Ionospheric Anomalies around the Time of the Powerful Nabro’s Eruption Triggered by June 12, 2011 Earthquakes

Ionospheric variability resulting from earthquake events is a known phenomenon as revealed by various seismo-ionospheric coupling studies. Variations resulting from seismo-ionospheric couplings are known to be much weaker, and noted to occur only locally in an area that is specified by the magnitude of the earthquake. Whereas disturbances generated by other sources like geomagnetic storms, exhibit a more global behaviour. For this study, GPS-TEC data of 31 days (15 days before and 15 days after the occurrence of June 12, 2011 earthquakes) were examined. There were 14 earthquakes within 6 hours of that day that triggered the eruption that occurred on the 19th and 20th. This eruption produced the highest level of sulfur dioxide emissions in the earth’s atmosphere that was ever detected from space. Any correlation between the identified TEC anomalies and the earthquakes were examined. The results showed an anomaly which started two days before the earthquakes. There was a consistent decrease in the GPS-TEC two days before the earthquake. The day of the earthquake also witnessed the most anomalous decrease during the days understudy. The 19th day of June 2011 eruptions however reflected in the ionosphere through the decrease in electron concentrations.