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

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

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朝鲜半岛南部三维地壳速度结构成像

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地球物理学报 2007年第4期50卷 1073-1081页

作者：李清河张元生 So Gu KIM 江苏省地震局南京210014 中国地震局兰州地震研究所兰州730000 seismo logicalinstitute Hanyang UniversitySouth Korea

对多震相走时层析成像方法进行改进和优化,使用朝鲜半岛陆地和近海的地震记录,对朝鲜半岛南部(34.5°N～39°N,125°E～130°E)进行地震波走时反演,获得了本研究区的三维速度结构成像结果.分析了沉积层、基底、上地壳、康腊面、下地壳... 详细信息

对多震相走时层析成像方法进行改进和优化,使用朝鲜半岛陆地和近海的地震记录,对朝鲜半岛南部(34.5°N～39°N,125°E～130°E)进行地震波走时反演,获得了本研究区的三维速度结构成像结果.分析了沉积层、基底、上地壳、康腊面、下地壳和莫霍面的特征.研究了不同地质区的深部结构的主要差别、主要断裂特征、海陆交界的地壳特征等.可以发现京畿山地与沃川褶皱带、太白山褶皱带、临津江褶皱带深部结构的差异尤为明显.

关键词：朝鲜半岛南部三维速度结构成像深部结构特征

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PALEOGEOGRAPHIC EVOLUTION OF THE BEIJING PLAIN DURING THE PAST 30,000 YEARS

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Science in China,Ser.B 1984年第11期27卷 1183-1196页

作者：赵希涛孙秀萍张英礼黄兴根 Institute of Geology Academia Sinica Beijing Department of Geography Beijing Normal University seismo-geological Brigade National Bureau of seismology

Based on the landforms, sedimentary sequence, fossil fauna and flora, and paleoclimatereflected by them as well as 14~C datings, the Late Quaternary strata in Beijing Plain canbe divided into six members. In this paper, the history of paleogeographic evolution and theinteraction between geographic elements of this area during the past 30,000 years are de-scribed in detail.

关键词： PALEOGEOGRAPHIC EVOLUTION OF THE BEIJING PLAIN DURING THE PAST 30,000 YEARS

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SIMULATION OF THE SEISMIC TECTONIC STRESS FIELD IN NORTH CHINA

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Science China Chemistry 1982年第9期25卷 1000-1010页

作者：王仁黄杰藩孙荀英安欧郭世凤宋惠珍潘善德黄庆华沈淑敏杨建华 Institute of Geology State seismological Buream Institute of Geomechanics Ministry of Geology Hebei Province Peking University Beijing seismo-geological Team Geological Team No. 562 Chinese Academy of Geological Sciences State seismological Bureau

The paper reviews several methods of simulation used in this country to recover currenttectonic stress field related to earthquake occurrence in North China. The aim is to evaluatethe degree of seismic risk around Beijing area. The methods used are computational ormathematical simulation by the finite element method and experimental or physical simulationby the photoelastic method and the grid method. The results obtained by these methods arebriefly described. Most simulations indicate that Beijing is not a region of seismic risk.

关键词： SIMULATION OF THE SEISMIC TECTONIC STRESS FIELD IN NORTH CHINA

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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

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Probing the lower ionospheric perturbations associated with earthquakes by means of subionospheric VLF/LF propagation

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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

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seismogenic ULF/ELF Wave Phenomena: Recent Advances and Future Perspectives

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Open Journal of Earthquake Research 2023年第3期12卷 45-113页

作者： Masashi Hayakawa Alexander Schekotov Jun Izutsu Alexander P. Nickolaenko Yasuhide Hobara 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) Tokyo Japan Institute of Physics of the Earth Russian Academy of Sciences Moscow Russia Chubu University International Digital Earth Applied Science Research Center Kasugai Aichi Japan Usikov Institute for Radio-Physics and Electronics National Academy of Sciences of the Ukraine Kharkov Ukraine UEC Graduate School of Informatics and Engineering Tokyo Japan

