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Since the 1990s, in areas with natural geothermal manifestations studies on the association between exposure to pollutants and health effect have become increasingly relevant. These emissions consist of water vapor mixed with carbon dioxide, hydrogen sulfide (H2S), methane and, to a lesser extent, rare gases and trace elements in volatile forms. Considering the indications of the World Health Organization and the growth in the use of geothermal energy for energy production, this review aims to report studies exploring the health status of the populations living in areas where geothermal energy is used to produce heat and electricity. Studies on the health effects of the general population exposed to emissions from both natural geothermal events and plants using geothermal energy at domestic or commercial level have been considered between 1999 and 2019. Studies were classified into those based on health indicators and those based on proxy-individual level exposure metrics. Both statistically significant results (p

Geothermal plants have been producing power in Italy for more than a century. Since local opposition to geothermal development is often fuelled by incomplete and inaccurate environmental information, this paper provides a comprehensive description of the effect of geothermal development on the air, water and soil and investigates potential disturbance from noise, subsidence, and seismicity, as well as the visual impact on the local area. After discussing the risks associated with the geothermal development and the reference data, the paper describes the wide-reaching environmental monitoring and mitigation measures in Italy that have maintained impact values below the thresholds defined by European and Italian regulation. The social benefits for areas where geothermal energy is developed are also described, with the aid of case studies highlighting that citizens do not feel that they are sufficiently informed to have a voice in the innovation process. A regular and comprehensive review of the geothermal environmental and safety regime, as the one carried out in this paper, and a mutual exchange of knowledge between the different stakeholders should be strongly encouraged.

This paper reports on a case study on the citizens’ engagement with developments towards the harnessing of geothermal energy in central Italy. The research has been conducted within the framework of a larger project on the feasibility of further geothermal developments in Italy, funded by the Italian government. The aims of the case study research were first to explore the role of public and stakeholder engagement in the processes of innovation in the geothermal energy sector. Second, to design, implement and consolidate a methodological framework for comparative analysis of case studies on citizens’ engagement, thus bringing a social scientific perspective into geothermal energy research. The results show general support for renewable energy but knowledge and understanding of the potential of geothermal is remarkably low. Lack of trust in politics and unsure public communication emerged as prominent themes where the common good and community developments are sharply contrasted with corporate and private interests. As geothermal energy is included and encouraged under the European Strategic Energy Plan and in the Paris agreement on halting climate change, the results can make significant input into future policy making, by providing concrete guidelines on citizens’ engagement in processes of culturally sustainable innovation.

A revised surface heat flow map of a sector of the Northern Apennines is presented, constrained by recently available thermal and petrophysical logs from 174 wells drilled for geothermal and hydrocarbon exploration purposes. The borehole temperatures have been corrected for drilling, inclination, and palaeoclimate effects. The corrected temperature data, combined with petrophysical parameters for each individual formation, have been used to derive shallow geotherms (down to a maximum depth of 8 km), which have yielded site-specific heat flow values. These values, once corrected for palaeoclimatic topographic and erosion/sedimentation effects, have been contoured by a kriging procedure to obtain the heat flow map. The map shows a clear distinction between a western zone (the Tyrrhenian Domain) of high heat flow (>150 mW m −2 ), with closely spaced heat flow isolines, and an eastern zone (the Adriatic Domain) of relatively low ( −2 ), spatially uniform heat flow. The boundary between the two zones is roughly parallel to the axis of the Apennines. Five crustal geotherms (extending to the Moho) and the corresponding rheological profiles confirm that the 70 mW m −2 isoline corresponds to a major tectonic boundary, across which the thermal, structural, and seismic properties of the lithosphere go through a significant change.

Summary This work presents the two-dimensional stochastic inverse modelling of a magnetotelluric profile from the Larderello geothermal area (Italy). For the first time, the algorithm Particle Swarm Optimization was applied to this kind of field data to investigate a complex electrical structure without the initial assumption given by an external starting model driving the inversion. The outcome was in good agreement with results of previous research with the advantage of a lower data misfit as well as the contribution that the modelling was not initially constrained by a priori information (e.g., from well-log or other geophysical methods) that, in geothermal areas, can be unavailable or even misleading.

