Lower Ionospheric variations during the intense tectonic activity in the broader area of Greece on October of 2020

2021 ◽  
Author(s):  
Michael E. Contadakis ◽  
Demetrios Arabelos ◽  
Christos Pikridas ◽  
Stelios Bitharis ◽  
Emmanuel M. Scordilis
Keyword(s):  
Statistical Analysis ◽  
Seismic Activity ◽  
Strong Earthquake ◽  
Tectonic Activity ◽  
Activity Period ◽  
Electron Content ◽  
Ionospheric Turbulence ◽  
Eastern Aegean ◽  
The Mediterranean ◽  
Of Greece

<p>In this paper we investigate the Lower ionospheric variations from TEC observations during the intense seismic activity of October 2020 in the area of Greece (35<sup> o</sup> £ j £ 42<sup>o</sup> N, 19<sup> o</sup> £ l £ 29<sup>o</sup> E).  The Total Electron Content (TEC) data are been provided by the  Hermes GNSS Network managed by GNSS_QC, AUTH Greece, the HxGN/SmartNet-Greece of Metrica S.A, and the EUREF Network. These data were analysed using both, statistical analysis of TEC variations in order to detect uneven gross variations and Discrete Fourier Analysis in order to investigate the TEC turbulence. The results of this investigation indicate that the High- Frequency limit f<sub>o</sub> of the ionospheric turbulence content, increases as aproaching the occurrence time of the earthquake, pointing to the earthquake epicenter, in accordane to our previous investigations (Contadakis et al., 2009; Contadakis et al., 2012; Contadakis et al., 2015; Scordilis et al., 2020). We conclude that the LAIC mechanism through acoustic or gravity waves could explain this phenomenology. Thus, observing the frequency content of the ionospheric turbidity we observe a decrease of the higher limit of the turbitity frequency band, as a result of  the differential  frequency attenuation of the propagating wave. In addition, the statistical analysis shows an excess greater than  3σ from the mean TEC values one and seven days before the earthquake. Since no major disturbance of the geomagnetic field occured during these days, we conclude that we probably observed precursory Ionospheric variations in accordance to analogous findings from the variation of VH/VHF electromagnetic wave propagrations over strong earthquake areas (e.g. Biagi et al. 2019)  </p><p> </p><p>References</p><p> </p><p>Biagi and 11 co authors, The INFREP Network: Present Situation andRecent Results. Open Journal of Earthquake Research, vol.8, p. 101-115, 2019.</p><p>Contadakis, M.E., Arabelos, D.N., Asteriadis, G., Spatalas, S.D., Pikridas, C., TEC variations over the Mediterranean during the seismic activity period of the last quarter of 2005 in the area of Greece, Nat. Hazards and Earth Syst. Sci., 8, 1267-1276, 2008.</p><p>Contadakis, M.E., Arabelos, D.N., Asteriadis, G., Spatalas, S.D., Pikridas, C. TEC variations over Southern Europe before and during the M6.3 Abruzzo earthquake of 6<sup>th</sup> April 2009, Annals of Geophysics, vol. 55, iss. 1, p. 83-93, 2012.</p><p>Contadakis, M. E., Arabelos, D.N., Vergos, G., Spatalas, S. D., Scordilis, E.M., 2015,TEC variations over the Mediterranean before and during the strong earthquake (M = 6.5) of 12th October 2013 in Crete, Greece, Physics and Chemistry of the Earth, Volume 85, p. 9-16., 2015.</p><p>Scordilis E.M., Contadakis M.E, Vallianatos  F., Spatalas S., Lower Ionospheric turbulence variations during the intense tectonic activity in Eastern Aegean area, Annals of Geophysics, 63, 5, PA544, 2020</p>

scholarly journals TEC variations over the Mediterranean during the seismic activity period of the last quarter of 2005 in the area of Greece

2008 ◽  
Vol 8 (6) ◽  
pp. 1267-1276 ◽  
Author(s):  
M. E. Contadakis ◽  
D. N. Arabelos ◽  
G. Asteriadis ◽  
S. D. Spatalas ◽  
C. Pikridas
Keyword(s):  
Frequency Dependence ◽  
Seismic Activity ◽  
Tectonic Activity ◽  
Activity Period ◽  
Electron Content ◽  
Total Electron ◽  
Time Frequency ◽  
Time Period ◽  
Precursory Phenomena ◽  
Of Greece

