Correlations between Earthquake Properties and Characteristics of Possible ULF Geomagnetic Precursor over Multiple Earthquakes

Yusof, Khairul Adib; Abdullah, Mardina; Hamid, Nurul Shazana Abdul; Ahadi, Suaidi; Yoshikawa, Akimasa

doi:10.3390/universe7010020

Cited by 21 publications

(14 citation statements)

References 35 publications

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“…Hayakawa et al asserted that 0.01 Hz is the most useful frequency to detect seismogenic ultralow-frequency emissions [12,21]. Our results indicate that the frequency inferred from the depth according to the skin effect was also a good candidate to detect ULF anomalies prior to earthquakes.…”

Section: Discussionsupporting

confidence: 51%

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Detection of Geomagnetic Signals as Precursors to Some Earthquakes in China

2022

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Extracting weak seismic-magnetic signals from strong electromagnetic backgrounds has always been an important part of seismic-electromagnetic research. Based on the data of D/H/Z components measured through a three-axis ring-core-type fluxgate magnetometer in GLM (Geermu), JYG (Jiayuguan), and KSH (Kashi) observatories, we analyzed geomagnetic signals as precursors to some earthquakes in China using the polarization method. The most effective main frequency of seismic-electromagnetic emission was determined according to the skin effect. The results showed that only 5 out of 37 earthquakes were found to have probable signals of seismomagnetic anomalies before them. Further research revealed that the significant enhancements of polarization ratios of YZH and YZG (YZH, the spectral power ratio of Z to H and YZG, the spectral power ratio of Z to G) occurred five days prior to the Jinta earthquake (Ms5.4) and continued for about two months. The polarization ratio of YZH reached an abnormally high value about one month before some earthquakes (Ms7.4, Ms6.7, Ms6.7) near the KSH station and lasted for about one week to half a month, then returned to the normal value. Similarly, some enhancements of polarization ratios of YZH and YZG occurred two months before the Haixi earthquake (Ms5.0) and lasted for about one month. Analysis results showed that the enhancements prior to earthquake events may be closely related to the Jinta earthquake and a series of earthquakes near the KSH station; however, the high value of YZH and YZG in GLM station had nothing to do with the Haixi earthquake.

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Section: Discussionsupporting

confidence: 51%

“…They applied the improved polarization method to the ULF data observed in China and found some significant precursory effects for three earthquakes. Nevertheless, it was demonstrated that this special phenomenon should be large-scale or even global [21][22][23], and it can be identified by multiple-station comparisons.…”

Section: Introductionmentioning

confidence: 99%

Detection of Geomagnetic Signals as Precursors to Some Earthquakes in China

2022

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“…After the FFT analysis of 1 s sampling ULF data at Kakioka, we estimate the power spectral densities of three magnetic field components, Fh, and Fz and also the polarization Pz/h [5] at different frequencies. The polarization is defined as the ratio of the power spectral densities of the vertical component to the horizontal component, and this parameter is found to effectively detect seismogenic ULF radiation [73,74].…”

Section: Lithospheric Ulf Radiationmentioning

confidence: 99%

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

et al. 2021

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The purpose of this paper is to discuss the lithosphere–atmosphere–ionosphere coupling (LAIC) effects with the use of multiparameter precursor observations for two successive Japanese earthquakes (EQs) (with a magnitude of around 7) in February and March 2021, respectively, considering a seemingly significant difference in seismological and geological hypocenter conditions for those EQs. The second March EQ is very similar to the famous 2011 Tohoku EQ in the sense that those EQs took place at the seabed of the subducting plate, while the first February EQ happened within the subducting plate, not at the seabed. Multiparameter observation is a powerful tool for the study of the LAIC process, and we studied the following observables over a 3-month period (January to March): (i) ULF data (lithospheric radiation and ULF depression phenomenon); (ii) ULF/ELF atmospheric electromagnetic radiation; (iii) atmospheric gravity wave (AGW) activity in the stratosphere, extracted from satellite temperature data; (iv) subionospheric VLF/LF propagation data; and (v) GPS TECs (total electron contents). In contrast to our initial expectation of different responses of anomalies to the two EQs, we found no such conspicuous differences of electromagnetic anomalies between the two EQs, but showed quite similar anomaly responses for the two EQs. It is definite that atmospheric ULF/ELF radiation and ULF depression as lower ionospheric perturbation are most likely signatures of precursors to both EQs, and most importantly, all electromagnetic anomalies are concentrated in the period of about 1 week–9 days before the EQ to the EQ day. There seems to exist a chain of LAIC process (cause-and-effect relationship) for the first EQ, while all of the observed anomalies seem to occur nearly synchronously in time for the send EQ. Even though we tried to discuss possible LAIC channels, we cannot come to any definite conclusion about which coupling channel is plausible for each EQ.

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“…As a result, 20 possible precursory sources of the EQ have been identified. Overall, it was concluded that while the area of the study was restricted due to the location, the EQ characteristics could correlate with several characteristics of possible precursors [Yusof, et al, 2021] (see Table 2).…”

Section: Recent Studıesmentioning

confidence: 99%

Geodynamics

Piriyev¹

2021

JGD

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Interest in research on the detection of earthquake (EQ) precursors is growing year by year. In this direction, the paper analysed the results of earlier studies, as well as positive results of some studies conducted in the last 5 years. In particular, during the study of EQs, ultra-low frequency (ULF) precursors attract special attention. The study compared the results of electromagnetic (EM) monitoring studies conducted in the ULF range in earlier years and the results of EM monitoring studies conducted in the last 5 years have been compared. The positive results of the researchers investigating the changes in the EM field before the EQ in the ULF range were reviewed. Thus, ULF anomalies from relatively weak (with 4<Mw<5) and shallow (with a depth of less than 50 km) EQs were repeatedly observed in 2017 in Indonesia. Before strong EQs, ULF promising EQ precursors were revealed. High ULF amplitude anomalies were recorded before the 2011 Tohoku megaEQ. Anomalous changes of the Earth's induction vector were identified in 6 observatories in Japan. Similar anomalies were also recorded in the ULF range (0.001-0.083 Hz) by the Teoloyucan (Mexico) and Tucson (the United States) geomagnetic observatories from August 1 to September 16, 2017, before the Chiapas EQ in Mexico with a magnitude 8.1. On the whole, the research discovered several dozen EM precursors of EQs with different amplitude, spectral and time parameters. The study was based on the analysis of numerous data for the periods 1976-2010 and 2007-2016 conducted by various researchers. In addition, an original approach is proposed. It consists in the study of geoelectric field changes (ULF precursors of EQs) as they are more sensitive. Processing and interpreting these changes can lead to precise detection of EQ precursors. Thus, this makes it possible to identify geodynamic active zones in which an EQ may occur.

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Correlations between Earthquake Properties and Characteristics of Possible ULF Geomagnetic Precursor over Multiple Earthquakes

Cited by 21 publications

References 35 publications

Detection of Geomagnetic Signals as Precursors to Some Earthquakes in China

Detection of Geomagnetic Signals as Precursors to Some Earthquakes in China

Lithosphere–Atmosphere–Ionosphere Coupling Effects Based on Multiparameter Precursor Observations for February–March 2021 Earthquakes (M~7) in the Offshore of Tohoku Area of Japan

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