diffuse silicification of the host sediment is related to a change in sediment transmissivity between the two silicification periods. A four-fold scheme of concretionary growth is proposed. The supply of silica is from sponge spicules and that of carbonate from seawater via porewater. The distribution of organic matter, either as sporadic large carcasses or as small carcasses concentrated in particular horizons, is believed to be vital for carbonate precipitation and controls the distribution of concretions. Awareness of the multiplicity of diagenetic changes is essential in interpretation of early porewater systems and in the origin of products which are often metastable and destined to subsequent changes. No single model is an explanation for all types of concretionary growth.     

澳大利亚的第三纪及第三纪—第四纪过渡期(英文)

第三纪的板块运动驱动着澳大利亚的气候和植被进行演化。广布的湿润森林区是澳大利亚老第三纪的特征。一直到始新世 ,生物多样性都在不断地提高。毫无疑问 ,这是澳大利亚由高南纬区向北部中纬区运移的结果。从始新世到上新世 ,澳大利亚的气候总体上要比现在湿润 ,但降水量季节性变化的增强推动了中新世以后硬叶植物和旱生植物的发展。上新世晚期似乎与第四纪一样 ,都出现过周期性干旱。这种干旱与冰期条件有关 ,至少由南澳大利亚晚第四纪的记录可以认识到这一点 ,澳大利亚的这段历史与东亚的气候变迁是同步发生的。在东亚 ,印—澳板块的运动致使青藏高原抬升 ,从而引发了区内乃至全球气候的巨变。穿越赤道区的季风和信风的环流格局 ,致使新第三纪和第四纪中国与澳大利亚的气候系统的相关性更强。     

Conversion between solid and beam element solutions of finite element method based on meta-modeling theory: development and application to a ramp tunnel structure

In this study, a new method for conversion of solid finite element solution to beam finite element solution is developed based on the meta-modeling theory which constructs a model consistent with continuum mechanics. The proposed method is rigorous and efficient compared to a typical conversion method which merely computes surface integration of solid element nodal stresses to obtain cross-sectional forces. The meta-modeling theory ensures the rigorousness of proposed method by defining a proper distance between beam element and solid element solutions in a function space of continuum mechanics. Results of numerical verification test that is conducted with a simple cantilever beam are used to find the proper distance function for this conversion. Time history analysis of the main tunnel structure of a real ramp tunnel is considered as a numerical example for the proposed conversion method. It is shown that cross-sectional forces are readily computed for solid element solution of the main tunnel structure when it is converted to a beam element solution using the proposed method. Further, envelopes of resultant forces which are of primary importance for the purpose of design, are developed for a given ground motion at the end.     

Regional setting of Håkon Mosby Mud Volcano, SW Barents Sea margin

The Håkon Mosby Mud Volcano (HMMV) is a seafloor mud volcano, having a 1-km-diameter circular shape and a relief of 8–10?m. HMMV is located within a slide scar on the Bjørnøya glacial submarine fan on the SW Barents Sea slope, and is underlain by a >6-km-thick Cenozoic sequence. Multichannel seismic data reveal a 1- to 2-km-wide disturbed zone, which extends to a depth of >3?km below the HMMV. We relate the zone to the presence of free gas. The seismic data are compatible with an intrasedimentary sourced mud volcano related to the glacial sedimentation history and mass movements.     

A system for large volume aerosol sampling in the stratosphere using electrostatic precipitation

Summary An instrumental system for securing aerosol samples in the stratosphere by electrostatic precipitation has been developed. The system is designed to be balloon borne to altitudes between 30 km and 45 km and to collect with high efficiency the aerosol content of the stratosphere at these altitudes. Volumetric sampling rates of one meter³ sec^–1 ambient air are obtained with the sampling configuration with collection efficiency in excess of 95 percent for particles between .01 microns (mmd) and 2 microns (mmd).Specially developed associated instrumentation for altitude and air flow measurement points to an important versatility in the application of gas discharges for low-pressure (or high altitude) altimetry and anemometry over a very wide range of air densities and tempertures.The theory, operation, and performance of the aerosol sampling system and associated subsytems are described. Certain new observations of low-density corona physics phenomena are reported and potential applications to other areas of research and technology are indicated.

