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TEC measurements from (a) Iqqe, (b) Antc, (c) Sant, and (d) GIM within the seismogenic zone of M w 7.6 for the month of December 2016 before and after the earthquake. The blue dotted lines are representation of confidence bounds and red dashed line for earthquake. Similarly, the influence of a geomagnetic storm in May 2016 was also checked in TEC for all studied stations. We observed no pronounced perturbations particularly to this storm, which support our hypothesis of seismo ionosphere disturbance on December 21, 2016 prior to Chile earthquake.
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The recent advances in space based ionospheric measurements can help to investigate seismic precursors before earthquake with multi-parameter observations and more dedicated instrumentations. In this paper, seismo ionospheric anomalies before the December 25, 2016, Mw 7.6, Chile earthquake are investigated in Total Electron Content (TEC) and Global...
Contexts in source publication
Context 1
... TEC from GNSS stations within Dobrovolsky et al. (1979) region and GIM over the epicenter show significant ionospheric anomalies beyond the confidence intervals prior to main shock. We observed significant ionospheric perturbations in TEC from GNSS stations around epicenter within the seismogenic zone for 10 days before the main shock (Figure 3). However, the storm in Kp is significantly active with an intensity of Kp> 3 on the same day as ionospheric variation. ...
Context 2
... monitoring of solar activity and geomagnetic storms is very important in earthquake precursory study to distinguish the earthquake induced anomaly from geomagnetic storm. There are several reports about the association of TEC anomalies with geomagnetic storms (e.g., (Figure 3c). Similarly, the GIM TEC anomaly correlated with GPS stations (Iqqe and Antc) on December 21, 2016, where an enhancement of more than 10 TECU occurs on the suspected day. ...
Context 3
... this paper, multi-ionosphere parameters are analyzed in the context of Mw 7.6 Chile earthquake and an active geomagnetic storm (Kp >3) from GPS, GIMs and Swarm three satellites in December 2016 over the epicenter. Evidence reports abnormal enhancement in temporal TEC in ionosphere over the epicenter due to geomagnetic storm (Figure 3-5). The earthquake anomalies are not evident before and after the earthquake. ...
Context 4
... three Swarm satellites provide sufficient evidence to justify storm time ionospheric coupling, as storm is clear in one index (Kp) of all geomagnetic activity indices. Moreover, there is a lack of seismic abnormality in lower and upper ionosphere (Figure 3-5). The purpose of this paper of deriving ionospheric anomalies from different satellites is to draw a concrete conclusion to the mechanism of seismo ionospheric anomalies for revealing the features originated from seismic activities. ...
Context 5
... around epicenter from GNSS stations and over epicenter from GIM completely correlated within 10 days before the main shock over the seismogenic zone (Figure 3 and Figure 4). This shows that the theory of positive holes generation at ground and its propagation to ionosphere can be acceptable in the light of Freund et al. (2009). ...
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In this paper, we focused on the characteristics of the seismo-ionospheric effects related to two successive earthquakes, namely, the earthquakes in 2022 in Taitung Sea, Taiwan, China, with magnitudes (M) of 6.7 and 6.3, at 23.45° N, 121.55° E and 23.39° N, 121.52° E and with the same focal depth of 20 km, which were detected by the China Seismo-El...
The Global Positioning System (GPS) provides insights into the Earthquakes (EQs) ionospheric anomalies. Different space-and-ground parameters are used to observe EQ precursors. This paper uses the Total Electron Content (TEC) from nearby operating GPS stations to detect perturbation in the ionosphere before and after four EQs in Japan in 2011. In a...
Early studies have shown evidence of the seismo-ionospheric perturbations prior to large earthquakes. Due to dynamic complexity in the ionosphere, the identification of precursory ionospheric changes is quite challenging. In this study, we analyze the total electron content (TEC) in the global ionosphere map and investigate the TEC changes prior to...
The ionosphere can be perturbed by solar and geomagnetic activity, earthquakes, thunderstorms, etc. In particular, electromagnetic pulses produced by thunderstorms can generate wave structures in the ionospheric plasma, which are known as atmospheric gravity waves (AGWs), which can be detected by measuring the total electron content (TEC). We studi...
We investigate the veracity of the reports by Iwata and Umeno (2016, https://doi.org/10.1002/2016ja023036) and Iwata and Umeno (2017, https://doi.org/10.1002/2017ja023921), both of which claimed that the observed perturbations in Global Navigation Satellite System (GNSS)‐based ionospheric total electron content (TEC) could serve as a "precursor" of...
