Radon Anomalies Research Articles

Time-dependent variations of groundwater radon: Insights from a twelve-year study in the Baikal region, East Siberia, Russia

Time-dependent variations of 222Rn concentration (Q) in groundwater have been monitored for twelve years (2012–2023) at eight sites of groundwater discharge within the Baikal region in East Siberia, Russia. The concentrations of radioactive gas at different sites vary from 30% to 60% of average values (Qav). The sampled waters are of three groups with Qav ≈ 15 Bq/l (I), ≈30 Bq/l (II1), and ≈50 Bq/l (II2). Cluster analysis shows closest linkage between the two subgroups of group II due to similarity in the discharge mechanisms. Fourier analysis of periodic 222Rn behavior reveals major cycles of 365, 180, 126, and 30 days correlated with variations of air temperature and pressure, as well as with the patterns of groundwater discharge. In addition, radon anomalies are related with seismicity. Earthquakes are reflected in the radon field as three distinct anomaly types, occurring either subsequent to or prior to the seismic event. The anomalies responding to earthquake nucleation can be considered as precursors and used in earthquake prediction. The revealed trends make basis for a model designed to predict Q variations in groundwater of the area to 80% average efficiency. The external and internal factors that affect the concentration of radioactive gas in groundwater are linked in a hierarchic system and are classified according to the degree and type of their influence.

Seismic and radon signatures: A multiparametric approach to monitor surface dynamics of a hazardous 2021 rock–ice avalanche, Chamoli Himalaya

AbstractThe observation of precursory signals of the 2021 Chamoli rock–ice avalanche provides an opportunity to investigate the multidisciplinary analysis approach of rock failure. On 7 February 2021, a huge rock–ice mass detached from the Raunthi peak at Chamoli district in Uttarakhand, India. The tragic catastrophe resulted in more than 200 deaths and significant economic losses. Here, we analyse radon concentration and seismic signals to characterise the potential precursory anomalies prior to the detachment. Continuous peaks of radon anomalies were observed from the afternoon of 5 to 7 February and decreased suddenly after the event, while a cumulative number of seismic tremors and amplitude variations are more intensified ~2.30 h before the main event, indicating a static to dynamic phase change within the weak zone. This study not only characterises abnormal signals but also models the rock failure mechanisms. The analysis unveils three time‐dependent nucleation phases, physical mechanisms of signal generation and a complete scenario of physical factors that affected the degree of criticality of slope failure. The results of this study suggest gradual progression of rock cracks/joints, subsequent material creep and slip advancement acceleration preceded the final failure. Furthermore, the study highlights the importance of an early warning system to mitigate the impact of events like the 2021 Chamoli rock–ice avalanche.

Investigation of the relationship between the decline in well waters radon anomalies and the earthquake magnitude (Mw)

Afyonkarahisar and its surroundings are in the middle of the Akşehir-Simav Fault System. Before the earthquakes in the region, radon anomalies were observed in some well waters. Linear equations between radon minima and earthquake magnitudes (Mw) were obtained, and correlation coefficients (R2) were calculated. The correlation coefficient (R2) values of the wells from 1 to 6 were obtained as 0.93, 0.83, 0.82, 0.97, 0.87 and 0.85, respectively. Good correlations (high R2 values) were obtained between the radon minimum and the earthquake magnitude (Mw) in 6 wells. The precursory minimum observed at the radon concentration in groundwater decreased as the earthquake's magnitude increased.

Comparing wavelet-based artificial neural network, multiple linear regression, and ARIMA models for detecting genuine radon anomalies associated with seismic events

Comparing wavelet-based artificial neural network, multiple linear regression, and ARIMA models for detecting genuine radon anomalies associated with seismic events

Features of Degassing from Overburden Rock Massifs: A Case Study Using Radon

Overburden rock massifs resulting from open-pit coal mining are very common objects in the world’s mining regions. These locations pose a significant challenge as the global mining industry expands. These dumps are capable of self-burning for quite a long time. The displacement and sliding of these massifs can cause catastrophic consequences. In addition, these objects emit a significant amount of greenhouse gases into the atmosphere. Therefore, it is necessary to manage such objects and implement appropriate measures to limit their impact on the environment. In this work, we studied soil radon volume activity (VAR) and radon flux density (RFD) on the surface of the overburden rock massif of coal-bearing mining rocks and also made visual fixation of disturbances in the body of the massif, which appeared in the process of its movement. We found anomalies of VAR and RFD on the surface of the overburden extending from north to south. These anomalies were extended along the strike of the faults found in the body of the massif. Additionally, the radon anomalies coincided with the anomalies of methane gas emission previously measured for this object. Thus, we determined that the exit of gases from the body of the massif is carried out through fault (weakened) zones in the body of the massif. According to the results of the study, we propose to carry out radon monitoring in order to detect the spontaneous ignition process of the massif or the increase of its mobility. This will also allow us to take appropriate measures to stabilize the massif or to extinguish the dump before or simultaneously with the biological stage of reclamation.

