S. Rohadi¹ , B. Bambang Sunardi² , B.M. Buldan Muslim³

¹Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), National Seismological Center, Jakarta, Indonesia
²Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG), Research Centre, Jakarta, Indonesia
³National Institute of Aeronautics and Space (LAPAN), Jakarta, Indonesia

Abstract:

Atmospheric gravity and infrasonic waves can be excited by seismic activities such as earthquakes and tsunamis. If the tsunami and earthquake are strong enough, the waves can propagate to a height in the ionosphere so that fluctuations in the ionosphere in the period order of atmospheric gravity and infrasonic waves can appear in the ionosphere. Monitoring the system of ionospheric waves associated with the earthquake from GPS data has been developed from a network of GPS observation stations. Using sliding Fast Fourier Transform (SFFT) on differential Total Electron Content (TEC) data estimated from the carrier phase data of the GPS signal, ionospheric irregular fluctuations in periods of the order of seconds to tens of minutes can be detected in the ionosphere with an average amplitude which varies in the order of less than 0,01 TECU. At a certain moment the ionospheric fluctuations becomes more regular and have a greater amplitude of more than 0,01 TECU. The methodology of examining the GPS data during the occurrence of some earthquakes shows that the ionospheric waves can be detected a few minutes to a few hours after the earthquake and tsunami. The Nuclear explosions were also examined using this method. The results indicate a little TEC anomaly after the explosion.