NH4.2

The north-central region of Algeria has been characterized by a swarm-type seismicity, after the strong Mw6.8 Boumerdès earthquake of May 21, 2003, culminating with the earthquake that occurred on July 17, 2013 of magnitude Mw=5. A magnetotelluric station was installed on December 2014 in the Medea region, 60 km south of the capital Algiers. We measured the five components of the telluric and magnetic field with a sampling frequency of 15 Hz. The seismic activity in the region provided the opportunity to observe and study the earthquake’s related electromagnetic signal. The scaling properties of the recorded electric and magnetic time series were investigated. On the basis of multifractal detrended fluctuation analysis, which is a powerful method for detecting scaling in non-stationary time series, deviations from the uniform scale of the power law were identified and quantified. We investigated the time dynamics of the earthquake related electromagnetic time series measured at the magnetotelluric station. The multifractal detrended fluctuation analysis showed the different multifractality properties of electromagnetic signals before, during and after the seismic event. The results of this work show an unstable scaling behavior in electromagnetic data during the occurrence of the seismic event. These first results could be useful in the framework of seismo-electromagnetic signals studies.

How to cite: Kasdi, A. S., Bouzid, A., Hamoudi, M., and Abtout, A.: Investigation scaling behavior of earthquake-related signals in magnetotelluric measurements, Northern Algeria, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-325, https://doi.org/10.5194/egusphere-egu21-325, 2021.

The Mugello basin (Tuscany, Italy) is one of the areas with the highest seismic risk of Tuscany, having been subjected in the past to earthquakes up to Mw 6.38 (Rovida et al., 2020). As detailed in the seismic risk map of Italy, this region is characterized by a quite high value of the Peak Ground Acceleration index (PGA> 0.175, Stucchi et al., 2011). As a part of a seismic prevention/prediction program of the Regional Government of Tuscany, the Mugello basin was chosen, ten years ago, as a monitoring site for possible hydrogeochemical precursors of seismic activity. For this purpose, the IGG-CNR of Pisa has realized an automatic continuous monitoring station, equipped with sensors for the concurrent measurement of temperature, pH, redox potential, electrical conductivity, CO₂ and CH₄ dissolved concentration (Cioni et al., 2007). According to literature guidelines (e.g. Martinelli and Albarello, 1997), after a preliminary hydrogeochemical screening carried out on 2011, the automatic surveying station was placed in correspondence of the Postignana spring. This spring is located at an altitude of 476 m a.s.l., in correspondence to a major extensional structure, the Ronta fault system (Sani et al., 2009), held responsible for the Mw = 6.8 destructive earthquake of June 29^th, 1919. With a stable temperature of 13°C and a permanent outflow of a few liters/minute (with reduced seasonal oscillations), the Postignana spring discharges low salinity waters (600 mg/l). Here we present the anomalous variations in the dissolved content of CO₂ and electrical conductivity recorded by the automatic station, before the Mw 4.5 Mugello earthquake occurred on December 9^th, 2019.

Cioni, R., Guidi, M., Pierotti, L., Scozzari, A., 2007. An automatic monitoring network installed in Tuscany (Italy) for studying possible geochemical precursory phenomena. Nat. Hazards Earth Syst. Sci. 7, 405–416.

Martinelli, G., Albarello, D., 1997. Main constraints for siting monitoring networks devoted to the study of earthquake related phenomena in Italy. Ann. Geophys. 40, 1505–1522.

Rovida A., Locati M., Camassi R., Lolli B., Gasperini P. (2020). The Italian earthquake catalogue CPTI15. Bull Earthq Eng, 18, 652 2953-2984. https://doi.org/10.1007/s10518-020-00818-y

Sani, F., Bonini, M., Piccardi, L., Vannucci, G., Delle Donne, D., Benvenuti, M., ... & Tanini, C. (2009). Late Pliocene–Quaternary evolution of outermost hinterland basins of the Northern Apennines (Italy), and their relevance to active tectonics. Tectonophysics, 476(1-2), 336-356.

