Acoustic-gravity wave driven traveling ionospheric disturbances: Analytical modeling and application to 2025 Kamchatka earthquake GNSS data

We present an analytical framework for ionospheric ion velocity and density perturbations driven by acoustic-gravity waves generated by seismic sources. Neutral motions are computed using a horizontally layered model, and ion responses are obtained from the linearized frequency-domain momentum and continuity equations, including neutral-ion collisions and geomagnetic effects. Simulations show that ion motion undergoes an altitude-dependent transition from a collision-dominated regime to a magnetically controlled regime, producing strong anisotropy. We further show that total electron content (TEC) disturbances are strongly controlled by the geometry between the Line-of-Sight and the wavefront. A case study of the 2025 Kamchatka earthquake demonstrates that the modeled TEC perturbations reproduce key observational features, including Rayleigh-wave and gravity-wave arrivals. These results provide new insights into seismic-ionospheric coupling and support analytical modeling of coseismic TEC responses.