Preseismic Ionospheric Anomalies Detected Before the 2016 Taiwan Earthquake

Goto, Shin-itiro; Uchida, Ryoma; Igarashi, K.; Chen, Chia-Hung; Kao, Minghui; Umeno, Ken

doi:10.1029/2019ja026640

Cited by 10 publications

(15 citation statements)

References 17 publications

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“…Some TEC anomalies were observed within one day after the earthquakes due to acoustic resonance of the aftershocks. Reference [10] investigated the TEC variation related to the February 5, 2016 (UTC) Tainan earthquake with ML = 6.6. The TEC data were calculated using the phase delays of the signals observed from the densely arranged ground-based stations in Taiwan for GNSS.…”

Section: B Related Studies Of Tec Precursorsmentioning

confidence: 99%

“…(6) Their results demonstrated that the TEC precursors were mostly located over the epicenter. Moreover, TEC data processing was complicated, which could require considerable examination time to sufficiently determine the earthquake TEC precursors instead of short-term prediction, e.g., within 1 h before an earthquake [10]. Therefore, the aim of this study is to identify the ionospheric TEC precursors, which are generally detectable, using a type of mathematical tool without the disadvantage of the previous methods so that the research method and the data acquisition should be not as expensive as possible and the data processing is not complicated thereby making it a better survey method dealing with TEC precursors.…”

Section: B Related Studies Of Tec Precursorsmentioning

confidence: 99%

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Detecting All Possible Ionospheric Precursors by Kernel-Based Two-Dimensional Principal Component Analysis

Lin

Chao

2019

IEEE Access

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Kernel-based two-dimensional principal component analysis (K2DPCA), a nonlinear method, was performed to examine ionospheric 2-D total electron content (TEC) variations obtained from the NASA Global Differential GPS (GDGPS) network, which consisted of low spatial resolution ionospheric TEC data, to detect TEC precursors prior to the China Ludian earthquake at 08:30:13 UT on 03 August 2014 (M = 6.1). Simultaneously, two-dimensional principal component analysis (2DPCA), a linear method, was performed to examine data related to the same earthquake for comparison purposes. The results have shown that two TEC precursors were observed three days prior to this earthquake. The characteristics of all principal eigenvalues were considered to determine the TEC precursors of the earthquake in this paper. This paper aimed to differentiate the previous studies of Lin about 2DPCA using only the characteristic of the first principal eigenvalue to determine the TEC precursors of the earthquake. However, some other TEC precursors could be lost in processes that do not analyze the characteristics of other principal eigenvalues. Therefore, this research can be considered as a full analysis that examined the detailed surrounding TEC precursors of the earthquake and could be treated as a new study scope with 2DPCA and K2DPCA. The TEC precursor during 06:15 to 06:20 (UT) on 01 August 2014 localized near the epicenter was more intense compared with the characteristic of the first largest principal eigenvalue. However, another localized TEC precursor, which occurred from 06:15 to 06:20 (UT) on 01 August 2014 at a site west of the epicenter, was found to be more intense. The more plausible reason for the two TEC precursors could be the density variances caused by radon-gas release due to the fine crack stress transfer from the rocks according to Coulomb stress transfer theory as applied to a far TEC precursor. The durations of both TEC precursors were at least 5 min. This research could be treated as a full and detailed examination of surrounding TEC precursors. K2DPCA was better at identifying the TEC precursors. INDEX TERMS Kernel-based two-dimensional principal component analysis (K2DPCA), 2D total electron content (TEC), TEC precursors, NASA global differential GPS (GDGPS) network, two-dimensional principal component analysis (2DPCA), China Ludian earthquake, Radon-gas release, Coulomb stress transfer theory.

