Investigation of Seismo-Ionospheric Anomalies before large Earthquakes during 2001-2018

Abstract

Advances in space and remote sensing have contributed highly to the concept of lithosphere-atmosphere-ionosphere coupling over earthquake active zone. For the identi fication of ionospheric perturbations linked to earthquakes, Total Electron Content (TEC) data has been retrieved from Global position system stations within Dobrovolsky’s radi us. This research has been conducted for 10 shallow-depth earthquakes worldwide with a magnitude greater than 7 from 2001 to 2018. The TEC changes have been observed for 15 days before and 10 days after the main shock with the condition of the day being ge omagnetically quite (KP<40 & Dst>-50nT). Nine out of ten earthquakes exhibit substan tial Total Electron Content (TEC) features within a window of one to eleven days, and these anomalies disappear after the earthquake occurrence, which is consistent with the forecasted outcomes. Among which six earthquakes have anomalous values of TEC two days before the main shock, three earthquake showed anomalies eleven days prior while four earthquakes gives ionospheric anomalies six days prior to the earthquakes. Like wise, the land surface temperature (LST) plot for one earthquake as secondary data has also proven to show temperature variation four days before the earthquake on the epicen ter. The discharge of a significant amount of energy from the epicenter during the EQ preparation period may be the cause of all these positive anomalies in TEC and LST. This is initial research, and more work is needed to contribute broadly for the earthquake fore casti