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Radon emanation, magnetic and VLF temporary variations: Removing components not associated with dynamic processes

Authors:
Lev V. Eppelbaum at Tel Aviv University
Lev V. Eppelbaum
M. Finkelstein
M. Finkelstein
M. Finkelstein
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Abstract

Measurements of magnetic, gas radon, and VLF temporal variations contain important information about the dangerous geodynamic events at a depth. Some field examples of the earthquake precursors of the mentioned fields are demonstrated. Different ways of noise removal (or elimination) in the above fields are briefly shown.
Earthquake Paper
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Eppelbaum&Finkelstein Radon, Magnetic & VLF precursors 19
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Eppelbaum & Finkelstein Earthquake Prediction 19
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Eppelbaum&Finkelstein Radon&VLF 19
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1992
... Short-and long-term magnetic precursors are discussed abundantly in the geophysical literature (e.g., Pudovkin et al. 1973;Gokhberg et al. 1979;Eppelbaum and Finkelstein 1998;Alperovich and Zheludev 1999;Gaffet et al. 2003;Finkelstein et al. 2012). Anomalous geomagnetic variations (AVG) have different characteristics, and their tectonomagnetic effects may only be seen after removing all the noise and incident factors ( Fig. 6.39). ...
... Such a clear magnetic effect could be recorded because of the proximity of the observation station to the earthquake epicenter. However, analysis of the differential magnetic function is preferable (Eppelbaum and Finkelstein 1998), but it is necessary to take into account that the most optimal distance between the magnetic observation stations is 30-50 km (Finkelstein et al. 2012). ...
... There is growing recognition of the importance of nonlinear phenomena in many branches of geophysics. It was shown that phenomenon such as earthquakes (e.g., Keilis-Borok 1990;Voisin 2002) and their reflection in geophysical fields (Eppelbaum and Finkelstein 1998) as well as the propagation of geophysical fields in non-uniform geological media is a nonlinear process (e.g., Aleinikov et al. 2001). However, it is still common practice to solve complex geophysical problems by removing visible nonlinear effects and reducing the problem to a linear one. ...
Geodynamics and Seismology
Chapter
  • Sep 2017
The territory of Azerbaijan is characterized by high seismic activity, where during the historical period (registered), strong and catastrophic earthquakes with magnitude M 6 were observed. Azerbaijan territory may be subdivided by the level of seismic activity and character of the spatial distribution of strong and weak earthquakes in the following manner: (1) the southern slope of the eastern part of the Greater Caucasus, (2) the Kur Depression, (3) the Talysh Mts., (4) the Gusar-Devechi (now — the Gusar-Shabran) depression, and (5) the Caspian Sea. The history of seismic studies in Azerbaijan can be divided into two main periods: (1) pre-instrumental (historical), including all the information from ancient times reflected in the historical Arab chronicles, manuscripts, travel notes of travelers, etc., and (2) instrumental (contemporary) period which includes information about earthquakes from the beginning of the twentieth century (when after the strong Shamakhy earthquake in 1902, the first seismic station in Azerbaijan “Shamakhy” was founded) till the present time.
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... Short-and long-term magnetic precursors are discussed abundantly in the geophysical literature (e.g., Pudovkin et al. 1973;Gokhberg et al. 1979;Eppelbaum and Finkelstein 1998;Alperovich and Zheludev 1999;Gaffet et al. 2003;Finkelstein et al. 2012). Anomalous geomagnetic variations (AVG) have different characteristics, and their tectonomagnetic effects may only be seen after removing all the noise and incident factors ( Fig. 6.39). ...
... Such a clear magnetic effect could be recorded because of the proximity of the observation station to the earthquake epicenter. However, analysis of the differential magnetic function is preferable (Eppelbaum and Finkelstein 1998), but it is necessary to take into account that the most optimal distance between the magnetic observation stations is 30-50 km (Finkelstein et al. 2012). ...
... There is growing recognition of the importance of nonlinear phenomena in many branches of geophysics. It was shown that phenomenon such as earthquakes (e.g., Keilis-Borok 1990;Voisin 2002) and their reflection in geophysical fields (Eppelbaum and Finkelstein 1998) as well as the propagation of geophysical fields in non-uniform geological media is a nonlinear process (e.g., Aleinikov et al. 2001). However, it is still common practice to solve complex geophysical problems by removing visible nonlinear effects and reducing the problem to a linear one. ...
