Wavelet Transform Analysis of Ionospheric Electron Content Changes before Large Earthquakes

Earthquake is one of the most destructive events which menace human life. Therefore، researchers and scientists are trying to find any signals before this natural disaster and maybe to predict it. According to previous efforts and researches done by different scientists، one of earthquake precursors could be unusual changes in electron content before the occurrence of large earthquakes (greater than 6). In this study، the changes in ionospheric electron density on 11 August 2012 Ahar-Vaezeghan and on 16 April 2013 Saravan earthquakes are quantified. For this purpose، single-layer ionospheric model using GPS data of continuous stations in NW and SE Iran was considered. In this paper، an integrated wavelet analysis methodology is proposed to detect and report any relationship between ionospheric total electron content (TEC) anomalies and seismic activities. Cross-wavelet analysis as a mathematical tool represented the relationship between abnormal ionospheric total electron anomalies and sun activities. There are some limitations due to high solar activity، magnetic storms and the lack of final satellites orbit at the real time، which should be considered in this method. In order to do a better study to detect ionospheric TEC anomalies related to seismic activities، it can produce a time series of these anomalies by using GPS sites distributed in active faults zones، DEMETER satellite and iono-sound data