We exploit the concept of the geothermal favourability, widely used for hydrothermal and EGS systems, to present an innovative methodology for assessing geopressured-geothermal resources occurring in terrigenous units in sedimentary basin plays. Geopressured-geothermal systems are an unconventional resource for power trigeneration exploiting three forms of energy from hydrocarbons, hydrothermal fluids, and well-head overpressure. This paper is intended to be a practical analytical framework for the systematic integration of the relevant data required to assess geopressured-geothermal resources. For this purpose, innovative parameters were also implemented in the methodology. The final result is the favourability map for identifying prospective areas to be further investigated for the appraisal of the geopressured-geothermal potential. We applied our methodology to the foredeep-foreland domains of the Apennines thrust belt in the Abruzzo region (central Italy). We analysed hundreds of deep hydrocarbon wells in order to create 3D geological and thermo-fluid dynamic models at a regional scale as well as to obtain information on the pressure regimes and on the chemistry of the system. The final favourability map for the Abruzzo case study is a first attempt at ranking these kinds of unconventional geothermal resources in a region that has been historically explored and exploited mostly for hydrocarbons.

We revised the concept of convective, intrusive geothermal plays, considering that the tectonic setting is not, in our opinion, a discriminant parameter suitable for a classification. We analysed and compared four case studies: (i) Larderello (Italy), (ii) Mt Amiata (Italy), (iii) The Geysers (USA) and (iv) Kizildere (Turkey). The tectonic settings of these geothermal systems are different and a matter of debate, so it is hard to use this parameter, and the results of classification are ambiguous. We suggest a classification based on the age and nature of the heat source and the related hydrothermal circulation. Finally we propose to distinguish the convective geothermal plays as volcanic, young intrusive and amagmatic.

Italy has a pioneering role in the geothermal sector: from ancient Romans thermal baths, to the development of the first geothermal power plant, the Country has contributed to the development of this technology. Italian geothermal power plants are located in Tuscany, where part of the local population is opposing to old and new geothermal developments. In this chapter we describe the current expectations and concerns of the Italian citizens regarding geothermal energy and we report on two social acceptance assessment case studies conducted by the Italian National Research Council in Southern and Central Italy, applying both quantitative (survey) and qualitative (focus groups) methods. As the energy question is increasingly recognized to be both technical and social domains, public engagement experiences in the field are rapidly growing internationally and other studies are also mentioned and described. Our review show that the opinions around geothermal energy among the Italian public are shrouded in uncertainty and many participants ask for more information on pros and cons in order to contribute to the discussion. The debate on geothermal energy development in Italy is strongly entangled with values, ethics, local identity and political issues. Lack of trust in the decision makers was the main reason for public concerns even if the presence of environmental and health risks were also questioned by part of the population.

This chapter describes geothermal energy as a source of renewable energy, its use in the production of heat and electricity, and the main applications and technologies. Geothermal energy is the thermal energy stored underground, including any contained fluid, which is available for extraction and conversion into energy products. Electricity generation, which today produces 73.7 TWh (12.7 GW of capacity) worldwide, usually requires geothermal temperatures of over 100 °C. For heating, geothermal resources that span a wider range of temperatures can be used in various heat applications such as; space and district (and cooling, with the appropriate technology), spas and swimming pools, greenhouses and soil, aquaculture ponds, industrial processes and snow melting. The geothermal heat produced worldwide is 164.6 TWh, with a capacity of 70.9 GW. Geothermal resources are immune from weather and seasonal variations, and can produce a base-load (continuously) or adapt to the energy demand, providing a flexible and “smart” renewable energy source. To guarantee a sustainable use of geothermal energy, the consumption rate should not exceed the generation rate, so that the heat removed from the resource is replaced within a similar time scale, and geothermal plants typically produce energy below a certain level. In addition, any impact on the environment should be controlled, mitigated and managed. Any non-sustainable use of geothermal technologies can create a misperception of geothermal energy and social resistance to geothermal development.

We have developed an innovative, simultaneous 1D optimization of electromagnetic (EM) data. Our scheme is suitable for the simultaneous analysis of magnetotelluric (MT) and time-domain EM (TDEM) data based on the probabilistic and evolutionary particle swarm optimization (PSO) algorithm. The simultaneous optimization also identifies and removes the static shift from the MT data. In our scheme, the static shift of the MT apparent resistivity curve is considered as an additional parameter [Formula: see text] to be optimized. We tested the suggested method on the synthetic data and then applied it to the data from an EM geophysical study carried out in the geothermal area of Larderello-Travale (Tuscany, Italy). Apart from the novelty of using the PSO algorithm to estimate the model parameters by joint analysis, the simultaneous optimization of the static shift parameter addresses a major problem in MT, i.e., how to define and remove the galvanic effects on MT curves according to independent information, such as that provided by TDEM data. The procedure is expected to strongly influence the application of MT, particularly in geothermal exploration, which commonly relies extensively on EM methods.