Geodynamics and Seismology
Chapter
Full-text available
  • Aug 2016
The territory of Azerbaijan is located within the central part of the Mediterranean tectonic belt. The territory of Azerbaijan is characterized by high seismic activity, where during the historical period (registered), strong and catastrophic earthquakes with magnitude M ≥ 6 were observed. Azerbaijan's seismicity is caused by the intensive geodynamic interaction of the Eurasian and Arabian lithospheric plates (Khain, 2000). Azerbaijan territory may be subdivided by the level of seismic activity and character of the spatial distribution of strong and weak earthquakes in the following manner: (1) the southern slope of the eastern part of the Greater Caucasus, (2) Kur Depression, (3) Talysh Mts., (4) Gusar-Devechi (now - Gusar-Shabran) depression, and (5) Caspian Sea (Aliyev et al. 2005). The history of seismic studies in Azerbaijan can be divided into two main periods: (1) pre-instrumental (historical), including all the information from ancient times reflected in the historical Arabian chronicles, manuscripts, travel notes of travelers, etc., and (2) instrumental (contemporary) period which includes information about earthquakes from the beginning of the twentieth century (when after strong Shamakhy earthquake in 1902, the first seismic station in Azerbaijan "Shamakhy" was founded) till the present time. Among the strong (historical) earthquakes, we can note such events as the Azerbaijan earthquake of 427, Goygel of 1139, Ganja of 1235, Eastern Caucasian of 1668, Mashtaga of 1842, numerous Shamakhy events (1192, 1667, 1669, 1828, 1859, 1868, 1872, 1902), Ardebil of 1924, Lenkaran of 1913, and Caspian earthquakes (957, 1812, 1842, 1852, 1911, 1935, 1961, 1963, 1986, 1989, 2000) triggered earth relief changing, building destructions, and numerous casualties. A significant contribution to solving the seismological problem in Azerbaijan was made by E.B. Agalarova, R.A. Agamirzoev, S.T. Agayeva, F.S. Akhmedbeyli, G.R. Babayev, O.B. Babazade, E.I. Byus, A.G. Gasanov, R.I. Gasanov, D.Kh. Jafarov, K.Sh. Islamov, F.A. Kadirov, I.K. Kerimov, V. P. Kouznetsov, F.T. Kuliyev, N.V. Malinovsky, T.Ya. Mammadli, B.M. Panakhi, Sh.S. Ragimov, Z.Z. Sultanova, G.D. Yetirmishli, and others.
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... Automatic variation recordings can be carried out with a discretization interval of 1-3 seconds. This method substantially eliminates observation distortions caused by field variations with time (both over the course of a day and at different days during a VLFsurvey) by reducing observation results to the some common level (Eppelbaum and Finkelstein, 1998). ...
... VLF temporal variations as possible precursors of dangerous geodynamic events. Agdara area, Nagorny Garabakh, Azerbaijan (modified afterEppelbaum and Finkelstein, 1998) Scheme of the VLF self-integration and combining with other methods ...
VLF-method of geophysical prospecting: A non-conventional system of processing and interpretation (implementation in the Caucasian ore deposits)
Article
Full-text available
  • Nov 2021
Investigating the electromagnetic (EM) fields from distant VLF military transmitters is one of the most prompt and low-expensive geophysical methods. It currently finds frequent applications in prospecting for various deposits, searching for underground subsurface water, archaeogeophysical studies, and various types of geological mapping. The VLF-radiations propagate in a spherical waveguide formed by the Earth and ionosphere where the energy of radio frequencies is not attenuated even at great distances due to the channel effect. A few dozen VLF transmitters in various countries can be used for geophysical investigations. The different frequencies and angles of registered EM radiation enable the obtaining of additional preferences through interpretation. The depth of the investigation depends on the host medium's radio wave frequency and averaged resistivity and usually ranges from several tens to several hundred meters (last values – under very favorable conditions). Both the electric and magnetic components of the EM field are used in the investigation by the VLF method. Generally, only the magnetic field (H) is employed. The absence of reliable methods limited the widespread use of the VLF technique to eliminate the EM field time variations, rugged relief influence, and procedures for quantitative interpretation of the VLF anomalies. These problems are successfully solved, and a unified methodological system is developed. A continuous, direct filtering procedure is proposed to eliminate the temporal variations. The correlation technique enables a significant reduction in the influence of rugged relief. It is possible to use the modern interpreting methods elaborated in magnetic prospecting for complex geological-geophysical conditions for a quantitative interpretation. Finally, for revealing hidden objects against the high-intensive geological noise background, an application of non-conventional statistical, informational, and wavelet algorithms is suggested. The main components of the developed system were successfully tested in the Caucasian polymetallic, copper, and gold deposits. An example of the VLF quantitative analysis in an archaeological site is shown. The possibility of VLF-data utilization as precursors of dangerous geodynamic events at a depth is demonstrated.
