ULF magnetic field depression as a possible precursor to the 2011/3.11 Japan earthquake

The depression (reduction in amplitude) of ULF magnetic field variations of magnetospheric origin is studied at various distances from the epicenter of the strongest earthquake (EQ), which occurred in Japan on March 11, 2011. For this purpose, we have used the ULF data in Japan recorded by fluxgate magnetometers at three places located at distances of ~300 km to ~1300 km from the epicenter of the main shock. The period of data analysis is from December 1, 2010 to May 31, 2011. We have found a sharp depression of the horizontal ULF magnetic field component at the frequency of 0.03…0.05 Hz (30…50 mHz) at all of three Japanese observatories (Kakioka, Memambetsu and Kanoya) three days before the first strong foreshock (Mw 7.5) and five days before the main shock (Mw 9). This maximum depression is found to be several times greater than all previous deviations, but the depression seems to be most enhanced at Kakioka, the station nearest to the EQ epicenter. So that it is likely that this phenomenon could be a possible precursor to the huge 3.11 EQ.Розглядаються електромагнітні провісники землетрусів; на різних відстанях від епіцентру сильного землетрусу в Японії 11 березня 2011 досліджується депресія (зменшення амплітуди) УНЧ-варіацій геомагнітного поля, що спричинена магнітосферними джерелами. Використовуються записи флюксгейт-магнетометрів, розташованих від епіцентру на відстанях ~300 і ~1300 км. Інтервал спостережень відноситься до періоду з 1 грудня 2010 р. по 31 травня 2011 р. Виявлено різке зниження УНЧ-коливань геомагнітного поля в діапазоні частот 0,03…0,05 Гц (30…50 мГц) у всіх японських обсерваторіях (Какіока, Мамабетсу і Канойя). Ефект спостерігали за 3 дні до форшоку магнітудою М 7,5 і за 5 днів до головного поштовху магнітудою М 9. Максимальна депресія в кілька разів перевищила ті, що спостерігалися раніше, причому в найближчій до епіцентру обсерваторії (Какіока) ефект був найбільшим. Таким чином, депресію можна розглядати як провісника гігантського землетрусу в Японії 11 березня 2011 р.Рассматриваются электромагнитные предвестники землетрясений; на различных расстояниях от эпицентра сильнейшего землетрясения в Японии 11 марта 2011 г. исследуется депрессия (уменьшение амплитуды) УНЧ-вариаций геомагнитного поля, вызванная магнитосферными источниками. Используются записи флюксгейт-магнетометров, расположенных от эпицентра на расстояниях ~300 и ~1300 км. Интервал наблюдений относится к периоду с 1 декабря 2010 г. по 31 мая 2011 г. Обнаружено резкое снижение УНЧ-колебаний геомагнитного поля в диапазоне частот 0,03…0,05 Гц (30…50 мГц) во всех японских обсерваториях (Какиока, Мамабетсу и Канойя). Эффект наблюдался за 3 дня до форшока магнитудой М 7,5 и за 5 дней до главного толчка магнитудой М 9. Максимальная депрессия в несколько раз превысила те, которые наблюдались ранее, причем в ближайшей к эпицентру обсерватории (Какиока) эффект был наибольшим. Таким образом, депрессию можно рассматривать как предвестника гигантского землетрясения в Японии 11 марта 2011 г

About possibility to locate an EQ epicenter using parameters of ELF/ULF preseismic emission

A relation between parameters of preseismic ULF/ELF emissions and EQ is studied. The magnetic data measured at Karymshino station (Kamchatka, Russia) along with data on local seismic activity during eight years of observations (2001–2008) are taken for the analysis. Source azimuth is detected in different techniques, based on the analysis of the total field and its polarized pulsed component. The latter technique shows a better accuracy in the source azimuth detection. The errors of the method are associated with existence of non-seismic sources and with use of one-point observation. The second error can be eliminated by development of multi-point observations

Study of electromagnetic emissions associated with seismic activity in Kamchatka region

International audienceA review of data processing of electromagnetic emission observation collected at the Complex Geophysical Observatory Karimshino (Kamchatka peninsula) during the first 5 months (July?November, 2000) of its operation is given. The main goal of this study addresses the detection of the phenomena associated with Kamchatka seismic activity. The following observations have been conducted at CGO: variations of ULF/ELF magnetic field, geoelectric potentials (telluric currents), and VLF signals from navigation radio transmitters. The methods of data processing of these observations are discussed. The examples of the first experimental results are presented

