Macroseismic risk classification of historical constructions: the LEXSIS approach

The present paper deals with the elaboration of a methodology to assess the macro-seismic risk of monumental historical buildings, representing a fundamental part of the European cultural assets. Monumental buildings typically arise from a very complex constructive and morphological evolution process characterised by modifications occurred over the centuries. Therefore, they are usually heterogeneous buildings similar to 'structural aggregates' rather than single constructions and characterised by a structural behaviour depending on the mutual interaction of different structural units. An accurate knowledge process can allow the determination of structural units within the complex: such units can be therefore analysed using a specific evaluation form conceived to provide a 'risk ranking' of the different portions constituting the aggregate and accounting for vulnerability, exposure and seismic hazard parameters. The proposed methodology exploits what is already used to quickly determine structural features and eventual damages in the post-earthquake phase for ordinary buildings, introducing specific aspects typical of historical-cultural heritage requiring attention. According to the results achieved, retrofit interventions or deepen investigations can be planned for units provided by a higher position in the risk scale, optimising and rationally planning the use of available economic and time resources. In the present work, the proposed methodology is applied to the monumental complex of the Certosa di Calci, Pisa (Italy).

Modelling forest ruin due to climate hazards

Estimating the risk of forest collapse due to extreme climate events is one of the challenges of adapting to climate change. We adapt a concept from ruin theory, which is widely used in econometrics and the insurance industry, to design a growth–ruin model for trees which accounts for climate hazards that can jeopardize tree growth. This model is an elaboration of a classical Cramer–Lundberg ruin model that is used in the insurance industry. The model accounts for the interactions between physiological parameters of trees and the occurrence of climate hazards. The physiological parameters describe interannual growth rates and how trees react to hazards. The hazard parameters describe the probability distributions of the occurrence and intensity of climate events. We focus on a drought–heatwave hazard. The goal of the paper is to determine the dependence of the forest ruin and average growth probability distributions on physiological and hazard parameters. Using extensive Monte Carlo experiments, we show the existence of a threshold in the frequency of hazards beyond which forest ruin becomes certain to occur within a centennial horizon. We also detect a small effect of the strategies used to cope with hazards. This paper is a proof of concept for the quantification of forest collapse under climate change.

The presence of radioactive heavy minerals in prospecting trenches and concomitant occupational exposure

Uranium, perhaps the most strategically important component of heavy minerals, finds particular significance in the nuclear industry. In prospecting trenches, the radioactivity of 238U and 232Th provides a good signature of the presence of heavy minerals. In the work herein, the activity concentrations of several key primordial radionuclides (238U, 232Th, and 40K) were measured in prospecting trenches (each of the latter being of approximately the same geometry and physical situation). All of these are located in the Seila area of the South Eastern desert of Egypt. A recently introduced industry standard, the portable hand-held RS-230 BGO gamma-ray spectrometer (1024 channels) was employed in the study. Based on the measured data, the trenches were classified as either non-regulated (U activity less than 1000 Bq kg-1) or regulated (with 238U activity more than 1000 Bq kg-1). Several radiological hazard parameters were calculated, statistical analysis also being performed to examine correlations between the origins of the radionuclides and their influence on the calculated values. While the radioactivity and hazard parameters exceed United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR) guided limits, the mean annual effective doses of 0.49 and 1.4 mSv y-1 in non-regulated and regulated trenches respectively remain well below the International Commission on Radiological Protection (ICRP) recommended 20 mSv/y maximum occupational limit. This investigation reveals that the studied area contains high uranium content, suitable for extraction of U-minerals for use in the nuclear fuel cycle.

Natural radioactivity and radiological risks of common building materials used in Semnan Province dwellings, Iran

Impact assessment of building materials is a focused topic in the field of radioecology. A radiological survey has conducted to monitor radioactivity of most common building materials in Semnan Province, Iran, and assess the radiation risk. Activity concentrations of 226Ra, 232Th, and 40K were measured in 29 samples including nine commonly used building materials that were collected from local suppliers and manufacturers, using a high purity germanium gamma-ray detector. The activity concentrations of 226Ra, 232Th, and 40K varied from 6.7±1 to 43.6±9, 5.9±1 to 60±11, and 28.5±3 to 1085±113 Bq kg−1 with averages of 26.8±5, 22.7±4, and 322.4±4 Bq kg−1, respectively. By applying multivariate statistical approach (Pearson correlation, cluster, and principal component analyses (PCA)), the radiological health hazard parameters were analyzed to obtain similarities and correlations between the various samples. The Pearson correlation showed that the 226Ra distribution in the samples is controlled by changing the 232Th concentration. The variance of 95.58% obtained from PCA resulted that the main radiological health hazard parameters exist due to the concentration of 226Ra and 232Th. The resulting dendrogram of cluster analysis also shows a well coincidence with the correlation analysis.

GIS-based Flood Susceptibility Mapping Using Overlay Method in Central Sulawesi

Central Sulawesi is the largest province on the Sulawesi island with a dominant sloping topographic condition and has a variety of soil types, flow density, land use and rainfall that makes this region vulnerable to flooding. Flooding is a hydrometeorological disaster that will adversely affect aspects of human life such as social and economic activities in an area because it can cause environmental damage, casualties and disrupt economic activity. Because of its enormous impact, the purpose of this research study is to find out areas in the province of Central Sulawesi that are suscept to flooding. The method used in this research study is scoring the classification of flood hazard parameters such as slope level, elevation, soil type, rainfall, land use and flow density which are then overlay using ArcGis 10.2.2. The results obtained that the province of Central Sulawesi has three categories of areas suscept to flooding with a low category 6630.3 km2, moderate 46081.9 km2 and high category 7104.7 km2. Based on the results and discussion, it can be concluded that Central Sulawesi province has a dominant level of vulnerability which is moderate.