This paper describes a data integration tool used to identify potentially undiscovered geothermal resources in the island of Sicily. The factors facilitating the recovery of exploitable geothermal energy were defined, and their spatial correlation established by Geographic Information System (GIS) models. By prioritizing favourable conditions using an Index Overly method, “favourability” maps of Sicily were obtained. The maps considered both geological and economic aspects, and energy recovery was considered for current technologies. Our approach and maps are useful for developing and planning local or national energy policies including geothermal energy.

First comprehensive geothermal exploration in Sri Lanka was conducted in 2010 encompassing seven thermal springs, of which Kapurella records the highest temperature. The study consisted of passive magnetotelluric (MT) soundings, in which static shifts were corrected using time domain electromagnetic method (TDEM). A frequency range of 12,500–0.001 Hz was used for MT acquisition and polar diagrams were employed for dimensionality determination. MT and TDEM data were jointly inverted and 2D models were created using both transverse electric and transverse magnetic modes. A conductive southeast dipping structure is revealed from both phase pseudosections and the preferred 2D inversion model. A conductive formation starting at a depth of 7.5 km shows a direct link with the dipping structure. We suggest that these conductive structures are accounted for deep circulation and accumulation of groundwater. Our results show the geothermal reservoir of Kapurella system with a lateral extension of around 2.5 km and a depth range of 3 km. It is further found that the associated dolerite dike is not the source of heat although it could be acting as an impermeable barrier to form the reservoir. The results have indicated the location of the deep reservoir and the possible fluid path of the Kapurella system, which could be utilized to direct future geothermal studies. This pioneering study makes suggestions to improve future MT data acquisition and to use boreholes and other geophysical methods to improve the investigation of structures at depth.

The Global Geothermal Energy Database of the International Geothermal Association (IGA) is an internet-based platform providing access to the world geothermal production data. This platform is unique for the geothermal sector, and provides an excellent tool for showing geothermal use in the world and promoting the development of geothermal energy. The platform is also an important example of organization and access to widely distributed data, since it allows analyzing, synthetizing and quickly interpreting stored data. The global and country-specific information regard both electricity generation and direct use applications. The platform, which has been built using an open-source Business Intelligence application and can be accessed through the IGA website, allows to access, navigate and organize information in various ways. Data lists related to geothermal fields and plants, direct uses, geothermal turbine manufactures and geothermal companies can be accessed, aggregated and filtered, producing reports, charts and maps. Aggregation and filtering options synthetize and organize data for direct use, power plants and installed capacity by region, category and operative status. The mapping tool, providing geothermal fields location, power plants and direct uses geographical references, allows also map browsing, and to zoom, to measure distance, to pan and to query for further information. The chart analysis produces pie charts and bar diagrams of data, dynamically sorted and aggregated.

The Larderello geothermal field, located in southern Tuscany (Italy), is one of the most important long-living hydrothermal system in the world. The inner zone of the Northern Apennines is characterized by high heat flow, well constrained by several hundred measurements deriving from both shallow boreholes and deep exploration wells. It is widely accepted that the interplay among extensional tectonics, thinning of the previously overthickened crust and lithosphere, and magmatism related to crustal melting and hybridism, controlled the NW-SE trending geothermal anomaly occurring in southern Tuscany. At Larderello, the geothermal exploitation started at the beginning of the last century from the shallow evaporitecarbonate reservoir (about 700 - 1000 m b.g.l. on average) hosting a super-heated steam with temperature ranging from 150C to 260C. A deep exploration program was carried out in the early 1980s. Deep boreholes found a super-heated steam-dominated system hosted in the metamorphic basement (about 2500 - 4000 m b.g.l), characterized by temperatures ranging from 300C to 350C. In the SW part of the Larderello area (Lago locality), a temperature exceeding 400C was measured down to 3000 m b.s.l. The 2D and 3D seismic exploration activities provided evidences of a seismic marker, locally showing bright spot features, defining the top of a deeper reflective crustal interval, named as "K-horizon". The K-horizon has not yet been drilled, but some boreholes approached it. This seismic reflector exhibits interesting positive correlation with the maximum peak of the hypocentre distribution of low-magnitude earthquakes and, at the same time, its shape coincides with the thermal anomaly distribution, in plain view. The review and updating of the velocity and resistivity models suggest the existence of over-pressurized fluids, likely of magmatic and/or thermo-metamorphic origin, which originate the seismic velocity anomalies. The upward migration and storage of the fluids can be controlled by: i) structural conduits crossing a multi-layered crust affected by magmatic intrusions; ii) mechanisms controlling the fluid migration in different rheological settings; and iii) self-sealing processes of magmatic hypersaline fluids arising from the brittle/ductile transition. Our study is addressed to the better understanding of the structure of the deepest part of the Larderello geothermal field, by integrating structural, geological, geochemical and geophysical data. Based on downward temperature extrapolation, fluid inclusions and geothermometers analyses, the possible occurrence of super-hot fluids, in supercritical conditions, nearby the K-horizon is envisaged. The final goal is to achieve a comprehensive understanding of the geological structure and the physical conditions (pressure and temperature) of the deep reservoir including also the zone corresponding to the K-horizon, to characterize the supercritical geothermal system as well as the deep crustal processes that work in synergy leading to the regional anomaly.

