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Earthquake Science 2011年第6期24卷 609-637页

作者： masashi hayakawa Advanced Wireless Communications Research Center and Research Station on Seismo Electromagnetics The University of Electro-Communications1-5-1 ChofugaokaChofu Tokyo 182-8585Japan Earthquake Analysis Laboratory Information Systems Inc.Kita-Aoyama 2-12-42-R305Minato-kuTokyo 107-0061Japan

There have been reports for many years that the ionosphere is very sensitive to seismic effects, and the detection of ionospheric perturbations associated with earthquakes （EQs） attracts a lot of attention as a very promising candidate for short-term EQ prediction. In this review we present a possible use of VLF/LF （very low frequency （3-30 kHz）/low frequency （30-300 kHz）） radio sounding of seismo-ionospheric perturbations. In order to avoid the overlapping with my own previous reviews, we first show some pioneering results for the Kobe EQ and we try to present the latest results including the statistical evidence on the correlation between the VLF/LF propagation anomalies （ionospheric perturbations） and EQs （especially with large magnitude and with shallow depth）, medium-distance （6-8 Mm） propagation anomalies, the fluctuation spectra of subionospheric VLF/LF data （the effect of atmospheric gravity waves, the effect of Earth＇s tides, etc.）, and the mechanism of lithosphere-atmosphere-ionosphere coupling. Finally, we indicate the present situation of this kind of VLF/LF activities going on in different parts of the globe and we suggest the importance of international collaboration in this seismo-electromagnetic study.

关键词： Earth-ionosphere waveguide subionospheric VLF/LF propagation seismo-ionosphericperturbation earthquake lithosphere-atmosphere-ionosphere coupling

A new electric field mill array with each of the mill’s rotor controlled precisely by a GPS module:Equipment and initial results

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Earth and Planetary Physics 2024年第2期8卷 423-435页

作者： Kozo Yamashita Hironobu Fujisaka DaoHong Wang Hiroyuki Iwasaki Kazuo Yamamoto Koichiro Michimoto masashi hayakawa Department of Production Systems Engineering and Sciences Komatsu UniversityNu 1-3 Shicho-machiKomatsuIshikawa 923-8511Japan Fujisaka Technology Office 1058-5 Yoshizawa-choOhta-shiGunma 373-0019Japan Department of Electrical Electronic and Computer EngineeringGifu University1-1 YanagidoGifu CityGifu 501-1193Japan Cooperative Faculty of Education Gunma University4-2-Aramaki-machiMaebashiGunma 371-8510Japan Department of Electrical and Electronic Engineering Chubu University1200 Matsumoto-choKasugaiAichi 487-8501Japan Independent Researcher Kosenba Town 2-44-11-406Kawagoe CitySaitama350-0036Japan Advanced Wireless&Communications Research Center The University of Electro-Communications1-5-1 ChofugaokaChofuTokyo 182-8585Japan

We have newly designed an electrostatic sensor,called an electric field mill(EFM),to simplify the estimation of the charge position and charge amount transferred by lightning *** is necessary for this remote estimation of the transferred charge to measure electric field changes caused by charge loss at the time of a lightning strike at multiple *** multiple-station measurement of electric field changes,not only speed but also phase for exposure and shielding of the sensing plates inside each EFM of the array should be synchronized to maintain the sensitivities of the deployed ***,there is no such EFM with specified speed and phase control performance of the rotary ***,we developed a new EFM in which the rotary mechanism was controlled consistently to within 3%error by a GPS *** EFMs had been distributed in the Hokuriku area of Japan during the winter season of 2022-2023 for a test *** we describe the design and a simple calibration method for our new EFM *** analysis method based on the assumption of a simple monopole charge structure is also *** validation,locations of assumed point charges were compared with three-dimensional lightning mapping data estimated by radio observations in the MF-HF *** results indicated the validity to estimate transferred charge amounts and positions of winter cloud-to-ground lightning discharges with our new EFM array.

