Assessing seismo-ionospheric disturbances using Vanuatu and Honshu earthquakes of March 25, 2007, employing DEMETER and GPS data

Abstract

The signals of detection of electromagnetic emissions transmitted from earthquake regions (DEMETER), plasma ion analyser, instrument Sonde de Langmuir sensors, global positioning system and total electron content (TEC) were used to decipher variations of electron and ion density in the neighbourhoods of twin seismic events. These events took place on March 25, 2007, at Vanuatu and Honshu (Japan). Investigations through statistical analysis revealed that ionospheric plasma parameters of electron density and ion density were disturbed on both sets of data on the 6th and 4th days before the Honshu earthquake in Japan, during quiet geomagnetic period. However, for the Vanuatu earthquake, all detected irregularities from DEMETER data occurred during geomagnetic storm. Nevertheless, TEC anomaly showed unusual variations exactly two weeks before the seismic activity on quiet geomagnetic day. The disturbance storm time and planetarische Kennziffer indices were engaged in isolating pre-earthquake irregularities from other irregularities associated with geomagnetic actions.