Abstract. In this paper the Total Electron Content (TEC) data of eight Global Positioning System (GPS) stations of the EUREF network (AUT1, Thessaloniki, TUC2, Crete in Greece, MATE, Matera, LAMP, Lampedusa in Italy, GAIA, in Portugal, RABT, Rabat, EVPA, Evpatoria in Ukrain and TRAB, Trabson in Turkey) were analysed using wavelet analysis in order to detect any frequency dependence of the correlation between TEC over different stations. In the same time frequency dependence of Dst (Global geomagnetic field disturbances) and TEC variations over each GPS station are searched in order to detect any correlation between them. The main conclusion of this analysis is that the components of TEC variation with periods <3 h are more suitable in searching for earthquake precursors. On the base of this conclusion the analyzed TEC series are searched for possible precursory phenomena on the occasion of the seismic activity of the last quarter of 2005 in the area of Greece. An exalting (i.e. an increase in the amplitude) of variations with periods up to the tidal ones (period of 6 h,8 h,12 h) may be observed a month before and during the seismic activity over the stations TUC2 and AUT1 and may be attributed to this tectonic activity. Statistical properties of the 1.5 h component of the Total Vertical Electron Content (TVEC) over the nearest GPS stations (TUC2 and AUT1) of the areas of the seismic activity indicate that this component present characteristic exalting in the time period of 15 days before the shock.

scholarly journals Lower Ionospheric turbulence variations during the intense tectonic activity in Eastern Aegean area

2020 ◽  
Vol 63 (5) ◽  
Author(s):  
Emmanuel Scordilis ◽  
Michael Contadakis ◽  
Filippos Vallianatos ◽  
Spiridon Spatalas
Keyword(s):  
High Frequency ◽  
Lower Ionosphere ◽  
Earthquake Hazard ◽  
Tectonic Activity ◽  
Ionospheric Turbulence ◽  
Frequency Limit ◽  
Total Electron ◽  
Aegean Area ◽  
Eastern Aegean ◽  
Global Positioning

This paper may be considered as an additional approval of the way the tectonic activity affects the lower Ionosphere. The results of our investigation, on the occasion of the recent East Aegean tectonic activity, indicate that the High - Frequency limit, fo, of the ionospheric turbulence content, increases as the site and the time of the earthquake occurrence is approaching, pointing to the earthquake location.We conclude that the Lithosphere Atmosphere Ionosphere Coupling (LAIC) mechanism through acoustic or gravity wave could explain this phenomenology, as a result of a the frequency differential damping of the propagating turbulent in the ionosphere. Proper use of this result may lead to a method of earthquake hazard mitigation using the byproducts of the Global Positioning Network (actually Total Electron Contain, TEC, estimations) which are available freely.

Lower Ionospheric turbulence variations during the intense seismic activity of the last half of 2019 in the broader Balkan region.

2020 ◽  
Author(s):  
Michael E. Contadakis ◽  
Demetrios Arabelos ◽  
George Vergos ◽  
Emmanuel M. Scordilis
Keyword(s):  
Global Positioning System ◽  
Seismic Activity ◽  
Main Shock ◽  
Electron Content ◽  
Marmara Sea ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Global Positioning ◽  
Balkan Region

&lt;p&gt;In this paper, we investigate the ionospheric turbulence from TEC observations, before and during the intense seismic activity of September 2019 at Albania (main shock at l=19.445&lt;sup&gt;o&lt;/sup&gt;E, j=41.372&lt;sup&gt;o&lt;/sup&gt; N, M&lt;sub&gt;w&lt;/sub&gt;=5.6) &amp;#160;and at Marmara sea (main shock at l=28.19 &lt;sup&gt;o&lt;/sup&gt;E, j=40.872&lt;sup&gt;o&lt;/sup&gt;N, M&lt;sub&gt;w&lt;/sub&gt;=5.7), as well as of November 2019 at Albania (main shock at l=19.470&lt;sup&gt;o&lt;/sup&gt;E, j=41.381&lt;sup&gt;o&lt;/sup&gt;N, M&lt;sub&gt;w&lt;/sub&gt;=6.4), and at Bosnia-Herzegovina (main shock at l=17.961&lt;sup&gt;o&lt;/sup&gt;E, j=43.196&lt;sup&gt;o&lt;/sup&gt;N, M&lt;sub&gt;w&lt;/sub&gt;=5.4).&lt;/p&gt;&lt;p&gt;The Total Electron Content (TEC) data of 6 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The results of this investigation indicate that the High- Frequency limit f&lt;sub&gt;o&lt;/sub&gt;, of the ionospheric turbulence content, increases by aproaching the site and&amp;#160; the time of the earthquake occurrence, pointing to the earthquake location (epicenter). We conclude that the LAIC mechanism, through acoustic or gravity wave, could explain this phenomenology. In addition the proximity of the tectonic active areas to the GPS stations offer us an opportunity to discriminate the origin of the disturbances&lt;/p&gt;