关键词： lightning electrostatic field electric field mill electric field change

The ultra-low-frequency magnetic disturbances associated with earthquakes

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Earthquake Science 2011年第6期24卷 523-534页

作者： masashi hayakawa Yasuhide Hobara Kenji Ohta Katsumi Hattori Advanced Wireless Communications Research Center The University of Electro-Communications1-5-1 ChofugaokaChofu Tokyo 182-8585Japan Research Station on Seismo Electromagnetics The University of Electro-Communications1-5-1 ChofugaokaChofu Tokyo 182-8585Japan hayakawa Institute of Seismo Electromagnetics Co.Ltd.Incubation Center The University of Electro-Communications Chofu Tokyo182-8585Japan Information Systems Corp. Earthquake Analysis LaboratoryKita-Aoyama 2-14-42-305Minato-ku Tokyo 107-0061Japan Graduate School of Informatics and Engineering The University of Electro-CommunicationsChofu Tokyo 182-8585Japan Department of Electronic Information Chubu University1200 Matsumoto-choKasugai Aichi 487-8501Japan Faculty of Science Chiba University1-33 YayoiInage Chiba 263-8522Japan

The ultra-low-frequency （ULF） electromagnetic emission is recently recognized as one of the most promising candidates for short-term earthquake （EQ） prediction. This paper reviews previous convincing evidence on the presence of ULF emissions before three major EQs. Then, we present further statistical study on the ULF occurrence, our networks of ULF monitoring in different spatial scales in Japan and finally we present several signal processings to identify the seismogenic emissions by showing latest results for recent large EQs.

关键词： seismogenic ULF emission earthquake prediction magnetic sensor signal processing

On the Tempo-Spatial Evolution of the Lower Ionospheric Perturbation for the 2016 Kumamoto Earthquakes from Comparisons of VLF Propagation Data Observed at Multiple Stations with Wave-Hop Theoretical Computations

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Open Journal of Earthquake Research 2018年第3期7卷 161-185页

作者： Tomokazu Asano masashi hayakawa hayakawa Institute of Seismo Electromagnetics Co. Ltd. (Hi-SEM) University of Electro-Communications (UEC) Alliance Center 1-1-1 Kojima-cho Chofu Japan Advanced Wireless & Communications Research Center UEC Chofu Japan

There have been published many papers on VLF (very low frequency) characteristics to study seismo-ionospheric perturbations. Usually VLF records (amplitude and/or phase) are used to investigate mainly the temporal evolution of VLF propagation anomalies with special attention to one particular propagation path. The most important advantage of this paper is the simultaneous use of several propagation paths. A succession of earthquakes (EQs) happened in the Kumamoto area in Kyusyu Island;two strong foreshocks with magnitude of 6.5 and 6.4 on 14 April (UT) and the main shock with magnitude 7.3 on 15 April (UT). Because the EQ epicenters are not far from the VLF transmitter (with the call sign of JJI in Miyazaki prefecture), we can utilize simultaneously 8 observing stations of our network all over Japan. Together with the use of theoretical computations based on wave-hop theory, we try to trace both the temporal and spatial evolutions of the ionospheric perturbation associated with this succession of EQs. It is found that the ionospheric perturbation begins to appear about two weeks before the EQs, and this perturbation becomes most developed 5 - 3 days before the main shock. When the perturbation is most disturbed, the maximum change in vertical direction is depletion in the VLF effective ionospheric height of the order of 10 km, and its horizontal scale (or its radius) is about 1000 km. These spatio-temporal changes of the seismo-ionospheric perturbation will be investigated in details in the discus-sion, a comparison has made with the VLF characteristics of the 1995 Kobe with the same magnitude and of the same fault-type, and a brief discussion on the generation mechanism of seismo-ionospheric perturbation is finally made.