Stucchi M., Meletti C., Montaldo V., Crowley H., Calvi G.M., Boschi E. Seismic Hazard Assessment (2003-2009) for the 686 Italian Building Code. Bulletin of the Seismological Society of America 2011, 101, 1885-1911.

How to cite: Pierotti, L., Droghieri, E., Facca, G., and Gherardi, F.: Geochemical continuous signals in seismic areas: the case of the Mugello Basin, Central Italy, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16117, https://doi.org/10.5194/egusphere-egu21-16117, 2021.

The present study assesses two signal processing methods on geomagnetic data to detect precursory signals appearing before M>5.0 Vrancea, Romania earthquakes occurred between 2016 and 2021. Geomagnetic data are obtained from Muntele Rosu Seismological Observatory situated in one corner of Vrancea seismogenic zone – as primary station, and from Intermagnet Surlari National Geomagnetic Observatory of IGR, located about 150Km South-East to Vrancea zone as remote station respectively. The first method, the diurnal variation ratio method computes difference between daily maximum with minimum value before finding ratio of primary to remote station for each individual component. The second method, the polarization ratio analysis is performed on both stations data to compute the ratio of vertical to total horizontal component in ultra-low frequency range. Geomagnetic indices taken from NOAA/Space Weather Prediction Center are compared to separate the global variation from seismo-electromagnetic anomalies possibly presented in a seismic area like Vrancea zone and to ensure that any geomagnetic fluctuations are not caused by solar-terrestrial effect.

In the end, the paper aims to compare the results from both methods in term of reliability and effectiveness.

Acknowledgements. This work was funded by: PN19 08 01 01/2019 Multirisc Nucleu Project, by MCI , Phenomenal Project PN-III-P2-2.1-PED-2019-1693, 480PED/2020 and AFROS Project PN-III-P4-ID-PCE-2020-1361, PCE/2021 supported by UEFISCDI

How to cite: Moldovan, I. A., Mihai, A., Toader, V. E., Enescu, B. D., and Ghita, C.: The geomagnetic field behavior inside Vrancea zone (Romania) in correlation with tectonic, atmospheric and solar activity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-15517, https://doi.org/10.5194/egusphere-egu21-15517, 2021.

Earthquakes occur when the fault stress accumulates to the critical level. External forces such as tidal forces may contributes to the triggering of earthquakes reaching the critical state. For example, in the case of 2011 Tohoku Earthquake, it is reported that there is a correlation between tidal forces and the earthquakes prior to the mainshock. Earthquakes with smaller magnitude are also affected by tidal forces and expected to show correlation with tidal forces.

Tidal triggering of non-volcanic seismic swarm has not been well documented. So, we choose the Wakayama Prefecture as a targeting region. The cause of the earthquakes occurring in the region is considered to be the presence of the water below the seismogenic depth. The swarm activity continues from 1980s. We analyzed the shallow earthquakes in the northern part of Wakayama Prefecture from 1998 to 2016. We used statistical method called Schuster test to analyze correlation between earthquakes and tidal stress.

The result of the analysis shows that the earthquakes have a correlation with tidal forces which have the periodicity near the half of the lunar day and the amplitude of the seismicity-rate variation is about 16% of the average earthquake frequency. Correlation between the earthquakes and tidal forces is stronger at the periods when larger number of earthquakes occur. From tidal stress calculation, it is found that both solid tide and oceanic tide are important at this region. This study confirms that most of the earthquakes larger than M_w 4 in the region occur in the rising period of tidal normal stress or just after the maximum of tidal normal stress. Therefore, tidal observation gives information about the criticality of rocks and temporal heterogeneity of the earthquake occurrence.

How to cite: Machida, K., Nagahama, H., and Muto, J.: Statistical analysis of tidal effect on non-volcanic earthquake swarm activity in Wakayama Prefecture, southwest Japan, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13890, https://doi.org/10.5194/egusphere-egu21-13890, 2021.