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Section: B Related Studies Of Tec Precursorsmentioning

confidence: 99%

Section: B Related Studies Of Tec Precursorsmentioning

confidence: 99%

Detecting All Possible Ionospheric Precursors by Kernel-Based Two-Dimensional Principal Component Analysis

Lin

Chao

2019

IEEE Access

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“…Thus we know that TEC disturbances spread out to almost all directions from the epicenter, with the speed of several hundreds of meters to several kilometers per second. Pre-seismic ionospheric anomalies appearing several hours to several days before the main shock have also been reported by lots of researchers as observed in TEC or other ionospheric parameters (De Santis et al 2019;Liu et al 2004Liu et al , 2006aGoto et al 2019;Heki & Enomoto 2013). Pre-seismic TIDs are often reported in time of the probability of a new EQ precursor.…”

mentioning

confidence: 76%

Combining Swarm Langmuir probe observations, LEO-POD-based and ground-based GNSS receivers and ionosondes for prompt detection of ionospheric earthquake and tsunami signatures: case study of 2015 Chile-Illapel event

Jarmołowski

Belehaki

Hernández‐Pajares

et al. 2021

J. Space Weather Space Clim.

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The study investigates ionospheric electric field responses to the earthquake (EQ) of magnitude 8.3, and to the related seismic activity and tsunami triggered by the mainshock in Chile-Illapel region, at 22:54 UTC, in the evening of 16.09.2015. The work is a wider review of available ground and satellite data and techniques available in detection of seismically induced traveling ionospheric disturbances (TID) and irregularities of smaller scale. The data used in the experiment includes several types of ground and satellite observations from low-Earth orbit (LEO) satellites. The number of techniques applied here is also extended and includes spectral analysis of LEO along-track data and composed analysis of ground GNSS data. The timeframe of the analyses is focused on 16.09 and 17.09.2015, but also extended to several adjacent days, where an enhanced seismic activity has been recorded. Several examples of seismically triggered TIDs are shown, as detected by combined observations from more than one source and with the application of different methods, including spectral analysis. These disturbances occur before the mainshock, just after, or in time following this large EQ, and can be found in close neighborhood of Chile-Illapel or far away from the epicenter. The objective of the work was to demonstrate increasing number of available data and techniques, which can be limited when applied alone, but their combination can provide many advantages in the analysis of seismically disturbed ionosphere. The combination of LEO satellite data reaching all regions of the globe with local, but dense ground-based GNSS data and ionospheric HF sounders looks promising, especially in view of nearby availability of CubeSat constellations equipped with instruments for ionosphere sounding. An important conclusion coming from the study is a need for spectral analysis techniques in the processing of LEO along-track data and requirement of the validation of LEO observations with separate LEO data or ground-based data. A general, but key finding refers to the complementarities of different observations of ionospheric electric field, which is critically important in case of analyzing ionospheric irregularities in the extended and composed ionosphere, especially if not every sounding direction can successfully find it.

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“…CRA to detect total electron content (TEC) anomalies before large earthquakes is based on the very long baseline interferometry's concept and spreading spectrum communications technology. It has been implemented to report in the references: 2016, Iwata & Umeno (hereafter I & U16) [1], 2017, Iwata & Umeno (hereafter I & U17) [2], and 2019, Goto, et al, (hereafter Goto et al 2019) [3].…”

Section: Introductionmentioning

confidence: 99%

Capability of TEC correlation Analysis and Deceleration at Propagation Velocities of Medium-Scale Traveling Ionospheric Disturbances: Preseismic Anomalies before the Large Earthquakes

Umeno¹,

Nakabayashi²,

Iwata³

et al. 2021

OJER

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Preseismic Ionospheric Anomalies Detected Before the 2016 Taiwan Earthquake

Cited by 10 publications

References 17 publications

Detecting All Possible Ionospheric Precursors by Kernel-Based Two-Dimensional Principal Component Analysis

Detecting All Possible Ionospheric Precursors by Kernel-Based Two-Dimensional Principal Component Analysis

Combining Swarm Langmuir probe observations, LEO-POD-based and ground-based GNSS receivers and ionosondes for prompt detection of ionospheric earthquake and tsunami signatures: case study of 2015 Chile-Illapel event

Capability of TEC correlation Analysis and Deceleration at Propagation Velocities of Medium-Scale Traveling Ionospheric Disturbances: Preseismic Anomalies before the Large Earthquakes

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