On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes
Anomalous behavior of ionospheric total electron content (TEC) prior to earthquake has been observed in many studies. Evidence of such seismo-ionospheric coupling effects suggests that it is plausible to rely on TEC signatures for early earthquake warning. However, the detection of pre-earthquake TE...
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sg-ntu-dr.10356-1456492020-12-30T09:22:40Z On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes Lim, B. J. M. Leong, Eng Choon School of Civil and Environmental Engineering Engineering::Civil engineering Earthquake Pre-cursor Anomalous behavior of ionospheric total electron content (TEC) prior to earthquake has been observed in many studies. Evidence of such seismo-ionospheric coupling effects suggests that it is plausible to rely on TEC signatures for early earthquake warning. However, the detection of pre-earthquake TEC anomalies (PETA) has not been adopted in practice due to two pertinent issues. Firstly, the effects of space weather activity can affect TEC levels and cause anomalous behavior in the TEC. Usually arbitrary thresholds are set for space weather indices to eliminate TEC anomaly due to space weather effects. Secondly, the choice regarding moving time-window length used to characterise background variation of TEC within the statistical envelope approach has an effect on detection of PETA. While the rule-of-thumb in selecting the moving window length is to have a time window capable of capturing background variability and short-term fluctuations, the length of the time window used in the literature varies with little justification. In this study, a critical examination is conducted on the statistical envelope approach and in particular, to eliminate the effect of space weather activity without the use of arbitrary space indices to detect PETA. A two-part PETA identification procedure is proposed, consisting of wavelet analyses isolating non-earthquake TEC contributions, followed by the statistical envelope method using a moving window length standardized based on observed periodicities and statistical implications is suggested. The approach is tested on a database of 30 large earthquakes (M ≥ 7.0). The proposed procedure shows that PETA can be detected prior to earthquakes at higher confidence levels without the need to separately check for space weather activity. More importantly, the procedure was able to detect PETA for studies where it was previously reported that PETA could not be detected or detected convincingly. Economic Development Board (EDB) Accepted version The authors acknowledge use of space weather data from the NASA/GSFC's Space Physics Data Facility's OMNIWeb and the National Oceanic and Atmospheric Administration (NOAA) Space Weather Prediction Center. Also, GPS TEC data were provided by the International GNSS Service (IGS) and the Center for Orbit Determination in Europe (CODE). The authors would also like to acknowledge the support given by Nanyang Technological University (NTU) – Satellite Research Centre (SaRC) under the project grant (EDB VELOX-CI M4061198.040.70213100) for this study. 2020-12-30T09:22:40Z 2020-12-30T09:22:40Z 2019 Journal Article Lim, B. J. M., & Leong, E. C. (2019). On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes. Advances in Space Research, 63(6), 1961–1978. doi:10.1016/j.asr.2018.10.020 0273-1177 https://hdl.handle.net/10356/145649 10.1016/j.asr.2018.10.020 6 63 1961 1978 en Advances in Space Research © 2018 COSPAR. All rights reserved. This paper was published by Elsevier Ltd in Advances in Space Research and is made available with permission of COSPAR. application/pdf |
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Engineering::Civil engineering Earthquake Pre-cursor Lim, B. J. M. Leong, Eng Choon On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
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Anomalous behavior of ionospheric total electron content (TEC) prior to earthquake has been observed in many studies. Evidence of such seismo-ionospheric coupling effects suggests that it is plausible to rely on TEC signatures for early earthquake warning. However, the detection of pre-earthquake TEC anomalies (PETA) has not been adopted in practice due to two pertinent issues. Firstly, the effects of space weather activity can affect TEC levels and cause anomalous behavior in the TEC. Usually arbitrary thresholds are set for space weather indices to eliminate TEC anomaly due to space weather effects. Secondly, the choice regarding moving time-window length used to characterise background variation of TEC within the statistical envelope approach has an effect on detection of PETA. While the rule-of-thumb in selecting the moving window length is to have a time window capable of capturing background variability and short-term fluctuations, the length of the time window used in the literature varies with little justification. In this study, a critical examination is conducted on the statistical envelope approach and in particular, to eliminate the effect of space weather activity without the use of arbitrary space indices to detect PETA. A two-part PETA identification procedure is proposed, consisting of wavelet analyses isolating non-earthquake TEC contributions, followed by the statistical envelope method using a moving window length standardized based on observed periodicities and statistical implications is suggested. The approach is tested on a database of 30 large earthquakes (M ≥ 7.0). The proposed procedure shows that PETA can be detected prior to earthquakes at higher confidence levels without the need to separately check for space weather activity. More importantly, the procedure was able to detect PETA for studies where it was previously reported that PETA could not be detected or detected convincingly. |
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School of Civil and Environmental Engineering |
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School of Civil and Environmental Engineering Lim, B. J. M. Leong, Eng Choon |
format |
Article |
author |
Lim, B. J. M. Leong, Eng Choon |
author_sort |
Lim, B. J. M. |
title |
On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
title_short |
On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
title_full |
On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
title_fullStr |
On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
title_full_unstemmed |
On the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
title_sort |
on the detection of anomalous seismo-ionospheric behavior in the presence of space weather stimuli for large earthquakes |
publishDate |
2020 |
url |
https://hdl.handle.net/10356/145649 |
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1688665362251382784 |