关键词： VLF/LF Propagation Anomaly Ionospheric Perturbations Earthquake Precursor Earthquake Prediction the 2016 Kumamoto Earthquakes Japanese VLF/LF Network Wave-Hop Computation Nighttime Fluctuation Method Atmospheric Oscillation Hypothesis

Anomalous phenomena in DC–ULF geomagnetic daily variation registered three days before the 12 May 2008 Wenchuan M_S 8.0 earthquake

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Earth and Planetary Physics 2019年第4期3卷 330-341页

作者： Mei Li Li Yao YaLi Wang Michel Parrot masashi hayakawa Jun Lu HanDong Tan Tao Xie China Earthquake Networks Center China Earthquake Administration Beijing 100045 China Laboratoire de Physique et Chimie de l’Environnement et de l’Espace Université d’Orléans CNRS Orléans France hayakawa Institute of Seismo Electromagnetics Co. Ltd. University of Electro–Communications (UEC) Chofu Japan UEC Advanced Wireless Communications Research Center Chofu Japan School of Geophysics and Information Technology China University of Geosciences Beijing 100083 China

The hourly data of the vertical Z and the horizontal H components of 37 ground-based DC-ULF geomagnetic stations are examined during 20 April-12 May 2008. On 9 May 2008, three days before the Wenchuan MS 8.0 shock, anomalies-a double low-point and a decreased amplitude-are registered on the curves of the Z component at 25 stations in a large-scale area surrounding the Wenchuan epicentral area. The H component shows none of the double low-point phenomenon but does exhibit a reduced magnitude at the same time. The geomagnetic index Kp is also examined and indicates that the anomalies appear at a solar quiet period. The appearing time shift(Tzs) between the first low-point on May 9 and the minimum point occurring time of May 1-5, 2008 is also *** results show that Tzs is on the order of 1-2 hours earlier or later than usual and there is a 2-6 hours’ gap between these two lowpoints. However, there is still a transition area which includes the epicenter where Tzs=0. Variation amplitude examined on vertical Z increases as the distance from the epicenter decreases. An Earth-air-ionosphere model has been employed to investigate a possible mechanism of this phenomenon and positive results have been unexpectedly attained. All these above-related results tend to prove that the variations of the Z and H on May 9, 2008 during the solar quiet period are probably associated with the forthcoming Wenchuan MS 8.0 earthquake.

关键词： Wenchuan MS 8.0 earthquake geomagnetic abnormity spatial variations Earth-air-ionosphere model

Variations of Atmospheric ELF/VLF Radio Noise Due to Seismogenic Modifications in Tropospheric Conductivity

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Open Journal of Earthquake Research 2024年第2期13卷 113-132页

作者： masashi hayakawa Alexander P. Nickolaenko hayakawa Institute of Seismo Electromagnetics Co. Ltd. (Hi-SEM) UEC Alliance Center #521 Tokyo Japan The University of Electro-Communications (UEC) Advanced Wireless & Communications Research Center (AWCC) Chofu-shi Tokyo O.Ya. Usikov Institute for Radiophysics and Electronics National Academy of Sciences of the Ukraine Kharkov Ukraine

We suggest a possible explanation of the influence of pre-seismic activity on the registration rate of natural ELF(extremely low frequency)/VLF(very low frequency) pulses and the changes of their characteristics. The main idea is as follows. The distribution of the electric field around a thundercloud depends on the conductivity profile of the atmosphere. Quasi-static electric fields of a thundercloud decrease in those tropospheric regions where an increase of air conductivity is generated by pre-seismic activities due to emanation of radioactive gas and water into the lower atmosphere. The electric field becomes reduced in the lower troposphere, and the probability decreases of the cloud-to-ground (CG) strokes in such “contaminated” areas. Simultaneously, the electric field grows inside and above the thunderclouds, and hence, we anticipate a growth in the number of horizontal and tilted inter-cloud (or intra-cloud) (both termed as IC discharges) strokes. Spatial orientation of lightning strokes reduces vertical projection of their individual amplitudes, while the rate (median number strokes per a unit time) of discharges grows. We demonstrate that channel tilt of strokes modifies the spectral content of ELF/VLF radio noise and changes the rate of detected pulses during the earthquake preparation phase.

