Manifestations of the earthquake preparations in the ionosphere total electron content variations

Abstract

Recent ionospheric observations report anomalous total electron content (TEC) deviations prior strong earthquakes. We discuss common fetures of the pre-earthquake TEC disturbances on the basis of statistics covering 50 strong seismic events during 2005-2006. The F2-layer ionospheric plasma drift under action of the electric fields of seismic origin is proposed as the main reason of producing TEC anomalies. The origin of such electric fields is discussed in terms of the lithosphere-atmosphere-ionosphere coupling system. This theory is supported by numerical simulations using global Upper Atmosphere Model (UAM). UAM calculations show that the vertical electric current with the density of about 20 - 40 nA/m<sup>2</sup> flowing between the Earth and ionosphere over an area of about 200 by 2000 km is required to produce the TEC disturbances with the amplitude of about 30% - 50% relatively to the non-disturbed conditions. Ionosphere responses on the variations of the latitudinal position, direction and configuration of the vertical electric currents have been investigated. We show that not only the vertical component of the ionospheric plasma drift but also horizontal components play an important role in producing pre-earthquake TEC disturbances

Physical bases of the generation of short-term earthquake precursors: A complex model of ionization-induced geophysical processes in the lithosphere-atmosphere-ionosphere-magnetosphere system

“…One of the modern trends in the modeling of seismo ionospheric coupling is the arbitrary introduc tion of electric currents and fields at different altitudes (Sorokin, 2007;Klimenko et al, 2011;Kuo et al, 2011;Namgaladze et al, 2012). As a driver for the mechanism external, Sorokin (2007) uses an external current generated by charged aerosols, which may be injected into the atmosphere in seismically active areas.…”

DWT-based methodology for detection of seismic precursors on electric field signals in Mexico

“…They often encompass a large frequency range, which comes from quasi-dc to high frequencies, being ultra-low-frequency (ULF) range (0.001-1 Hz) the most promising, because it has been associated with anomalies produced in Earth's EM field before large earthquakes (Johnston 1997; Kushwah et al 2009). Other physical anomalies related to pre-earthquake disturbances such as an increment in radon emanation from the ground to the atmosphere, water chemistry alterations, haze production and induced changes in the electric field, among others have been reported Pulinets et al 2003;Pulinets and Boyarchuk 2004;Rishbeth 2006;Freund 2013;Depueva et al 2007;Liu et al 2006a;Liu et al 2006b;Karatay et al 2010;Le et al 2011;Namgaladze et al 2012;Devi et al 2014;Akhoondzadeh 2015;Heki and Enomoto 2015).…”

Monitoring Ionospheric Variation for a Definite Period Time in Turkey

“…A signal coming from a satellite to a receiver is affected by this ionization and this is named as group delay (or phase advance) briefly. The ionization is not only subject to the sun and its activity but also to seasonal, diurnal variations and geographical location (Namgaladze et al, 2012). Total Electron Content (TEC), also called Slant Total Electron Content (STEC), is a parameter that changes in relation to ionospheric conditions, and has a highly variable structure.…”