Distribution of Radionuclides in the Surface Covering of the Barun Uranium Mining Area in Erlian Basin, Inner Mongolia

In order to identify the distribution pattern of radionuclides in the surface soil in the area of a sandstone-type uranium deposit, and to explore its spatial relationship with the location of the orebody, soil radon measurements and ground gamma-ray spectroscopy were carried out in the Barun study area, and soil properties were analyzed. The results show that the soil radon concentrations exhibited a bimodal feature, while the uranium content showed a decreasing trend along the tendency direction of the orebody. In the ground projection area of the orebody, radon concentration showed a positive correlation with uranium content, with both showing relatively low values. Combined with the results of field geological observation and soil property analysis, it is believed that the relatively low radon concentration and uranium content above the orebody is related to the soil being mainly sandy soil. Relatively high uranium values are distributed within approximately 1.5 km north of the northern boundary of the orebody and near the southern boundary of the orebody. High-value radon anomalies occur within about 2 km north of the northern boundary of the orebody and within about 1.3 km south of the southern boundary of the orebody.

Structural control of gas migration pathways in the hydrocarbon-rich Val d’Agri basin (Southern Apennines, Italy)

Val d’Agri is a seismically active intermontane basin in southern Italy known for hosting the largest on-shore hydrocarbon reservoir in western Europe. Despite extensive study of the basin, important questions remain regarding fluid circulation and the possible link between deep hydrocarbon reservoirs, faults, natural and induced seismicity, and gas migration towards the surface. To address some of these issues we performed near-surface gas geochemistry and structural geology surveys throughout the basin at both the regional and local scale. While carbon dioxide data are due to shallow, biological processes in the soil, anomalous results for other gas species are interpreted as being linked to structural discontinuities. Coincident methane and ethane anomalies, which imply a deep thermogenic origin, occur primarily in the northern part of the Val d’Agri basin. The most dominant alignment of these gases starts from a surface hydrocarbon seep and extends above a buried, NE-SW-striking fault that transects the valley. In contrast, radon anomalies are localized in the southern part of the basin along the western border, in correspondence with the Monti della Maddalena Fault System (MMFS) and a cluster of background natural seismicity. The origin and implications of the observed anomalies are discussed.

Estimating atmospheric radon deviation using statistical coefficients: Sulaymaniyah city, Iraq, as a case of study

ABSTRACT The authors studied the atmospheric radon concentration with associated meteorological parameters variation during the dust events from July to November 2017. We obtained the meteorological parameters data in weather station of Sulaymaniyah city, Iraq. In the environmental monitoring plan, the atmospheric radon fluctuated from 15 to 48 Bq m–3 around the mean value of 31.5 ± 7 Bq m–3 within the summer. In autumn, varied from 22 to 46 Bq m–3 with a mean value of 34 ± 12 Bq m–3. We employed this to determine the radon level anomalously. Using the modified statistical coefficients, such as the residual deviation (RD), residual fluctuation ratio (RFR), F-test, and p-value coefficients. Among the atmospheric radon fluctuation values, particularly one anomalous (42 Bq m–3) on 25 July was determined because the excessive value of the RD was 1.9 σ, and the RFR value was 66 %. Corresponding to our coefficients criteria, the minimum level of atmospheric radon (22 Bq m–3) does not consider anomalous because of increasing wind speed. Based on this, our method for determining the atmospheric radon anomalies that are influenced by the missed factors beyond the mentioned meteorological parameters is accurate.

