Pre-seismic geomagnetic anomaly and earthquake location

Chen, Chieh‐Hung; Liu, Jann Yenq; Lin, Pei Ying; Yen, Horng Yuan; Hattori, Katsumi; Liang, Wen‐Tzong; Chen, Yuh Ing; Yeh, Yung‐Hui; Zeng, Xiaoping

doi:10.1016/j.tecto.2010.04.018

Cited by 35 publications

(22 citation statements)

References 28 publications

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“…Some ULF monitoring systems all over the world have registered anomalous ULF electromagnetic signals preceding moderate-large EQs (e.g., Kopytenko et al, 1990;Fraser-Smith et al, 1990;Hayakawa et al, 1996Hayakawa et al, , 2007Nagao et al, 2000;Uyeda et al, 2002;Hattori, 2004;Hattori et al, 2004aHattori et al, , b, 2013Schekotov et al, 2006;Hirano and Hattori, 2011;Chen et al, 2010;Han et al, 2011;Wen et al, 2012). Hattori (2004) found that the appearance of ULF electromagnetic anomalies prior to an EQ is related to its magnitude and the epicentral distance.…”

Section: F Febriani Et Al: Ultra Low Frequency (Ulf) Electromagnetimentioning

confidence: 99%

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

Febriani

Han

Yoshino

et al. 2014

Nat. Hazards Earth Syst. Sci.

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Abstract. Indonesia is one of the most seismically active regions in the world and mitigation of seismic hazard is important. It is reported that Ultra low frequency (ULF) geomagnetic anomalies are one of the most convincing phenomena preceding large earthquakes (EQs). In this paper we have analyzed geomagnetic data at Pelabuhan Ratu (PLR) (7.01 • S, 106.56 • E), Sukabumi, West Java, Indonesia, from 1 September 2008 to 31 October 2010. There are twelve moderate-large EQs (M ≥ 5) within 160 km from the station during the analyzed period. The largest one is the M = 7.5 EQ (depth = 57 km, epicentral distance = 135 km, 2 September 2009) based on EQ catalog of Indonesian Meteorological, Climatological and Geophysical Agency (BMKG). To investigate the ULF geomagnetic anomalous variations preceding all the EQs, spectral density ratio at the frequency range of 0.01 ± 0.003 Hz based on wavelet transform (WT) and detrended fluctuation analysis (DFA) have been carried out. The spectral density ratio results show the enhancements a few weeks before the largest EQ. The enhancement persists about one week and reaches a maximum on 16 August 2009. At the same time, the result of the DFA presents the decrease of α value. For other EQs, there are no clear increases of the spectral density ratio with simultaneous decrease of α value. When these phenomena occur, the value of Dst index shows that there are no peculiar global geomagnetic activities at the low latitude region. The above results are suggestive of the relation between the detected anomalies and the largest EQ.

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Section: F Febriani Et Al: Ultra Low Frequency (Ulf) Electromagnetimentioning

confidence: 99%

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

Febriani

Han

Yoshino

et al. 2014

Nat. Hazards Earth Syst. Sci.

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“…Another one is that it cannot be applied to the earthquake right after a strong one, such in the case of Chia-Yi earthquake in this study. Nonetheless, if this method is well integrated with other geophysical observations, such as geomagnetic anomalies (Chen et al, 2010c) and crustal displacements (Chen et al, , 2013, variations in groundwater levels and electromagnetic anomalies could be quantified and/or modelled by using volume changes via possible physical mechanisms. These integrated results will be highly promising to understanding underlying mechanisms of major earthquakes and to build a strong earthquake forecast system in the future.…”

Section: Discussionmentioning

confidence: 99%

Anomalous frequency characteristics of groundwater level before major earthquakes in Taiwan

Chen

Wang

Wen

et al. 2013

Hydrol. Earth Syst. Sci.

