scholarly journals Possible Seismo Ionospheric Anomalies before the 2016 Mw 7.6 Chile Earthquake from GPS TEC, GIM TEC and Swarm Satellites

2020 ◽  
Vol 1 (1) ◽  
pp. 11-20
Author(s):  
Zahid Ur Rahman
Keyword(s):  
Main Shock ◽  
Intensity Variation ◽  
The Other ◽  
Electron Content ◽  
Seismic Precursors ◽  
Total Electron ◽  
Low Intensity ◽  
Swarm Satellites ◽  
Chile Earthquake ◽  
Global Ionosphere Map

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 Ionosphere Map (GIM). The temporal TEC from GPS stations and GIM show enhancement during 5- 10 days (local daytime) before main shock. Similarly, spatial TEC confirms abnormal dense cloud at LT=12h-14h on December 21, 2016, that lingers over the epicenter of Chile earthquake. On the other hand, the geomagnetic indices show Dst < -50nT of low intensity variation. Similarly, Kp > 3 on December 21, 2016 within 5-10 days before the Mw 7.6. This study emphasizes that the ionosphere anomalies may not be the possible association of earthquakes induced variation but it is due to the active storm conditions (Kp>3).

scholarly journals Suspected Seismo-Ionospheric Anomalies before Three Major Earthquakes Detected by GIMs and GPS TEC of Permanent Stations

2021 ◽  
Vol 14 (1) ◽  
pp. 20
Author(s):  
Yanfeng Dong ◽  
Chengfa Gao ◽  
Fengyang Long ◽  
Yuxiang Yan
Keyword(s):  
Main Shock ◽  
Sampling Interval ◽  
The Other ◽  
Electron Content ◽  
Coupling Mechanism ◽  
Total Electron ◽  
Gps Tec ◽  
Ionospheric Total Electron Content ◽  
Before And After ◽  
Global Ionospheric Maps

Many studies have reported that there is a coupling mechanism between ionosphere and earthquake (EQ). Ionospheric anomalies in the form of abnormal increases and decreases of ionospheric Total Electron Content (TEC) are even regarded as precursors to EQs. In this paper, TEC anomalies associated with three major EQs were investigated by Global Ionospheric Maps (GIMs) and GPS-TEC, including Kumamoto-shi, Japan—EQ occurred on 15 April 2016 with Mw = 7.0; Jinghe, China—EQ occurred on 8 August 2017 with Mw = 6.3; and Lagunas, Peru—EQ occurred on 26 May 2019 with Mw = 8.0. It was found that the negative ionospheric anomalies linger above or near the epicenter for 4–10 h on the day of the EQ. For each EQ, the 10-min sampling interval of TEC was extracted from three permanent GPS stations around the epicenter within 10 days before and after the EQ. Variations of TEC manifest that the negative ionospheric anomalies first appear 10 days before the EQ. From 5 days before to 2 days after the main shock, the negative ionospheric anomalies were more prominent than the other days, with the amplitude of negative ionospheric anomaly reaching −3 TECu and the relative ionospheric anomaly exceeding 20%. In case of Kumamoto-shi EQ, the solar-geomagnetic conditions were not quiet (Dst < −30 nT, Kp > 4, and F10.7 > 100 SFU) on the suspected EQ days. We discussed the differences between ionospheric anomalies caused by active solar-geomagnetic conditions and EQ. Combining the analysis results of Jinghe EQ and Lagunas EQ, under quiet solar-geomagnetic conditions (Dst > −30 nT, Kp < 4, and F10.7 < 100 SFU), it can be found that TEC responds to various solar-geomagnetic conditions and EQ differently. The negative ionospheric anomalies could be considered as significant signals of upcoming EQs. These anomalies under different solar-geomagnetic conditions may be effective to link the lithosphere and ionosphere in severe seismic zones to detect EQ precursors before future EQs.

scholarly journals Investigation of GIM-TEC disturbances before M ≥ 6.0 inland earthquakes during 2003–2017

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Fuying Zhu ◽  
Yingchun Jiang
Keyword(s):  
Rapid Development ◽  
Science Research ◽  
Satellite System ◽  
Statistical Investigation ◽  
Electron Content ◽  
Total Electron ◽  
Spatial And Temporal Distributions ◽  
Before And After ◽  
Global Ionosphere Map ◽  
Global Navigation Satellite

