Time–frequency analysis of VLF for seismic-ionospheric precursor detection: Evaluation of Zhao-Atlas-Marks and Hilbert-Huang Transforms

Skeberis, Christos; Zaharis, Zaharias D.; Xenos, Thomas D.; Spatalas, Spyridon; Arabelos, D.; Contadakis, M. E.

doi:10.1016/j.pce.2015.02.006

Cited by 8 publications

(7 citation statements)

References 34 publications

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“…The data are processed by the Hilbert Huang Transform (HHT) [Skeberis et al, 2015] which is a two step process.…”

Section: Discussionmentioning

confidence: 99%

“…In the frame of the International Network for Frontier Research on Earthquake Precursors (INFREP) [Biagi et al, 2011] a receiver in Thessaloniki, Greece (40.59N, 22,78E) is monitoring the VLF transmitters based in Tavolara, Italy, Niscemi, Italy, and Le Blanc, France, [Skeberis et al, 2015]. The transmission paths of these transmitters to the Thesaloniki receiver passes over the broader area of the Amatrice erthquakes epicenters.…”

Section: Detection Of Vlf/lf Disturbancesmentioning

confidence: 99%

“…The data acquired for VLF/LF signal observations are from the receiver of Thessaloniki (40.59N, 22.78E), Greece [Skeberis et al, 2015] 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.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

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

Contadakis

Arabelos

Vergos

et al. 2020

Annals of Geophysics

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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.

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“…The data are processed by the Hilbert Huang Transform (HHT) [Skeberis et al, 2015] which is a two step process.…”

Section: Discussionmentioning

confidence: 99%

Section: Detection Of Vlf/lf Disturbancesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

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

Contadakis

Arabelos

Vergos

et al. 2020

Annals of Geophysics

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“…Unfortunately, in the cases of the Cephalonia EQs under study, this requirement was not fulfilled. To the best of our knowledge, only one paper reporting the emergence of VLF seismic-ionospheric disturbances 4 days before the first Cephalonia EQ (Skeberis et al, 2015) has been published up to now. It is very important that the specific disturbances, which also correspond to a spatially extensive process as happens with the MHz EME, were recorded during the same time window with the herein presented MHz critical signals.…”

Section: Discussionmentioning

confidence: 99%

Recent seismic activity at Cephalonia (Greece): a study through candidate electromagnetic precursors in terms of non-linear dynamics

Potirakis

Contoyiannis

Melis

et al. 2016

Nonlin. Processes Geophys.

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Abstract. The preparation process of two recent earthquakes (EQs) that occurred in Cephalonia (Kefalonia), Greece, ((38.22 • N, 20.53 • E), 26 January 2014, M w = 6.0, depth ∼ 20 km) and ((38.25 • N, 20.39 • E), 3 February 2014, M w = 5.9, depth ∼ 10 km), respectively, is studied in terms of the critical dynamics revealed in observables of the involved non-linear processes. Specifically, we show, by means of the method of critical fluctuations (MCF), that signatures of critical, as well as tricritical, dynamics were embedded in the fracture-induced electromagnetic emissions (EMEs) recorded by two stations in locations near the epicentres of these two EQs. It is worth noting that both the MHz EMEs recorded by the telemetric stations on the island of Cephalonia and the neighbouring island of Zante (Zakynthos) reached a simultaneously critical condition a few days before the occurrence of each earthquake. The critical characteristics embedded in the EME signals were further verified using the natural time (NT) method. Moreover, we show, in terms of the NT method, that the foreshock seismic activity also presented critical characteristics before each event. Importantly, the revealed critical process seems to be focused on the area corresponding to the western Cephalonia zone, following the seismotectonic and hazard zoning of the Ionian Islands area near Cephalonia.

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“…Compared with the Fourier transform, the Hilbert-Huang transform is simple and reliable in studying the microseismic wave before the occurrence of impact ground pressure and can extract MS waveform feature information more completely [34]. At present, the signal processing method has been applied in the elds of earthquake and blast prediction, biomedicine, nance, and geology [35,36]. e basis of the HHT transform is EMD decomposition, also known as signal sorting, which eliminates some of the superimposed waves in the signal.…”

Section: Microseismic Signal Acquisition and Denoisingmentioning

confidence: 99%

Experimental Study on Stress Evolution and Microseismic Signals under Vibration Conditions of Coal during Excavation and Subsequent Waiting Time

Wang

Lyu

et al. 2019

Shock and Vibration

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An experiment designed to simulate coal during excavation was conducted. Microseismic signals of coal under vibration conditions during excavation and subsequent waiting time of the coal roadway at different excavation speeds were collected and analyzed. During the excavation and subsequent waiting time, the stress in coal is redistributed, and the concentrated stress is gradually transferred to the deeper section of the coal seam. The Hilbert–Huang transform (HHT) is used to effectively denoise the collected signals. According to the noise-reduced signal, the amplitude and pulse number of the microseismic signals emitted during the excavation process are much larger than those of the waiting time process. During excavation, the energy and event numbers of microseismic signals increase first and then decrease as the excavation speed increases. The faster the excavation speed, the more the energy, and the higher the event numbers of the microseismic signals released during the subsequent waiting time. When the excavation speed is faster, more elastic potential accumulates in the coal seam and the concentration stress is greater. As the concentrated stress moves forward in time without excavation, more coal seams fail, and more microseismic signals are released. The microseismic signal and the stress evolution law can provide a reasonable explanation for the forward movement of the concentrated stress and coal failure during roadway excavation.

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Time–frequency analysis of VLF for seismic-ionospheric precursor detection: Evaluation of Zhao-Atlas-Marks and Hilbert-Huang Transforms

Cited by 8 publications

References 34 publications

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

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

Recent seismic activity at Cephalonia (Greece): a study through candidate electromagnetic precursors in terms of non-linear dynamics

Experimental Study on Stress Evolution and Microseismic Signals under Vibration Conditions of Coal during Excavation and Subsequent Waiting Time

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