Tidal wave anomalies of geoelectrical field before remote earthquakes

Abstract

In this paper, geoelectrical field anomalies at Changli and Xingji station in Hebei Province were analyzed before five remote earthquakes. It was found that the anomalies mainly occurred two or three months before earthquakes, which is of importance to short-term and impendent earthquake prediction. There exhibited different characteristics in geoelectrical field anomalies, but they were closely related to tidal waves, for example, the increasing in amplitude at semidiurnal and semimonthly periods of tidal waves; the decreasing or disappearing in amplitude of tidal waves that should have been recorded normally at that time; while there accompanied incremental signals with high frequency, such as jump variations. It was thought that the formation mechanism of the geoelectrical anomalies before strong earthquakes resulted from stress-strain resonance effects when rock was weakened during the preparation process in seismic area, and then signals of electric field propagated to remote stations in free space or crust, and superposed on the geoelectric field tidal waves recorded at the stations, leading to increasing or decreasing in amplitude of geoelectrical tidal waves. The high frequency signals may be related to the variation of rock porosity, permeability and so on beneath the stations, as a result of the dynamic effects of remote earthquakes.

Nonlocal elasticity based magnetic field affected vibration response of double single-walled carbon nanotube systems

“…They confirmed the dependence of the magnitude and direction of the magnetic field on the electronic properties of double-walled CNTs. Roche and Saito, 36 Sebastiani and Kudin, 37 and Zhang et al 38 investigated the electronic properties of carbon nanotubes in the presence of a magnetic field. Mechanical studies, viz., vibration of single-walled and multiwalled nanotubes (MWNTs) under a magnetic field have also been reported in the literature.…”

Features of Regional Variations of the Spontaneous Field

“…In accordance with various microscopic mechanisms and processes of the formation of telluric field, it can be classified as TGF-A, TGF-B, geoelectric storm and so on (Sun and Wang, 1984;Tan et al, 2010). Based on Tan et al's research in recent years (2010Tan et al's research in recent years ( , 2011Tan et al's research in recent years ( , 2012Tan et al's research in recent years ( , 2013, since the intensities of TGF-A and TGF-B tidal geoelectric fields and geoelectric storms are significantly affected by lithologic structure of the field, fissure and fissure water, stress and strain and other factors, the seismo-electromagnetic precursor can also be manifested in the variation of the telluric field of the field (Huang and Liu, 2006;Zhang et al, 2007;Tan et al, 2010Tan et al, , 2011Tan et al, , 2012Tan et al, , 2013.…”

“…But as for the studies on the regional variation characteristics of spontaneous field, the correlation between micro-mechanism and macro-phenomena and others by employing electro-kinetic effects, contact-diffusion, oxidation reduction and other micro-mechanisms of spontaneous field (Sun and Wang, 1984;Qian and Zhao, 2005;Huang et al, 2011), there have been very few results up till now. Zhao and Lu (2003) pointed out that there existed a correlation between the diurnal variation of apparent resistivity and solid tides; Huang et al (2005; believed that when extracting relatively weak seismic electromagnetic signals from the complex electromagnetic environment, it was necessary to explore a physical analysis method combining math, signal processing and seismic electromagnetic physical process; in the years between 2006, Huang and Liu (2006, Zhang et al (2007) analyzed the spectral characteristics of the solid tidal phenomena of geoelectric field and the variations before earthquakes. Based on the research results on space Sq current by Xu (1992) and Zhao et al (2008), and those on solid tidal waves of geoelectric field by Huang et al (2010a), Tan et al (2010) classified the tidal wave of geoelectric field into two categories of TGF-A and TGF-B, he explored the preliminary principles of physical resolution for spontaneous field and telluric field (Tan et al, 2012).…”

The Variation of Waveform and Analysis of Composition for the Geoelectrical Field before Moderate and Strong Earthquakes in Qinghai‐Tibetan Plateau Regions

“…Fig. 1b, the distribution of observatories with TGF-A waveforms is discrete, and the large water area nearby is helpful for the formation of tidal waves [2,3,7] ; observatories with TGF-B waveforms are basically located in the regions where the rock has a high water content, a strong water permeability and thick Quaternary sediments [7,10−11] ; the observatories without the waveform of diurnal variation are mostly concentrated in the bedrock mountains in southeastern part of Gansu, southern Sichuan and Yunnan. These two regions have an intense tectonic activity, complex lithology and electric structures [16−19] , and at the same time they are seismogenic zones of strong earthquakes [18] .…”

“…Before and after 2000, Qian Jiadong and Steven Park investigated the tidal wave phenomenon of the geoelectric field of Chongming observatory in Shanghai; in 2003, in the trial analysis of using artificial super low frequency (SLF) electromagnetic waves to monitor earthquakes, Zhao et al [1] pointed out that there existed a good correlation between diurnal variation of apparent resistivity and solid tides; in 2006, Huang [2] conducted a quantitative analysis of the spectral characteristics of the solid tides of the geoelectric field of Niijima observatory in Japan and its abnormal variations before the earthquake; in 2007, Zhang [3] discussed the abnormal variation phenomenon and the mechanism of solid tidal waves of geoelectric field at Changli observatory before remote earthquakes. Based on the research results of Sq currents of space by Xu et al [4−5] and the solid tidal waves of geoelectric field by Huang et al [1][2][3]6] , in 2010, Tan et al [7] divided the tidal waves E-mail: tandc@gssb.gov.cn of geoelectric field into two types: TGF-A and TGF-B, and thought they were derived respectively from solid tides and space Sq currents. The observation data of geoelectric field contains the spontaneous field, telluric field [8−9] , and interference components.…”