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Abstract. Unusual decreases of water levels were consistently observed in 78 % (= 42/54) of wells in the Choshuichi Alluvial Fan of central Taiwan about 250 days before the Chi-Chi earthquake (M = 7.6 on 20 September 1999) while possible factors of barometric pressure, earth tides, precipitation as well as artificial pumping were removed. Variations in groundwater levels measured on anomalous wells from 1 August 1997 to 19 September 1999, which covers the 250 day unusual decreases, were transferred into the frequency domain to unveil frequency characteristics associated with the Chi-Chi earthquake. Analytical results show that amplitudes at the frequency band between 0.02 day −1 and 0.04 day −1 generally maintained at the low stage and were apparently enhanced a few weeks before the Chi-Chi earthquake. Variations of amplitude at this particular frequency band were further examined along with other Taiwan earthquakes (M > 6) from 1 August 1997 to 31 December 2009. Features of the enhanced amplitudes at the frequency band are consistently observed prior to the other two earthquakes (the Rei-Li and Ming-Jian earthquakes) during the 12.5 yr study period. In addition, surface displacements recorded from GPS, which provides insights into understanding stress status in subsurface during the Chi-Chi earthquake, are also inspected. The result confirms that abnormal rise and fall changes in groundwater level yield an agreement with forward and backward surface displacements around the epicentre prior to the Chi-Chi earthquake.

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“…Merzer and Klemperer (1997) and Yen et al (2004) suggested that high conductivity and/or currents along faults are main causes of observed anomalies during earthquakes. Otherwise, Chen et al (2009bChen et al ( , 2010 proposed a hybrid system and observed seismo-magnetic waves emitted from SMARTs (surface magnetic anomalous reference tips). In short, materials with high conductivity or susceptibility can be formed near epicenters, faults or SMARTs by any possible mechanism.…”

Section: Discussionmentioning

confidence: 99%

“…Chen et al (2009a) prudently examined data quality of the 11 stations by the Chapman-Miller method (Chapman and Miller, 1940), and found that tiny signals caused by the magnetic lunar effects can be observed. Although these total intensity data retrieved from this network are difficult to be used to observe changes in direction of magnetic fields, good quality and a long observation period (from 1988 to now) of data are sufficient to be utilized in most geomagnetic studies (Chen et al, , 2009a(Chen et al, , 2010(Chen et al, , 2011aLiu et al, 2006;Yen et al, 2004Yen et al, , 2009). The M = 9.0 Tohoku earthquake (142.38 • E, 38.30 • N) occurred on 11 March 2011, striking northern and eastern Japan as the most destructive earthquake thus far in the 21st century.…”

Section: Introductionmentioning

confidence: 99%

Magnetic storm free ULF analysis in relation with earthquakes in Taiwan

Wen

Chen

Yen

et al. 2012

Nat. Hazards Earth Syst. Sci.

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Abstract. Despite early optimism, pre-earthquake anomalous phenomena can be determined by using enhanced amplitude at the ultra-low-frequency range from geomagnetic data via the Fourier transform. In reality, accuracy of the enhanced amplitude in relation to earthquakes (deduced from time-varied geomagnetic data) would be damaged by magnetic storms and/or other unwanted influences resulting from solar activity and/or variations in the ionosphere, respectively. We substitute values of the cross correlation between amplitudes, summarized from the earthquake-related (0.1-0.01 Hz) and the comparable (0.01-0.001 Hz) frequency bands, for isolated amplitude enhancements as indexes of determination associated with seismo-magnetic anomalies to mitigate disturbance caused by magnetic storms. A station located about 300 km away from the others is also taken into account to further examine whether changes of the cross correlation values are caused by seismo-magnetic anomalies limited within local regions or not. Analytical results show that the values suddenly decrease near epicenters a few days before and after 67 % (= 6/9) of earthquakes (M > = 5) in Taiwan between September 2010 and March 2011. Seismomagnetic signals determined by using the values of cross correlation methods partially improve results yielded from the Fourier transform alone and provide advantageous information of earthquake locations.

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Pre-seismic geomagnetic anomaly and earthquake location

Cited by 35 publications

References 28 publications

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

Ultra low frequency (ULF) electromagnetic anomalies associated with large earthquakes in Java Island, Indonesia by using wavelet transform and detrended fluctuation analysis

Anomalous frequency characteristics of groundwater level before major earthquakes in Taiwan

Magnetic storm free ULF analysis in relation with earthquakes in Taiwan

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