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Zusammenfassung Es wurde ein Instrument entwickelt, mit dem man Aerosolproben aus der Stratosphäre durch elektrostatischen Niederschlag erhalten kann. Das System wird von einem Ballon in Höhen zwischen 30 und 45 km getragen und sammelt mit hoher Wirksamkeit Proben des Aerosolgehalts in diesen Höhen. Mit dem Instrument wird eine Sammelgeschwindigkeit von 1 m³/sek erreicht bei einer Sammelwirksamkeit von mehr als 95% für Partikel von Größen zwischen 0,01 und 2 Mikron.Besonders entwickelte angeschlossene Instrumente zur Messung der Höhe und der Luftströmungen zeigen die wesentliche Vielseitigkeit der Anwendung von Gasentladungen für die Höhenmessung und Windmessung bei niedrigem Druck (oder in großen Höhen) in einem großen Bereich der Luftdichte und der Temperatur.Es werden die Theorie, die Arbeitsweise und die Ausführung des Aerosolprobeninstrumentes und der angeschlossenen Hilfssysteme beschrieben. Es wird über einige neue Beobachtungen aus dem Bereich der Phänomene der Gasentladungen bei niedriger Dichte berichtet und neue mögliche Anwendungen in anderen Zweigen der Forschung und Technologie werden angegeben.

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Résumé On a construit un instrument au moyen duquel on peut obtenir des échantillons d'aérosole stratosphérique par précipitation électrostatique. Le système est emporté par un ballon à des altitudes de 30 à 45 km et rassemble avec efficacité des echantillons du contenu de l'aérosole à ces altitudes. Avec cet appareil, on obtient une vitesse de prise de 1 m³/sec avec une efficacité de plus de 95% pour les particules comprises entre 0,01 et 2 microns.Des appareils spéciaux annexes permettent de mesurer la hauteur et les courants d'air. Ils démontrent les possibilités multiples de l'utilisation de la décharge dans un gaz pour la mesure de l'altitude et des vents par pression très faible (ou à très haute altitude) dans un domaine étendu tant de la densité de l'air que de la température.On décrit dans ce mémoire la théorie, le mode de travail et l'exécution de cet instrument de prise d'échantillons d'aérosoles ainsi que des systèmes auxiliaires annexes. On rapporte sur quelques nouvelles observations faites dans le domaine des phénomènes connexes à la décharge dans un gaz par faible densité. On indique en outre de nouvelles possibilités d'utilisation du système dans d'autres branches de la recherche ou de la technologie.

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With 16 Figures

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This work has been supported by the Division of Biology and Medicine, U. S. Atomic Energy Commission, under contract at (30-1)-2363 with Del Electronics.     

Structure of the crust and upper mantle in Canada

The seismic probing of the crust and upper mantle in Canada started in 1938 and since then has involved many government and university groups using a wide variety of techniques. These have included simple profiling with both wide and narrow station spacing, areal time-term surveys, detailed deep reflection experiments, very long-range refraction studies and the analysis of surface wave dispersion between stations of the Canadian Standard Network.

A review of the published interpretation leads to the general conclusion that:

1. (1) P_n-velocities vary from a value possibly as low as 7.7 km/sec under Vancouver Island to 8.6 km/sec and higher in the extreme eastern part of the shield and some parts of the Atlantic coast.

2. (2) Large areas of Canada have a crustal thickness of 30–40 km, with Vancouver Island, the southwestern Prairies, the Lake Superior basin and parts of the eastern shield of Quebec being thicker. No continental area in Canada is known to have a crust thinner than 29 km.

3. (3) The Riel discontinuity — a deep intra-crustal reflector and sometime refractor, is widely reported in the Prairies and Manitoba. It is not seen to the north in the vicinity of Great Slave Lake, nor in the Hudson Bay, Lake Superior and Maritime regions, nor in the interior of British Columbia. It may be present in some areas of the eastern shield.

4. (4) As experiments have become more detailed, crustal structures of greater complexity have been revealed. The concept that crustal structure becomes simpler with increasing depth is apparently unfounded.

Long-range refraction studies suggest that the Gutenberg P-wave low-velocity channel is poorly developed under the Canadian Shield. The analysis of the dispersion of surface waves, however, suggests that the channel is better developed for S-waves, and is present throughout the country. The lid of the channel is deepest under the central shield and shallowest under the Cordillera.