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... It is well known that radon gas distribution in subsurface and surface is of great danger for people (e.g., Mishel 1987;Blue et al. 1989). It should be pointed out that radon measurements in the subsurface are influenced by a number of factors (Eppelbaum and Finkelstein 1998;Finkelstein et al. 2006): ...
Engineering, Environmental, and Archaeological Geophysics
Chapter
  • Sep 2017
Geophysical monitoring of oil and gas pipelines (primarily in Baku–Tbilisi–Ceyhan (BTC) and the South Caucasus Pipelines (SCP)) (Balat, 2006) is one of the most critical problems in Caucasus engineering geophysics (Rabinowitz et al., 2004; Babazade et al., 2008; Tanircan et al., 2011; Bayramov et al., 2016) (Fig. 9.1). It is evident that for this purpose, ground (e.g., Modin, 2010) and satellite (e.g., Kostianoy et al., 2008) observations, and underground geophysical monitoring can be used. An integrated wavelet approach (Eppelbaum et al., 2011) that associates different geophysical methods, including satellite imaging and topography data, has proved to be the most successful. Bayramov et al. (2016) examined ground cover restoration and soil erosion risks along petroleum and gas pipelines in Azerbaijan territory using GIS and remote sensing. Figure 9.2 shows meaningful relationships between elevation and precipitation (a), elevation and evapotransportation (b), height and annual air temperature (c), and elevation and land surface temperature (d). Such an integrated approach to these essential targets analysis is of high perspective. The following environmental analysis stage must include, apparently, the employment of multifactor (or similar methodology) analysis.
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... From Figure 16, perturbations are observed five days before the earthquake occurred on 30 August 2005 18:10:45 UT with a magnitude of 6.2, where the epicenter of the quake is 38.55 • north latitude and 143.06 • east longitude, and similar perturbations are observable with intensification at around 500 Hz in ELF in both the electric field and magnetic field. In addition, some examples of earthquake precursors for VLF temporary variations are demonstrated by Eppelbaum and Finkelstein [75]. Figure 17a shows the histograms and summary statistics obtained for distances from the epicenters of the seismic-related data. ...
Identification of Electromagnetic Pre-Earthquake Perturbations from the DEMETER Data by Machine Learning
Article
Full-text available
  • Nov 2020
The low-altitude satellite DEMETER recorded many cases of ionospheric perturbations observed on occasion of large seismic events. In this paper, we explore 16 spot-checking classification algorithms, among which, the top classifier with low-frequency power spectra of electric and magnetic fields was used for ionospheric perturbation analysis. This study included the analysis of satellite data spanning over six years, during which about 8760 earthquakes with magnitude greater than or equal to 5.0 occurred in the world. We discover that among these methods, a gradient boosting-based method called LightGBM outperforms others and achieves superior performance in a five-fold cross-validation test on the benchmarking datasets, which shows a strong capability in discriminating electromagnetic pre-earthquake perturbations. The results show that the electromagnetic pre-earthquake data within a circular region with its center at the epicenter and its radius given by the Dobrovolsky’s formula and the time window of about a few hours before shocks are much better at discriminating electromagnetic pre-earthquake perturbations. Moreover, by investigating different earthquake databases, we confirm that some low-frequency electric and magnetic fields’ frequency bands are the dominant features for electromagnetic pre-earthquake perturbations identification. We have also found that the choice of the geographical region used to simulate the training set of non-seismic data influences, to a certain extent, the performance of the LightGBM model, by reducing its capability in discriminating electromagnetic pre-earthquake perturbations.
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... Thus, the proposed scheme of eliminating variations in the VLF method is based on synchronous recording of the observations along the profile and variations at CP. Automatic variation recording presents no difficulties and can be realized with a discretization interval of 3-5 seconds. This method substantially eliminates observation distortions caused by field variations with time (both during a day and at different days of the survey) by reducing observation results to some common level (Eppelbaum and Finkelstein, 1998). ...
Remote Operated Vehicle Geophysical Survey Using Magnetic and VLF Methods: Proposed Schemes For Data Processing and Interpretation
Conference Paper
Full-text available
  • Apr 2008
Aircraft geophysical investigations are recognized now as a powerful tool for geological‐geophysical mapping, searching economic minerals, environmental studying, ecological monitoring, etc. Two main reasons limit the practical application of such conventional investigations: (a) essential impediments to performing geophysical surveys at small altitudes and (b) heightened danger for the aircraft crew, especially in regions with rugged topography. Remote Operated Vehicles (ROV) are free from the limitations mentioned above. The new ROV generation — small and maneuvering vehicles — can fly at levels of a few (and even one) meters over the earth's surface (flowing the relief forms) with simultaneous performing geophysical measurements.
