ULF Wave Activity Observed in the Nighttime Ionosphere Above and Some Hours Before Strong Earthquakes

Ouyang, Xinyan; Parrot, M.; Bortnik, J.

doi:10.1029/2020ja028396

Cited by 34 publications

(19 citation statements)

References 35 publications

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“…The distance between the center of each cell and epicenter was calculated to analyze the relationship of the distance from the epicenter, seismic magnitude, and occurrence time of the anomalies based on the statistical study. Meanwhile, similar to studies by Parrot (2012) and Ouyang et al (2020), a random dataset with 206 Mw ≥ 6.0 earthquakes was obtained to carry out comparative analysis with real earthquakes. De Santis et al ( 2019) compared their real results between real earthquakes and random anomalies.…”

Section: A Worldwide Analysis: Statistical Studymentioning

confidence: 99%

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

et al. 2022

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Due to the complex processes of earthquake preparation, the observations and studies associated with earthquakes have attracted the attention of geophysicists for many years. The CSES was successfully launched on 2 February 2018. This satellite can provide global data of the electromagnetic field, plasma, and energetic particles in the ionosphere to monitor and study the ionospheric perturbations associated with earthquakes. Focusing on the characteristics of CSES, a spatial analysis method was proposed to extract the disturbances of electron density prior to earthquakes. Taking Indonesia Mw6.9 earthquake that occurred on 5 August 2018 as an example, the spatial method was illustrated and verified by another analysis method also using the data of electron density and GPS TEC data with the same analysis method. Based on the electron density of CSES for more than 2 years, this method was applied to carry out the statistical study prior to Mw ≥ 6.0 global earthquakes using the superposed epoch and space approach (SESA) method. It was found that 1) relative to the epicenters, seismo-ionospheric disturbances are more obvious in the equator direction than those in the polar direction; 2) the anomalies within 300 km distance from the epicenter are significant 11, 3, and 2 days prior to Mw ≥ 6.0 earthquakes; 3) the influence region of perturbances associated with earthquakes enlarges with the magnitude increase, and the stronger magnitude is the earlier disturbance appears. These statistical characteristics were not detected for the random earthquakes. Comparing the statistical result with the simulation output, the electric field pathway could be considered as the main channel of lithosphere–atmosphere–ionosphere coupling.

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Section: A Worldwide Analysis: Statistical Studymentioning

confidence: 99%

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

et al. 2022

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“…Additionally, the possibility of ground electromagnetic signals being propelled into atmosphere and ionosphere has been verified by satellite electromagnetic observations [14,15]. Many scholars have discovered abnormal changes in the electric and magnetic fields within the ULF range before earthquakes based on the observation data of DEMETER and other satellites [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Research on Pre-Seismic Feature Recognition of Spatial Electric Field Data Recorded by CSES

Huang

et al. 2022

Atmosphere

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In order to study the abnormal disturbance of the space ionosphere caused by strong earthquakes, the methods of SGF + WTA and EMD + ER are proposed and compared. The methods are applied to the 7.7 magnitude earthquake that occurred on the southern coast of Cuba on 29 January 2020 based on the electric field ultra-low frequency waveform data recorded by the ZH-1 electromagnetic satellite. Analyzing the electric field waveform data of the six orbits in and around the epicenter within five days before the earthquake and revisiting the orbit within two months, the significant information about the changes in the ionospheric electric field before the earthquake is obtained. The results demonstrate that: (1) in terms of time, large anomalies appeared before the earthquake on 16 January, and some orbital perturbations lasted until 2 February; (2) in terms of location, the disturbance changes are mainly concentrated over the central earthquake zone, and there are few conjugate zones; (3) in terms of amplitude, during the five days before the impending earthquake, most of the orbital disturbances exceeded the threshold of the background value while some of the orbital disturbances were less than the threshold; (4) in terms of morphology, the fluctuation that did not exceed the threshold appeared in the south of the earthquake area while a few appeared in the north. At the same time, the analysis method proposed in this paper is able to effectively extract the characteristics of electric field signal, clearly describe the abnormal signal change information before the earthquake, and provide a new method reference for the study of spatial electric field waveform data.

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“…A few case studies have demonstrated anomalous electromagnetic signals in the ULF range before earthquakes observed by satellites, e.g., [10][11][12][13]. The most recent statistical study confirmed the association between earthquakes and ULF wave activity in the nighttime ionosphere [14]. It is common in pre-earthquake effect studies to use geomagnetic activity indices to exclude disturbances in the space environment.…”

Section: Introductionmentioning

confidence: 99%

“…However, electromagnetic disturbances in the ionosphere are affected by many energy sources other than intense geomagnetic activity. In addition, most previous studies on ULF disturbances related to earthquakes are based on the electric field in the DC/ULF band recorded by the DEMETER satellite [10][11][12]14,15]. However, only using electric field data limits further analyses of wave properties such as wave mode and polarization parameters.…”

Section: Introductionmentioning

confidence: 99%

A New Analysis Method for Magnetic Disturbances Possibly Related to Earthquakes Observed by Satellites

et al. 2022

Self Cite

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Studies on magnetic disturbances in ultralow frequency ranges related to earthquakes observed by satellites are still limited. Based on Swarm satellites, this paper proposes a new analysis method to investigate pre-earthquake magnetic disturbances by excluding some known non-earthquake magnetic effects that are not confined to those caused by intense geomagnetic activity. This method is demonstrated by two earthquake cases. One is an interplate earthquake, and the other is an intraplate earthquake. Magnetic disturbances around these two earthquakes are associated with solar wind and geomagnetic activity indices, electron density and field-aligned currents. Magnetic disturbances several days before earthquakes do not show clear relations with the already known magnetic effects. These nightside disturbances (LT~17/18, ~02), possibly related to earthquakes observed by Swarm satellites, oscillate in the transverse magnetic field below 2 Hz, propagate along the background magnetic field and are mostly linearly polarized.

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ULF Wave Activity Observed in the Nighttime Ionosphere Above and Some Hours Before Strong Earthquakes

Cited by 34 publications

References 35 publications

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

Using a Spatial Analysis Method to Study the Seismo-Ionospheric Disturbances of Electron Density Observed by China Seismo-Electromagnetic Satellite

Research on Pre-Seismic Feature Recognition of Spatial Electric Field Data Recorded by CSES

A New Analysis Method for Magnetic Disturbances Possibly Related to Earthquakes Observed by Satellites

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