Diplomazia2 is framed within the program "Science for Diplomacy: Multi-disciplinary Training Program", and it is the result of closer and more mature collaboration between the Directorate General for Cooperation on Development of the Ministry for Foreign Affairs and International Cooperation (MAECI), the Italian Agency for Cooperation on Development (AICS) and the National Research Council (CNR). The implementation of joint projects such as DIPLOMAzia2 highlights the effectiveness of the diplomacy-science partnership as the driving force behind the achievement of relevant goals jointly pursued by the international community.

The Italian National Geothermal Database (BDNG), is the largest collection of Italian Geothermal data and was set up in the 1980s. It has since been updated both in terms of content and management tools: information on deep wells and thermal springs (with temperature > 30 °C) are currently organized and stored in a PostgreSQL relational database management system, which guarantees high performance, data security and easy access through different client applications. The BDNG is the core of the Geothopica web site, whose webGIS tool allows different types of user to access geothermal data, to visualize multiple types of datasets, and to perform integrated analyses. The webGIS tool has been recently improved by two specially designed, programmed and implemented visualization tools to display data on well lithology and underground temperatures. This paper describes the contents of the database and its software and data update, as well as the webGIS tool including the new tools for data lithology and temperature visualization. The geoinformation organized in the database and accessible through Geothopica is of use not only for geothermal purposes, but also for any kind of georesource and CO2 storage project requiring the organization of, and access to, deep underground data. Geothopica also supports project developers, researchers, and decision makers in the assessment, management and sustainable deployment of georesources.

Mo.nalis.a is a conceptual model aimed at identifying the most suitable local geothermal sources to match the nearest industrial thermal needs. The methodological approach proposed is based on investigating industrial thermal processes and then identifying suitable geothermal solution plants that match these thermal requirements. The model was tested in Apulia (southern Italy) as a case study for assessing how the methodology could contribute to reducing the use of conventional energy resources for the industrial heat supply sector. The medium thermal needs in Apulia are always higher than 60 °C, and the main strategic industrial processes discussed into this work are “pasta and flour production” “wastewater treatment/sludge digestion” and “swimming pool management”. In order to match these industrial thermal demands, the most suitable proposed plant is the ground water heat pump system, limited to the first 100 m, the depth involved in the heat exchange through vertical probes of model. Finally, Mo.nalis.a identifies the Apulian areas with a possible development of these three activities using geothermal resource: the Foggia province, Murge and Salento sectors.

Low-to-medium temperature fluid reservoirs hosted in carbonate rocks are some of the most promising and unknown geothermal systems. Western Sicily is considered a key exploration area. This paper illustrate a multidisciplinary and integrated review of the existing geological, geochemical and geophysical data, mainly acquired during oil and gas explorations since the 1950s, specifically re-analyzed for geothermal purposes, has led to understanding the western Sicily geothermal system as a whole, and to reconstructing the modalities and particular features of the deep fluid circulation within the regional reservoir. The data review suggests the presence of wide groundwater flow systems in the reservoir beneath impervious cap rocks. We identified the main recharge areas, reconstructed the temperature distribution at depth, recognized zones of convective geothermal flow, and depicted the main geothermal fluid flow paths within the reservoir. We believe that our reconstruction of geothermal fluid circulation is an example of the general behavior of low-to-medium enthalpy geothermal systems hosted in carbonate units on a regional scale. Due to the recent technological developments of binary plants, these systems have become more profitable, not only for geothermal direct uses but also for power production.

