Investigation of TEC anomalies possibly caused by the 6 February 2023 Kahramanmaraş (Turkey) earthquakes with space weather conditions

This study investigates the Total Electron Content (TEC) variations associated with major earthquakes in Kahramanmaraş (Turkey) on 6 February 2023, utilising Global Navigation Satellite System (GNSS) measurements and TEC values published by the Jet Propulsion Laboratory. Covering a 37-day period, including 18 pre/post-earthquake days, TEC values, originally from 15 CORS-TR stations in the earthquake region, were analysed in the gridded version. The study assesses pre/post-earthquake anomalies with the purpose of differentiating TEC changes caused by seismic events from those influenced by space weather conditions (SWCs). The examination of SWCs (disturbance storm time, geomagnetic storm index, GSM interplanetary magnetic field, solar wind speed, pressure, electric field, and proton density) reveals a general pre-earthquake quietness. Positive and negative TEC anomalies observed at the station locations during the study period indicate seismic events as potential precursors. Post-earthquake anomalies on 15 and 16 February 2023 are likely linked to SWCs and aftershocks. The study concludes that earthquake-induced TEC variations manifest approximately 16 days before the event, with positive anomalies, transitioning to both positive and negative anomalies approximately eight days before the earthquake. This suggests an eight-day period as a potential earthquake precursor, emphasising the potential for a future development of an early earthquake warning system through the integrated analysis of TEC variations and SWCs.