The 6 February 2023 Turkiye Earthquake Sequence as Detected in the Ionosphere

On 6 February 2023, a series of large earthquakes struck Turkey and Northern Syria. The main earthquake of Mw 7.8 occurred at 01:17:34 UTC and was followed by the three notable (Mw > 5.5) aftershocks within the next 18 min. Then, & SIM;9 hr later, the biggest aftershock with magnitude Mw 7.5 and a Mw 6.0 earthquake occurred to the north-east from the first main earthquake. In this work, we use data of ground-based Global Navigation Satellite Systems (GNSS) receivers in Turkey, Israel and Cyprus to analyze the ionospheric response to this series of earthquakes. We separate these events in two groups: the first sequence of earthquakes (at 01-02 UTC) and the second sequence (at 10-11 UTC). For the first sequence, we observe a clear N-shaped total electron content (TEC) response after the Mw 7.8 mainshock earthquake and Mw 6.7 aftershock, and a smaller TEC disturbance that is, most likely, caused by the Mw 5.6 earthquake. The latter is now the smallest earthquake detected by using ionospheric GNSS data. The co-seismic ionospheric disturbances (CSID) propagated from the epicentral area in the south-west direction with velocities of about 750-830 m/s. For the second sequence, we observed the response to the Mw 7.5 aftershock earthquake and the Mw 6.0 aftershock. The CSID propagated both to the south-west and the north-west to the epicentral area, with velocities of about 950-1,100 m/s.