ULF Magnetic Field Depression as a Possible Precursor to the 2011/3.11 Japan Earthquake

The depression (reduction in amplitude) of ULF magnetic field variations of magnetospheric origin is studied at various distances from the epicenter of the strongest earthquake (EQ), which occurred in Japan on March 11, 2011. For this purpose, we have used the ULF data in Japan recorded by fluxgate magnetometers at three places located at distances of ~300 km to ~1300 km from the epicenter of the main shock. The period of data analysis is from December 1, 2010 to May 31, 2011. We have found a sharp depression of the horizontal ULF magnetic field component at the frequency of 0.03…0.05 Hz (30…50 mHz) at all of three Japanese observatories (Kakioka, Memambetsu and Kanoya) three days before the first strong foreshock (Mw 7.5) and five days before the main shock (Mw 9). This maximum depression is found to be several times greater than all previous deviations, but the depression seems to be most enhanced at Kakioka, the station nearest to the EQ epicenter. So that it is likely that this phenomenon could be a possible precursor to the huge 3.11 EQ.Розглядаються електромагнітні провісники землетрусів; на різних відстанях від епіцентру сильного землетрусу в Японії 11 березня 2011 досліджується депресія (зменшення амплітуди) УНЧ-варіацій геомагнітного поля, що спричинена магнітосферними джерелами. Використовуються записи флюксгейт-магнетометрів, розташованих від епіцентру на відстанях ~300 і ~1300 км. Інтервал спостережень відноситься до періоду з 1 грудня 2010 р. по 31 травня 2011 р. Виявлено різке зниження УНЧ-коливань геомагнітного поля в діапазоні частот 0,03…0,05 Гц (30…50 мГц) у всіх японських обсерваторіях (Какіока, Мамабетсу і Канойя). Ефект спостерігали за 3 дні до форшоку магнітудою М 7,5 і за 5 днів до головного поштовху магнітудою М 9. Максимальна депресія в кілька разів перевищила ті, що спостерігалися раніше, причому в найближчій до епіцентру обсерваторії (Какіока) ефект був найбільшим. Таким чином, депресію можна розглядати як провісника гігантського землетрусу в Японії 11 березня 2011 р.Рассматриваются электромагнитные предвестники землетрясений; на различных расстояниях от эпицентра сильнейшего землетрясения в Японии 11 марта 2011 г. исследуется депрессия (уменьшение амплитуды) УНЧ-вариаций геомагнитного поля, вызванная магнитосферными источниками. Используются записи флюксгейт-магнетометров, расположенных от эпицентра на расстояниях ~300 и ~1300 км. Интервал наблюдений относится к периоду с 1 декабря 2010 г. по 31 мая 2011 г. Обнаружено резкое снижение УНЧ-колебаний геомагнитного поля в диапазоне частот 0,03…0,05 Гц (30…50 мГц) во всех японских обсерваториях (Какиока, Мамабетсу и Канойя). Эффект наблюдался за 3 дня до форшока магнитудой М 7,5 и за 5 дней до главного толчка магнитудой М 9. Максимальная депрессия в несколько раз превысила те, которые наблюдались ранее, причем в ближайшей к эпицентру обсерватории (Какиока) эффект был наибольшим. Таким образом, депрессию можно рассматривать как предвестника гигантского землетрясения в Японии 11 марта 2011 г

Evidence of critical dynamics in various electromagnetic precursors

A wide variety of electromagnetic phenomena possibly related with earthquake (EQ) preparation processes have been reported in the literature during the last few decades. An interesting aspect in their study is the time series analysis of the related observables aiming at the investigation of any embedded dynamics. In this review article we focus on the study of fracto-electromagnetic emissions (fracto-EME) at the MHz band, the ultra-low frequency (ULF) magnetic field variations (<3 Hz) and the subionospheric very low frequency (VLF) propagation anomalies. We present recent analysis results for these electromagnetic signals using two independent methods which are known for their ability to uncover critical dynamics, the recently proposed method of critical fluctuations (MCF) and the natural time (NT) analysis method. Our results show that all three considered electromagnetic signals present critical characteristics from a few weeks up to a few days before the main shock occurrence. On the other hand, signatures for the departure from the critical (highly symmetrical) state towards a low symmetry state, a state during which there is high localization of the EQ preparatory process, have been identified in specific cases for the MHz fracto-EME as well as for the ULF magnetic field variations. Based on a multidisciplinary analysis, a four-stage model of EQ dynamics by means of fracto-EME in the MHz and kHz bands has recently been proposed. The hypothesis that the precursors considered in this article emerge during the spatially extensive phase of EQ preparation, which corresponds to the first stage of the abovementioned four-stage model, as well as their relation with the foreshock seismic activity are discussed

