The MICROPRONY project aims to study a unique shallow serpentinized alkaline hydrothermal system located in Prony Bay in the southern lagoon of New Caledonia. The hydrothermal circulation at Prony is created by in-depth serpentinization reactions while the meteoric water percolates through the peridotite, generating very alkaline fluids, rich in H2, CH4, and abiotically formed organic compounds. This system has characteristics similar to those of terrestrial serpentinized sources (ex California, Oman) but also underwater (ex. Lost City). The study of these systems brings important elements for the understanding of the processes at the origin of life on Earth. The main objective of the project - which builds on the results of our previous researches on this site - is to understand the functioning of this ecosystem, focusing on metabolisms using H2, CH4, and abiotically formed organic compounds. Our working assumptions are as follows: i) Prony microorganisms are specific to serpentinized environments and have developed specific metabolic strategies to cope with very difficult living conditions (few or no electron acceptors, extremely high pH); (ii) Contrary to the widely shared assumption that microbial life in the deep subsurface is mainly due to chemiolithoautrophy (the "SLIME" hypothesis), we propose that the organic compounds produced by the serpentine reactions allow the growth of chemoorganotrophic bacteria, in particular, uncultivated relatives of Clostridiales as well as Phyla candidates such as Parcubacteria, Acetothermia, and Omnitrophica, and possibly of methanogenic archaea (Methanosarcinales). These bacteria, along with the methanogens, could thus constitute major primary producers in this type of ecosystem. To respond exhaustively to these two hypotheses, we propose a multidisciplinary approach led by a scientific team that will gather among the best specialists in their field. This approach will incorporate advanced analytical techniques to cover a wide range of spatial resolution. It is subdivided into 5 main tasks: 1) Identify the main microbial actors of the Prony ecosystem and elucidate their functions using cultural and molecular (metagenomic) approaches - 2) Characterize the age, nature and structure of microbial habitats, their associated microflora, and micro-mineral interactions, using a range of isotopic dating techniques, molecular imaging (coupled confocal microscope - Raman/FTIR spectrometry, FISH, SEM), 3) Describe in detail the fluid geochemistry for a robust interpretation of the biogeochemical processes operating at Prony and compare them with those of other terrestrial or marine serpentinized systems using a panel of geochemical analysis techniques. 4) Determine the relative importance of biotic vs abiotic productions, particularly CH4 and other organic compounds (HC, organic acids, etc.) present in fluids, by clumped isotopes thermometry methods (13C and D) - 5) Model the key metabolisms of the Prony microbial ecosystem by integrating on the one hand bioenergetic calculations based on the thermodynamics of metabolic reactions and geochemical data, and on the other hand the functional annotation of metagenomes/metatranscriptomes. The realization of the scientific program proposed here will allow us to exhaustively define the interactions between geochemical and microbiological processes in an environment that may have been abundant on Earth at the beginning of abiogenesis and that can now be compared to that of other planets of the solar system, candidates to host alien life forms (e.g. Europa, Enceladus).

Almost 2/3 of Earth's surface is covered by oceanic crust formed at mid-ocean ridges where >70% of the total magma flux is concentrated. In the last decades it has been shown that the magmatic system, which has long been seen as a melt-dominated system, is rather mushy: magmatic but with a high crystal fraction. This modifies the expected thermal regime, the modes of melt migration, and the igneous processes that give rise to the crust by differentiation and magma emplacement. Despite tremendous progress made over the last decades by a multidisciplinary marine geoscience community, our understanding of the oceanic magma plumbing architecture and of the related igneous processes at both fast- and slow-spreading ridges still needs to be refined and quantified. More specifically, the modes of differentiation that have been considered during decades to be governed by fractional crystallization (operating in crystal-poor mediums) are now revisited, and a yet poorly constrained reactive porous flow process is now widely proposed. The objective of MUSH-OCEAN is to make a breakthrough in our understanding of oceanic magmatic systems. With MUSH-OCEAN we will provide brand new constraints on 1/ the temporal (e.g., lifespan), spatial, and thermal relations between magma (s.s.) bodies (with 40 % crystals, thus not mobilizable), 2/ the kinematics of melt collection and migration in mushy reservoirs, and 3/ the igneous processes that govern mush evolution, and thus the overall differentiation of oceanic igneous reservoirs (reactive porous flow). Finally, beyond allowing a major advance in our understanding of oceanic magmatic systems (>2/3 of magmatism on Earth), the understanding of the processes governing the evolution of magmatic mushes will allow a better understanding of the majority of igneous systems in other geodynamic contexts since these crystal-rich mediums seem to be dominant in general.