There are many reports on electromagnetic pre-earthquake phenomena such as geomagnetic, ionospheric, and atmospheric anomalous changes. Ionospheric anomaly preceding large earthquakes is one of the most promising phenomena. Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) model has been proposed to explain these phenomena. In this study, to evaluate the possibility of chemical channel of LAIC by observation, we have installed sensors for atmospheric electric field, atmospheric ion concentration, atmospheric Rn concentration, underground Rn concentration (GRC), and weather elements at Asahi station, Boso, Japan. Since the atmospheric electricity parameters are very much influenced by weather factors, it is necessary to remove these effects as much as possible. In this aim, we apply the MSSA (Multi-channel Singular Spectral Analysis) to remove these influences from the variation of GRC and estimate the underground Rn flux (GRF). We investigated the correlations (1) between GRF and precipitation and (2) between GRF and the local seismic activity around Asahi station. The preliminary results show that there is a tendency of correlation (1) between GRF and heavy rain and (2) between GRF and local seismicity within an epicenter distance of 50 km from the station.

How to cite: Hattori, K., Kojima, H., Nemoto, K., Yoshino, C., Konishi, T., and Ouzounov, D.: Multi-channel singular spectrum analysis of underground Rn concentration at Asahi station, Japan: Preliminary report on the variation of underground Rn flux, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14065, https://doi.org/10.5194/egusphere-egu21-14065, 2021.

The recent pandemic is the first stage of a worldwide spreading diseases manifold¹. The events of new complex viruses’ network are in results of some universal and natural processes²; therefore, all the mechanisms related to these types of complex viruses’ pandemics must be handled and taken considering its true nature; unfortunately, the topics excluding the natural science disciplines related to pandemics may not bring a valuable contribution to the solution of the recent problems generated with the worldwide diseases’ chains. The tactics of world widely attacking complex viruses and pandemics are valuably intelligent so they control and command their behaviors as covering a simultaneously widen activity. This brings considering of communication-like and intelligence-like mechanisms embedded in molecular structures of such complex viruses as an algorithmic process. The motivating approach of this thesis is related to the studies connecting virus and/or virus-like, say virutic, environs and especially itself of the virus body with an electromagnetic problem topic which have high potential to contribute deterministic, fast solutions for the recent unusual pandemic and possible pandemics in future. The solutions would provide strategies for the healthcare from viruses without having to use undiscovered methods and techniques yet, independently. There is some specific self-optimization processes behind both the minor and the majorant natural events iff the Earth is considered with its all ingredients to downwards from upwards as a single and compact system³.

Some specific spatial processes generate simple molecular structures, say virutic structures, VSs. The VSs prepare a way for occurrence of complex molecules after collisions’ chains. Some complex molecules related to VSs construct active particles as active matter. These active particles design Brownian-like motors consuming the wave energy coming from both the seismic activities and mean spectral power density in the Earth’s atmosphere per frequency and per volume and per surface according to bandwidth. These Brownian-like motors create Brownian-like bridges. These Brownian-like bridges can carry the active particles involving VSs to the extremely long distances and locations; therefore, they may move among continentals, easily but conditionally. The collisions among VSs create viruses and/or virus-like particles in complicated design algorithms as complex molecules during the Brownian-like transportations along the swarming-like paths governed with 2^nd order stochastic partial differential equations. These paths are highly modulated in an anomalous super diffusion pattern by the waves related to the significant seismic activities.

The natural physical settlement of the initial values of the 2^nd order stochastic initial boundary value problem, 2^ndoSIBVP, was occurred around 1999 according to above said Brownian-like processes. The pike of the distribution relatable to the process is approximately 2019. If the process is considered as a stable distribution having the pick in 2019, then it has a half bandwidth of around 20 years. If the process is accepted propagating with a standard probability density function, then the initial ending of the process is around 2039^2,4.

______________________________

¹https://www.researchgate.net/project/Relational-Equivalence-Mechanisms-of-Electromagnetism-to-the-Widened-Virus-Problems.

² doi:10.23919/URSI- ETS.2019.8931455.

³ http://meetingorganizer.copernicus.org/EGU2019/EGU2019-17127.pdf.