Abstract With the rapid development of the Global Navigation Satellite System (GNSS) and its wide applications to atmospheric science research, the global ionosphere map (GIM) total electron content (TEC) data are extensively used as a potential tool to detect ionospheric disturbances related to seismic activity and they are frequently used to statistically study the relation between the ionosphere and earthquakes (EQs). Indeed, due to the distribution of ground based GPS receivers is very sparse or absent in large areas of ocean, the GIM-TEC data over oceans are results of interpolation between stations and extrapolation in both space and time, and therefore, they are not suitable for studying the marine EQs. In this paper, based on the GIM-TEC data, a statistical investigation of ionospheric TEC variations of 15 days before and after the 276 M ≥ 6.0 inland EQs is undertaken. After eliminating the interference of geomagnetic activities, the spatial and temporal distributions of the ionospheric TEC disturbances before and after the EQs are investigated and compared. There are no particularly distinct features in the time distribution of the ionospheric TEC disturbances before the inland EQs. However, there are some differences in the spatial distribution, and the biggest difference is precisely in the epicenter area. On the other hand, the occurrence rates of ionospheric TEC disturbances within 5 days before the EQs are overall higher than those after EQs, in addition both of them slightly increase with the earthquake magnitude. These results suggest that the anomalous variations of the GIM-TEC before the EQs might be related to the seismic activities.

Analysis of ionospheric vertical total electron content before the 1 April 2014 Mw 8.2 Chile earthquake

2017 ◽  
Vol 21 (6) ◽  
pp. 1599-1612 ◽  
Author(s):  
Weiping Jiang ◽  
Yifang Ma ◽  
Xiaohui Zhou ◽  
Zhao Li ◽  
Xiangdong An ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Electron Content ◽  
Vertical Total Electron Content ◽  
Total Electron ◽  
Chile Earthquake

scholarly journals Assessing the performance of a Northeast Asia Japan-cantered 3-D ionosphere specification technique during the 2015 St. Patrick’s day solar storm

2021 ◽  
Author(s):  
Nicholas Ssessanga ◽  
Mamoru Yamamoto ◽  
Susumu Saito
Keyword(s):  
Northeast Asia ◽  
Three Dimensional ◽  
Satellite System ◽  
Electron Content ◽  
Potential Candidate ◽  
Storm Events ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Swarm Satellites ◽  
Solar Storm

Abstract This paper demonstrates and assesses the capability of the advanced three- dimensional (3-D) ionosphere tomography technique, during severe conditions. The study area is northeast Asia and quasi-Japan-centred. Reconstructions are based on Total electron content data from a dense ground-based global navigation satellite system receiver network and parameters from operational ionosondes. We used observations from ionosondes, Swarm satellites and radio occultation (RO) to assess the 3-D picture. Specifically, we focus on St. Patrick’s day solar storm (17–19 March 2015), the most intense in solar cycle 24. During this event, the energy ingested into the ionosphere resulted in Dst and Kp and reaching values ~-223 nT and 8, respectively, and the region of interest, the East Asian sector, was characterized by a ~ 60% reduction in electron densities. Results show that the reconstructed densities follow the physical dynamics previously discussed in earlier publications about storm events. Moreover, even when ionosonde data were not available, the technique could still provide a consistent picture of the ionosphere vertical structure. Furthermore, analyses show that there is a profound agreement between the RO profiles/in-situ densities and the reconstructions. Therefore, the technique is a potential candidate for applications that are sensitive to ionospheric corrections.

scholarly journals LEAST SQUARE SUPPORT VECTOR MACHINE FOR DETECTION OF TECSEISMO- IONOSPHERIC ANOMALIES ASSOCIATED WITH THE POWERFUL NEPAL EARTHQUAKE (M<sub>w</sub> = 7.5) OF 25 APRIL 2015

2016 ◽  
Vol III-8 ◽  
pp. 3-11
Author(s):  
M. Akhoondzadeh
Keyword(s):  
Support Vector Machine ◽  
Main Shock ◽  
Warning System ◽  
Least Square ◽  
Support Vector ◽  
Electron Content ◽  
Total Electron ◽  
Strong Earthquakes ◽  
Nepal Earthquake ◽  
New Challenges

Due to the irrepalable devastations of strong earthquakes, accurate anomaly detection in time series of different precursors for creating a trustworthy early warning system has brought new challenges. In this paper the predictability of Least Square Support Vector Machine (LSSVM) has been investigated by forecasting the GPS-TEC (Total Electron Content) variations around the time and location of Nepal earthquake. In 77 km NW of Kathmandu in Nepal (28.147° N, 84.708° E, depth&thinsp;=&thinsp;15.0 km) a powerful earthquake of M&lt;sub&gt;w&lt;/sub&gt;&thinsp;=&thinsp;7.8 took place at 06:11:26 UTC on April 25, 2015. For comparing purpose, other two methods including Median and ANN (Artificial Neural Network) have been implemented. All implemented algorithms indicate on striking TEC anomalies 2 days prior to the main shock. Results reveal that LSSVM method is promising for TEC sesimo-ionospheric anomalies detection.

