Search

Studies on the individuation of surface and buried faults in seismic areas using geochemical methods can be considered a valid approach for improving sustainability in the risk assessment framework. Appropriate scientific knowledge of structural geology and its evolution pre/during/post seismic events can play a fundamental role in human safety and resilience. The Abruzzo region (central Italy) underwent to a Mw 6.3 seismic event, in April 2009, that interested L'Aquila city (the county seat of the region) and many villages in the surrounding area. A first soil gas survey including radon (222Rn) and thoron (220Rn) measurements was accomplished soon after the main shock, in an area of ~24 km2 a few kilometers away from L'Aquila city. Results highlighted the spatial influence of the active tectonic on gas migration towards the surface. The area was investigated again in spring 2016, both to evaluate the natural degassing during a period without further meaningful earthquakes and to verify the presence of faults supposed after the previous survey results. Comparing data from the two surveys, a variation in the 222Rn/220Rn ratio was observed, suggesting different sources (deep or superficial) of gas degassing strictly correlated with the temporal variation in soil vertical permeability. Furthermore, the results infer a new structural system different from that known in the literature. [ABSTRACT FROM AUTHOR]

Between October 2021 and July 2024, radon measurements in air and soil were carried out in the South and East flanks of Etna volcano to check the possible correlation between radon emissions and active faults/eruptive fissures and to obtain preliminary data on any negative impacts on human health. Fifteen continuous indoor radon monitors were installed in homes, some of which are inhabited by patients suffering from Multiple Sclerosis and Amyotrophic Lateral Sclerosis. In all sites, the limit of 300 Bq/m3 indicated by the Euratom Directive 2013/59 was exceeded, even if slightly and for short periods. The highest values were recorded closest to active fault zones and during winters. Furthermore, 27 discrete indoor radon measurements were carried out using a passive method by means of activated charcoal canisters that were exposed for 48 h. Most of the values (>70%) were <100 Bq/m3; six canisters gave values >100 Bq/m3 and one >200 Bq/m3. Measurements of radon in soils were carried out using a Durridge RAD7 in the gardens of the homes in which the indoor radon measurements were made. The background radon values in soils were <5000 Bq/m3; the highest values (12,500 Bq/m3) were measured near the Aci Catena fault. The role of Etna's faults in draining the deeper radon towards the surface and, therefore, into nearby homes is evident, with a consequent increase in the health risk caused by indoor radon pollution. [ABSTRACT FROM AUTHOR]

Indoor radon is one of the most significant contributors to lung cancer after smoking. Mitigation strategies based on protecting buildings with radon barrier materials, combined with home ventilation or room pressurization, are regularly used. A scale model room made from a porous ignimbrite rich in radon precursors was used as an analogue to test the efficiency of fifteen airtight membranes to reduce radon levels, also in combination with room pressurization. The results of these experiments were considered together with previous ones to propose the scale model room approach as a tool for rapidly evaluating the performance of specially designed radon barrier materials, and for radiation exposure assessment. Relative reduction of indoor radon (RIR) ranges from −20 to −94%. The most effective materials were FPO membrane, single-component silane-terminated polymer membranes and synthetic resins. The presence of additives likely modified the composition and structure of some products, improving their radon barrier capacity. The introduction of room pressurization further reduced radon levels in the model room where the membranes were applied. The overpressure necessary to reach RIRs of the order of 85–90% is very low for materials that powerfully stop radon even without ventilation, but necessarily higher for poorer membranes. [ABSTRACT FROM AUTHOR]

In the frame of Radon rEal time monitoring System and Proactive Indoor Remediation (RESPIRE), a LIFE 2016 project funded by the European Commission, the contribution of building materials of volcanic origin to indoor radon concentration was investigated. First, total gamma radiation and related outdoor dose rates of geological materials in the Caprarola area (Central Italy) were measured to define main sources of radiation. Second, 222Rn and 220Rn exhalation rates of these rocks used as building materials were measured using an accumulation chamber connected in a closed loop with a RAD7 radon monitor. Among others, the very porous “Tufo di Gallese” ignimbrite provided the highest values. This material was then used to construct a scale model room of 62 cm × 50 cm × 35 cm (inner length × width × height, respectively) to assess experimental radon and thoron activity concentration at equilibrium and study the effects of climatic conditions and different coatings on radon levels. A first test was carried out at ambient temperature to determine experimental 222Rn and 220Rn equilibrium activities in the model room, not covered with plaster or other coating materials. Experimental 222Rn equilibrium was recorded in just two days demonstrating that the room “breaths”, exchanging air with the outdoor environment. This determines a dilution of indoor radon concentration. Other experiments showed that inner covers (such as plasterboard and different kinds of paints) partially influence 222Rn but entirely cut the short-lived 220Rn. Finally, decreases in ambient temperature reduce radon exhalation from building material and, in turn, indoor activity concentration.