Earthquake prediction with machine learning models based on peak of radon anomalies

Earthquake prediction with machine learning models based on peak of radon anomalies

Динамика выброса радона из штолен бывшего уранового рудника на склонах горы Бештау

This article presents the results of monitoring measurements of radon concentration in the air, the gamma dose rate, as well as the velocity and direction of air movement at the adit mouths of the former Beshtaugorsky mine No.1 (Mount Beshtau). The data obtained indicate the very powerful seasonal radon anomalies at the adit mouths associated with the periodic release of mine air from the tunnels into the atmosphere. During mine air discharge, radon concentrations in the open atmosphere locally around the adit mouth reach 594,685 Bq/m3, averaging 50000 – 250000 Bk/m3. The equivalent equilibrium concentration of radon in the air ranges from 1600 to 80000 Bq/m3. The release of significant concentrations of radon and its progeny leads to significant increase in the dose rate of gamma radiation locally around the adit mouth to values of 1–18 mSv/h. This means that abandoned adit mouths are objects of increased radiation risk. Comparison of the results of measurements of radon concentration at the adit mouths and in the zone of a natural radon anomaly associated with a tectonic fault shows that radon emissions in both cases are caused by a single process – air circulation in permeable zones of the rock massif due to the temperature difference between the mountain range and the atmosphere.

Detailed geophysical studies of the Ilych-Chikshinskaya fault system (Izyma-Pechora Monocline)

Research subject. The Ilych-Chikshinskaya fault system involved in the structure of the Izhma-Pechora monocline. The Ilych-Chikshinskii deep fault is the southern branch of the Pripechorskaya fault system, which separates the Timansky and Pechoromorsko-Bolshezemelsky geoblocks. Materials and methods. The data obtained during profile detailed magneto-metric and radon surveys, the materials of fund seismic surveys, and the maps of gravitational and magnetic fields of various scales were used. Measurements of the volume radon activity were carried out using portable radiometers РРА-01М-01 and Alfarad plus. Magnetometric observations were carried out with a MINIMAG magnetometer. Results. Radon surveys on two profiles were conducted in different years. According to the obtained results, the faults of the Ilych-Chikshin skaya system have no obvious manifestation in the radon field. The volume radon activity in different periods varied across a wide range from 50–200 to 200–600 Bq/m3, which indicates the absence of a constant deep source of radon. According to the data of detailed magnetometric surveys, the Ilych-Chikshinskii fault, against the background of a calm negative field, corresponds to a gradient zone of 4 km wide. Conclusion. The presence of low-intensity discontinuous radon anomalies along the line of profiles is associated with increased concentrations of parent uranium radionuclides in the soil and near-surface rocks. Since the rocks of the basement and sedimentary cover are nonmagnetic, the local magnetic anomaly indicates the presence of mafic and ultramafic intrusions in the zone of the Ilych-Chikshinskii fault.

Radon transport in permeable geological environments

This article presents the results of a long-term soil radon and meteorological parameter monitoring study in the fault zone at Mt. Beshtau, North Caucasus, which for more than 3 years. Strong seasonal variations in the radon levels with maxima during summer and minima during winter were recorded. The values of radon exhalation and soil radon concentration have a range of 0.025–25 Bq m 2 s −1 and 1–170 kBq m −3, respectively. In addition, measurements of the air radon concentration, and direction of air movement at the adits mouths of the former uranium mine on the same mountain were carried out. Seasonal radon variations, similar to those observed in fault zones, were recorded at the mouths of adits. It was established that radon anomalies are associated with the periodic release of mine air from the fractures and tunnels into the atmosphere. Above an altitude of 900 m a. s. l., an abnormal release of radon occurs in winter, when the mine air is warmer than the surrounding atmosphere. At the altitudes below 900 m the cold radon rich air blows from the adit mouths in summer. During mine air discharge, radon concentrations in the open atmosphere locally around the adit mouth reach 600,000 Bq m−3, averaging 50,000–250,000 Bq m−3. The temporal pattern of radon fluctuations in fault zones and at the adit mouths is similar. A very close correlation between radon levels and atmospheric air temperature was observed both in the fault zone and at the adits mouths. It indicates that radon release in both cases are caused by a single mechanism. This mechanism probably is the atmospheric air circulation in shallow permeable zones due to the temperature difference between the inside mountain and ambient atmosphere.

