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

Abstract

Focusing on the M7.9 earthquake in Myanmar in 2025, this study comprehensively utilizes data from BeiDou geostationary satellites of the Chinese Continental Crustal Movement Observation Network and multi-system Global Navigation Satellite Systems (GNSS). The spatiotemporal evolution characteristics and physical mechanisms of pre-seismic ionospheric anomalies and co-seismic ionospheric disturbances were systematically analyzed. By employing the moving interquartile range method combined with solar-terrestrial environmental parameters, 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 revealed a multi-path coupling effect between the lithosphere, atmosphere, and ionosphere. The extraction of Coherent Ionospheric Disturbance (CID) signals based on wavelet transform and band-pass filtering indicated that the co-seismic ionospheric disturbances were dominated by acoustic-gravity waves in the 2-8 mHz frequency band, propagating at a speed of approximately 1.2 km/s, and exhibiting an asymmetric pattern in the southeast direction. A spatial density-weighted method for locating the source of ionospheric disturbances was proposed, elucidating the joint control mechanism of fault strike-slip motion, geomagnetic field modulation, and equatorial electrojet on the disturbance energy. The results confirm that the high spatiotemporal resolution of BeiDou GEO satellites and multi-system GNSS significantly enhances the capability to capture weak ionospheric anomaly signals associated with earthquakes. These results provide additional observational constraints on space-based Lithosphere-Atmosphere-Ionosphere Coupling (LAIC) processes and may contribute to the development of ionosphere-based earthquake monitoring techniques.