scholarly journals Investigation of VLF and HF waves showing seismo-ionospheric anomalies induced by the 29 September 2009 Samoa earthquake (<i>M</i><sub>w</sub>=8.1)

2010 ◽  
Vol 10 (5) ◽  
pp. 1061-1067 ◽  
Author(s):  
M. Akhoondzadeh ◽  
M. Parrot ◽  
M. R. Saradjian
Keyword(s):  
Comparative Analysis ◽  
Langmuir Probe ◽  
Plasma Waves ◽  
The Other ◽  
Electron Content ◽  
Total Electron ◽  
Total Electron Content Data ◽  
Electromagnetic Emissions ◽  
Electromagnetic Signals ◽  
Geomagnetic Activities

Abstract. In Samoa Islands, a powerful earthquake took place at 17:48:10.99 UTC (06:48:10.99 LT) on 29 September 2009 with a magnitude Mw=8.1. Using ICE (Instrument Champ Electrique) and IMSC (Instrument Magnetic Search Coil) experiments onboard the DEMETER (Detection of Electromagnetic Emissions Transmitted from Earthquake Regions) satellite we have surveyed possible variations in electromagnetic signals transmitted by the ground-based VLF transmitter NPM in Hawaii and in HF plasma waves close to the Samoa earthquake during the seismic activity. The indices Dst and Kp were used to distinguish pre-earthquake anomalies from the other anomalies related to the geomagnetic activities. In a previous study we have shown that anomalies in IAP (plasma analyzer) and ISL (Langmuir probe) experiments onboard the DEMETER and also TEC (Total Electron Content) data appear 1 to 5 days before the Samoa earthquake. In this paper we show that the anomalies in the VLF transmitter signal and in the HF range appear with the same time scale. The lack of significant geomagnetic activities indicates that these anomalous behaviors could be regarded as seismo-ionospheric precursors. It is also shown that comparative analysis is more effective in seismo-ionospheric studies.

An opposite response of the low-latitude ionosphere at Asian and American sectors during storm recovery phase: drivers from below and above

2020 ◽  
Author(s):  
Chao Xiong ◽  
Hermann Luehr ◽  
Yosuke Yamazaki
Keyword(s):  
Geomagnetic Storms ◽  
Recovery Phase ◽  
The Philippines ◽  
Lower Atmosphere ◽  
Electron Content ◽  
Early Recovery ◽  
Total Electron ◽  
Ionospheric Response ◽  
Swarm Satellites ◽  
Opposite Response

&lt;p&gt;The energy input from the solar wind and magnetosphere is thought to dominate the ionospheric response during geomagnetic storms. However, at the storm recovery phase, the role of forces from lower atmosphere could be as important as that from above. In this study, we focused on the geomagnetic storm happened on 6&amp;#8211;11 September 2017. The ground-based total electron content (TEC) data as well as the F region in situ electron density measured by the Swarm satellites reveals that at low and equatorial latitudes the dayside ionosphere shows as prominent positive and negative responses at the Asian and American longitudinal sectors, respectively. The global distribution of thermospheric O/N2 ratio measured by global ultraviolet imager on board the TIMED satellite cannot well explain such longitudinally opposite response of the ionosphere. Comparison between the equatorial electrojet variations from stations at Huancayo in Peru and Davao in the Philippines suggests that the longitudinally opposite ionospheric response should be closely associated with the interplay of E region electrodynamics. By further applying nonmigrating tidal analysis to the ground&amp;#8208;based TEC data, we find that the diurnal tidal components, D0 and DW2, as well as the semidiurnal component SW1, are clearly enhanced over prestorm days and persist into the early recovery phase, indicating the possibility of lower atmospheric forcing contributing to the longitudinally opposite response of the ionosphere on 9&amp;#8211;11 September 2017.&lt;/p&gt;

scholarly journals Neural network based tomographic approach to detect earthquake-related ionospheric anomalies

2011 ◽  
Vol 11 (8) ◽  
pp. 2341-2353 ◽  
Author(s):  
S. Hirooka ◽  
K. Hattori ◽  
M. Nishihashi ◽  
T. Takeda
Keyword(s):  
Neural Network ◽  
Electron Density ◽  
Electron Content ◽  
Total Electron ◽  
Ionospheric Tomography ◽  
Maximum Electron Density ◽  
Southern Side ◽  
Global Ionosphere Map ◽  
Residual Minimization ◽  
Tomographic Approach