Application of the extreme gradient boosting method to quantitatively analyze the mechanism of radon anomalous change in Banglazhang hot spring before the Lijiang Mw 7.0 earthquake

Radon concentration in groundwater is affected by meteorological and seismo-tectonic factors and is sensitive indicators of crustal stress. While previous studies have focused on the mechanisms of periodic and precursory radon anomalies, few have quantitatively assessed their influences, and compared their rates of change under normal and earthquake conditions. This study constructs four models to analyze the mechanisms of radon variation under natural and seismic conditions using the Extreme Gradient Boosting method: 1) the multi-year dynamic variation model, 2) the maximal radon concentration model, 3) the minimum radon concentration model, and 4) the precursory anomaly model. The feature relative importance of external factors influencing radon concentration in groundwater are estimated. The optimized extreme gradient boosting model estimated the feature importance of spring discharge (SD), water temperature (WT), precipitation (P), barometric pressure (BP), and antecedent radon (AR) to be 23.79%, 22.16%, 9.81%, 18.8% and 25.44%, respectively. Thus, SD is the most important influence on radon variation under normal conditions. For radon variation during the earthquake preparation period, the feature relative importance indicates significant changes in WT (increasing from 22.16% to 27.70%) and SD (decreasing from 23.79% to 17.99%). Although WT was the most important predictor in the precursory anomaly model, its effect on radon solubility is insufficient to explain the radon anomalies prior to the Lijiang Mw 7.0 earthquake. Analysis of the precursory mechanisms of these radon anomalies in terms of SD, WT, P, BP, and radon emanation found that radon anomalies are most likely caused by increases in radon emanation due to the earthquake-induced formation of microfractures in rock.

Preliminary Study on the Generating Mechanism of the Atmospheric Vertical Electric Field before Earthquakes

Precursor signals for earthquakes, such as radon anomalies, thermal anomalies, and water level changes, have been studied in earthquake prediction over several centuries. The atmospheric vertical electric field anomaly has been observed in recent years as a new and valuable signal for short-term earthquake prediction. In this paper, a physical mechanism of the atmospheric vertical electric field anomaly before the earthquake was proposed, based on which the Wenchuan earthquake verified the correctness of the model. Using Monte Carlo simulations, the variation of the radon concentration with height before the earthquake was used to simulate and calculate the ionization rates of radioactive radon decay products at different heights. We derived the atmospheric vertical electric field from −593 to −285 V/m from the surface to 10 m before the earthquake by solving the system of convection-diffusion partial equations for positive and negative particles. Moreover, negative atmospheric electric field anomalies were observed in both Wenjiang and Pixian before the Wenchuan earthquake on 12 May, with peaks of −600 V/m in Pixian and −200 V/m in Wenjiang. The atmospheric electric field data obtained from the simulation were shown to be in excellent concordance with the observed data of the Wenchuan earthquake. The physical mechanism can provide theoretical support for the atmospheric electric field anomaly as an earthquake precursor.

Using geogenic radon potential to assess radon priority area designation, a case study around Castleisland, Co. Kerry, Ireland

Globally, indoor radon exposure is the leading cause of lung cancer in non-smokers and second most common cause after tobacco smoking. Soil-gas radon is the main contributor to indoor radon, but its spatial distribution is highly variable, which poses certain challenges for mapping and predicting radon anomalies. Measurement of indoor radon typically takes place over long periods of time (e.g. 3 months) and is seasonally adjusted to an annual average concentration. In this article we investigate the suitability of using soil-gas radon and soil-permeability measurements for rapid radon risk assessments at local scale. The area of Castleisland, Co. Kerry was chosen as a case study due to availability of indoor radon data and the presence of significant radon anomalies. In total, 135 soil-gas and permeability measurements were collected and complemented with 180 indoor radon measurements for an identical 6 km2 area. Both soil-gas and indoor radon concentrations ranged from very low (<10 kBqm−3, 0.1 Bqm−3) to anomalously high (>1433 kBqm−3, 65,000 Bqm−3) values. Our method classifies almost 50% of the area as a high radon potential area, and allows assessment of geogenic controls on radon distribution by including other geological variables. Cumulatively, the percentage of indoor radon variance explained by soil-gas radon concentration, bedrock geology, subsoil permeability and Quaternary geology is 34% (16%, 10%, 4% and 4% respectively). Soil-gas and indoor radon anomalies are associated with black shales, whereas the presence of karst and geological faults are other contributing factors. Sampling of radon soil-gas and soil permeability, used in conjunction with other geogenic data, can therefore facilitate rapid designation of radon priority areas. Such an approach demonstrates the usefulness of high-resolution geogenic maps in predicting indoor radon risk categories when compared to the application of indoor radon measurements alone. This method is particularly useful to assess radon potential in areas where indoor radon measurements are sparse or lacking, with particular application to rural areas, land rezoned for residential use, or for sites prior to building construction.