Populations located on active volcanoes are at huge risk from both explosive and effusive eruptions. Although the explosive risk is well known and researched, the effusive risk less so. Fatalities are very rare during effusive eruptions, but lava flow inundation will require replacement and/or relocation of community and all infrastructure, as well as timely evacuation. In addition, all vegetation will be burnt and buried. However, even though most effusive centers with significant populations are heavily vegetated, the effect of vegetation on the ability of lava to move is unknown. If drying and burning of vegetation does have a cooling effect, then placement of vegetation barriers may even reduce the rate of flow propagation; thus being an ecologically friendly means of delaying lava ingress into populated areas. Likewise, we have no knowledge on the effect of down flow degassing on flow cooling, crystallization, rheology and hence dynamics. We will thus fill these knowledge gaps to allow improved modeling of lava flows through vegetation and into vulnerable populations. Execution of modeling as part of a geographical information system containing building type, population and land value layers will also allow assessment of, and preparation for, loss. The system will also allow implementation of cost benefit analyses to assess the need for, and effect of, diversion, mitigation and replacement measures. Recent studies have shown that the way in which we respond to volcanic disasters is framed by the media is key if the nature of the crisis is to be correctly understood and prepared for. Thus, we also need to research the way in which results and science are communicated to, and then used by, the media and recipient population, to understand and respond to the crisis with which they are faced. If we understand the framing process, we can implement effective communication and education protocols to ensure that the message is correctly received. Scientifically, we need to be prepared to help resident populations to use hard information to respond and develop resilience. Preparation will thus also involve use of open-access information nodes to allow effective education and outreach, as well as workshop-based exercises that involve the entire community. We will fulfill these science needs by combining two foreign partners and four French laboratories at three different institutions to provide a response system capable of real-time implementation during an effusive crisis, as well as education prior to crises. There will be special focus on the French Island of La Réunion which is heavily vegetated and where volcanic risk is a major concern.

STRAP is a project for trans-disciplinary collaboration to investigate volcano plumes risks. It involves volcanologists and atmospheric scientists of four “Observatoires des Sciences de l’Univers INSU-CNRS” (OSU-R, OPGC, IPGP and OMP). All volcanic plumes can cause environmental, economic and societal hazards, but lack of knowledge on their physics and time evolution make prediction and forecast difficult. Improving our ability to quantify and model of the genesis, spread and impact of a volcanic plume is thus a key challenge for scientists and societal stakeholders. Mitigation of such volcanic crises relies on efficient, and effective, communication and interaction between key scientific actors in geology, physics, chemistry and remote sensing. The ultimate goal is to fully constrain on the volcanic source terms needed by physical and chemical modellers to predict the ascent, dispersion and the impact of volcanic ash and gas in the atmosphere. Within this context, this project aims apply an integrated approach to investigate, analyse and model the processes of formation and maturation of volcanic plumes during their transport from their source to their most distal points. The main scientific objective is to reduce the large uncertainties in characterisation of the key volcanic source terms, i.e. mass discharge rate and composition of the gas and particles mixture erupted from the vent. It needs to be convolved with fundamental atmospheric parameters, such as formation of particles in the upper atmosphere, plus direct and indirect radiative forcing due to the presence of volcanic particles. A first task will be to parameterize the process of volcanic convection in an atmospheric mesoscale model, with three main lines of enquiry: i) field-based studies of pyroclastic deposits, ii) study of dilute volcanic plumes, iii) study of dense ash and gas volcanic plumes. The second task will be to analyse the physicochemical evolution of