Influence Factors of Harmonic Waves and Directional Waveforms for the Tidal Geoelectrical Field

Abstract

The waveform of tidal geoelectrical field is an approximate sine wave. The TGF-A waveform appears in all-day and the TGF-B only appears in the prenoon-postnoon. The harmonic periods of the waves of first 5 orders are 23∼24, 12, 7.9, 6 and 4.8 h, respectively. On different sites, the amplitude spectrum of the tidal geoelectrical field could be different. The vertical and horizontal tidal forces produced by the moon change periodically, of which amplitude spectra are also different. To the different directions of crack planes, the tidal forces generate varied effects. This could be the reason for the different amplitude spectra of the tidal geoelectrical field. On the same site, the obvious difference of the directional waveform characteristics in wave amplitude and stability could be caused by the preferential orientation of cracks. The wave amplitude of the tidal geoelectrical field is much larger and stable along the preferential orientation, and on the contrary, the wave amplitude is smaller and could be unstable in the direction perpendicular to the cracks. The cracks of mesh shape could cause similar waveform characteristics in all directions. The characteristics and amplitude spectra can be used to estimate water seeping direction and crack plane direction. The analysis result of dominant crack orientation on several sites is roughly consistent with the regional or local stress field.

Correlation between abnormal trends in the spontaneous fields of tectonic plates and strong seismicities

“…Figure 2e shows that during 2008-2009, the EW and NE long polar distances at Yanyuan station exhibited distinctive diurnal waveforms. E SP , E T , and the adjacent Lugu lake station exhibited quasi-synchronization (Tan et al 2010(Tan et al , 2011(Tan et al , 2012(Tan et al , 2014. However, the day correlation coefficients of long and short distances data in all directions were lower than 0.3.…”

“…A possible explanation is that there were spectrum and other differences between the pre-seismic SESs and the contemporary seismic signals despite the lack of evidence. Thus, the application of long and short polar distances is mainly to explore the short-impending SESs from the seismic sources, nearfield variation of geoelectric fields, tidal waves, and distortions, which can be regarded as ''interference'', despite the existence of these variations (Huang and Liu 2006;Tan et al 2010Tan et al , 2011Tan et al , 2012Tan et al , 2014. Figure 2e shows that during 2008-2009, the EW and NE long polar distances at Yanyuan station exhibited distinctive diurnal waveforms.…”

The Diurnal Variation of Geo‐Electric Field Along the Longitude and Latitude Chains in China Mainland

“…Literature [23] studies the tidal response of geo-electric field that may be induced by the predominant arrangement of the underground rock fissure direction under the action of the tides and the fissure water transfusion. The anisotropy induced by the cracks in the earth's crust medium exists generally [25] ; Accordingly, literature [23] in fact discussed the geo-electric variation that is induced by the conduction current in the anisotropic medium composed of predominant orientation (or directional alignment) of the micro-cracks within the underground medium. The conductivity mechanism of the geo-electric variation is mainly the electrokinetic effects in the medium, among which the migration and redistribution of conducting solution, distribution of micro cracks and pore configuration are major factors.…”

“…Refs. [21][22][23] have, based on the observation data obtained by some geo-electric stations of China, studied the time-frequency distribution characteristics of the geo-electric field diurnal variation (hereinafter mentioned as "GEFDV"). However, the application of such data doesn't show the features of the large Chinese mainland region and thus the research achievements are limited and related understanding is different in certain degree, thus, such data is insufficient to tell the spatio-temporal distribution regularity of the GEFDV.…”

“…Considering that Chinese geo-electric network is featured with high intensity and richly accumulated data in some regions, this paper has, based on the research achievements of Refs. [21][22][23], used the observation data obtained at geoelectric stations along two longitude chains in the east and west part of mainland China respectively and two latitude chains (at the middle to low latitude and the middle latitude), to study the spatio-temporal distribution regularity of the GEFDV, hoping to understand further the wide distribution characteristics of the GEFDV in mainland China.…”