Disruption index,DI: an approach for assessing seismic risk in urban systems (theoretical aspects)

Urban systems are characterized by very complex interactions. After an earthquake, a wide variety of services, networks and urban facilities may be unavailable to the public during the system failure and recovery processes, thereby causing disruptions in the basic social needs of the affected area. After a disaster, communities face several challenges. For example, the lack of education may impose population migrations, or malfunctions in the electricity distribution system can produce electrical power outages of varying duration with respect to time and space, which generates consequences in the water distribution system, transportation, communications, etc. A methodology called the Disruption index (DI), based on graph theory, includes these multiple interdependencies. It has been developed to estimate the dysfunction of some fundamental dimensions of urban systems on a broad level, starting with the physical damages directly suffered by the exposed assets, proceeding to the impacts that each node has on the functional performance of the nodes depending on them, until reaching the top node. This paper presents the fundamental theory to support the DI concept. The DI provides the likely impacts and consequences of an earthquake in an urban area to fulfill hazard mitigation and provide civil protection agencies and local and state governments with a new decision-making instrument to reduce or prevent severe and recurrent impacts. The DI concept can also be extended to other natural and man-made disasters and may be used as a tool for optimizing the resources of the system components.     

Mechanics of thick-skinned Variscan overprinting of Cadomian basement (Iberian Variscides)

Remnants of the Cadomian basement can be found in the Iberian Variscides (IBVA) in several key sectors of its autochthonous units (composed of Neoproterozoic to Lower Palaeozoic metasedimentary sequences) and within the Continental Allochthonous Terrane (CAT). Comprehensive characterization of these critical exposures shows that the prevailing features are related to major geological events dated within the age range of 620–540 Ma. Indeed, near the Cambrian–Ordovician boundary, the IBVA Internal Zones experienced pervasive basement thinning and cover thickening, reflecting diffusive displacement of intracratonic rifting that continued until Lower Devonian times. In the thick-skinned Internal Zones, Helvetic/Penninic style nappes were generated, whereas flower upright axial structures developed along transpressive, intraplate shear zones. These features contrast with those preserved in the thin-skinned IBVA External Zones, dominated by décollements above (un-)deformed Palaeozoic and Cadomian basement. The inferred attenuation of rheological contrast between Cadomian basement and Palaeozoic cover can be explained by inherited fabrics due to thermal softening operated during the Cambrian–Lower Devonian extensional regime. Deeper décollements (and subsequent strain partitioning) are also expected to develop at the upper-lower crust (and at the Moho?) transition, as imaged by the available seismic profiling and MT surveys. The whole data implies a significant discontinuity between Cadomian and Variscan Cycles that should have constrained subsequent lithospheric evolution.     

Protection areas of the São Pedro do Sul Spa, Portugal

This paper presents a case study of the protection areas of one of the Portugal's most important spas. According to its chemical composition this thermal mineral water is rich in bicarbonate, sodium, carbonate, fluor and sulfate. The therapeutic indications are mainly illnesses related to rheumatism and respiratory system. As a complement the thermal mineral water is also used for geothermal purposes, as in the heating of greenhouses for the production of Bananas and Ananas. The study presents geological and hydrogeological characterization of the area and its vulnerability to pollution and the physical and chemical characterization of the thermal mineral water. Finally, in accordance with the Portuguese legislation, the protection areas are defined: for immediate, intermediate and distant zones. The criteria and other aspects that led to their definition are also presented.     

Acute toxicity of platinum to coho salmon (Oncorhynchus kisutch)

The effects of short-term exposure to tetravalent platinum on survival, opercular movement and post-treatment growth of coho salmon fry (Oncorhynchus kisutch) was investigated. Employing a static water acute toxicity bioassay with platinum as PtCl₄2HCl·6 H₂O, at 8.5±0.2°C, and a water hardness of 55.9±3.5 mg l.^?1 (as CaCo₃), the 24, 48, and 96-h LC₅₀ values were 15.5, 5.2, and 2.5 mg Pt⁴⁺ l.^?1 respectively.Rates of opercular movement for fish exposed to platinum increased with increasing concentrations to a level of 1.0 mg l.^?1. No further significant increases were evident above this level. Hypoactivity of fish exposed to 0.3 mg l.^?1 and higher was evident during the acute toxicity bioassay and much of the post-treatment study. Post-treatment rate of growth for fish exposed to sublethal concentration of platinum for 96 h was less than that of the controls.All organs examined histopathologically were within normal ranges with the exception of the gills and olfactory organ. Lesions in fish exposed to concentration of 0.3 mg l.^?1 and higher were characterized by branchial epithelial hypertrophy and hyperplasia, and necrosis of olfactory epithelial cells.     

Rare-gas dating,I. A demountable metal system with low blanks

The construction and method of operation of an all-metal system for KAr and U-He dating is described in detail. The system is capable of handling samples in batches of about 15 g total weight. Blanks are typically 6 × 10^?9 cm³ STP for⁴⁰Ar_atmos, <1.2 × 10^?9 cm³ STP for⁴He, and ～2 × 10^?9 STP for⁴⁰Ar_radiogenic. The last of these quantities is independent of the quantity of⁴⁰Ar_radiogenic processed in the preceding run because vapor transport of the sample out of the hottest region of the crucible is very substantial and release of the rare gases in the sample is therefore almost complete. The system is very stable manometrically; monitoring of spike peaks therefore permits detection of any gas loss which amounts to more than a few percent. The system is not very suitable for analysis of large samples.     