In this paper we develop a model of the ground deformation behaviour occurred at Ischia Island (Southern Italy) in the 1992–2010 time period. The model is employed to investigate the forces and physical parameters of the crust controlling the subsidence of the Island. To this aim, we integrate and homogenize in a Finite Element (FE) environment a large amount of data derived from several and different observation techniques (i.e., geological, geophysical and remote sensing). In detail, the main steps of the multiphysics model are: (i) the generation of a 3D geological model of the crust beneath the Island by merging the available geological and geophysical information; (ii) the optimization of a 3D thermal model by exploiting the thermal measurements available in literature; (iii) the definition of the 3D Brittle/Ductile transition by using the temperature distribution of the crust and the physical information of the rocks; (iv) the optimization of the ground deformation velocity model (that takes into account the rheological stratification) by considering the spatial and temporal information detected via satellite multi-orbit C-Band SAR (Synthetic Aperture Radar) measurements acquired during the 1992–2010 time period. The achieved results allow investigating the physical process responsible for the observed ground deformation pattern. In particular, they reveal how the rheology modulates the spatial and temporal evolution of the long-term subsidence phenomenon, highlighting a coupling effect of the viscosities of the rocks and the gravitational loading of the volcano edifice. Moreover, the achieved results provide a very detailed and realistic velocity field image of the subsurface crust of the Ischia Island Volcano.

Determining the suitability of a local area at a regional or local scale for the geothermal application of low enthalpy systems requires the knowledge of rock thermal conductivity values to evaluate the possibility of low-enthalpy heat exchange. A digital cartographic tool is also needed to synthesize the thermal properties of the underground. This tool should be easily accessible and upgradeable and thus suitable for territorial planning and environmental control. In order to address these key issues, a methodological approach was developed within the framework of the national VIGOR Project, dedicated to evaluating the geothermal potential in southern Italy. In this paper the region of Calabria was selected as a case study. Around 70 samples that were representative of the main geological formations were collected from all over the area. Thermal property tests were carried out both in dry and wet conditions, using a thermal device in accordance with the modified transient plane source method. The thermal conductivity values were then compared with data from the international literature. In order to consider the influence of the entire stratigraphic sequence on the thermal conductivity parameters, a geostatistical analysis of the available lithostratigraphic data was performed using the MATLAB toolbox Modalstrata, specially developed for this purpose. A comprehensive geothermal subsurface characterization of Calabria was thus obtained. © 2014 Springer-Verlag Berlin Heidelberg.

This paper presents a multidisciplinary methodology to estimate the underground heat-exchange potential for Borehole Heat Exchangers (BHEs) coupled with Ground Source Heat Pumps (GSHPs) over wide areas. The proposed methodology was tested in four sites in western Sicily (southern Italy) where the shortage of subsurface geological data, in addition to the undefined authorization processes for this kind of system, is probably the main barrier to planning and exploiting geothermal heat for heating and cooling purposes. Reliable high-resolution 3D geological and petrophysical models were built based on the integration of airborne electromagnetic data and laboratory measurements of the thermal properties of rock samples. A GIS-based procedure was applied to assess the geothermal heat-exchange potential using 3D models of thermal conductivity as the main input. The results of the analyses are represented by thematic maps of the underground heat exchange potential for BHEs coupled with GSHPs. The study areas show a generally high suitability for the use of this technology and several municipalities in the area could take advantage of the resulting maps for energy planning.

Electromagnetic (EM) data provide a substantial contribution to the geophysical mapping and monitoring of geothermal reservoirs. This paper presents an up-to-date picture of the achievements of EM methods for geothermal exploration as they have emerged over the last few years. It has been proved that EM sounding of geothermal zones and distant monitoring macro-parameters of the reservoirs, fluid-filled faults and other elements of the geothermal system are possible provided that modern 3-D inversion is used along with techniques that reduce the effects of industrial and geological noise. In addition, geological and petrophysical data also need to be included in the analysis.

An empirical method aimed at generating maps of potential of geothermal energy exchange for shallow vertical closed-loop systems is proposed here. The method uses both geological and technological information. In particular, the ground parameters that mainly influence the heat transfer in borehole heat exchangers, the energetic parameters driving efficient operations of geothermal systems and heating and cooling requirements of a typical residential building are taken into account. Spatial modeling is carried out in a Geographic Information System leading to an effective and easy-to-use digital cartographic tool. An application of the method to four regions of southern Italy is also shown. (C) 2015 Elsevier Ltd. All rights reserved.

