Seismic hazard represents a major worldwide scientific issue in view of potential catastrophic consequences experienced by people and facilities. Methodological developments to improve our ability to evaluate the seismic hazard are then of particular importance. We focus here on the so-called site effects that correspond to the modification of the seismic motion by the local geological configuration and that can lead to dramatic seismic amplifications. By being related to local conditions, site effects are highly variable from one site to another. That is why site-specific studies can greatly contribute to improve the hazard prediction at a specific site in comparison to ergodic estimates based on data from global databases. However site-specific studies have historically been considered difficult to carry out in low-to-moderate areas (such as France and Germany) where moderate to large earthquakes have long return periods. The DARE project proposes to exploit data from 2 complimentary dense passive experiments (100s of captors) that will be acquired on one specific km-scale sedimentary basin in the French Rhône valley. These data will be used to investigate the contribution and interest of innovative methods combining dense array processing and the use of seismic noise to offer possibilities to perform site-specific studies using relatively short temporary experiments in low-to-moderate areas. The density of instruments proposed will help to 1) improve the spatial resolution of imaging studies, allowing for a better characterization of the basin and 2) to catch the variability and multi-dimensional features of the site effects. We propose to adopt a multi-approach estimation of site effects using different seismic observations (noise & seismicity) and approaches (numerical & empirical). This strategy will allow us to propose and confront alternative methods; evaluate their own interests, uncertainties and limitations. The application of this integrated procedure in the Rhône Valley will lead to a robust estimation of site effects in an area where many critical infrastructures are located. Beyond improving our knowledge of this specific basin, the results of the project DARE will more generally contribute to improve seismic site effect estimation in terms of 1) methodological developments, 2) understanding of physical processes leading to seismic amplifications and 3) observations on km-scale western European sedimentary basins. Site-specific results obtained in this project will be confronted to estimates based on ergodic approaches that are commonly used in seismic hazard assessment studies especially in low-to-moderate areas. This will help understand the conditions of applications and limitations of the use of such ergodic approaches in seismic site effect estimations.

Human activities linked to nuclear industry generate ionizing radiation (IR). However, their ecotoxicological properties are poorly studied on non-human organisms. In radio-contaminated areas, there is no scientific consensus concerning their effects on structure and functioning of the ecosystems, and the potential underlying mechanisms of their action are poorly known. Therefore, it is important to acquire data on the potential effects of IR on ecosystems both in experimental and realistic conditions. This project will try to estimate the environmental consequences of a major nuclear accident by studying an emblematic of pollinating insect, the honeybee, which presents scientific, economic and societal stakes, through the services provided by this species to the society and ecosystems. This project will also contribute to improve knowledge on effects and mechanisms of action of IR on honeybees, by using a combined approach of laboratory and field experiments and could allow to foresee more global consequences on pollinators responsible for a great part of vegetal biodiversity. The main objectives of the project are: - To define the exposure conditions both in laboratory and field experiments (in order to compare results obtained via these two approaches) and measure in both conditions the real external dose rates experimented by the bees by means of carried micro-dosimeters; these values, in addition to the internal dose rates, will give an accurate estimation of the total dose rates absorbed by bees (WP1), - To measure the physiological and toxico-pathological effects induced by IR at sub-individual levels including molecule, cell and tissue, particularly with response to an infectious agent (WP2), - To measure the effects induced by IR at individual and populational levels through the effects on reproduction/development and cognitive process (WP3), - Compare both types of exposure (laboratory/field), integrate the responses and extrapolate to other living organisms (other bee species, other pollinating insects) through modelling in order to conclude on the level of effects of IR on bees and other pollinating insects (WP4). Expected results cover a large broad of domains: (i) what are the accurate absorbed (external + internal) dose rates and doses experimented by bees, (ii) what are the modes of action by which IR induce adverse effects in bees, (iii) which physiological and toxico-pathological parameters are affected by IR, with a focus on combined effects of IR on sensitivity of bees to pathogens, (iv) which parameters are modified by IR at the colony level, including hive production (in relation with ecosystem services), (v) what is the resilience of hives exposed to IR during an apicultural season, (vi) if bees exposed in the field are more or less sensitive to IR than bees exposed in the laboratory (comparison of responses) and (vii) through modelling approaches, what can be the expected consequences of IR exposure on other pollinating insects. Our results will offer the possibility of a better risk assessment by a better prediction of the biological responses induced by IR on pollinating insects. This project is innovative for several reasons. It proposes (i) to study the effects of IR on honeybees, very poorly known up to now, (ii) to establish a basis of knowledge on mechanisms of action of IR in honeybees and (iii) to relate responses observed at the cellular/organ scale to integrative process at the individual/population scale by studying reproduction and repercussions of effects at the colony level. Moreover, the project will combine experiments in the laboratory and in the field, more representative of the environment. This complementarity will serve to draw useful conclusions for the environmental radioprotection. The benefits of this program can be expected at scientific, agro-environmental and socio-economic levels.