Lower Ionospheric turbulence variations during the tectonic activity of the last quarter of 2019 in the Hellenic Arc (Greece)

2020 ◽  
Author(s):  
Dimitrios N. Arabelos ◽  
Michael E. Contadakis ◽  
George Vergos ◽  
Emmanuel M. Scordilis
Keyword(s):  
Global Positioning System ◽  
High Frequency ◽  
Main Shock ◽  
Tectonic Activity ◽  
Electron Content ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Hellenic Arc ◽  
Global Positioning

&lt;p&gt;In this paper we investigate the ionospheric turbulence from TEC observations before and during the tectonic activity of the last quarter of 2019 in the Hellenic Arc, Greece (main shock at l=23.26&lt;sup&gt;o&lt;/sup&gt;E, j=35.69&lt;sup&gt;o&lt;/sup&gt;N, M&lt;sub&gt;w&lt;/sub&gt;=6.1). The Total Electron Content (TEC) data of 6 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The results of this investigation indicate that the High- Frequency limit f&lt;sub&gt;o&lt;/sub&gt;, of the ionospheric turbulence content, increases by aproaching the site and the time of the earthquake occurrence, pointing to the earthquake location (epicenter). We conclude that the LAIC mechanism through acoustic or gravity wave could explain this phenomenology.&lt;/p&gt;

scholarly journals Ionospheric turbulence from TEC variations and VLF/LF transmitter signal observations before and during the destructive seismic activity of August and October 2016 in Central Italy

2020 ◽  
Vol 63 (5) ◽  
Author(s):  
Michael Contadakis ◽  
Demetrios Arabelos ◽  
George Vergos ◽  
Christos Skeberis ◽  
Tomas Xenos ◽  
...  
Keyword(s):  
Seismic Activity ◽  
Visual Analysis ◽  
Central Italy ◽  
Electron Content ◽  
Ionospheric Turbulence ◽  
Total Electron ◽  
Discrete Fourier Analysis ◽  
Hilbert Huang Transform ◽  
Global Positioning ◽  
The Moment

In this paper we investigate the ionospheric turbulence from observations of TEC variations as well as from VLF/LF transmitter signal observations before and during the disastrous seismic activity of August and October 2016 in Central Italy. The Total Electron Content (TEC) data of 8 Global Positioning System (GPS) stations of the EUREF network, which are being provided by IONOLAB (Turkey), were analysed using Discrete Fourier Analysis in order to investigate the TEC variations. The data acquired for VLF/LF signal observations are from the receiver of Thessaloniki (40.59N, 22,78E), Greece, which monitor the VLF/LF transmitters of the International Network for Frontier Research on Earthquake Precursors (INFREP). A method of normalization according to the distance between the receiver and the transmitter is applied on the above data and then they are processed by the Hilbert Huang Transform (HHT) to produce the corresponding spectra for visual analysis. The results of both methods indicate that the High- Frequency limit fo, of the ionospheric turbulence content, increases as the site and the moment of the earthquake occurrence is approaching, pointing to the earthquake locus.

scholarly journals Morphotectonic Analysis along the Northern Margin of Samos Island, Related to the Seismic Activity of October 2020, Aegean Sea, Greece

Geosciences ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 102
Author(s):  
Paraskevi Nomikou ◽  
Dimitris Evangelidis ◽  
Dimitrios Papanikolaou ◽  
Danai Lampridou ◽  
Dimitris Litsas ◽  
...  
Keyword(s):  
Fault Zone ◽  
Seismic Activity ◽  
Volcanic Rocks ◽  
Active Tectonics ◽  
Normal Fault ◽  
Aegean Sea ◽  
Northern Margin ◽  
The North ◽  
Eastern Aegean ◽  
Half Graben