Citations
... Many studies have some promising findings regarding ionosphere precursors, such as observing anomalous GPS Total Electron Content (TEC). The statistical significance of the electron density variations before the seismic activities has been found very evident in almost every study, indicating a positive gesture towards the possible EQ forecasts in the near future with the increasing cluster of satellites (Denisenko & Zeng, 2020;Rahman, 2020;. Similarly, some studies have described the possible mechanisms of triggering these ionospheric anomalies. ...
The Global Positioning System (GPS) provides insights into the Earthquakes (EQs) ionospheric anomalies. Different space-and-ground parameters are used to observe EQ precursors. This paper uses the Total Electron Content (TEC) from nearby operating GPS stations to detect perturbation in the ionosphere before and after four EQs in Japan in 2011. In addition, the TEC variations in relation to the depth and magnitude of the EQs are noticed. The analysis shows significant variations in TEC to depth and magnitude in association with each main shock. TEC value abruption starts on 8 March and continues for 6 days in March. In April, TEC abnormalities start 5 days before and after the man shock. The geomagnetic Kp index is higher than four from March 10 to 12. The anomalies in this study are clearly associated with geomagnetic storms, as the Kp index is active. Moreover, the Dst index is below the negative 50 (nT) in the seismic period of March and April. The ionosphere parameters will define the severity of seismic activity in future.
... Ionospheric anomalies occur before EQs in the form of both positive and negative perturbations. P-holes are thought to cause positive ionospheric anomalies when the drift towards the ionosphere from an EQ induced an electric field and vice versa [14][15][16]. During adiabatically fluctuating conditions, positive ions are combined near the atmosphere and then move upward to the ionosphere. ...
Citation: Shah, M.; Shahzad, R.; Ehsan, M.; Ghaffar, B.; Ullah, I.; Jamjareegulgarn, P.; Hassan, A.M. Seismo Ionospheric Anomalies around and over the Epicenters of Pakistan Earthquakes. Atmosphere 2023, 14, 601. https://doi. Abstract: Global Navigation Satellite System (GNSS)-based ionospheric anomalies are nowadays used to identify a possible earthquake (EQ) precursor and hence a new research topic in seismic studies. The current study also aims to provide an investigation of ionospheric anomalies associated to EQs. In order to study possible pre-and post-seismic perturbations during the preparation phase of large-magnitude EQs, statistical and machine learning algorithms are applied to Total Electron Content (TEC) from the Global Positioning System (GPS) and Global Ionosphere Maps (GIMs). We observed TEC perturbation from the Sukkur (27.8 • N, 68.9 • E) GNSS station near the epicenter of Mw 5.4 Mirpur EQ within 5-10 days before the main shock day by implementing machine learning and statistical analysis. However, no TEC anomaly occurred in GIM-TEC over the Mirpur EQ epicenter. Furthermore, machine learning and statistical techniques are also implemented on GIM TEC data before and after the M w 7.7 Awaran, where TEC anomalies can be clearly seen within 5-10 days before the seismic day and the subsequent rise in TEC during the 2 days after the main shock. These variations are also evident in GIM maps over the Awaran EQ epicenter. The findings point towards a large emission of EQ energy before and after the main shock during quiet storm days, which aid in the development of lithosphere ionosphere coupling. However, the entire analysis can be expanded to more satellite and ground-based measurements in Pakistan and other countries to reveal the pattern of air ionization from the epicenter through the atmosphere to the ionosphere.
... About 60-1000 Km above the surface of the Earth, an ionized layer called the ionosphere exists having a considerable quantity of ions and free electrons generated as a result of a process known as photoionization (Bilitza, 1986). When ultraviolet and X-ray reaches neutral particles, photoionization occurs (Tariq et al., 2019;2020). The density of a columnar number of electrons incorporated between two points corresponds to TEC, which is descriptive amount for the ionosphere of the Earth (Mehmood et al., 2021). ...
... The GPS has been utilized around the world as the measurements attained by GPS receiver are proved significant in the assessment of TEC and its variability in the ionosphere (Rahman, 2020;Hussain & Shah, 2020). In the absence of measurements, ionospheric models can be used to estimate VTEC, such as IRI models (Tariku, 2019). ...
