Depositional facies and stratal geometry of an Upper Carboniferous prograding and aggrading high-relief carbonate platform (Cantabrian Mountains, N Spain)

Seismic‐scale continuous exposures of an Upper Carboniferous (Bashkirian–Moscovian) carbonate platform (N Spain) provide detailed information about the lithofacies and stratal geometries (quantified with differential global positioning system measurements) of microbial boundstone‐dominated, steep prograding and aggrading platform margins. Progradational and aggradational platform‐to‐slope transects are characterized by distinct lithological features and stratal patterns that can be applied to the understanding of geometrically comparable, high‐relief depositional systems. The Bashkirian is characterized by rapid progradation at rates of 415–970 m My^?1. Characteristic outer‐platform facies are high‐energy grainstones with coated intraclasts, ooids and pisoids, moderate‐energy algal‐skeletal grainstones to packstones and lower energy algal packstone and boundstone units. The Moscovian aggradational phase is characterized by aggradation rates of 108 m My^?1. Coated‐grain shoals are less common, whereas crinoidal bars nucleated in well‐circulated settings below wave‐base. Boundstones form a belt (30–300 m wide) at the platform break and interfinger inwards with massive algal‐skeletal wackestones (mud‐rich banks). The progradational phase has divergent outer‐platform strata with basinward dips of 12° to 2°. Steep clinoforms with dips of 20–28° are 650–750 m in relief and possibly sigmoidal to concave in the lower part. The basinward‐dipping outer‐platform strata might be depositional for less than 6°, consistent with lithofacies deepening seaward. The basinward dip is attributed to the downward shift of upper‐slope boundstone, forced by late highstand and relative sea‐level fall, and to compaction‐induced differential subsidence during progradation. The aggradational phase is characterized by horizontally layered platform strata. Clinoforms steepen to 30–45° reaching heights of 850 m and are planar to concave. The evolution from progradation to aggradation, at the Bashkirian–Moscovian boundary, is attributed to increased foreland‐basin subsidence and decreased boundstone accumulation rates. Progradation was primarily controlled by boundstone growth rather than by highstand shedding from the platform top. Within the major phases, aggradational–progradational increments are produced by third‐ to fourth‐order relative sea‐level fluctuations.     

Quantitative risk analysis for hyperconcentrated flows in Nocera Inferiore (southern Italy)

This paper reports on a quantitative estimation of the risk to residents at the toe of Mount Albino, a carbonatic relief covered by shallow deposits of pyroclastic soils, which threatens the municipality of Nocera Inferiore (southern Italy). The quantitative risk analysis (QRA) focuses on one type of mass transport phenomena typical for the context at hand, namely the hyperconcentrated flows. The methodological approach includes three main steps: hazard analysis, consequence analysis and risk estimation. Based on historical incident data, the hazard analysis makes use of a high-resolution digital terrain model and advanced models that incorporate relevant geological and geotechnical input data collected via in situ investigations and laboratory tests. The consequence analysis takes into account information on the exposed persons (age, gender) and their vulnerability. The estimated risk to life is calculated at the individual level (risk to the average and most exposed person). The reported procedure is one of the first QRA’s applications to instabilities which potentially affect natural slopes in Italy, and it was successfully used as technical basis for a public participatory process in Nocera Inferiore, designed and developed to support decisions about risk mitigation measures.

     

Recent geophysical investigation at Somma-Vesuvio volcanic complex

Activity at Somma-Vesuvio volcanic area in southern Italy is monitored by seismic stations and periodic geodetic and gravity surveys. The seismic network, which consists at present of four vertical stations and one three-component station, recorded an increase in earthquake activity in 1978 and between November 1988 and March 1989. During the later activity, earthquakes were located in a cluster about 3 km beneath the summit of the volcano. Two tide gauges, two tiltmeters and a recording gravimeter are also operating at Somma-Vesuvio. Yearly levelling surveys are conducted along several closed routes that extend from as much as 6 km from the base of the volcano to the summit area. Survey results reveal no significant ground movement since 1959, except for a slight subsidence around the rim of the summit crater. Gravity changes have been larger than the expected 10 μGal uncertainty of the measurements. The lack of contemporary elevation changes implies that the observed gravity changes are the result of a slight change in density structure. The cone of Somma-Vesuvio has been very stable for the last few decades, showing no indications of a buildup to activity. The lack of surface movement should rule out a magma-supply rate to this volcano at the historic eruptive rate of 0.002 km³/yr.     

Use of microfluidic experiments to optimize MICP treatment protocols for effective strength enhancement of MICP-treated sandy soils

Microbially induced calcium carbonate (CaCO₃) precipitation (MICP) has been extensively studied for soil improvement in geotechnical engineering. The quantity and size of calcium carbonate crystals affect the strength of MICP-treated soil. In this study, microfluidic chip experiments and soil column experiments were conducted to optimize MICP treatment protocols for effective strength enhancement of MICP-treated sandy soils. The microscale experiments reveal that, due to Ostwald ripening, longer injection intervals allow crystals to dissolve and reprecipitate into larger crystals regardless of the concentration of cementation solution. Even though a cementation solution input rate of 0.042 mol/l/h is sufficient to maintain a high chemical transformation efficiency, a further reduction in the input rate by about four times resulted in an increase in the size of crystals produced by the end of treatment from about 40 to 60 μm. These findings were applied in soil column experiments. Results showed that significantly larger crystals and higher soil strength were achieved when the normalized rate of cementation solution injection was reduced from 0.042 to 0.021 mol/l/h. Crystal size and soil strength increased slightly more when the normalized input rate was further reduced from 0.021 to 0.010 mol/l/h. This study demonstrates how data from microscale microfluidic experiments that examine the effects of injection intervals and concentration of cementation solution on the properties of calcium carbonate crystals can be used to optimize MICP treatment in macroscale sand soil column experiments for effective strength enhancement.