Abstract. A tomographic approach is used to investigate the fine structure of electron density in the ionosphere. In the present paper, the Residual Minimization Training Neural Network (RMTNN) method is selected as the ionospheric tomography with which to investigate the detailed structure that may be associated with earthquakes. The 2007 Southern Sumatra earthquake (M = 8.5) was selected because significant decreases in the Total Electron Content (TEC) have been confirmed by GPS and global ionosphere map (GIM) analyses. The results of the RMTNN approach are consistent with those of TEC approaches. With respect to the analyzed earthquake, we observed significant decreases at heights of 250–400 km, especially at 330 km. However, the height that yields the maximum electron density does not change. In the obtained structures, the regions of decrease are located on the southwest and southeast sides of the Integrated Electron Content (IEC) (altitudes in the range of 400–550 km) and on the southern side of the IEC (altitudes in the range of 250–400 km). The global tendency is that the decreased region expands to the east with increasing altitude and concentrates in the Southern hemisphere over the epicenter. These results indicate that the RMTNN method is applicable to the estimation of ionospheric electron density.

scholarly journals Seismo-ionospheric anomalies in ionospheric TEC and plasma density before the 17 July 2006 <i>M</i>7.7 south of Java earthquake

2017 ◽  
Vol 35 (3) ◽  
pp. 589-598 ◽  
Author(s):  
Dan Tao ◽  
Jinbin Cao ◽  
Roberto Battiston ◽  
Liuyuan Li ◽  
Yuduan Ma ◽  
...  
Keyword(s):  
Total Electron Content ◽  
Plasma Density ◽  
Spatial Variations ◽  
Asymmetric Structure ◽  
Electron Content ◽  
Total Electron ◽  
Significant Evidence ◽  
Demeter Satellite ◽  
Global Ionosphere Map ◽  
Geomagnetic Activities

Abstract. In this paper, we report significant evidence for preseismic ionospheric anomalies in total electron content (TEC) of the global ionosphere map (GIM) and plasma density appearing on day 2 before the 17 July 2006 M7.7 south of Java earthquake. After distinguishing other anomalies related to the geomagnetic activities, we found a temporal precursor around the epicenter on day 2 before the earthquake (15 July 2006), which agrees well with the spatial variations in latitude–longitude–time (LLT) maps. Meanwhile, the sequences of latitude–time–TEC (LTT) plots reveal that the TECs on epicenter side anomalously decrease and lead to an anomalous asymmetric structure with respect to the magnetic equator in the daytime from day 2 before the earthquake. This anomalous asymmetric structure disappears after the earthquake. To further confirm these anomalies, we studied the plasma data from DEMETER satellite in the earthquake preparation zone (2046.4 km in radius) during the period from day 45 before to day 10 after the earthquake, and also found that the densities of both electron and total ion in the daytime significantly increase on day 2 before the earthquake. Very interestingly, O+ density increases significantly and H+ density decreases, while He+ remains relatively stable. These results indicate that there exists a distinct preseismic signal (preseismic ionospheric anomaly) over the epicenter.

scholarly journals Occurrence of GPS Loss of Lock Based on a Swarm Half-Solar Cycle Dataset and Its Relation to the Background Ionosphere

2021 ◽  
Vol 13 (11) ◽  
pp. 2209
Author(s):  
Michael Pezzopane ◽  
Alessio Pignalberi ◽  
Igino Coco ◽  
Giuseppe Consolini ◽  
Paola De Michelis ◽  
...  
Keyword(s):  
Global Positioning System ◽  
European Space Agency ◽  
Rate Of Change ◽  
The Other ◽  
Electron Content ◽  
Positioning System ◽  
Total Electron ◽  
Weather Effects ◽  
Space Agency ◽  
Global Positioning

This paper discusses the occurrence of Global Positioning System (GPS) loss of lock events obtained by considering total electron content (TEC) measurements carried out by the three satellites of the European Space Agency Swarm constellation from December 2013 to December 2020, which represents the longest dataset ever used to perform such an analysis. After describing the approach used to classify a GPS loss of lock, the corresponding occurrence is analyzed as a function of latitude, local time, season, and solar activity to identify well-defined patterns. Moreover, the strict relation of the occurrence of the GPS loss of lock events with defined values of both the rate of change of electron density index (RODI) and the rate of change of TEC index (ROTI) is highlighted. The scope of this study is, on one hand, to characterize the background conditions of the ionosphere for such events and, on the other hand, to pave the way for their possible future modeling. The results shown, especially the fact that GPS loss of lock events tend to happen for well-defined values of both RODI and ROTI, are of utmost importance in the light of Space Weather effects mitigation.

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