Eutrophication and some European waters of restricted exchange

Regions of Restricted Exchange (RREs) are an important feature of the European coastline. They are historically preferred sites for human settlement and aquaculture and their ecosystems, and consequent human use, may be at risk from eutrophication. The OAERRE project (EVK3-CT1999-0002) concerns ‘Oceanographic Applications to Eutrophication in Regions of Restricted Exchange’. It began in July 2000, and studies six sites. Four of these sites are fjords: Kongsfjorden (west coast of Spitzbergen); Gullmaren (Skagerrak coast of Sweden); Himmerfjärden (Baltic coast of Sweden); and the Firth of Clyde (west coast of Scotland). Two are bays sheltered by sand bars: Golfe de Fos (French Mediterranean); and Ria Formosa (Portuguese Algarve). Together they exemplify a range of hydrographic and enrichment conditions. The project aims to understand the physical, biogeochemical and biological processes, and their interactions, that determine the trophic status of these coastal marine RRE through the development of simple screening models to define, predict and assess eutrophication. This paper introduces the sites and describes the component parts of a basic screening model and its application to each site using historical data. The model forms the starting point for the OAERRE project and views an RRE as a well-mixed box, exchanging with the sea at a daily rate E determined by physical processes, and converting nutrient to phytoplankton chlorophyll at a fixed yield q. It thus uses nutrient levels to estimate maximum biomass; these preliminary results are discussed in relation to objective criteria used to assess trophic status. The influence of factors such as grazing and vertical mixing on key parameters in the screening model are further studied using simulations of a complex ‘research’ model for the Firth of Clyde. The future development of screening models in general and within OAERRE in particular is discussed. In addition, the paper looks ahead with a broad discussion of progress in the scientific understanding of eutrophication and the legal and socio-economic issues that need to be taken into account in managing the trophic status of RREs.     

4.4 billion years of crustal maturation: oxygen isotope ratios of magmatic zircon

Analysis of δ¹⁸O in igneous zircons of known age traces the evolution of intracrustal recycling and crust-mantle interaction through time. This record is especially sensitive because oxygen isotope ratios of igneous rocks are strongly affected by incorporation of supracrustal materials into melts, which commonly have δ¹⁸O values higher than in primitive mantle magmas. This study summarizes data for δ¹⁸O in zircons that have been analyzed from 1,200 dated rocks ranging over 96% of the age of Earth. Uniformly primitive to mildly evolved magmatic δ¹⁸O values are found from the first half of Earth history, but much more varied values are seen for younger magmas. The similarity of values throughout the Archean, and comparison to the composition of the “modern” mantle indicate that δ¹⁸O of primitive mantle melts have remained constant (±0.2‰) for the past 4.4 billion years. The range and variability of δ¹⁸O in all Archean zircon samples is subdued (δ¹⁸O(Zrc)=5–7.5‰) ranging from values in high temperature equilibrium with the mantle (5.3± 0.3‰) to slightly higher, more evolved compositions (6.5–7.5‰) including samples from: the Jack Hills (4.4–3.3 Ga), the Beartooth Mountains (4.0–2.9 Ga), Barberton (3.5–2.7 Ga), the Superior and Slave Provinces (3.0 to 2.7 Ga), and the Lewisian (2.7 Ga). No zircons from the Archean have been analyzed with magmatic δ¹⁸O above 7.5‰. The mildly evolved, higher Archean values (6.5–7.5‰) are interpreted to result from exchange of protoliths with surface waters at low temperature followed by melting or contamination to create mildly elevated magmas that host the zircons. During the Proterozoic, the range of δ¹⁸O(Zrc) and the highest values gradually increased in a secular change that documents maturation of the crust. After ∼1.5 Ga, high δ¹⁸O zircons (8 to >10‰) became common in many Proterozoic and Phanerozoic terranes reflecting δ¹⁸O(whole rock) values from 9 to over 12‰. The appearance of high δ¹⁸O magmas on Earth reflects nonuniformitarian changes in the composition of sediments, and rate and style of recycling of surface-derived material into magmas within the crust. Electronic Supplementary Material Supplementary material is available for this article at     

The Greer Lake leucogranite, Manitoba, and the origin of lepidolite-subtype granitic pegmatites

The Archean Greer Lake leucogranite intruded metabasalts of the Bird River Greenstone Belt in the southwestern part of the Superior Province of southeastern Manitoba. The considerably evolved, multiphase, peraluminous, B-, P-, and S-poor leucogranite (K/Rb 132 to 24) was probably generated by fault-friction-assisted anatexis of dominantly metatonalitic rocks and subsequent differentiation. The leucogranite produced interior, transitional, non-crosscutting pods of barren, beryl-columbite- and lepidolite-subtype pegmatites that solidified from local segregations of highly fractionated residual melt. Steep fractionation gradients characterize the granite-to-pegmatite transition, most conspicuously so in the case of the most evolved, Li, Rb, Cs, Be, Mn, Sn, Nb-Ta, F-rich, lepidolite-subtype pod AC #3 (with K/Rb ≥ 16 and Cs 330 ppmwt in accessory K-feldspar, ≥2.5 and ≤11,200 ppmwt, respectively, in lepidolite, Cs ≤28,000 ppmwt in beryl, and Ta/(Ta+Nb) at. ≤ 0.95 in manganotantalite). The Greer Lake example documents beyond any doubt the igneous derivation of lepidolite-subtype pegmatites from a plutonic parent. Most cases of generally very scarce lepidolite-subtype pegmatites obscure this relationship, as the volatile-rich, highly fluid melts stable to relatively low temperatures commonly migrate to great distances from their plutonic sources.