Large continental earthquakes often produce a complex surface rupture pattern, including multiple strands, jogs, or deformation along secondary faults. Such variability of the surface ruptures signs similar complexity happening at depth, where earthquake propagates along complex faults. Although surface rupture is still a primary observation for earthquakes, it has been long disregarded as not representative of deeper seismic processes. New high-resolution satellite imagery now allows quantifying surface deformation in details and brings new insights on earthquake processes. At the same time, hazard practitioners, who were mostly focused on seismic hazard, for practical reasons are now more often turning their attention to fault displacement hazard assessment, meaning assessing the probability of occurrence of surface ruptures at a given site and for a given earthquake. The project DISRUPT addresses the physical processes controlling the occurrence of surface ruptures to be able, in fine, to test the predictive power of numerical simulation tools to be used by hazard practitioners. To do that we propose to develop new deformation measurement methodologies, to look how distributed deformation is triggered through successive earthquake cycles, to use analogue modeling to assess parameters controlling rupture morphology, and to confront all our observations with dynamic rupture simulation tools to test their capacity to predict realistic rupture patterns. Deformation measurement methods: On one hand, we will develop methods to take advantage of the large archive of analogue historical aerial and satellite images to be correlated with modern optical satellite imagery, to increase the number of well-documented earthquake ruptures. On the other hand, we will use systematic multi-stereoscopic sub-metric image acquisition by satellites to build direct high-resolution 3D deformation maps. Secondary deformation and earthquake cycle: Taking advantage of the well-documented 1905, M8+, Bulnay earthquake in Mongolia, using paleoseismological methods we will test if secondary ruptures are systematically activated during successive large earthquakes or if there is a magnitude threshold. The 1967, M7+, Mogod rupture (Mongolia) will offer the possibility to test the impact of preexisting geologic structures on fault growth. Earthquake analogue modeling: We will take advantage of new materials with properties allowing for stick-slip behavior in a controlled experimental set-up to run parametric studies on parameters controlling rupture morphology. Surface deformation simulation: We will implement two codes allowing for simulation of surface ruptures due to dynamic earthquake propagation. On one hand, we will run earthquake simulations within complex 3D fault systems to assess impact of fault geometry on surface rupture morphology. On the other hand we will run simulation where off-fault deformation can spontaneously develop as part of surface ruptures. These simulations will be both confronted to our observational datasets to assess their respective predictive power.