plume optical properties and their variation over local scale and regional scales. This analysis involves tri-phase processes with the partition of the mixture between gas, particles and atmospheric plus volcanic- and atmospheric-origin water. The highly variable concentrations between the source and distal areas, as well as competition between different mechanisms (homogeneous and heterogeneous nucleation, condensation, coagulation, and activation) have to be considered. The final task will be to combine the two precedent tasks, accurately accounting for complex other external heat sources (e.g., atmospheric convection to concurrent lava flows beneath a dispersing plume). The principal aim is to integrate all of these processes in a tri-dimensional atmospheric mesoscale model. One of the deliverables of this final objective relates to a better analysis of environmental and human health risks related to population exposure to high concentrations of gas and particle charged air. Etna (or Stromboli -as an alternative) volcanoes in Italy, as well as Piton de la Fournaise volcano (La Réunion, France) will be used as test beds for deployment of new instrumentation. Kilauea (Hawai’i, USA) will constitute an alternative target to Piton de la Fournaise given the on-going collaboration with Hawaiian Volcano Observatory. These test beds will provide well-documented case data-sets for input into modelling activities. With regard to observations, the strategy will be to implement observing systems near the vents (for gas and particles thermodynamic observations) and around the convective plumes (for gas concentrations, particle size distributions, cloud optical properties, condensation nuclei properties, and aerosol chemistry). Physical modelling will focus on a 1-D model for volcanic plumes propagation at local scale and incorporating detailed parameterization of air entrainment, to scale up to a 3-D non-hydrostatic model at a regional scale.

Perennially frozen slopes occur in many mountain ranges of the world, and temperature changes in these environments have notable impacts on the state of permafrost, leading to increased slope instability and hazard from mass movements. In areas of discontinuous permafrost, these slopes can be hard to identify with certainty. This project investigates “molards” – cones of loose debris that result from thawing of blocks of ice-rich sediments mobilised by landslides in permafrost terrains. Molards are an understudied landform and have recently been shown to be an indicator of recent and ongoing permafrost degradation. In addition, they have spatial and geomorphic characteristics that reveal the dynamics of large mass movements. The PERMOLARDS project aims to build on these exciting new results and use molards as a geomorphological tool to understand climate change and natural hazard. We will use a multidisciplinary combination of field investigation, dating, laboratory and numerical simulations, modelling and remote sensing analysis to understand molard formation, evolution, morphology, longevity, and their environmental settings. We will explore three unique case studies in Greenland, Canada and Iceland, where we have identified with certainty molards that formed under climatic conditions from the Holocene to the present in a variety of geographic settings. We will constrain the morphological degradation of molards in space and time by using a morphological approach and novel luminescence dating techniques. We will define the range of material properties and ice configurations under which molards can form through field investigations and through simulation via analogue models in a laboratory cold room. Based on these results ancient molards can then be used to infer ground-ice contents. We will establish the baseline criteria to distinguish molards from other mounds in landslide deposits using remote sensing and field data that can be used by other researchers. We will use 3D numerical models to assess the potential role of thaw fluids in molard-hosting landslides in modifying the flow behaviour and its impact on hazard. We will monitor and model the state of permafrost at the field site in Greenland to ascertain the state of permafrost degradation represented by molards in new and recent landsides. Finally, we will establish the use of molards as a geomorphological tool to track permafrost degradation in time and in different geological and geographical settings around the globe. By developing these actions, the project provides insights into permafrost degradation in space and time, and the hazard posed by landslides in cold environments.