There has been enormous progress in the field of electromagnetic phenomena associated with earthquakes (EQs) and EQ prediction during the last three decades, and it is recently agreed that electromagnetic effects do appear prior to an EQ. A few phenomena are well recognized as being statistically correlated with EQs as promising candidates for short-term EQ predictors: the first is ionospheric perturbation not only in the lower ionosphere as seen by subionospheric VLF (very low frequency, 3 kHz f 30 kHz)/LF (low frequency, 30 kHz f 300 kHz) propagation but also in the upper F region as detected by ionosondes, TEC (total electron content) observations, satellite observations, etc, and the second is DC earth current known as SES (Seismic electric signal). In addition to the above two physical phenomena, this review highlights the following four physical wave phenomena in ULF (ultra low frequency, frequency Hz)/ELF (extremely low frequency, 3 Hz frequency 3 kHz) ranges, including 1) ULF lithospheric radiation (i.e., direct radiation from the lithosphere), 2) ULF magnetic field depression effect (as an indicator of lower ionospheric perturbation), 3) ULF/ELF electromagnetic radiation (radiation in the atmosphere), and 4) Schumann resonance (SR) anomalies (as an indicator of the perturbations in the lower ionosphere and stratosphere). For each physical item, we will repeat the essential points and also discuss recent advances and future perspectives. For the purpose of future real EQ prediction practice, we pay attention to the statistical correlation of each phenomenon with EQs, and its predictability in terms of probability gain. Of course, all of those effects are recommended as plausible candidates for short-term EQ prediction, and they can be physically explained in terms of the unified concept of the lithosphere-atmosphere-ionosphere coupling (LAIC) process, so a brief description of this coupling has been carried out by using these four physical parameters though

关键词： ULF/ELF seismogenic Wave Effects Statistical Significance Lithosphere-Atmosphere-Ionosphere Coupling

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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

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Contaminated Effect of Geomagnetic Storms on Pre-Seismic Atmospheric and Ionospheric Anomalies during Imphal Earthquake

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Open Journal of Earthquake Research 2020年第5期9卷 383-402页

作者： Sagardweep Biswas Subrata Kundu Soujan Ghosh Swati Chowdhury Shih-Sian Yang Masashi Hayakawa Suman Chakraborty Sandip K. Chakrabarti Sudipta Sasmal Indian Centre for Space Physics Kolkata India Institute of Space Science National Central University Chinese Taipei Hayakawa Institute of seismo Electromagnetics Co. Ltd. UEC Alliance Center Chofu Tokyo Japan Physical Research Laboratory Navrangpura Ahmedabad India

Study of seismo-ionospheric coupling mechanism demands the quiet geomagnetic condition to eliminate any kind of contamination in the lower atmospheric and ionospheric parameters. In this manuscript, we present the effect of back to back two geomagnetic storms before a strong earthquake happened in Imphal, India on January 4, 2016 (M = 6.7). We studied the lower ionospheric irregularities for the duration of 31 days by computing the nighttime fluctuations in Very Low Frequency (VLF) radio signal received transmitter JJI (22.2 kHz) in Japan at Ionospheric and Earthquake Research Centre & Optical Observatory (IERCOO), Sitapur, India. We also studied the presence of Atmospheric Gravity Wave (AGW) in nighttime VLF signal in lower ionospheric heights and the same computed that from SABER/TIMED satellite. Two geomagnetic storms occurred on December 21, and 31, 2015. By the conventional analysis, we found that there is a significant decrease in nighttime trend and an increase in nighttime fluctuations around 15 days before the earthquake and just on the first storm and thus the pre-seismic effects on VLF signal gets contaminated due to the presence of storms. The wave-like structure in VLF fluctuations shows significant increase in intensity by using Fourier and Wavelet analysis before the earthquake. By analysis of SABER data, we found significant enhancement in AGW around 10 days before the earthquake. As the wavelike structures are coming from neutral acoustics reasons from pressure or temperature variations, this paper exhibits a significant example of contamination in ionospheric parameters due to geomagnetic storm where the acoustics parameters remain un-contaminated.

关键词： Very Low Frequency Wave Propagation Earthquake Precursory Atmospheric Gravity Wave Geomagnetic Strom SABER/TIMED

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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

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