The relationship between the ionospheric and magnetic disturbances during the 28 March 2005 Sumatran earthquake

The paper investigates the ionospheric and geomagnetic responses during the 28 March 2005 earthquake in Sumatra using measurements from 7 GPS stations and a magnetometer station in the near zone of the epicenter. The earthquake occurred during low solar and geomagnetic activity. TEC oscillations of short periods in the range of 4.8 to 10 minutes were observed at GPS stations located to the northeast of the epicenter, while no significant disturbances were observed relatively east and south of the epicenter. The magnetic field measurements show rapid fluctuations of 4 to 5 seconds shortly after the earthquake, followed by a Pc5 pulsation of 4.8 minutes detected about 11 minutes after the earthquake. The comparison between the ionospheric and geomagnetic responses shows a good agreement in the period and time lag of the peak disturbance arrival, i.e. about 11 to 13 minutes after the earthquake.