⁴Sengor T, On the Availability of Electromagnetically Equivalence Processes Relevant to Worldwide Spreadable Diseases Manifolds. 34th URSI GASS 2021 Rome (submitted).

How to cite: Sengor, T.: Natural Cooperation of Seismic Activities Related Wave Propagation on the Worldwide Pandemics Processes, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-16480, https://doi.org/10.5194/egusphere-egu21-16480, 2021.

The mechanisms of the seismic-electromagnetic phenomena (SEP) attracted as precursors of short-term earthquake forecast have been suggested, however, it is still incompletely understood. Among the possible mechanisms of the SEP is the surface charging mechanism related to the electron and hole trapping centers in quartz. Previous studies evaluated the plausibility of the mechanism from the surface charge density by the measurement of current or potential changes. On the other hand, only a few studies have evaluated the plausibility from the direct measurements of the trapping centers’ concentration.

We have performed low-velocity friction experiments mimicking the fracture with low-frictional heating for simulated fault gouges (commercial natural quartz sands) at a normal stress of 1.0 MPa with displacements up to 1.4 m. In order to measure the concentration of the trapping centers in the simulated-fault gouges, we conducted electron spin resonance for the standard sample, TEMPOL (4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl), and the gouges before and after friction. In recent decades, researchers also have obtained the concentrations of the trapping centers in the quartz damaged in the rock fracture experiments using ESR and a radical scavenger. From those concentrations with the measured or assumed surface areas, we calculated the surface charge density of the quartz and discussed the plausibility of the surface charging mechanism of the SEP.

In our friction experiments, the E’ type centers were detected at g₂ = 2.001 (e.g., E₁’ center; ≡Si･, E_S’ center; ≡Si･, E_α’ center; =Si:, where − is an electron pair, : is a lone pair, and ･ is an unpaired electron) in the ESR spectra of the simulated-quartz gouges and the trapping center increased by the fracture of low-velocity friction. Assuming that the trapping centers were produced on the grain surfaces by the fracture, the range of the increase in the surface charge density was (0.21–8.0) ×10^-4 C/m². The rock fracture experiments found the E₁’ center, non-bridging oxygen hole center (NBOHC; ≡Si−O･), and peroxy center (≡Si−O−O･) in quartz. On the same assumption, the total surface charge density of those trapping centers and the density of the E₁’ center or NBOHC were estimated as 2.7×10^-1 and 5.0×10^-2–3.94 C/m², respectively.

The surface charge density required for a corona discharge that can cause the SEP in the air over a flat plane is reported over 5.0×10^-5 C/m². The quantities calculated above are almost enough to induce a corona discharge. The surface charges can form the electric dipoles on the fault plane, inducing the electric and magnetic fields. Our experiment showed that the fracture by fault motions could produce the surface charges on the fault. It proves that the electromagnetic abnormalities by the fault motions may also be observed through the surface charging mechanism. Therefore, our study supports that the surface charging mechanism is plausible.

How to cite: Tanaka, K., Nagahama, H., Muto, J., Oka, T., and Yabe, Y.: Supporting the surface charging mechanism of seismic-electromagnetic phenomena by the direct measurements of the electron and hole trapping centers, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14204, https://doi.org/10.5194/egusphere-egu21-14204, 2021.

Despite the existence of a large number of observational data and physical models describing the preparation, performance and consequences of Earthquakes (EQ) events, scientists still do not know much about this physical phenomena. A vast amount of efforts and financial means have already been invested in searching for possible precursors of geodynamic and EQ events, which might be considered disproportionate to the progress already achieved. Nevertheless, this important task deserves further investigation, as any encouraging obtained result will pay off all efforts.

