The end of iron-mining operations in France's Lorraine region has raised the problem of post-mining management. Collapses and subsidence have recently occurred in this region, which focused on the necessity to develop a specific methodology for risk zoning. The proposed methodology is based on the multi-criteria decision-aid approach called 'ELECTRE TRI', with aim to assign zones at risk into predefined classes. It allows experts opinions, qualitative and quantitative criteria and uncertainties to be taken into account.

Abstract. Rockfalls are a major and essentially unpredictable sources of danger, particularly along transportation routes (roads and railways). Thus, the assessment of their probability of occurrence is a major challenge for risk management. From a qualitative perspective, it is known that rockfalls occur mainly during periods of rain, snowmelt, or freeze-thaw. Nevertheless, from a quantitative perspective, these generally assumed correlations between rockfalls and their possible meteorological triggering events are often difficult to identify because (i) rockfalls are too rare for the use of classical statistical analysis techniques and (ii) not all intensities of triggering factors have the same probability. In this study, we propose a new approach for investigating the correlation of rockfalls with rain, freezing periods, and strong temperature variations. This approach is tested on three French rockfall databases, the first of which exhibits a high frequency of rockfalls (approximately 950 events over 11 years), whereas the other two databases are more typical (approximately 140 events over 11 years). These databases come from (1) national highway RN1 on Réunion, (2) a railway in Burgundy, and (3) a railway in Auvergne. Whereas a basic correlation analysis is only able to highlight an already obvious correlation in the case of the "rich" database, the newly suggested method appears to detect correlations even in the "poor" databases. Indeed, the use of this method confirms the positive correlation between rainfall and rockfalls in the Réunion database. This method highlights a correlation between cumulative rainfall and rockfalls in Burgundy, and it detects a correlation between the daily minimum temperature and rockfalls in the Auvergne database. This new approach is easy to use and also serves to determine the conditional probability of rockfall according to a given meteorological factor. The approach will help to optimize risk management in the studied areas based on their meteorological conditions.

The extraction of ore and minerals by underground mining often causes ground subsidence phenomena. In urban regions, these phenomena may induce small to severe damage to buildings. To evaluate this damage, several empirical and analytical methods have been developed in different countries. However, these methods are difficult to use and compare due to differences in the number of criteria used (from 1 to 12). Furthermore, the results provided by damage evaluation may be significantly different from one method to another. The present paper develops vulnerability functions based on a concept that has been applied in other areas, such as earthquake engineering, and that appears to be a more efficient way to assess building vulnerability in undermined cities. A methodology is described for calculating vulnerability functions in subsidence zones using empirical methods. The first part of the paper focuses on existing empirical methods for damage evaluation, and selected necessary improvements or modifications are justified. The second part focuses on the development of a building typology in subsidence zones and its application in the Lorraine region, where many villages are subject to subsidence problems due to iron-ore mining. The third section describes and discusses the adopted methodology for determining vulnerability and fragility functions or curves. Finally, vulnerability functions are tested and validated with a set of three subsidences that occurred in Lorraine between 1996 and 1999.

This paper presents a synthesis of a multidisciplinary study carried out along the Nîmes Roman aqueduct, located in the southeast part of France. The study was motivated by archaeologists attempting to explain the partial destructions of only one aerial bridge of the aqueduct (Pont de la Lône). Given its close proximity to the Nîmes seismically active fault, a possible seismic origin for the destructions was invoked. Seismologists and structural engineers thus carried out a variety of field and numerical investigations to test the seismic hypothesis. Supporting field evidence was found first along the aerial bridge section of the aqueduct: broken stalactites, arch warping, cracks and destruction of the bridge just above a breast wall shortly after its construction. Secondly, the underground part of the canal was analysed: irregularity in the thickness of calcite deposits of the canal walls, presence of numerous cracks, horizontal shift of the otherwise linear structure of the canal and presence of calcite twins in the deposits, found only where P. Volant Á O. Scotti (&) IRSN/DEI/SARG/BERSSIN, the canal crosses the Nîmes fault system. Numerical modelling and experimental results show that (1) only the Pont de la Lône would have suffered serious damage under seismic solicitation (assuming an M6 earthquake at 10 km distance). The second aerial bridge, the three levels arches Pont du Gard, an historical monument still standing today, would have suffered less damage, due to its very different fundamental frequency of around 0.4 Hz, far from the amplified seismic near-field spectrum; (2) the numerical models also show that a fall of the canal wall would require a higher magnitude event (M [ 6); (3) the presence of calcite twinning requires a differential static stress of 4 MPa or greater, which can only be achieved very close to the fault rupture of a M [ 6 earthquake; (4) finally, local surface rupturing of such a fault would also corroborate the hypothesis that the observed offset of the canal may be partly seismically induced. Although other possible origins for each individual evidence may not be excluded, the observed spatiotemporal concentration of architectural/geological anomalies together with the numerical results allow us to support a possible co-seismic origin for these disorders, indirectly attesting to the potential seismic activity (M [ 6) of the nearby Nîmes fault. Furthermore, following the conclusions of archaeological studies, the disorders occurred between 250 and 350 year AD, thus providing timing for this possible seismic event, an essential parameter in seismic hazard analysis. These results validate the archaeo-seismological approach as a tool that may help improve the knowledge of major infrequent earthquakes in areas of moderate seismic activity.

Abstract. This paper attempts to provide a decision support framework that can help risk managers in urban areas to improve their decision-making processes related to sustainable management. Currently, risk management strategies should no longer be selected based primarily on economic and technical insight. Managers must address the sustainability of risk management by assessing the impacts of their decisions on the sustainable development of a given territory. These assessments require tools that allow ex ante comparisons of the effectiveness and the likely economic, social and ecological impacts of the alternative management strategies. Therefore, this paper reports a methodological and operational framework, which aims to incorporate sustainability principles in a particular decision by taking all the dimensions that affect sustainability into account. This paper is divided into two main parts: one on the theoretical aspects of the proposed methodology and the other on its application to a flood risks management case in a municipality located in Meurthe-etMoselle county (France). The results of the case study have shown how the methodology can be suitable for determining the most sustainable decision.