Indoor radon surveying and remediation were implemented in a single-family home affected by high levels of indoor radon in the Celleno municipality (central Italy) with the aim of identifying the contribution of radon sources, evaluating the factors affecting radon entry into the building, and reducing radon risk. Average radon levels were relatively low at the ground floor (286 ± 202 Bq m−3) and first floor (167 ± 84 Bq m−3) in autumn when the temperature was still warm and the windows were open, but increased up to 2776 ± 1768 Bq m−3 and 970 ± 202 Bq m−3 in the first half of December, when the heating system was on and the windows were closed. The inner walls of the pilot room at the ground floor, semi buried on one side, were then treated with a waterproof product (a silane terminated polymer) and the average radon was halved (1475 ± 1092 Bq m−3) in the following month, which was still characterised by winter conditions. Radon entry in the room was identified and sealed with the same product, and a radon accumulation space behind a NE-SW oriented wall was naturally ventilated, reducing radon below the reference level in April with northerly winds conditions. [ABSTRACT FROM AUTHOR]

Indoor radon is the second cause of lung cancer. Mitigation strategies are based on (i) building protection with radon barrier materials, (ii) increasing home ventilation or (iii) room pressurization. A scale model room created with a porous ignimbrite rich in radon precursors was used as an analogue to test the indoor radon reduction ability of various radon barrier materials in a real room. The properties of these materials were tested with and without room pressurization by introducing outdoor air at different flow rates. The best materials reduced indoor radon up to 80% and, when the highest pressurization was applied, to 93%. [ABSTRACT FROM AUTHOR]

Indoor/outdoor air exchange on indoor radon concentration was investigated. We evaluated the effect of air extraction versus air introduction at different flow rates on equilibrium 222 Rn activity concentrations in a scale model room of 62 cm × 50 cm × 35 cm (inner length x width × height), made of a porous, radium and thorium-rich lithoid ignimbrite (Tufo di Gallese) from Vico volcano (Lazio, central Italy). Experiments were carried either with the inner walls of the chamber covered with a plasterboard shield or without any inner coating. Air introduction was always more effective than air extraction to reduce indoor 222 Rn and, in both cases, higher flow rates produced higher 222 Rn decreases. The presence of the plasterboard enhanced 222 Rn reduction when outdoor air was introduced in the chamber. Main results were that, with plasterboard, maximum reductions of 89.5 % and 25.0 % were obtained introducing and extracting air, respectively; without plasterboard, we found maximum radon decreases of 33.2 % and 26.6 %, namely with air introduction or extraction. The diffusion of 222 Rn through the walls of the scale model room was modelled with a modified version of Fick's second law, where a term considering air flow velocity was added. These findings suggested that the combined use of proper coatings on the inner walls of a house and outdoor air introduction at suitable rates are a good strategy to approach radon mitigation actions. [ABSTRACT FROM AUTHOR]

Thermal gradients due to magma dynamics in active volcanic areas may affect the emanating power of the substrate and the background level of radon signal. This is particularly effective in subvolcanic substrates where intense hydrothermal alteration and/or weathering processes generally form hydrous minerals, such as zeolites able to store and release great amounts of H2O (up to ~25 wt.%) at relative low temperatures. To better understand the role played by thermally induced devolatilization reactions on the radon signal, a new experimental setup has been developed for measuring in real time the radon emission from a zeolitized volcanic tuff. Progressive dehydration phenomena with increasing temperature produce radon emissions two orders of magnitude higher than those measured during rock deformation, microfracturing and failure. In this framework, mineral devolatilization reactions can contribute significantly to produce radon emissions spatially heterogeneous and non-stationary in time, resulting in a transient state dictated by temperature gradients and the carrier effects of subsurface gases. Results from these experiments can be extrapolated to the temporal and spatial scales of magmatic processes, where the ascent of small magma batches from depth causes volatile release due to dehydration phenomena that increase the radon signal from the degassing host rock material. [ABSTRACT FROM AUTHOR]