Here, we propose to investigate a multi-parametric integrated approach, augmented by observation from a wide set of possible/potential EQ manifestations in the Lithosphere, Troposphere and Ionosphere. To better tackle the problem of possible EQ precursor detection, four EQ events with magnitudes of 3.9–4.4 M, which occurred in Lake Kinneret pull-apart basin, Israel from the period of May 1 to September 30, 2018, were examined. The multi-parametric observation were simultaneously collected from several stations within a 100 km radius from the studied EQ epicenters. Thus, the following parameters which were investigated are: gamma-ray emissions both from the subsurface and atmosphere, precipitation, atmospheric temperature and pressure, groundwater level and electrical conductivity measured in two wells, precipitable water vapor (PWV) in the atmosphere extracted from GNSS tropospheric path delays, Total Electron Content (TEC) in the ionosphere extracted from GNSS ionospheric path delays. In addition, geomagnetic and solar parameters such as A- and Kp-indices, 10.7 cm radio flux and sun spot number (SSN), were used to exclude the influence of solar-terrestrial coupling and mitigate false positive signatures.

Preliminary results indicate anomalous signals (exceeding 2σ) at all stations for most of the measured parameters, approximately one month before the studied EQ events. Five significant anomalies, lasting 4-7 days, observed in sub-surface gamma-ray emissions were chosen as reference main precursors. Two of those anomalies (35±2 days and 26±2 days before the EQ events) were accompanied by signal enhancements, measured at other stations located several tens of kilometers apart, in PWV, TEC, groundwater electrical conductivity, Rn and CO2. Another two sub-surface gamma-ray anomalies were correlated with precipitation events, while the last observed anomaly (11±3 days before the EQ events), which is the weakest among the five, was not accompanied by any enhanced measured parameter. According to these results, the multi-parametric approach seems to provide a powerful analysis tool used to differentiate between signals originated from geodynamic and other sources. It is suggested that future research can benefit tremendously from vast multi-parametric continuous data collection and analysis.

How to cite: Skorokhod, T., Inbar, N., and Reuveni, Y.: On the Potential of Multi-Parametric Measurements for Earthquake Precursors Analysis, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-14544, https://doi.org/10.5194/egusphere-egu21-14544, 2021.

A new analytical model has been developed to determine the characteristics of the VLF complex eigenmodes in the waveguide Earth-Ionosphere (WGEI). The developed analytical model, in combination with appropriate numerical methods, provides all important characteristics of (i) complex eigenmodes and their excitation by external electric current source in WGEI, (ii) radiation from WGEI of ELF waves into the upper ionosphere/magnetosphere. After propagation of electromagnetic waves over a certain distance (~ 100 km) from input antenna, either set of complex modes or input boundary conditios for an effective beams may be determined and then the theory [1] for coupled VLF beams in WGEI may be applied. This approach is considered in the context of Nonlinear evolution equations for wave processes in layered structures (NEELS) method for modeling wave processes in layered artificial/natural media [2] (i) taking into account importance of boundary conditions at the input of waveguide region, where the external current source is located, as well as complex impedance boundary conditions at WGEI boundaries [1] and (ii) using appropriate system of evolution equations for coupled wave beams. The measurements of VLF in Japan (from Hayakawa Institute of Seismo Electromagnetics) were used in this study. Fluctuations in VLF amplitudes are revealed with the periods of  (i) 2-3 hours; (ii) 5-10 minutes  corresponding to the fundamental mode of acoustic-gravity waves (AGW) near the Brunt–Väisälä period (to the best of our knowledge for the first time it has been done based on VLF signals). There is also a weekly antropogenic trend in VLF data. Since 2019, a number of VLFs and LFs signals (radiated mostly by European transmitters) have been monitored at NCCSSAU  and demonstrate the quasi-wave disturbances with periods of ~10 minutes. The analysis of the relevant data indicates the need to eliminate the impact of hardware effects. Significant influence on the distribution of TEC geomagnetic perturbations was found, in particular, during analysis of  St. Patrick's Day geomagnetic storm (March 17, 2015). To use global TEC maps for studying ionospheric processes, including possible precursors of the most powerful earthquakes, it is recommended to use data with less then one minute time resolution. Different spectral methods for data processing and entropy approach for detecting pre-catastrophic state of LAIM system are discussed. The developed methods can be useful for ionospheric monitoring of catastrophic events in the LAIM system, based on the complex studies (i) of ionospheric disturbances in VLF and TEC, in particular caused by the same source located in the lithosphere/lower atmosphere, magnetosphere or ionosphere; and (ii) the impact of AGW on VLF characteristics in WGEI.

