Cross-sphere Coupling and Source Inversion of Ionospheric Disturbances Associated with the 2025 Myanmar Strike-slip Earthquake from BeiDou GEO and Multi-GNSS Observations

Summary Focusing on the 2025 M7.9 Myanmar earthquake, this case study uses BeiDou geostationary satellite observations from the Chinese Continental Crustal Movement Observation Network and multi-system Global Navigation Satellite Systems (GNSS). The spatiotemporal evolution characteristics of pre-seismic ionospheric anomalies and co-seismic ionospheric disturbances were analyzed within a lithosphere–atmosphere–ionosphere coupling (LAIC) framework. By employing the moving interquartile range method combined with solar-terrestrial environmental parameters, including F10.7 solar radio flux, a negative Total Electron Content (TEC) anomaly associated with the seismogenic region was identified three days before the earthquake. The equatorial conjugate structure of this TEC anomaly is consistent with a possible multi-path coupling scenario involving the lithosphere, atmosphere, and ionosphere. The extraction of co-seismic ionospheric disturbance (CID) signals based on wavelet transform and band-pass filtering indicated that the co-seismic ionospheric disturbances were dominated by acoustic-wave-like disturbances within the broader acoustic–gravity wave response in the 2–8 mHz frequency band, propagating at a speed of approximately 1.2 km s−1, and exhibiting an asymmetric pattern in the southeast direction. A spatial density-weighted method for locating the apparent source of ionospheric disturbances was proposed, and the resulting pattern suggests a possible joint influence of fault strike-slip motion, geomagnetic field geometry, and the equatorial electrojet on the disturbance energy distribution. For this case study, the combination of BeiDou GEO satellites and multi-system GNSS provides enhanced capability for capturing weak ionospheric anomaly signals and rapid co-seismic disturbance evolution. These observations offer additional constraints for discussing possible LAIC processes associated with large strike-slip earthquakes, while broader statistical validation is still required before extending the findings to earthquake monitoring applications.