The 2012 Pollino (Calabria, Italy) seismic sequence, culminating in the Mw5.2 earthquake of 25 October 2012, is investigated, exploiting data collected during a long-term continuous radon monitoring experiment performed in the epicentral area from late 2011 to the end of 2014. We analyse data collected both using a phenomenological approach based on quantitative evidence and a purely numerical analysis including the following: (i) correlation and cross-correlation investigations; (ii) an original approach aimed at limiting the impact of meteorological parameters variations on the interpretation of measured radon levels; (iii) a change point analysis; (iv) the implementation of an original detection algorithm aimed at highlighting the connections between radon emission variations and major seismic events occurrence. Results from both approaches suggest that radon monitoring stations can be subject to massive site effects, especially regarding rainfall, making data interpretation harder. The availability of long-term continuous measurements is crucial to precisely assess those effects. Nevertheless, statistical analysis shows a viable approach for quantitatively relating radon emanation variations to seismic energy release. Although much work is still needed to make radon time series analysis a robust complement to traditional seismological tools, this work has identified a characteristic variation in radon exhalation during the preparation process of large earthquakes. [ABSTRACT FROM AUTHOR]

For the first time, a high-density macroseismic survey has been carried out in the city of Palermo, Italy, after the 6 September 2002, Mw 5.9 earthquake. The aim was to investigate the spatial relationships and correlations between intensity data and surface geology. A very dense database has been created to store a large amount of macroseismic, stratigraphic, and geotechnical information. A Geographic Information Systems (GIS) tool, called City-GIS, enables data processing by instruments and research keys devoted to seismic hazard. The results show the feasibility of such procedures, especially for large cities where the surface geology critically influences the ground motion. Our analysis, made on the basis of more than 2000 intensity observations scattered in the Palermo urban area, demonstrates the role of the variable geology in the variability of shaking. Significant variations of intensity are related to the geometry of the geologic formations present in the area. Intensities increase by about one intensity class inside those city sectors where the stratigraphic succession is characterized by a thin layer of calcarenites overlying very thick layers of silty clayey sands. Major amplification of up to two classes occurs in alluvial deposits in the southeastern part of Palermo, as expected. These results extend our knowledge of the seismic response in the outskirts of Palermo, which until now, was limited to the city center. [ABSTRACT FROM AUTHOR]

Hydrogeochemistry of 12 moderate-flow springs located in the Rieti and L'Aquila Provinces was investigated immediately after the August 24, 2016 Accumoli-Amatrice earthquake (Mw 6.0). Physico-chemical parameters (pH, temperature, electrical conductivity), alkalinity, major, minor and trace components, stable isotopes (O, H and C), 87Sr/86Sr ratios, as well as dissolved gases were measured/analysed on a monthly basis up to October 2017; extra-samplings were done soon after the 26 October (Visso village, Mw 5.9 and 5.4) and 30 October (Norcia village, Mw 6.5) earthquakes. Two additional samplings were carried out in June and July 2018 in order to obtain observations in periods of reduced tectonic activity, when seismic energy release returned to pre-August 2016 levels. These springs had previously been sampled in 2009 and 2010, providing some pre-earthquake data. Investigated aquifers are hosted in the permeable layers of the terrigenous/turbiditic "Flysch della Laga" Formation overlaying the Mesozoic carbonates, the largest groundwater bodies in central Italy.The main goals of this research were to i) evaluate the effects on the hydrochemistry and flow paths of groundwater induced by a long-lasting seismic sequence characterised by around 100.000 events, 9 of which having Mw > 5.0; ii) individuate the mechanisms causing the observed changes and iii) tentatively compare hydrochemical and water dynamic responses to earthquakes between the two different hydrogeological frameworks existing in the epicentral area (i.e Laga Formation and carbonates). During the 2016-2017 seismic sequence Barberio et al. (2017) and Rosen et al. (2018) investigated Mesozoic carbonate aquifers, highlighting notable hydrochemical transient variations in groundwater springs. They attributed most of the observed transient chemical changes to fracture clearing and shaking of fluids from isolated dead-end karstic pore spaces, also taking into account the release of geothermal fluids and deeply trapped CO2 from the deep subsurface through dilation of fault conduits.Our geochemical data were displayed in conventional time-series plots and processed by using a multivariate statistical approach (Factor Analysis). It was accomplished for each spring with the main goals to constrain more quantitatively the observations on the time-series graphs and better infer the possible correlation between seismic and geochemical patterns. Main results highlight: i) a remarkable increase in the alkali components (Na and K) as well as in some trace element contents (Fe, B, Sr, V) just after the main earthquakes (Mw > 5.0). These trends, together with a noticeable pH increase, were also observed prior to the Visso and Norcia earthquakes (mid October sampling); ii) a general stability of O, H, C and Sr isotope values for all the considered period, iii) negligible alkalinity variations over time.We tentatively interpreted most of the transient chemical changes observed in the monitored aquifers as the result of within-aquifer changes through release of slow-moving pore fluids into the main flow paths after an increase in pore pressure, hydraulic conductivity, and shaking from coseismic (and possibly pre-seismic) aquifer stress. On the contrary, other processes such as mixing among groundwater having different chemical compositions, geothermal fluids, or rapid upward movement of deep CO2-rich fluids were assumed negligible or minimised. [ABSTRACT FROM AUTHOR]

