A method of searching for earthquake precursors based on remote sensing of local electric fields in the atmosphere

A method of remote sensing of local electrical fields with a mosaic spread in the atmosphere is described. The proposed method is based on searching for sources of infrared radiation by scanning the atmosphere and on analyzing the radiation spectrum.     

Physical models of coupling in the lithosphere-atmosphere-ionosphere system before earthquakes

The most important models of coupling in the lithosphere-atmosphere-ionosphere system are considered. In some of these models, it is assumed that atmospheric acoustic and acoustic gravity waves (AGWs), which propagate through the atmosphere and reach ionospheric altitudes (resulting in the generation of electric field disturbances and modulation of charged particle density), are generated in the near-Earth atmosphere over the earthquake preparation region. In other models it is assumed that ionospheric disturbances originate owing to the modification of electric fields and currents due to electric processes in the lithosphere or near-Earth atmosphere. It seems impossible to stress on only one model and reject the remaining models because the characteristic spatial scales of effects observed in the ionosphere before earthquakes vary from 200–300 km to several thousand kilometers, and the characteristic times vary from several minutes to several days. We can assume that there are several physical mechanisms by which the lithosphere-ionosphere coupling is actually implemented.     

Effects of weak-ends in the ionospheric spread-<Emphasis Type="Italic">F</Emphasis> over a megapolis

The hourly data of Kokubunji (within the Tokyo megapolis) and Akita (the station located in the rural area at a distance of 450 km from Tokyo) Japan vertical sounding stations for 20 years have been used. The observation probability of spread-F, characterizing the presence of large-scale (to several tens of kilometers) inhomogeneities in the ionospheric F region on nights from Saturday to Sunday and from Sunday to Monday (Saturday and Sunday nights) and the remaining nights, have been compared. It has been indicated that, according to the Kokubunji data, the spread-F observation probability on Saturday and Sunday nights is higher than on the working days with 0.95 reliability. It can be assumed that this effect is caused by an increase in the acoustic noise intensity over industrial regions due to an increase in the production intensity on working days. In this case an anthropogenic heating of the ionosphere increases, and diffusion processes responsible for spreading of inhomogeneities in the ionospheric F region intensify. According to the Akita data, such an effect was not observed.     

Irregularities in the Intensity of the Flow of Main Events: An Example of the Shallow Seismicity in the Kamchatka Region

Izvestiya, Physics of the Solid Earth - Abstract—The significant deviation of the regime of the main earthquakes from the stationary Poisson process is shown for the regional catalog of...     

Studying the spread <Emphasis Type="Italic">F</Emphasis> effect before earthquakes

The observations of spread F during the nighttime hours (0000–0500 LT) have been statistically analyzed based on data of Tokyo, Akita, Wakkanai, and Yamagawa Japan vertical ionospheric sounding stations for the time intervals a month before and a month after an earthquake. The disturbances in the probability of spread F appearance before an earthquake are revealed against a background of the variations depending on season, solar activity cycle, geomagnetic and solar disturbances. The days with increased solar (Wolf number W > 100) and geomagnetic (ΣK > 30) activity are excluded from the analysis. The spread F effects are considered for more than a hundred earthquakes with magnitude M > 5 and epicenter depth h < 80 km at distances of R < 1000 km from epicenters to the vertical sounding station. An average decrease in the spread F occurrence probability one-two weeks before an earthquake has been revealed using the superposed epoch method (the probability was minimal approximately ten days before the event and then increased until the earthquake onset). Similar results are obtained for all four stations. The reliability of the effect has been estimated. The dependence of the detected effect on the magnitude and distance has been studied.     

On the generation of modified low‐frequency Farley‐Buneman waves in the solar atmosphere

The possibility of the excitation of Farley‐Buneman turbulence in the solar atmosphere is examined. It is found that the conditions for the generation of the modified Farley‐Buneman instability can be realized in the chromosphere of the Sun 1000 km above the photosphere. While usual Farley‐Buneman waves studied in relation to the Earth's ionosphere are almost electrostatic, the modified Farley‐Buneman waves in the solar atmosphere are electromagnetic ones. This means, that not only the potential electric field caused by the charge distribution, but also the perturbations of the magnetic field and the circularly‐polarized electric field are essential. Although the physical pictures of usual and modified Farley‐Buneman waves are different, their dispersion equations are almost the same. However, the increment of the modified Farley‐Buneman waves is varied by additional electromagnetic effects. It is demonstrated that electromagnetic effects hinder a Farley‐Buneman instability in occurring while ξ < 1, where ξ is the square of the ratio of ion plasma frequency times ion‐neutral frequency to ion‐cyclotron frequency times wave number times speed of light in vacuum. Under the condition ξ > 1, no Farley‐Buneman disturbances appear at all. In weakly‐ionized solar regions, the modified (ξ < 1) and also the usual (ξ ≪ 1) Farley‐Buneman turbulence could make “electromagnetic” contributions to the process of energy dissipation of nonstationary streams of neutral gases. Besides, they may modify the low‐frequency acoustic noise. It seems that the modified Farley‐Buneman turbulence contributes to the sporadic radiation of the Sun. It is possible, that such an effect takes not only place in the chromosphere of the Sun, but also in the atmospheres of other stars.     

Modification Of Sporadic E-Layers Caused By Seismic Activity

Among all earthquake precursors, those related to electromagneticeffects are the most puzzling, and the many possible sources ofnoise are cause of lively controversies. A large number oflaboratory experiments clearly suggest that micro-fracturingis associated with the appearance of spontaneous charge production(electrification) and transient Electric or ElectroMagnetic (EM)Emission. Many electric and magnetic pre-seismic and co-seismiceffects have been reported in the past as well as ionosphericperturbations. The aim of this paper is to review some of theseionospheric perturbations performed in the former Soviet Union.The importance of sporadic E-layer formation is underlined.Statistical studies with the available observations are done.At the end, a physical model of lithosphere-ionosphere couplingis presented in order to explain the observations. This modeltakes into account the following effects at the Earth's surface:electric charge generation, emanation of radioactive gas,temperature variation, and surface vibration. It is shown thatthese effects can trigger sporadic E-layer formation.