[1]  Rapoport Y., Grimalsky V., … Grytsai A., Fedun V. et al. Model of propagation of VLF beams in the waveguide Earth-Ionosphere. Principles of tensor impedance method in multilayered gyrotropic waveguides , Ann. Geo.,  2020,  38,  207–230.

[2] Boardman A.D., Alberucci A., … Rapoport Yu. G., … Ivchenko V.M. [et al.]. Spatial Solitonic and Nonlinear Plasmonic Aspects of Metamaterials // World Scientific Handbook of Metamaterials and Plasmonics,  2017,  4,  419-469.

How to cite: Rapoport, Y., Reshetnyk, V., Grytsai, A., Liashchuk, A., Ivchenko, V., Fedorenko, A., Hayakawa, M., Grimalsky, V., Petrishchevskii, S., and Fedun, V.: Methods for determining the perturbations in VLF  in the Earth-ionosphere waveguide and TEC for ionospheric monitoring of catastrophic events in the Lithosphere-Atmosphere-Ionosphere-Magnetosphere (LAIM) system, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-6412, https://doi.org/10.5194/egusphere-egu21-6412, 2021.

Based on the comprehensive earthquake catalogue USGS ( HYPERLINK  https://earthquake.usgs.gov) the paper demonstrates that strong earthquake activity, seismic events with M≥6, exhibits a seasonal trend. This feature is the result of  analyses of earthquake data for the N- and S- Earth Hemisphere in period 2010-2019. It can be shown also for single earthquake prone regions as well, like Japan, Eurasia, S-America.

Any seasonal effect suggests an external influence. In that regard, one can think also of a solar-terrestrial effect, that is suggested already in several studies (e.g  M.Tavares, A.Azevedo, 2011; D.A.E. Vares, M.A.Persinger,2014; G.Duma, 2019). This assumption leads to the question: Which dynamic process can cause a trigger effect for strong earthquakes in the Earth's lithosphere.

In this study the intensity of solar flares and the resulting radiation, the solar wind, towards the Earth was taken into account. An appropriate parameter which has been regularity measured and reported for many decades and which reflects the intensity of solar radiation is the magnetic index Kp. It is measured at numerous geomagnetic observatories and describes the magnetic disturbances in nT within 3 hour intervals, respectively. Averages of all the measured 3-hour values are then published as Kp, therefore considered a planetary parameter (International Service of Geomagnetic Indices ISGI,France).

The temporal variations of strong earthquake activity over 10 years and their energy release was compared with the above mentioned index Kp. Actually, a distinct correlation between the two quantities, Kp and earthquake frequency, resulted in cases of different regions as well as globally. Another essential result of the study is that maxima of Kp preceed those of earthquake activity by about 60 to 80 days in most cases. The mechanism has not yet been modeled satisfactorily.

How to cite: Duma, G.: Strong earthquake activity influenced by solar flare intensity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-3078, https://doi.org/10.5194/egusphere-egu21-3078, 2021.

The short-term prediction of earthquakes is an essential issue connected with human life protection and related social and economics matter. Recent papers have provided some evidence of the link between the lithosphere, lower atmosphere, and ionosphere, even though with marginal statistical evidence. The basic coupling hypothesized being via atmospheric gravity wave (AGW)/acoustic wave (AW) channel. In this work we analyse the scenario of the low latitude earthquake (Mw=6.9) occurred in Indonesia on August 5, 2018, through a multi-instrumental approach, using ground and satellites high quality data. As a result, we derive a new analytical lithospheric-atmospheric-ionospheric-magnetospheric coupling model with the aim to provide quantitative indicators to interpret the observations around 6 hours before and at the moment of the earthquake occurrence.

