S. Rohadi¹ , B. Sunardi¹ , P. Susilanto¹ , U. Haryoko¹ , S. Sazad¹ , S. Pakpahan¹ , A. Nurvita¹

¹National Seismological Center, Meterological and Geophysical Agency

Abstract:

We conducted research to study the main characteristic features of the seismo-ionospheric variations derived from GPS data called Total Electron Content (TEC). TEC is a quantity for the ionosphere of the earth. It is the total number of electrons integrated between two points, along a tube of one meter squared cross section. We have analyzed some earthquakes (M>5) that occurred within 2018 to study the changes in TEC associated with these earthquakes. A monthly standard deviation of the TEC and spatial variation are utilized to identify anomalous signals before an earthquake. The results show anomalous in the TEC before some big earthquakes (Lombok, Palu, and Krakatau eruption). The TEC derived from the global positioning system (GPS) at Balikapapan (latitude 25.38 N, longitude 82.998 E), Indonesia has been observed during Palu’s earthquake 2018. These pre-earthquake ionospheric anomalies appear within about 2-5 weeks prior to earthquakes. A possible mechanism responsible for ionospheric anomalies before big earthquakes is proposed.