Evidence of critical dynamics in various electromagnetic precursors

A wide variety of electromagnetic phenomena possibly related with earthquake (EQ) preparation processes have been reported in the literature during the last few decades. An interesting aspect in their study is the time series analysis of the related observables aiming at the investigation of any embedded dynamics. In this review article we focus on the study of fracto-electromagnetic emissions (fracto-EME) at the MHz band, the ultra-low frequency (ULF) magnetic field variations (&lt;3 Hz) and the subionospheric very low frequency (VLF) propagation anomalies. We present recent analysis results for these electromagnetic signals using two independent methods which are known for their ability to uncover critical dynamics, the recently proposed method of critical fluctuations (MCF) and the natural time (NT) analysis method. Our results show that all three considered electromagnetic signals present critical characteristics from a few weeks up to a few days before the main shock occurrence. On the other hand, signatures for the departure from the critical (highly symmetrical) state towards a low symmetry state, a state during which there is high localization of the EQ preparatory process, have been identified in specific cases for the MHz fracto-EME as well as for the ULF magnetic field variations. Based on a multidisciplinary analysis, a four-stage model of EQ dynamics by means of fracto-EME in the MHz and kHz bands has recently been proposed. The hypothesis that the precursors considered in this article emerge during the spatially extensive phase of EQ preparation, which corresponds to the first stage of the abovementioned four-stage model, as well as their relation with the foreshock seismic activity are discussed. © 2021, EDP Sciences, Springer-Verlag GmbH Germany, part of Springer Nature

Intermittent criticality revealed in ULF magnetic fields prior to the 11 March 2011 Tohoku earthquake (MW=9)

The ultra-low-frequency (ULF) magnetic variations recorded prior to the 11 March 2011 Tohoku earthquake (EQ) are analyzed using the method of critical fluctuations (MCF). The first application of this specific method to ULF magnetic variations is performed on the unprocessed H-(horizontal) and Z-(vertical) components, as well as on the unprocessed total intensity, F, of the recorded magnetic field. The motivation for the present study was given by recent research results reporting criticality features in the ULF magnetic fields prior to the 2011 Tohoku EQ. These results call for a further analysis in order to verify the existence of criticality embedded in the specific ULF recordings using an independent method, as well as to investigate the type of the embedded criticality. The application of MCF indeed verifies the existence of criticality in the ULF magnetic fields a few days to one week before the occurrence of the main shock. Specifically, clear signatures of intermittent criticality are found in the recordings of 4 March 2011, while indications of critical behavior are also found in 3 and 6 March recordings, although not of the &quot;stability&quot; of those of 4 March. Moreover, it is found that only the ULF data of the nearest, to the epicenter of the EQ, geomagnetic observatory presented criticality. This finding further corroborates the view that the presented signal is indeed a precursor to the specific EQ. © 2016 Elsevier B.V. All rights reserved

Multi-point detection of the elf transient caused by the gamma flare of december 27, 2004

We present the experimental records of the radio pulse related to the gamma burst that took place on December 27, 2004. The records, which are synchronized by GPS time marks, were obtained in the observatories at Moshiri and Onagawa (Japan), Esrange (Sweden), Karimshino (Kamchatka, Russia), Nagycenk (Hungary), and Hornsund (Polish Polar Station Spitzbergen). The data demonstrate exceptional similarity and contain characteristic pulses that correspond to the time of gamma-ray arrival. Processing of the signals shows that along with the time match, the following modeling predictions are confirmed: radio pulses contain a signal at the main frequency of the Schumann resonance, the field source has positive polarity (the current is directed from the ionosphere towards the Earth), the polarization of the horizontal magnetic field of the radio wave is almost linear, and the directions towards the source indicate the epicenter of the gamma-quanta flux collision with the ionosphere. These properties correspond to the concept of the parametric electromagnetic pulse that is produced due to a significant change in the current in the global electric circuit, which is caused by a cosmic gamma-ray flare. © 2014 Springer Science+Business Media New York