The signature of the 2011 Tohoku mega earthquake on the geomagnetic field measurements in Japan

Takla, E. M.; Yumoto, K.; Okano, Shinji; Уозуми, Т.; Abe, Shuji

doi:10.1016/j.nrjag.2013.08.001

Cited by 18 publications

(9 citation statements)

References 25 publications

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“…Takla et al (2013) found an increase of 5 nT around the vicinity of the epicenter of the 2011 Tohoku earthquake, as well as a possible anomaly a couple of weeks prior to the tectonic movement. Hayakawa et al (2015) and Contoyiannis et al (2016) found a statistical relation between magnetic disturbances and earthquakes, with a transition phase in the behavior of magnetic field (anomalies in the ultralow-frequency band on the order of millihertz), where the critical point correspond to dates close to the 2011 Tohoku earthquake.…”

Section: Introductionmentioning

confidence: 88%

Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin

2018

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Abstract. We present a different view of secular variation of the Earth's magnetic field, through the variations in the threshold rigidity known as the variation rate of geomagnetic cutoff rigidity (VRc). As the geomagnetic cutoff rigidity (Rc) lets us differentiate between charged particle trajectories arriving at the Earth and the Earth's magnetic field, we used the VRc to look for internal variations in the latter, close to the 70 • south meridian. Due to the fact that the empirical data of total magnetic field BF and vertical magnetic field Bz obtained at Putre (OP) and Los Cerrillos (OLC) stations are consistent with the displacement of the South Atlantic magnetic anomaly (SAMA), we detected that the VRc does not fully correlate to SAMA in central Chile. Besides, the lower section of VRc seems to correlate perfectly with important geological features, like the flat slab in the active Chilean convergent margin. Based on this, we next focused our attention on the empirical variations of the vertical component of the magnetic field Bz, recorded in OP prior to the Maule earthquake in 2010, which occurred in the middle of the Chilean flat slab. We found a jump in Bz values and main frequencies from 3.510 to 5.860 µHz, in the second derivative of Bz, which corresponds to similar magnetic behavior found by other research groups, but at lower frequency ranges. Then, we extended this analysis to other relevant subduction seismic events, like Sumatra in 2004 and Tohoku in 2011, using data from the Guam station. Similar records and the main frequencies before each event were found. Thus, these results seem to show that magnetic anomalies recorded on different timescales, as VRc (decades) and Bz (days), may correlate with some geological events, as the lithosphereatmosphere-ionosphere coupling (LAIC).

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Section: Introductionmentioning

confidence: 88%

Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin

2018

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“…Earthquake no. 18 which is the 2011 M9.0 Tohoku earthquake was studied previously by Takla et al [36] in a similar manner in terms of the magnetometer station and method used. The results obtained in this study are in accord with those results regarding the lead time and frequency range.…”

Section: Precursor Detection and Direction Estimationmentioning

confidence: 96%

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

et al. 2021

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In this study, we improved and adapted existing signal processing methods on vast geomagnetic field data to investigate the correlations between various earthquake properties and characteristics of possible geomagnetic precursors. The data from 10 magnetometer stations were utilized to detect precursory ultra-low frequency emission and estimate the source direction for 34 earthquakes occurring between the year 2007–2016 in Southeast Asia, East Asia, and South America regions. As a result, possible precursors of 20 earthquakes were identified (58.82% detection rate). Weak correlations were obtained when all precursors were considered. However, statistically significant and strong linear correlations (r ≥ 0.60, p < 0.05) were found when the precursors from two closely located stations in Japan (Onagawa (ONW) and Tohno (TNO)) were exclusively investigated. For these stations, it was found that the lead time of the precursor is strongly (or very strongly) correlated with the earthquake magnitude, the local seismicity index, and the hypocentral depth. In addition, the error percentage of the estimated direction showed a strong correlation with the hypocentral depth. It is concluded that, when the study area is restricted to a specific location, the earthquake properties are more likely to have correlations with several characteristics of the possible precursors.

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“…Many researchers have also indicated that they use the same techniques for identification of the earthquake precursory signals Smirnova et al, 2004;Varotsos, 2005;Arora et al, 2012;Rawat, 2014]. Before the occurrence of earthquakes, anomalies in magnetic field data were observed by many researchers [Yen et al, 2004;Masci et al, 2009;Chen et al, 2010;Takla et al, 2013]. Moreover, Li et al [Li et al, 2011] observed abnormality in the 3 rd principal component of HComp of the magnetic field 40 days before occur rence of the M s 6.1 Panzhihua earthquake (China).…”

Section: Introductionmentioning

confidence: 99%

Observation of Ulf Electromagnetic Emissions Before the M 7.8 New Zealand Earthquake of November 13, 2016

Sahoo

Katlamudi

Lakshmi

2021

Geodin. tektonofiz.

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We analyzed the ground geomagnetic data obtained from a 3-component fluxgate magnetometer at the Eyrewell Geomagnetic Observatory (New Zealand) (43.474 °S, 172.393 °E) from October 1 to December 31, 2016. The study aimed to investigate electromagnetic precursors associated with the M 7.8 New Zealand earthquake of November 13, 2016. This earthquake occurred 54 km northeast of Amberley (New Zealand). Its epicenter was located 158 km from the Eyrewell Observatory. We used three methods focused on the polarization ratio, fractal dimension and principal component analysis to identify anomalies in the geomagnetic data. The time series showed an enhanced polarization ratio at two times, October 20 and October 30, 2016, i.e. before the occurrence of the New Zealand earthquake, and a value ~1 or more during these instances. Since the global geomagnetic indices Kp and Dst were normal in these cases, the enhanced polarization ratio may be related to the preparation phase of the New Zealand earthquake. To further classify them, we applied the principal component analysis to the magnetic data on component H. The first three principal components showed more than 90 % of the variance of the original ultra-low frequency (ULF) magnetic field time series. The first principal component was found to be well correlated with the storm index (Dst) recorded during this period. Again, the second principal component was dominated by daily variations, which were the periodic component of the recorded ULF magnetic field. The temporal variation of the third principal component was analyzed to verify a possible correlation between the ULF emissions and the occurrence of the earthquake. The fractal dimension of components D and Z of the magnetic data decreased initially and sharply increased three days before the New Zealand earthquake.

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The signature of the 2011 Tohoku mega earthquake on the geomagnetic field measurements in Japan

Cited by 18 publications

References 25 publications

Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin

Latitudinal variation rate of geomagnetic cutoff rigidity in the active Chilean convergent margin

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

Observation of Ulf Electromagnetic Emissions Before the M 7.8 New Zealand Earthquake of November 13, 2016

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