How to cite: Piersanti, M., Materassi, M., Battiston, R., Carbone, V., Cicone, A., D'Angelo, G., Diego, P., and Ubertini, P.: Magnetospheric-Ionospheric-Lithospheric coupling model. Observations  during the August 5, 2018 Bayan Earthquake, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13, https://doi.org/10.5194/egusphere-egu21-13, 2021.

In recent decades, many advances have been made on the study of the complex processes involved in the preparatory phases of earthquakes. Over time, different types of parameters (chemical, physical, biological, etc.) have been proposed as indicators of variability potentially related to this process. Among these, space weather parameters are assuming an increasingly important role due to their possible connection to the occurrence of strong and imminent earthquakes. The variations of the Total Electron Content (TEC) have been investigated as an indicator of the ionospheric status potentially affected by earthquake related phenomena.

In order to discriminate TEC variations related to normal ionospheric cycle as well as to non-terrestrial forcing phenomena (both mostly dominated by the solar cycle and activity) a key role is played by an in-depth and systematic analysis of multi-year historical data series.

In this work, a multi-year (>20 years) dataset of TEC measurements recorded by the GPS satellite constellation, was analysed using a modified InterQuartile Range (IQR; Liu et al., 2004) method in order to identify anomalous TEC transients. A correlation analysis was performed with seismic events (M≥4) occurred in Italy in between 2000-2020 considering all the period both in presence and in absence of seismic events.

The results obtained are discussed and compared with the results achieved through an independent RST analysis (Robust Satellite Techniques; Tramutoli, 1998; 2007) carried out on the Earth’s Thermal Infrared Radiation (TIR) parameter.

Both methodologies, while using a different approach, aim to discriminate anomalous signals from normal fluctuations of the signal itself related to other causes (e.g. meteorological, geographical, etc.) independent on the earthquake occurrence.

The joint analysis of the results obtained by the two parameters, TEC and TIR, is carried out in order to evaluate how and to what extent a multi-parametric approach can improve (compared with a single parameter approach) Time-Dependent Assessment of Seismic Hazard (T-DASH; Genzano et al., 2020; 2021) in the short-medium term.

References

Genzano, N., C. Filizzola, M. Lisi, N. Pergola, and V. Tramutoli (2020), Toward the development of a multi parametric system for a short-term assessment of the seismic hazard in Italy, Ann. Geophys, 63, 5, PA550, doi:10.4401/ag-8227.

Genzano, N., C. Filizzola, K. Hattori, N. Pergola, and V. Tramutoli (2021), Statistical correlation analysis between thermal infrared anomalies observed from MTSATs and large earthquakes occurred in Japan (2005 - 2015), Journal of Geophysics Research – Solid Earth, doi: 10.1029/2020JB020108 (accepted).

Liu, J. Y., Chuo, Y. J., Shan, S. J., Tsai, Y. B., Chen, Y. I., Pulinets, S. A., and Yu, S. B. (2004): Pre-earthquake ionospheric anomalies registered by continuous GPS TEC measurements, Ann. Geophys., 22, 1585–1593, https://doi.org/10.5194/angeo-22-1585-2004.

Tramutoli, V. (1998), Robust AVHRR Techniques (RAT) for Environmental Monitoring: theory and applications, in Proceedings of SPIE, vol. 3496, edited by E. Zilioli, pp. 101–113, doi: 10.1117/12.332714

Tramutoli, V. (2007), Robust Satellite Techniques (RST) for Natural and Environmental Hazards Monitoring and Mitigation: Theory and Applications, in 2007 International Workshop on the Analysis of Multi-temporal Remote Sensing Images, pp. 1–6, IEEE. doi: 10.1109/MULTITEMP.2007.4293057

How to cite: Colonna, R., Filizzola, C., Genzano, N., Lisi, M., Pergola, N., and Tramutoli, V.: Long-term analysis of the Ionospheric-Total Electron Content (TEC) parameter for the detection of anomalous behaviours potentially related to seismic activity, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13730, https://doi.org/10.5194/egusphere-egu21-13730, 2021.