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... recorded because of the proximity of the observation station to the earthquake epicenter. However, analysis of the differential magnetic function is preferable (Eppelbaum and Finkelstein, 1998), but it is necessary to take into account that the most optimal distance between the magnetic observation stations is 30e50 km (Finkelstein et al., 2012). ...
Monitoring of Dangerous Geodynamic Events
Chapter
Full-text available
  • Jul 2019
Are earthquakes predictable? To forecast dangerous geodynamic events at a depth, practically all geophysical methods can be employed. Magnetic, gravity, resistivity, and thermal observations are possible earthquake precursors that received a worldwide distribution. Despite several successful applications, self-potential observations were only sometimes accepted as reliable precursors. Short and long-term magnetic precursors are discussed abundantly in the geophysical literature. Anomalous geomagnetic variations have different characteristics, and their tectonomagnetic effects may only be seen after removing all the noise and incident factors. Thermal indicators of the dangerous impacts of geodynamics are discussed in detail. A short description of gravity and resistivity precursors is also presented. Some non-conventional geodynamic indicators compared the magnetic field gradients with the elements of seismic activity are described. Since complex geodynamic processes at the depth cannot be considered linear, the various nonlinear geophysical precursors are separately considered.
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A Novel Assessment of the Surface Heat Flux Role in Radon (Rn-222) Gas Flow within Subsurface Geological Porous Media
Article
Full-text available
  • Aug 2023
At present, Rn subsurface flow can be described only by diffusion and advection transportation models within porous media that currently exist. Even though the temperature is a strong driving force in climate and gas thermodynamics, the impact of the surface heating is missing from all gas flow models within geological porous media. In this work, it is shown that heating the ground surface by the sun, every day up to a maximum temperature at noon, creates a downward vertical temperature gradient related to the constant temperature in the upper shallow layer whose measured thickness is several meters. Undersurface, the Rn gas in the porous media is propelled in nonlinear dependency by the surface temperature gradient to flow downward, up to a measured depth of 100 m, revealing a daily periodicity with time delay depending on depth, similar to the diurnal cycle of the surface temperature. Moreover, regression analysis applied with the data implies a non-linear relationship between Rn and the temporal surface temperature. The relationship is non-linear and the best fit for it from a thermodynamic point of view is an exponential dependency. From now on, it will be possible according to the model to predict and extract, if required, by the time series of the surface-measured parameters (the ambient temperature and pressure), the semi-diurnal, diurnal, multiday, and seasonal Rn temporal variation at a shallow depth.
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Regional Physical-Geological Models and Regioning
Chapter
  • Apr 2012
The initial development of a medium model is the most crucial stage since the results of interpretation and the investigation, in general, depend considerably upon its quality. A preliminary model is devised to represent the geological objective when preparing a geophysical project for the given area. Otherwise, it is impossible to select the set of methods and interpretation procedures. The latter is revised before interpreting, if necessary.
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Methodological Specificities of Geophysical Studies in the Complex Environments of the Caucasus
Chapter
  • Apr 2012
Geophysical studies of the Caucasus need to cope with the mountainous environments of many of its regions and their inclined (oblique) magnetization in temperate latitudes. The uneven topography impedes geophysical surveys in mountainous areas due to poor accessibility and distorts the measurement results.
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Identification of anomalous radon concentrations due to geodynamic processes by elimination of Rn variations caused by other factors
Article
Full-text available
  • May 1998
It has been suggested that temporal variations of radon concentrations in various media may be used as a possible predictive indicator of geodynamic activity at a depth. However, observed Rn measurements are a function of several different physical processes, including geodynamic activity. This paper describes a generalized approach to removing ``noise components'' from the observed data to leave a residual component of radon concentration that reflects geodynamic processes at depth. The approach is demonstrated using data gathered in Israel before and after the 1992 October 12 Giza earthquake in Egypt.
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VLF method: Elimination of noises and quantitative interpretation
Conference Paper
Full-text available
  • Dec 1992
Time variations and the rugged-relief effect enormously complicate geophysical investigations by the Very Low Frequency (VLF) method. Effective statistical and filtering procedures have been developed to eliminate these kinds of noise. Quantitative interpretation of VLF anomalies under complex geological conditions can be conducted with modern methods developed in magnetic prospecting. Interpret the VLF data in physical-geological complex environments (e.g., inclined polarization and superposition of numerous anomalies) can be performed using original logical-informational algorithms.
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