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

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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.
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. ...
Chapter
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.
... 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. ...
Chapter
Full-text available
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.
... 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 ...
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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.
... 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): ...
Chapter
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.
... 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. ...
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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.
... 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). ...
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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). ...
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