关键词： ELF/VLF Radio Noise Earthquake Precursor Pre-Seismic Modification Conductivity Anomaly in the Lower Atmosphere Radioactive Radon Gases CG Lightning Discharges IC Discharges Cloud-to-Ionosphere Discharge

A Study on the Correlation of Milk Yield of Cows with Seismicity and ULF Magnetic Field Variations

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Open Journal of Earthquake Research 2016年第4期5卷 206-218页

作者： masashi hayakawa Tomokazu Asano Alexander Schekotov Hiroyuki Yamauchi hayakawa Institute of Seismo Electromagnetics Co. Ltd. University of Electro-Communications (UEC) Incubation Center Chofu Japan Advanced Wireless & Communications Research Center UEC Chofu Japan Institute of Physics of the Earth Russian Academy of Sciences Moscow Russia Department of Human and Animal-Plant Relationships Azabu University Sagamihara Japan

A statistical study on the basis of one-year data of 2014 has been performed in order to find whether abnormal animal behavior is related with seismic activity and also whether the ULF (Ultra Low Frequency) electromagnetic radiation might be a possible sensory mechanism of abnormal animal behavior. Abnormal animal behavior has been studied with the use of digitally recorded milk yield of cows at Ibaraki Prefecture Livestock Station, and the ULF magnetic field changes have been studied with the data at a magnetic observatory of Kakioka. As the result of correlation analyses, clear responses are observed for both the milk yield of cows and ULF magnetic field changes (both ULF radiation (ULF emissions from the lithosphere) and ULF depression (as an indicator of lower ionospheric perturbations)) for most powerful and not distant earthquakes (EQs) with magnitude > 6, that is, the milk yield of cows is found to exhibit a conspicuous depletion about 17 - 18 days before an EQ, though the correlation coefficient is not so big. Another important objective in this paper is to identify that ULF radiation is the main agent of abnormal behavior so that we have compared the temporal evolutions of milk yield of cows, ULF radiation and ULF depression for three major EQs. As a result, it is found that ULF radiation happens, at least, during the periods of abnormal depletion of milk yield of cows.

关键词： Milk Yield of Cows Correlation Analyses Earthquake Prediction ULF Radiation ULF Depression

Formation of Ionospheric Precursors of Earthquakes—Probable Mechanism and Its Substantiation

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Open Journal of Earthquake Research 2020年第2期9卷 142-169页

作者： Georgii Lizunov Tatiana Skorokhod masashi hayakawa Valery Korepanov Space Research Institute Kyiv Ukraine hayakawa Institute of Seismo Electromagnetics Co. Ltd. Tokyo Japan Lviv Center of Institute for Space Research Lviv Ukraine

The purpose of this article is to attract the attention of the scientific community to atmospheric gravity waves (GWs) as the most likely mechanism for the transfer of energy from the surface layers of the atmosphere to space heights and describe the channel of seismic-ionospheric relations formed in this way. The article begins with a description and critical comparison of several basic mechanisms of action on the ionosphere from below: the propagation of electromagnetic radiation;the closure of the atmospheric currents through the ionosphere;the penetration of waves throughout the neutral atmosphere. A further part of the article is devoted to the analysis of theoretical and experimental information relating to the actual GWs. Simple analytical expressions are written that allow one to calculate the parameters of GWs in specific experimental situations. Specificity of GW dispersion properties and features of their propagation are analyzed on this mathematical basis, processes of amplitude amplification and dissipation of GWs with height are investigated, the mechanism of generation of ionosphere-magnetosphere current systems is described and their quantitative characteristics are determined. The experimental part presents an analysis of GWs global distribution in the thermosphere derived from the data of the instrument NACS (Neutral Atmosphere Composition Spectrometer) onboard the satellite DE-2 (NASA, 1981-1983). The statistical association of registered ionospheric disturbances with earthquakes is demonstrated. The results of DE-2 data processing are backed up by comparison with data from the DEMETER satellite (CNES, 2005-2010) whose purpose was to study the ionospheric effects of earthquakes. Specific features of GWs that characterize these waves as a factor of influence on the ionosphere from below are indicated.