Assessment of the tectonic effects on soil radon activity along the margin of the Arabian plate boundary in northwestern Syria

The main purpose of the present study is to assess the role of active tectonics in influencing the emanation level of soil radon across two tectonically active structures of the Northern Dead Sea Fault (NDSF) in northwestern Syria: namely, the Qastoon and Al-Harif fault segments. The radon measurements were basically directed by the results drawn from earlier studies of archaeoseismic and paleoseismic investigation in Al-Harif, besides integrated geophysical and morphotectonic survey at the Qastoon site. In view of that, a total of 80 soil gas radon points were measured in this work with sampling depth of 75 cm, using AlphaGUARD PQ 2000Pro radon detector. The background range of normal radon emission from local soil was determined in area located away from the influence of the tectonic disturbances. The obtained radon data were statistically analyzed and the mean values have been standardized in terms of probability of magnitude which enhances the comparison process and so facilitating the separation of normal radon variations from other anomalous or geotectonic related values. The overall results revealed remarkable occurrences of fault-associated radon anomalies with maximum peak values of ~6 to 7 times above the background, trending in accordance with the predicted traces of the fault ruptures at the Qastoon and Al-Harif, respectively.

Identification of Groundwater Radon Precursory Anomalies by Critical Slowing down Theory: A Case Study in Yunnan Region, Southwest China

In this study, we use the critical slowing down (CSD) theory to identify the precursory anomalies of groundwater radon based on the 1000-day continuous data from 8 monitoring stations in Yunnan Province, China during the seismically active period of 1993–1996. The low-frequency and high-frequency information were extracted from raw groundwater radon data to calculate their one-step lag autocorrelation (AR-1) and variance, respectively, in order to identify the precursory anomalies. The results show that the anomaly characteristics can be divided into three categories: sudden jump anomalies, persistent anomalies, and fluctuation anomalies. The highest average seismic recognition rate is 72.78%, based on the high-frequency information’s autocorrelation, while the lowest is 45.08%, based on the low-frequency information’s variance. The crustal activity and the change in hydrogeological conditions are possibly the main factors influencing groundwater radon anomalies in the selected period in the study area. There is a positive correlation between the anomaly occurrence time and epicentral distance when epicentral distance is less than 300 km, which may be related to the seismogenic modes and hydrogeological conditions. This study provides a reference for identifying groundwater radon anomalies before earthquakes by mathematical methods.

Studies of scintillations and TEC variations with GPS satellite links together with soil radon anomalies preceding Nepal earthquakes of April–May 2015

Studies of scintillations and TEC variations with GPS satellite links together with soil radon anomalies preceding Nepal earthquakes of April–May 2015

Seismic induced soil gas radon anomalies observed at multiparametric geophysical observatory, Tezpur (Eastern Himalaya), India: an appraisal of probable model for earthquake forecasting based on peak of radon anomalies

Seismic induced soil gas radon anomalies observed at multiparametric geophysical observatory, Tezpur (Eastern Himalaya), India: an appraisal of probable model for earthquake forecasting based on peak of radon anomalies

Groundwater Radon Precursor Anomalies Identification by EMD-LSTM Model

Groundwater radon concentrations can reflect the changes of crustal stress and strain. Scholars and scientific institutions have also recorded groundwater radon precursor anomalies before earthquakes. Therefore, groundwater radon monitoring is an effective means of predicting seismic activities. However, the variation of radon concentrations within groundwater is not only affected by structural factors, but also by environmental factors, such as air pressure, temperature, and rainfall. This causes difficulty in identifying the possible precursor anomalies. Therefore, the EMD-LSTM model is proposed to identify the radon anomalies. This study investigated the time series data of groundwater radon from well #32 located in Sichuan province. Three models (including the LSTM (Long Short-Term Memory) model with auxiliary data, the EMD-LSTM (Empirical Mode Decomposition Long Short-Term Memory) model with auxiliary data, and the EMD-LSTM model without auxiliary data) were developed in order to predict groundwater radon variations. The results indicated that the prediction accuracy of the EMD-LSTM model was much higher than that of the LSTM model, and the EMD-LSTM model without auxiliary data also can obtain an ideal prediction result. Furthermore, the different durations of seismic activities T (T = ±10, ±30, ±50, and ±100) were also investigated by comparing the identification results. The identification rate of the precursor anomalies was the highest when T = ±30. The EMD-LSTM model identified five possible radon anomalies among the seven selected earthquakes. Taking well #32 as an example, we provided a promising method, that was the EMD-LSTM model, to detect the groundwater radon anomalies. It also suggested that the EMD-LSTM model can be used to identify the possible precursor anomalies within future studies.