Observational and modeling perspectives on seismo-ionospheric electromagnetic anomalies potentially associated with the 2022 Mexico earthquake

This study investigates potential anomalous electromagnetic signals and their characteristics during the 2022 Mexico M7.6 earthquake by integrating the satellite data with a lithosphere-atmosphere-ionosphere (LAI) coupling propagation model for extremely low frequency (ELF) electromagnetic waves. Satellite observations and wave vector analysis demonstrate that a significant upward-propagating ELF electromagnetic radiation anomaly emerged south of the epicentral region eight days before the earthquake, with signals concentrated in the 200−500 Hz frequency range. The full-wave simulations were employed to further analyze the spatial distribution characteristics of the anomaly and its frequency dependence. The simulation results reveal that the radiation entering the ionosphere exhibits a beam-like structure displaced southward with the wave energy reaching satellite altitude decreasing as frequency increases, while a distinct narrow-band (400−500 Hz) absorption feature observed. The qualitative agreement in spatial displacement and spectral characteristics between simulations and observations provides supporting evidence for the interpretation that the observed anomaly originated from a subsurface source, and contributes to our understanding of cross-sphere propagation mechanisms of seismo-electromagnetic radiation.