## 3 Multidisciplinary Data and Methods
### Electron Burst Data Analysis  
Electron loss phenomena (also generally known as particle burst, PB) are considered indirect evidence of the interaction between the lithosphere (where EM signals originate) and the magnetosphere. In this perspective, from the population of PB \"events\" (also due to other well-established magnetospheric sources), those that are earthquake-associated must be discriminated against through their characterisation. Starting from May 2013 to May 2023, PBs were analysed in depth, comparing them to the seismic activity, including the events of Kermadec on 15 June 2019, and Tonga on 15 January 2022 [64]. All PB-associated events with magnitudes greater or equal to 6.5 that occurred in the South Pacific were analysed, and, finally, a new kind of loss phenomenon was evidenced: it consisted of extended electron losses characterised by a more gradual increase in the CRs, lasting for several minutes; see Figure 4. A set of counting rates increasing around the South Atlantic Anomaly (SAA) is evidenced by a red ellipse. Moreover, a singular spike, which is defined as an electron burst, is highlighted in Figure 4 by a red rectangle. Extended electron losses were mainly observed westward of SAA and not far away from it. In rare cases, they were observed at longitudes less than 170\({}^{\circ}\). Extended electron losses were observed to persist in the ionosphere for up to a few hours, with a drift velocity of 30\({}^{\circ}\)-50\({}^{\circ}\)/h towards the east. Following the methodology reported in [64], this distinction will be made. Specifically, during a period of about two weeks before the Turkey mainshock, electron losses and geomagnetic activity were analysed. On 6 February 2023, the geomagnetic indices showed magnetic perturbations that may induce electron losses, so the days up to 5 February 2023 were analysed. The algorithm used to detect electron bursts is not able to always collect both phenomena. When an extended electron loss occurs, the algorithm can detect only the higher tips of the phenomenon. At the same time, the algorithm is not able to always detect a brief duration counting rate fluctuation because the daily averages of counting rates of all the intervals of the space phase are high during extended loss phenomena. Thus, the algorithm is able to detect brief-duration electron bursts when extended losses are not observed, while it is unable to detect brief-duration electron bursts when extended losses are observed. The result is a nonhomogeneous set of electron bursts. Furthermore, it was decided that several detections along a single semi-orbit constitute a unique electron burst, therefore increasing confusion about it. We collected and analysed data from the particle detectors working on-board all NOAA POES and MetOp satellites. Those instruments are composed of eight solid-state telescopes called Medium Energy Proton and Electron Detector (MEPED). The three NOAA satellites (NOAA-15, 18, and 19) are in quite sun-synchronous polar orbit, at altitudes between 807 and 854 km, and we considered data from all of them. Unfortunately, for MetOp  
Figure 4: The two kinds of electron loss phenomena, the electron burst inside the red square and several extended electron precipitations around the SAA as viewed by NOAA-19 on 31 January 2023.  
satellites, which fly at altitudes ranging from 810 to 830 km, we could resort to MetOp-01 and 03 only, since MetOp-02 ended its mission in 2021. The MEPED instrumentation is composed of two proton-telescopes, monitoring the particle flux in five energy bands, in the range of 40 keV to 2.5 MeV; two electron-telescopes, in three energy bands in the range of 40 keV to 2.9 MeV; and four omnidirectional detectors, sensitive to proton energies above 16 MeV.