Three sites of groundwater captation on Mt. Etna volcano (namely Currone, Ilice and Pavone) were sampled systematically for six years (from 2000 to 2006) for the determination of the major ionic composition of water. The monitored sites were chosen among those most representative of the geochemical characteristics of the groundwater systems of the volcano. The period studied was characterized by several strong eruptions of Mt. Etna, both at its summit craters and along its flanks. The overall composition of the waters sampled at Currone and Ilice falls in the group of bicarbonate-alkaline-earth compositions, whereas those from Pavone show a bicarbonate-alkaline composition. In all sites, however, some samples show input of chlorine-sulfate alkaline waters, likely due to interaction between fresh groundwater and either acidic waters from SO 2 -polluted rainwater, (more evident at Pavone) or geothermal brines (more evident at Currone). Significant temporal variations affected, in a more or less marked way, all of the parameters measured at the three sites. Basic statistical correlations among the parameters at each site allowed to discover a general coherent temporal behavior of all major ions dissolved in Mt. Etna's ground waters. Factor Analysis allowed showing up to three main groups of parameters with similar temporal behavior, depending on the site. A first group was explained by interaction between volcanic ground waters and geothermal fluids; a second group was related with leaching of the host volcanic rocks by CO 2 -rich volcanic water; a third group was explained as due to input of plume-SO 2 -derived sulfate through water recharge. Using normal probability plots for each parameter at the three sites it was possible to reveal different geochemical populations explained as background, anomalous values and, possibly, outliers. Plotting the temporal patterns of all the monitored parameters versus the concurrent eruptive episodes at Mt. Etna, we discovered significant correlations that, although with different intensity and rate depending on the parameter and on the site, highlighted several geochemical processes induced by interaction between cold groundwater and magmatic/hydrothermal fluids, mostly following changes in the ground permeability of the volcanic pile. These processes seemed to be enhanced during periods of shallow magma accumulation inside of the volcano that preceded summit or flank eruptions occurred at Mt. Etna during the monitored period. [ABSTRACT FROM AUTHOR]