The Total Electron Content (TEC) from the Sukkur GPS station is studied during the final phase of the solar cycle 24 and the initial phase of solar cycle 25 (2019-2020). TEC comparisons are made with three international reference ionospheric models: IRI-2007, IRI-2012 and IRI-2016. The finding of the study indicates that IRI-2016 is better than IRI-2007 and IRI-2012 in monthly values using wavelet transformation. Moreover, the seasonal variations between observed and modelled VTEC were observed maximum during the spring season. Similarly, the IRI-2016 exhibited maximum correlation (i.e., r > 0.8) as compared to the other two models for both solar cycle phases. This study also includes a cross-correlation of GPS-VTEC with several storm indices (Kp, Dst, Ap) via wavelet transformation. In this paper, the wavelet spectrum is analysed for two-year data (2019-2020) to visualize the impact of geomagnetic storm indices on VTEC. Storms of different intensities during 2019-2020 solar activity were also analysed, where maximum correlation from wavelet transformation between GPS VTEC and geomagnetic indices was recorded during the initial solar phase of cycle 25. These kinds of studies assist to correct the measured GPS VTEC and help to improve predicted VTEC over mid-latitude regions.
... All these reports emphasized more analysis of VTEC monitoring during Kp < 3 storm conditions with a well-equipped cluster of the ground and satellite-based observations for EQ precursors. Recently, more reports present different characteristics and morphologies of seismo-ionospheric and-atmospheric variations in the lower atmosphere followed by the ionosphere (Rahman, 2020;Ahmed et al., 2021;Adil et al., 2021a). ...
The recent advances in space-based ionosphere measurements provide more detailed information about transient ionospheric anomalies associated with earthquakes (EQs). In this paper, we study the possible relation of EQs and ionospheric anomalies in statistical analysis by analyzing 534 EQs of Mw > 5.0 during 2000-2020 from Vertical Total Electron Content (VTEC) acquired from the Global Navigation Satellite System (GNSS) of International GNSS Services (IGS) network. The selection criteria of these EQs was mainly subjected to two conditions: (1) at least three or more GNSS stations around the Dobrovolsky region were present (2) the EQs occurred during quiet geomagnetic activity (Kp < 3, Dst ≥ -20nT). Particularly, we performed statistical analysis on the basis of the median and interquartile range (IQR) over VTEC for each EQ and, the positive/negative anomalies were analyzed in the form of cumulative count for 20 days prior and after to mainshock day. Moreover, this study demonstrate that EQ-induced VTEC anomalies occurred more frequently with 3 or more GNSS stations around the epicenter in Dobrovolsky’s region within a 5-10-day window before the EQs. Furthermore, the anomalies with a low deviation also initiated after the mainshock day within a 5-10-day window. On the other hand, the deviations were more clear for Mw > 6.0 EQs, where positive anomalies were observed after excluding false anomalies in the corresponding IGS stations, showing a higher percentage of positive than negative anomalies and also more positive (negative) anomalies occur in solar maximum (minimum) years of the solar cycles 23 and 24. The false anomalies were the ionospheric perturbations associated with geomagnetic storms (Kp > 3) and VTEC values beyond upper/lower bounds outside the 5-10 days anomalous window. This statistical analysis assists to support lithosphere and ionosphere coupling for future EQ ionospheric precursors.
... [60][61][62][63] More results are published by the research community with new findings on LIAC coupling to enhance our knowledge. [64][65][66][67][68][69] All these analyses suggest that EQ precursors in the atmosphere and ionosphere are possible with improved clusters of multiple sensors onboard GNSS and other satellite missions. In addition, there is a need for more scientific groups to work dedicatedly on LAIC phenomena to search for adequate EQ precursors. ...
There have been a rapid advancement in earthquake (EQ) anomalies in the atmosphere and ionosphere from the Global Navigation Satellite System (GNSS), Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions (DEMETER), and other remotely sensed satellites under the hypothesis of lithosphere atmosphere ionosphere coupling (LAIC). Moreover, seismic precursors from conventional techniques, such as seismometers and strong motion accelerographs, are also recorded in the measurements of satellite observation to accurately monitor the world's most active seismogenic zones. Similarly, the long-and short-term anomalous patterns of EQ precursors provide more insights for studying seismic activity. Recently, advancements in space-based atmospheric and ionospheric measurements have provided more evidence to validate satellite-based anomalous patterns over seismic breeding zones. The reported anomalies were initiated as a result of squeezed rocks inside the Earth and propagated upward to the ionosphere via the lithosphere atmosphere medium due to the interaction of ions and molecules.
