TEC anomalies—Local TEC changes prior to earthquakes or TEC response to solar and geomagnetic activity changes?

Edward L Afraimovich,Elvira I Astafyeva

doi:10.1186/bf03352851

Edward L Afraimovich, Elvira I Astafyeva

Open Access

https://doi.org/10.1186/bf03352851

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Abstract

Abstract A number of papers have reported on deviations of daily values of the maximum electron concentration of the ionospheric F 2 layer and/or total electron content (TEC) in the vicinity of an earthquake’s epicenter some time prior to the quake. Owing to the importance of this problem, a question of a “locality” of those effects is emerging. To study this issue we have developed a method based on the calculation of global electron content and of local electron content in “check-region” with low seismic activity. The effect of TEC day-to-day changes before strong earthquakes is analyzed in this work. It is shown that in some cases this effect might be a reflection of global changes of the ionization caused by the 27-day variations as well as other fast alterations due to solar and geomagnetic activity changes. We discuss the problem of certain data corrections that permit local changes to be distinguished from global ones.

Highlights

The ionospheric effects produced by seismic activity have attracted geophysicists’ attention for many years due to the acute need for the timely prediction of large earthquakes that cause massive destruction and many hundreds of human deaths annually
A number of papers have reported on deviations in the daily values of the maximum electron concentration of the ionospheric F2 layer and/or total electron content (TEC) in the vicinity of an earthquake’s epicenter within some days prior to the main shock (Pulinets, 1998; Pulinets et al, 2003; Pulinets and Boyarchuk, 2004; Liu et al, 2001, 2004, 2006; Zakharenkova et al, 2007)
In this work we propose a method that allows us to test whether TEC daily variations preceding earthquakes are of local character; this method takes into account the possible influence of 27-day variations of the ionosphere, caused by the rotation of the Sun and other global TEC variations

Summary

Introduction

The ionospheric effects produced by seismic activity have attracted geophysicists’ attention for many years due to the acute need for the timely prediction of large earthquakes that cause massive destruction and many hundreds of human deaths annually. In this respect, the study of the ionosphere state prior to the occurrence of large earthquakes is one of the most important tasks of modern geophysics and radio physics. According to the review of Pulinets et al (2003), the main properties of TEC

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