Borgia et al. (2014) illustrated an active volcanic spreading model for the Amiata volcanic area (southern Tuscany, Italy). Although, at first glance, the model may appear appealing, this is not fully supported by the available data and the paper does not take into account their discussion. Accordingly, the supposed negative consequences of the Borgia et al. (2014) model on both contamination of shallow water and geothermal exploitation can likely be regarded as speculative.

This paper presents the results of an assessment of public views on eventual geothermal energy development in Sicily. The research was carried out under a much wider research project, VIGOR, with the aim to explore the feasibility of geothermal energy utilization in southern Italy. This study has two primary objectives: (1) to explore the views and opinions of local communities regarding the potential of geothermal energy applications; (2) to contribute to the growing literature on public engagement with energy issues. In order to explore public views towards geothermal technologies, we conducted a case study using both qualitative and quantitative methods. Although Italy has enormous geological potential for geothermal energy production, levels of knowledge of this energy source amongst the public are low. The results indicate that the issue is shrouded in uncertainty and that the Sicilian public expresses a diffused lack of trust in decision-making processes. Taken together, these factors are likely to strongly impact eventual further developments in this sector. The results clearly show the need for further societal dialogue supported by a sound communication action strategy as the first stage in a public participation.

Geothermal energy is a renewable and eco-compatible resource suitable for base-load power and thermal production, which means a daily continuous energy production. In the past few years this source has been of interest for governments, companies and research institutes worldwide that are working for the increase of geothermal exploitation with the aim of reducing greenhouse gas emissions and fossil fuels consumption. Italy was the first country (in 1913) where geothermal energy was exploited for industrial power production and is now the sixth-largest geothermal electricity producer in the world (Bertani, 2015). The geothermal potential of Italy, both for power production and direct uses, is really huge due to particular geological conditions; elsewhere it is mostly underexploited for non-technical barriers. In Italy, many industrial and scientific exploration pro¬jects have been carried out in the last few years for assessing shallow and deep geothermal resources. ElectroMagnetic (EM) methods play a fundamental role in the geothermal exploration due to particular sensitivity of the subsurface electrical resistivity (hereby resistivity) to hydro¬thermal circulation, thermal regime and rocks alteration. Many papers have been published on the study of geothermal areas by EM methods worldwide (Meju, 2002; Spichak and Manzella, 2009; Munoz, 2014 and references therein). In this paper, we propose an updated state-of-the-art of the main electromagnetic and direct current methods for geother¬mal exploration in Italy, describing innovative case studies and including a discussion about the direction of new researches. The Magnetotellurics (MT) represents the most common and effective method for investigating deep geothermal res¬ervoirs. A case study in southern Tuscany is herein described. We will also focus the attention on the resistivity measure¬ments for shallow geothermal exploration by means of Airborne EM (AEM), Transient or Time Domain EM (TEM or TDEM) and Electrical Resistivity Tomography (ERT). Among the various scientific projects for geothermal exploration that the Italian National Research Council (CNR) carried out, the VIGOR project (evaluation of the geothermal potential of Regions of Convergence) for Southern Italy provided the occasion of detailed geoelectro¬magnetic studies for assessing shallow and deep geothermal resources (Manzella et al. 2013a, VIGOR website). Some cases study of the VIGOR project are briefly described as: i) the innovative application of Airborne EM data acquired over large areas in Sicily and applied to the assessment of shallow geothermal potential and ii) a Deep Electrical Resistivity Tomography (DERT) acquired on a thermal area in Calabria region.

International audience; Geothermal data are published using different IT services, formats and content representations, and can refer to both regional and global scale information. Geothermal stakeholders search for information with different aims. E-Infrastructures are collaborative platforms that address this diversity of aims and data representations. In this paper, we present a prototype for a European Geothermal Information Platform that uses INSPIRE recommendations and an e-Infrastructure (D4Science) to collect, aggregate and share data sets from different European data contributors, thus enabling stakeholders to retrieve and process a large amount of data. Our system merges segmented and national realities into one common framework. We demonstrate our approach by describing a platform that collects data from Italian, French, Hungarian, Swiss and Icelandic geothermal data providers.