     

L'organisation capitaliste du territoire et le problème du logement en Italie

The capitalistic organization of territory and the housing problem in Italy.This paper provides the first results of a research programme regarding the selective and spatially differentiated use of the Italian territory by private capital in the housing sector.According to the 1971 census, in Italy there were 63,8 million rooms for 53,2 million inhabitants. As regards the 1951 census the increase of rooms has been of 26,5 million, i.e. of 70.9%, as against an increase of 15,6% of the population. In this period the investment in dwelling-houses has represented about 30% of total fixed investments which is more than in the other E.E.C. countries.The Italian building stock (with a medium average of 1.2 rooms per inhabitant), is theoretically sufficient to satisfy the population needs. This ratio, however, drops to 1.06 if we exclude the 7.6 million rooms in non-inhabited houses (“holiday houses”, new unsold houses, abandoned homes because of emigration or because of their poor conditions).Moreover, more than one third of the Italian population lives in overcrowded conditions (less than one room per person) and poor standard houses are 40% of the total.This is not only due to the fact that public investments in the housing sector have been insignificant (6% in the last ten years), or to the unequal social distribution of revenue, but also, moreover, to the speculative character of the building activity.The economic analysis shows that between 1951 and 1971, in the expansive stages of housing production, net incomes of the building and land sector have increased more rapidly than the total earned incomes and that they have been higher than the amount of investments in the sector. So, building and land estate rent have been among the main components of the Italian capitalistic accumulation through the exporpriation of a prominent share of wages. At the same time, the ever increasing growth in housing prices both for sale and for rent has forbidden the fulfilment of the needs of the lower classes, extending in an abnormal way the production of luxury and “holiday houses” to satisfy the requirements of the higher classes. This is the cause of the above mentioned contradiction between the amount of the unused or subused building stock and the existence of a large number of sub-standard and/or overcrowded houses.This mechanism of accumulation-expropriation worked because of a specific spatial structure. Its main character consists in a strong geographical concentration of the basic activities and of the population. 53.3% of 1960–1971 housing production has concentrated in 4.7% of the Italian communes with more than 20,000 inhabitants.The analysis carried out on a stratified sample including 1,524 communes allowed us to reach the following results: 1. We find situations of greater unsatisfaction of the needs in the largest industrial metropolitan north-western areas and in the underdeveloped southern communes with strong emigrations. 2. We have had the highest offer for houses, as regards the needs, in the communes with less than 5,000 inhabitants, in the communes with less than 250,000 inhabitants, with prevalently tertiary functions, and in the districts where development is more equilibrated, from a territorial point of view (i.e.: north-eastern Italy). 3. The mechanism of accumulation-expropriation worked mainly in the industrial areas and it grows at the ever increasing growth of agglomerations and urban overcrowding, determined by strong migratory flows. 4. Building activity of tertiary communes has been led, mainly, by the higher-class expansion of consumptions. 5. The same kind of demand has given rise to the strong increase of “holiday houses” which interests large periurban, coastal and Alpine areas. 6. The housing sector becomes in this way a component of territorial disequilibriums, caused by the industrial and tertiary polarization and it is inclined to enlarge them by the artful increase of urban rent. 7. This use of territory has the aim to encourage incomes removal among different social classes and to contribute in this way, to the process of capitalistic accumulation. But, by doing this, it causes a kind of growth, in the housing sector, which is unable to satisfy lower-class needs for houses. 8. The attainment of this last purpose would, therefore, mean an efficient regional planning and the elimination of urban rent, conditions which are in opposition to the maintenance of the present economic and social structure of the Italian economy, of which speculative building and rent sectors are, nowadays, essential components.     

Social acceptability of marine aquaculture: The use of survey-based methods for eliciting public and stakeholder preferences

The social acceptability of aquaculture is linked to its perceived environmental impact, and this clearly poses a challenge to policy makers in deciding what weight to attach to such a concern within a governance framework for the industry. Using salmon farming in Scotland as a case study, we have developed a survey-based approach to evaluating public and stakeholder attitudes towards the environmental performance of aquaculture. The survey of the general public finds marked regional variations in attitudes towards salmon farming, while the results of the stakeholder survey raise issues over how far the preferences of particular interest groups are truly representative of the community as a whole.     

Wave propagation velocity under a vertically vibrated surface foundation

The ultimate objective of the research conducted by the authors is to explore the feasibility of determining reliable in situ values of soil modulus as a function of strain. In field experiments, an excitation is applied on the ground surface using large‐scale shakers, and the response of the soil deposit is recorded through receivers embedded in the soil. The focus of this paper is on the simulation and observation of signals that would be recorded at the receiver locations under idealized conditions to provide guidelines on the interpretation of the field measurements. Discrete models are used to reproduce one‐dimensional and three‐dimensional geometries. When the first times of arrival are detected by receivers under the vertical impulse, they coincide with the arrival of the P wave; therefore related to the constrained modulus of the material. If one considers, on the other hand, phase differences between the motions at two receivers, the picture is far more complicated and one would obtain propagation velocities, function of frequency and measuring location, which do not correspond to either the constrained modulus or Young's modulus. It is necessary then to conduct more rigorous and complicated analyses in order to interpret the data. This paper discusses and illustrates these points. Copyright © 2008 John Wiley & Sons, Ltd.