ECOLOGICAL STATUS AND TRAJECTORIES OF CHANGE IN TEMPERATE AND TROPICAL REEFS

Amongst marine temperate and tropical ecosystems, Mediterranean rocky reefs and Maldivian coral reefs are the most productive and diverse, providing essential ecosystem services. Unfortunately, due to several co-occurring local and global pressures, they are ranked as the most threatened marine habitat. The present work attempts to analyse their ecological status and change over time in a global warming scenario. With this purpose, different methodological approaches have been adopted. Many studies have been conducted in Marine Protected Areas (MPAs), highlighting that the constant updating of species inventory and surveillance is still necessary, also after their establishment. Monitoring of target species is a valuable tool in assessing ecological status of the environment they live in. Tackling the case of a species in need of protection confirmed how detailed information on species distribution is mandatory to develop effective environmental management plans. Non-destructive techniques are to be preferred when studying and monitoring target species and valuable habitats. By comparing data collected from different observers, visual methods have proven reliable and effective in the characterization of habitat and evaluation of change over time. By applying standardized protocols and monitoring water temperature, mass mortality event and target species this work unveiled effects of climate change in all study areas, regardless of different latitude and level of protection. Due to the climate change marine ecosystems are increasingly exposed to the cumulative effects of different pressures. Analysis of short-term change in a benthic community showed that the cumulative effect of multiple stressors is stronger than that of any individual stressor, no matter how intense it is. As a result of local and global human pressures, marine ecosystems have undergone important changes that can only be detected by analysing long-term data series or revisiting sites already surveyed. By assessing change over time at three different level of complexity (i.e., population, community, and ecosystems), this work addresses the issue of decreasing abundance of native species in correspondence with increasing number of invasive species. The findings confirmed that in a given reef, a turnover in species composition determine a change in community structure. Biodiversity provides a buffer to maintain ecosystem functioning in the face of environmental changes, and decrease in functional redundancy, due to the community change, demonstrated reduced ecosystem resilience. Global warming, and the consequent changes in marine ecosystems, are occurring at an unprecedented rate and on a worldwide scale. In this context, a cooperative effort between research and international environmental policy is urgently needed

Implementation and Evaluation of Distributed Acoustic Sensing (DAS) for Continuous Seismic Monitoring of Geothermal Fields in the Munich Area (Germany)

Supplying district heating networks with geothermal energy becomes a high priority to support the energy transition in areas prone to geothermal exploitation. The growth of this energy sector provides the industry with previously unavailable resources to implement advanced monitoring strategies, aiming to foster sustainable operation of the resource. In this context, local operators of the Munich area (Germany) are interested in the capabilities of the Distributed Fiber Optic Sensing (DFOS) for routine monitoring of the production and of the operated hydrothermal system – the porous Malm reservoir. We share the outcomes and knowledge acquired from DAS measurements conducted over two years on two dedicated infrastructures in the Munich area. One consists of a 700 m long fiber optic cable (FOC), which is deployed in an injection well of the Schäftlarnstraße geothermal field. The second site consists of an 80-meter FOC section deployed in a loop configuration near surface and a dedicated well reaching a depth of 250 meters, complemented by a surface broadband seismometer. Our analysis encompasses a comprehensive range of monitoring tasks, starting from the handling of the substantial data flow using a dedicated data management system. We also explore its effective implementation as one additional component of the routine monitoring of the operational activity at the plant. The study covers different stages of data processing, from the data triggering and the detection of seismic events to the description of seismic sources, particularly in terms of location, moment magnitude, and stress drop. The presence of a co-located sensor allows for an assessment of the consistency of the DAS measurements. Moreover, the simultaneous deployment of a surface seismometer network and a low-aperture geophone array gives the opportunity to compare the capabilities of these different set-ups for detecting (micro-)seismic events within the study area. The contribution of DAS to the monitoring network varies according to the location of the observed seismicity. However, our measurements show that DAS can complement the surface network by providing increased sensitivity for low-magnitude events close to downhole measurement points, and offers advanced processing capabilities, for applications beyond seismic monitoring too

THE CHURCH OF SANT'ANDREA IN BERGAMO: AN INTEGRATED SURVEY FOR KNOWLEDGE AND CONSERVATION

Abstract. The church dedicated to Sant'Andrea (St. Andrew) in Porta Dipinta street in Bergamo city is a treasure that keep inside it a rich heritage of great historical and cultural value, both from the architectural and from the artistic point of view. Lacking of the façade (left unfinished), it is often neglected, despite being on the main road leading to the old town from Sant'Agostino Gate. The approach to an historical building like this requires a multi-disciplinary integration, in order to join the technical competence of engineering sciences to the sensitivity of human and fine arts sciences. For a better understanding of the structural performances of the building, historical research, measurement survey, material and decay condition study have to complement each other.</p

Stress characterization and temporal evolution of borehole failure at the Rittershoffen geothermal project

International audienceIn the Upper Rhine Graben, several innovative projects based on enhanced geothermal system (EGS) technology exploit local deep-fractured geothermal reservoirs. The principle underlying this technology consists of increasing the hydraulic performances of the natural fractures using different stimulation methods in order to circulate the natural brine at commercial flow rates. For this purpose, knowledge of the in situ stress state is of central importance to predict the response of the rock mass to different stimulation programs. Here, we propose a characterization of the in situ stress state from the analysis of ultrasonic borehole imager (UBI) data acquired at different key moments of the reservoir development using a specific image correlation technique. This unique dataset has been obtained from the open-hole sections of the two deep wells (GRT-1 and GRT-2, ∼ 2500 m) at the geothermal site of Rittershoffen, France. We based our analysis on the geometry of breakouts and drilling-induced tension fractures (DITFs). A transitional stress regime between strike-slip and normal faulting consistent with the neighboring site of Soultz-sous-Forêts is evident. The time-lapse dataset enables us to analyze both in time and space the evolution of the structures over 2 years after drilling. The image correlation approach developed for time-lapse UBI images shows that breakouts extend along the borehole with time and widen (i.e., angular opening between the edges of the breakouts) but do not deepen (i.e., increase in the maximal radius of the breakouts). The breakout widening is explained by wellbore thermal equilibration. A significant stress rotation at depth is evident. It is shown to be controlled by a major fault zone and not by the sediment-basement interface. Our analysis does not reveal any significant change in the stress magnitude in the reservoir