Two magnetotelluric (MT) surveys were carried out on the Mt. Etna volcano after two of the most intense eruptions of the last 30 years which took place in summer 2001 and winter 2002–2003. Surveying was pursued for two main reasons. First, we sought to contribute to the definition of the first-order structure and physico-chemical state (temperature, fluids, melts) of a volcano that has been extensively explored and monitored by means of various geophysical methods, but where only few electrical and electromagnetic surveys have been performed. Secondly, we acquired MT data in the same sites in the two different surveys with the aim of monitoring the possible changes of the first-order structure, since conditions are expected to vary on an active volcano such as Etna, and are supposed to be linked to the eruptive events. Soundings have been acquired in an E-W 10 km-long profile across the southern flank of Mt. Etna, at a distance of almost 6 km south from the Central Crater. The first survey was carried out three months after the 2001 eruption. Inverse models define a pronounced (4 km thickness) low resistivity section at a depth of about 1 km b.s.l. to the west. To the east, a low resistivity section is still present, but appears deeper, thinner and more resistive, and a shallow low resistivity anomaly also exists. The shallow anomaly to the east is tentatively correlated with altered and clayey volcanic units and/or temporary groundwater storage. The deep anomalies are interpreted as being due to melt storage at shallow depths which was not exhausted during the eruption. This would be confirmed by the abundance of lava erupted within one year from the end of the survey. The few good sites retrieved in the second survey, carried out a few weeks after the eruption of 2002–2003, confirm the picture defined in the first survey, and provide a better definition of the bottom of the deep anomaly located in the sedimentary basement.

This paper intends to throw some doubt on the consolidated practice of interpreting seismic data without considering mineral phase transitions. Reference is made to Southern Tuscany, where seismic surveys revealed the presence, within the crystalline basement of a prominent high-amplitude reflector exhibiting local "bright spot" features, known as the K-horizon. According to some researchers, the K-horizon is a layer of fractured rocks hosting high-pressure fluids, but its ultimate origin is unclear. On the basis of the extrapolation of measured temperatures in the Larderello and Amiata geothermal fields and gas geotemperatures from the San Pompeo-2 deep well, we propose that the K-horizon might be largely governed by the alfa–beta transition of quartz and by the very high volumetric thermal expansion of quartz, a main constituent of local crystalline rocks, with respect to other minerals. The effects of these processes are probably suppressed almost everywhere by the abundance of minerals other than quartz and by the occurrence of partial melting, but might be evident in relatively quartz-rich rocks and in regions of very high geothermal gradient, such as Southern Tuscany. As a consequence of these processes, a layer of fractured rocks roughly following the alfa–beta quartz transition temperature would develop and locally host high-pressure fluids, thus justifying in part the high reflectivity of the K-horizon. This hypothesis concords with previous interpretations, although the ruling factors in this case would be the alfa–beta transition and the peculiar physical characteristics of quartz compared to other minerals. In our interpretation, the K-horizon is expected to fade away in rocks where quartz is scarce or absent, where microfractures are not produced by the phase transition. The local disappearance of the K-horizon could, therefore, depend on lithology, whereas its reflectivity would depend on the quantity and type of fluids trapped in the porous layer micro-fractured by the volumetric expansion of quartz.

A fluid inclusion study of the hydrothermal minerals in two breccias from two wells in the Bagnore geothermal field (Italy) has provided information on the evolution of the fluids, and has also demonstrated that fluid inclusions can be utilized as geothermometers in this geothermal field. Both breccias come from reservoir zones: one (Bagnore 3bis (Bg 3bis)) was cored at a depth of 3111 m below ground level (b.g.l.), whereas the other (Bagnore 22 (Bg 22)) was ejected during a blow-out, probably from a fractured zone present between 2200 and 2300 m b.g.l. The hydrothermal cement of the breccias is mostly made up of quartz, K-feldspar, Na-rich plagioclase, calcite, chlorite and illite. Fluid inclusion studies were carried out on quartz (Bg 3bis and Bg 22 breccias) and adularia (Bg 22 breccia). Three types of fluid inclusions were recognized in the Bg 3bis breccia. Type I (liquid-rich) inclusions trapped an aqueous fluid with a CO2 concentration (1.7–2.7 mol/kg) that is significantly higher than present-day fluids (0.5 mol/kg). Type II (liquid-rich) inclusions formed after type I, and trapped a fluid with less CO2 (0.6–1.0 mol/kg). Type III (vapor-rich) coexist with type I inclusions, and record an early fluid circulation under boiling conditions. The decrease of the CO2 (and total gas) concentrations from type I inclusions to type II inclusions, and on to present-day conditions can be related to boiling with gas loss and/or mixing. Only one type of fluid inclusion (type II), with moderate CO2 concentration (0.7–0.3 mol/kg), was found in the Bg 22 breccia. Boiling and/or mixing explain the variation of the CO2 content in the Bg 22 reservoir fluid from inclusion formation to modern CO2 concentration (0.3 mol/kg). The absence of any type I inclusions in Bg 22 breccia may be related to non-uniform CO2 concentrations in different parts of the field. Present-day temperatures (295±10 °C for Bg 3bis and 320±10 °C for Bg 22) are close or equal to fluid inclusion average total homogenization temperatures (around 290 °C for Bg 3bis and 320 °C for Bg 22), suggesting that fluid inclusions can be useful for estimating local temperatures when direct measurements are not available or dubious.