The present investigation provides measurements of radon (222Rn) concentration levels in 20 thermal waters at the Campi Flegrei volcanic caldera, an important geothermal system with hydrothermal manifestations in the Neapolitan area (Southern Italy). We used a RAD7® Radon-in-air detector equipped with Big Bottle RAD H2O and DRYSTIK accessories (Durridge Co. Inc.). Water samples with different chemical and/or physical conditions, not used as drink waters, are taken from continental thermal groundwaters, springs, lakes, pools and one submerged thermal spring. The waters are mostly chlorine to bicarbonate, except of a few sulphate types sampled at the hydrothermal discharge areas of Solfatara and Pisciarelli, central in the caldera. Water temperature and pH values range from 18.1 to 91.3 °C and from 2 to 8, respectively. Sampling and measurement of radon in groundwater are complicated by the high volatility of the gas; a method is here proposed. In some of the 20 sites double or triple samples were collected by using different volume polyethylene terephthalate (PET) bottles, diluting sample with blank water, and modifying flow of pumped wells. We suggest that dilution can be considered when water is i) not enough to fill in the PET, resulting in large head space in the sampler, ii) too hot determining damage of the PET or iii) too saline to clog the Big Bottle System. Dissolved radon concentrations vary from 0.1 ± 0.1 to 1146 ± 57 Bq/L with an average value of 152 Bq/L, using the CAPTURE program, the default RAD7 data acquisition program. Similar values in radon concentration are obtained using the method proposed in De Simone et al. (2015) ranging between 0.1 ± 5.8 and 1286 ± 98 Bq/L with an average value of 167 Bq/L. The hottest and most acidic sulphate waters refer to a small boiling pool at Pisciarelli hydrothermal discharge area and have nearly zero 222Rn content. 222Rn concentrations from this study are mostly below the reference level of 1000 Bq/L recommended for human health protection by the European Commission and the most adopted in the scientific community (Catão et al., 2022). No correlation has been observed between temperature, pH, major anions and radon content values, nor between rock composition since it is almost homogeneous trachyte at the study sites. 222Rn levels therefore appear to reflect the local sedimentological, structural or hydrogeological conditions. The levels of 222Rn here presented are an important background for the scientific community that will intend to define the natural fluctuations of dissolved 222Rn in relation with seasons, environment, hydrogeology or volcanic dynamics at the geohazardous Campi Flegrei area. • 222Rn in thermal waters of the Campi Flegrei volcano is <1000 (152 on average) Bq/L. • RAD7®equipped with Big Bottle RAD H2O and DRYSTIK accessories. • Dissolved radon concentrations calculated using CAPTURE and De Simone et al. (2015). • No correlation observed between temperature, pH, major anions and radon values. • 222Rn levels higher than other worldwide areas except for Ischia and Iranian waters. [ABSTRACT FROM AUTHOR]

Radon ( 222 Rn) and thoron ( 220 Rn) are two isotopes belonging to the noble gas radon ( sensu lato ) that is frequently employed for the geochemical surveillance of active volcanoes. Temperature gradients operating at subvolcanic conditions may induce chemical and structural modifications in rock-forming minerals and their related 222 Rn- 220 Rn emissions. Additionally, CO 2 fluxes may also contribute enormously to the transport of radionuclides through the microcracks and pores of subvolcanic rocks. In view of these articulated phenomena, we have experimentally quantified the changes of 220 Rn signal caused by dehydration of a zeolitized tuff exposed to variable CO 2 fluxes. Results indicate that, at low CO 2 fluxes, water molecules and hydroxyl groups adsorbed on the glassy surface of macro- and micropores are physically removed by an intermolecular proton transfer mechanism, leading to an increase of the 220 Rn signal. By contrast, at high CO 2 fluxes, 220 Rn emissions dramatically decrease because of the strong dilution capacity of CO 2 that overprints the advective effect of carrier fluids. We conclude that the sign and magnitude of radon ( sensu lato ) changes observed in volcanic settings depend on the flux rate of carrier fluids and the rival effects between advective transport and radionuclide dilution., (© 2021 The Authors.)

Rock substrates beneath active volcanoes are frequently subjected to temperature changes caused by the input of new magma from the depth and/or the intrusion of magma bodies of variable thickness within the subvolcanic rocks. The primary effect of the influx of hot magma is the heating of surrounding host rocks with the consequent modification of their physical and chemical properties. To assess mobilization in subvolcanic thermal regimes, we have performed radon ( 220 Rn) thermal experiments on a phonolitic lava exposed to temperatures in the range of 100-900°C. Results from these experiments indicate that transient Rn signals are not unequivocally related to substrate deformation caused by tectonic stresses, but rather to the temperature-dependent diffusion of radionuclides through the structural discontinuities of rocks which serve as preferential pathways for gas release. Intense heating/cooling cycles are accompanied by rapid expansion and contraction of minerals. Rapid thermal cycling produced both inter- and intra-crystal microfracturing, as well as the formation of macroscopic faults. The increased number of diffusion paths dramatically intensified Rn migration, leading to much higher emissions than temperature-dependent transient changes. This geochemical behaviour is analogous to positive anomalies recorded on active volcanoes where dyke injections produce thermal stress and deformation in the host rocks. An increased Rn signal far away from the location of a magmatic intrusion is also consistent with microfracturing of subsurface rocks over long distances via thermal stress propagation and the opening of new pathways., Competing Interests: The authors declare no competing interests., (© 2019 The Authors.)