Pre-seismic ionospheric anomalies detected before the 2016 Kumamoto earthquake

摘要

On April 15, 2016, the Kumamoto earthquake (Mw 7.3) occurred in Japan with nowarning signals. Global Navigation Satellite System (GNSS) receivers provideuseful information on disturbances in ionosphere by calculating the changes inTotal Electron Content (TEC), which is the number of electrons in ionosphere.Here we show our recently proposed correlation analysis of TEC data which candetect the pre-seismic ionospheric anomalies from the public GNSS data. Ourmethod detected the ionospheric anomaly several tens of minutes before the 2016Kumamoto earthquake near its epicenter. Furthermore, we gave an indicator todistinguish between the pre-seismic TEC anomalies and the medium scaletraveling ionospheric disturbances (MSTIDs) by calculating the anomalous arearates. These results support the hypothesis for existence of the precedingphenomena before large earthquakes.