## 4 Results
### Suarm and CSES-01 Magnetic and Electron Density Data Analysis  
We searched for anomalous signals on satellite data tracks in a time period ranging from 90 days before and 10 days after the main earthquake (M7.8), analysing the Ne from all the Swarm satellites and CSES-01, and the three magnetic field components from Swarm-A only, as mentioned above in the Data section. From the analysis of the Swarm-A magnetic data, we collected some interesting \"anomalies\" on several days before the M7.8; the first of the two large earthquakes occurred on 6 February, taken as a time reference: on 10 and 13 November 2022 (i.e., 88 and 85 days before the mainshock, respectively), on 15 December 2022 (i.e., 53 days before), on 11, 20, 26, and 29 January 2023 (i.e., 26, 17, 11, and 8 days in advance, respectively), on 3 February 2023 (i.e., 3 days before the earthquake), and on 14 February 2023 (i.e., 8 days after the EQ \"doublets\" and with the seismic sequence running). Figure 15 shows the case of 26 January 2023, i.e., 11 days before the main EQ. Interestingly, [70] found evidence of an Ne anomaly on 27 January 2023 (i.e., 10 days before EQ) in the nightside, therefore, just one day after the magnetic anomaly seen after applying the MASS method (Figure 15). We have conducted the analogous analysis using the NeAD method: as explained before, it is similar to MASS but adapted to Ne data from Swarm (see [12] for more details). We found an anomaly detected by Swarm-C on the same day at 13:07 LT, which is also observed in the electron temperature (Te) and plasma potential (Figure 16). As found by [PERSON] [71], a law is expected to relate the precursory time (in the logarithmic scale) and the magnitude \(M\) of the earthquakes such as \(\log_{10}T=0.76M-1.83\). Applying the [PERSON] law to the case of the Turkey mainshock, in particular, for the electromagnetic anomalies extracted from satellite data [12], we learn that, for a M7.8 earthquake, we would expect to find anomalies about 2000 days before the earthquake, i.e., in September 2017 for our case study. Considering a reasonable interval between 25 August and 20 September 2017, we have carried out an automatic search using the MASS method. Interestingly, we happened to find anomalies around the expected days: 29 August 2017 (Figure 17) and 6 September 2017. We exclude the notion that the found anomalous train of waves is a kind of medium-scale travelling ionospheric disturbance (MSTID), because, here, the period is of the order of 5-10 s, while a typical MSTID has a period of 30-60 min [72]. Figure 15: Swarm-A (from left to right panels) first differences (MASS method for magnetic data) of: X, Y, Z, and F; and map with the location of the epicentre of the earthquake (green star), Dobrovolsky area (yellow circle; [63]), and analysed track (red line) for 26 January 2023 (i.e., 11 days before the earthquake). Coloured squares indicate the anomalies automatically detected by MASS. Regarding the CSES-01 electron density (Ne) data, we would like to point out a particular feature that has been detected in part of the data that span the period under study, i.e., 90 days before and 10 days after the seismic events. We have observed that some tracks are affected by jumps during the measurement (e.g., Figure 18), always around 20\({}^{\circ}\)-10\({}^{\circ}\) of geomagnetic latitude. Figure 16: Swarm-C (from left to right panels): electron density data with respect to geomagnetic latitude; first differences (NeAD method for Ne data); electron temperature data with respect to geomagnetic latitude; plasma potential data with respect to geomagnetic latitude; and map with the location of the epicentre of the earthquake (green star), Dobrovolsky area (yellow circle), and analysed track (red line) for 27 January 2023 (10 days before the earthquake). Coloured square indicates the anomaly automatically detected by NeAD.