The understanding of the coupled thermo-hydro-mechanical behaviour of fault zones in naturally fractured reservoirs is of fundamental importance for a variety of societal and economic reasons, such as the sustainable energy transition for the safe use of natural resources (energy storage, nuclear waste disposal or geothermal energy). The overall objective of this project is to better understand the physical processes resulting from a thermal and hydric load on an existing, identified and characterized fault zone. The idea here is to carry out a thermally controlled in situ fluid injection experiment in one of the faults accessible from the Tournemire underground research laboratory (URL). A heating system will be installed around the injection area and enable a precise and controlled incremental increase of the thermal load. In addition, an important monitoring system will be installed to measure the seismic and aseismic events induced either by thermal or by hydraulic loading. The monitoring system will be composed of acoustic and broadband sensors that will measure low to medium magnitude events. Furthermore, it is also planned to install a fibre optic network to measure temperature and displacement in a distributed manner in the investigation area. The active seismic methods will be deployed before and after the experiment to determine the structural network but also to detect the appearance of new structures triggered from the hydro-thermal pressurisation of the fault. A series of laboratory experiments will be conducted to understand the chemical and structural evolution occurring within the fault zones during the thermal and hydraulic loading. Experiments in climatic chambers exposing the samples to the same heat treatment as that of the in situ experiment will be carried out in order to compare the mineralogical composition evolution of the samples with those taken from the field investigated zone. Finally, a rock mechanical study, from the microscopic to the centimeteric scale with monitoring of the acoustic properties will be carried out. This study will include experiments from Scanning Electron Microscope with Energy Dispersive Spectroscopy (SEM-EDS) allowing the identification of the micro-scale mechanisms of deformation localization to which it is planned to add an acoustic measurement system. In order to study the evolution of mechanical behaviour as a function of scale, experiments in triaxial press, again with acoustic monitoring, are planned.

TRAJECTOIRE aims to establish past and predictive trajectories of contaminants at the outlets of the major French watersheds (Rhône, Loire, Seine, Garonne, Rhine, Meuse, Moselle) for substances brought about by human activities in these environments during the technological, industrial and environmental development that punctuated the 20th century: radionuclides, microplastics and their additives, and critical metals. These non-legacy substances are currently at the heart of reflections on the energy transition. By considering these three families of contaminants we expect to draw lessons learned based on the differentiated and successive time scales of their inputs, which were governed by institutions and public policies according to distinct management modes. By considering them, we expect to draw general lessons on the environmental resiliency regarding contaminants, and then to positioning or repositioning current environmental concerns face to new and future technologies. In other words, it will be a question of evaluating how society can be an actor of the resilience of the environment following anthropic disturbances from economic choices, political decisions and collective actions. In river systems, sediments convey and store most of contaminants introduced in the catchment. Therefore, sedimentary archives in perennial storage areas, such as riverbanks or alluvial margins, give testimonials on previous contaminations and anthropic pressures. Feedbacks on the ability of large rivers to absorb or remove anthropogenic pressures will be established by reconstructing time-series of: 1) contamination levels based on sedimentary records and 2) pressures exerted on environments and responses provided by institution and society, based on analyses of documentary archives. The difficulties of such retrospective exercise, requiring to cross multiple and complex information, are all the greater as the statistical sources concerning contaminants are rare or confidential. The causal links between the observed contamination levels in sedimentary archives (quantitative data sets) and the anthropic pressures determined from documented archives (qualitative and semi-quantitative data sets) will be assessed using neural network analyses for time series prediction. Time series models are purely dependent on the idea that past behavior and patterns can be used to predict future behavior and trends. By using these models on data sets acquired at the outlets of major French rivers, various anthropic pressures will be considered and their consequences on the concentration of contaminants over time will be identified. Socio-historical events, acquired from documented archive analyses, will be characterized regarding their impact on concentrations, the time-lag between their occurrence and the environmental impact, and the duration of the environmental perturbation. The values of these three parameters associated to the best fittings between the data and times series models will define key pressures to be implemented in a predictive model based on scenario in order to forecast the levels of contaminants in river systems and estimate trajectories and resiliencies for the short, medium and long terms. Our results will put forth the environmental changes that succeeded over the last industrial era, and will help to predict those expected depending on our future conduct. We consider that society needs such feedbacks as well as predictive vision in order to reinforce environmental awareness and future decision making related to the sustainability of ecosystems. Our project aims to give quantitative feed backs and predictive models based on scenarios in order to inform stakeholders on environmental impacts of their past and future decisions, over short and longer term time periods. It aims to demonstrate that society can act on environmental resiliency.