On 30 October 2020, a strong earthquake of magnitude 7.0 occurred north of Samos Island at the Eastern Aegean Sea, whose earthquake mechanism corresponds to an E-W normal fault dipping to the north. During the aftershock period in December 2020, a hydrographic survey off the northern coastal margin of Samos Island was conducted onboard R/V NAFTILOS. The result was a detailed bathymetric map with 15 m grid interval and 50 m isobaths and a morphological slope map. The morphotectonic analysis showed the E-W fault zone running along the coastal zone with 30–50° of slope, forming a half-graben structure. Numerous landslides and canyons trending N-S, transversal to the main direction of the Samos coastline, are observed between 600 and 100 m water depth. The ENE-WSW oriented western Samos coastline forms the SE margin of the neighboring deeper Ikaria Basin. A hummocky relief was detected at the eastern margin of Samos Basin probably representing volcanic rocks. The active tectonics characterized by N-S extension is very different from the Neogene tectonics of Samos Island characterized by NE-SW compression. The mainshock and most of the aftershocks of the October 2020 seismic activity occur on the prolongation of the north dipping E-W fault zone at about 12 km depth.

scholarly journals Analysis of soil radon data in earthquake precursory studies

2014 ◽  
Vol 57 (5) ◽  
Author(s):  
Hari Prasad Jaishi ◽  
Sanjay Singh ◽  
Raghavendra Prasad Tiwari ◽  
Ramesh Chandra Tiwari
Keyword(s):  
Statistical Analysis ◽  
Multiple Regression ◽  
Radon Concentration ◽  
Seismic Activity ◽  
Meteorological Parameters ◽  
Regression Method ◽  
Seismic Zone ◽  
Type Ii ◽  
Soil Radon ◽  
Multiple Regression Method

<p>Soil radon data were recorded at two selected sites along Mat fault in Mizoram (India), which lies in the highest seismic zone in India. The study was carried out during July 2011 to May 2013 using LR-115 Type II films. Precursory changes in radon concentration were observed prior to some earthquakes that occurred around the measuring sites. Positive correlation was found between the measured radon data and the seismic activity in the region. Statistical analysis of the radon data together with the meteorological parameters was done using Multiple Regression Method. Results obtained show that the method employed was useful for removing the effect of meteorological parameters and to identify radon maxima possibly caused by seismic activity.</p>

scholarly journals European Officers and the Mainland Irregular Forces on the Ionian Islands, 1798–1814: A Comparison of Command and Tactics

2021 ◽  
Vol 7 (2) ◽  
pp. 119-142
Author(s):  
Nicholas Pappas
Keyword(s):  
Nineteenth Century ◽  
Armed Forces ◽  
Napoleonic Wars ◽  
Early Nineteenth Century ◽  
Ionian Islands ◽  
War Of Independence ◽  
The Mediterranean ◽  
Irregular Forces ◽  
Of Greece ◽  
Successes And Failures

In the era of the Napoleonic wars, the Ionian Islands off the western coasts of Greece and southern Albania became a base of operations and an area of conflict in the Mediterranean in the years 1797–1814. In that period, Republican French, Russian, Imperial French, and British forces successively occupied these Greek-populated islands, formerly Venetian possessions. Each of these powers attempted to establish a nominally independent "Septinsular Republic" under their protectorate. There were efforts by all of these powers to organize native armed forces, some raised from among refugees from the mainland-bandits (klephtes), former Ottoman irregulars (armatoloi), and clansmen from the autonomous regions of Himara, Souli, and Mani. Although these refugee warriors were skilled in the use of weapons-flintlock firearms, sabres and yataghans-they fought and were organized according to traditions and methods that were different and considered "obsolete" in early nineteenth century Europe. This study will look into the organization, training and command of these troops by Russian, French, and British officers. It will study the successes and failures of these officers in forming these native warriors into regular or semi-regular forces. It will also examine how the attitudes and activities of these officers helped to develop the armed forces of the Greek War of Independence, 1821–1830. Keywords: Napoleonic wars, Ionian Islands, armatoloi and klephtes, military forces

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