The conductivity structure of the top 2 km of the crust is examined using data from collocated magnetotelluric (MT) and time-domain electromagnetic (TDEM) soundings across the Vesuvius volcano. The MT data were corrected for static shift using dual-configuration TDEM data. The TEM and MT data were jointly inverted to yield 1D models while the TE and TM mode MT data were jointly inverted using a 2D inversion approach. The resulting models reveal the presence of a resistive cover layer underlain by an anomalous conductive layer (c. 250–500 m below the ground surface) that is shallowest underneath the caldera. We suggest that the conductive body below the caldera is related to enhanced hydrothermal circulation; outside the caldera, the conductor is consistent with the hydrological system and is interpreted as mapping a suggested aquifer system and underlying clayey deposits. Our results show that the aquifer hosted in the Vesuvius edifice is not homogeneous, but appears particularly conductive in the western and southern sectors of the volcano. It was found from 3D numerical modelling study that the presence of the shallow and thick conductors and the Tyrrhenian sea changes the penetration depth of MT data and must be taken into account during interpretation. Recommendations are made for any future MT field studies aimed at resolving the deep resistivity structure of Mt Somma-Vesuvius.

The International Geothermal Association (IGA), founded on 6 July 1988, is an international, worldwide, non-profit and non-governmental association whose objective and mission is to promote the research and utilization of geothermal resources, through the compilation, publication, and dissemination of scientific and technical data and information. The Information Committee (IC) of the IGA is responsible for advising the IGA Board on policies concerned with the collection, compilation, publication, exchange and dissemination of geothermal information, including information on utilization, development, technical findings, scientific research, meetings, publications and Association activities. The Committee is also responsible for the implementation of information policies determined by the Board.

A novel procedure for estimating the geothermal energy exchanged by a unit volume was tested in northern Sicily (Italy), where public well data for depicting the complex geological setting were insufficient. An airborne electromagnetic survey was carried out in 2011, providing a 3D cell distribution of resistivity values. The integrated analysis of geological and resistivity data was used to identify six Litho-Electrical Units and to build a 3D geological model. This model was integrated with laboratory thermal conductivity measurements on rock samples, and was used to characterize the heat exchange at depths of up to 200 m, which in turn can be exploited for planning and designing geothermal heating and cooling plants using GSHP (Ground Source Heat Pump).

An integrated review of existing geological and geophysical data – partly acquired during oil and gas exploration – combined with new data provided by deep geothermal studies of selected key areas, was used for the 3D modeling and mapping of the top of the geothermal reservoir developed at a regional scale in Sicily (Central Mediterranean). The resulting 1:500,000 scale map covers the area of the whole Sicily (about 25,700 km2) and is devoted to represent the main input for both the thermal modeling and the evaluation of geothermal potential at a regional scale. As the map indicates the distribution at depth of a likely target for geothermal drilling, it can be also used as a rough indicator of expected drilling cost for geothermal projects. Such a map can be seen as a useful planning tool for any geothermal project, and related exploration to be carried out in the Sicily region in the future.

This paper describes a magnetotelluric (MT) survey carried out on the western edge of the Amiata geothermal region (Tuscany, Italy). In order to enhance the resolution of subsurface conductivity along the survey line and to define the deep features related to geothermal system heat recharge a continuous profiling method was used The standard wide-band MT data were collected at 28 sites, and 130 high frequency telluric-magnetotelluric (TMT) soundings were carried out at sites adjacent to the main wide-band sites. To tackle the problem of high electrical noise in the area the wide-band data were recorded simultaneously at two sites of the profile (local remote) and at a third far remote and electrically quiet site. Two-dimensional (2D) inversion of both TM and TM-TE data was performed, taking into account topographic and coast effects. The inversion results were able to define both shallow and deep resistivity anomalies whose structural significance is in good agreement with information derived from other geophysical data. Of particular geothermal interest is the evidence of a large conductive anomaly at a depth ranging between 2 and 4 km within the deep metamorphic basement. This anomaly could indicate the presence of a hitherto unidentified deep reservoir that is in communication with the reservoir exploited at present in the Amiata area.