关键词： Atmospheric Gravity Waves Seismic-Ionospheric Coupling Thermosphere

Characteristic Variations of VLF/LF Signals during a High Seismic Activity in Japan in November 2016

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Open Journal of Earthquake Research 2017年第4期6卷 204-215页

作者： Tomokazu Asano Alexander Rozhnoi Maria Solovieva masashi hayakawa hayakawa Institute of Seismo Electromagnetics Co.Ltd.(Hi-SEM) UEC(University of Electro-Communications)Alliance Center#521TokyoJapan Institute of Physics of the Earth Russian Academy of SciencesMoscowRussia UEC Advanced Wireless&Communications Research Center TokyoJapan

The measurements of very low frequency/low frequency (VLF/LF) signals at the Petropavlovsk-Kamchatsky (PTK) and Yuzhno-Sakhalinsk (YSH) stations in Russia and several observing stations in Japan were used for the analysis of lower ionospheric perturbations in possible association with two earthquakes (EQs) which occurred offshore the Pacific Ocean of Japan in November 2016. The first EQ with M (magnitude) = 6.1 (depth 42 km) happened close to the coast line on 11 November (UT). The second EQ was recorded in the sea on 21 November (UT) with M = 6.9 (depth 11 km) and they had a series of aftershocks with M up to 5.6. As for the long-range monitoring, the significant negative nighttime amplitude decreases as propagation anomalies were found for two subionospheric paths: NWC (Australia)-PTK and JJY (Fukushima, Japan)-YSH during about a week, mainly before the first EQ. The anomalies of signal in the path JJY-PTK were observed 4 - 5 days before the second EQ and 3 days after it. Extensive analyses have been performed as well for these two EQs by using the short-range monitoring of VLF data observed at all of the seven VLF/LF stations in Japan in relation to the JJY signal. As related with the 1st EQ, there were observed anomalies on the two paths of JJY-STU (Suttsu) and JJY-NSB (Nakashibetsu) (both stations in Hokkaido) on 2 and 3 November. While, for the 2nd EQ clear anomalies have been observed on 14 and 15, and on 21 November at Ito station in Izu peninsula, Kamakura, Togane and Katsuura in Chiba. Taking into account the possible influence of other factors which can produce perturbations in VLF/LF signals and also using control paths, we may conclude that observed anomalies were very likely to be signatures of lower ionospheric perturbations caused by impending EQs. Finally, we try to estimate the possible perturbation scale for both EQs.

关键词： VLF/LF Propagation Anomalies lonospheric Perturbations Earthquake Precursor Short-and Long-Range Monitoring

On the Anomalies in ULF Magnetic Field Variations Prior to the 2008 Sichuan Earthquake

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Open Journal of Earthquake Research 2015年第2期4卷 55-64页

作者： Qi Li Alexander Schekotov Tomokazu Asano masashi hayakawa Institute of Geophysics China Earthquake Administration Beijing China Institute of Physics of the Earth Russian Academy of Sciences Moscow Russia Earthquake Analysis Laboratory Information Systems Inc. Minato-ku Japan hayakawa Institute of Seismo Electromagnetics Co. Ltd. University of Electro-Communications (UEC) Chofu Japan UEC Advanced Wireless Communications Research Center Chofu Japan

There have been reported several papers on the ionospheric F region perturbations prior to the 2008 Sichuan earthquake (EQ) (magnitude 8.0), but it seems that very few reports have been published on the characteristics of ground-based ULF (ultra low frequency) magnetic field variations for this EQ. This paper deals with two different aspects of ground-based ULF magnetic field variations: 1) ULF radiation from the lithosphere, and 2) depression of ULF horizontal magnetic field as a signature of lower ionospheric perturbations. ULF data from two Chinese stations [Chengdu (epicentral distance, 80 km) and Xichang (about 300 km away from the EQ epicenter)] are analyzed, with paying attention to the local nighttime period (LT = 22 h to 02 h, UTC = 14 h to 18 h) in order to avoid man-made noise. We have analyzed powers of the horizontal component (H2), vertical component (Z2), polarization as their ratio (Z2/H2), depression of the horizontal component (as an inverse of horizontal magnetic field component power, 1/H2) and δDep as a variation of depression at a particular frequency of 0.01 - 0.02 Hz (10 - 20 mHz). It is then found that there seems no clear signature of lithospheric ULF radiation. Whilst, the most evident fact is the finding of depression of ULF horizontal magnetic field at Chengdu a few days before the Sichuan EQ, which suggests that the lower ionosphere was perturbed before the EQ. The characteristics of the lower ionospheric perturbations are compared with those of upper ionospheric perturbations reported before.

关键词： Earthquake Earthquake Prediction ULF Magnetic Variation Lithospheric ULF Radiation ULF Depression