Geomagnetic and Ionospheric Responses Following the July 29, 2025 Kamchatka Megathrust Earthquake

Abstract

Using ground-based magnetometer stations and vertical ionospheric sounding stations, we investigate the intensification of variations in the geomagnetic field and ionospheric electron density associated with the July 29, 2025 strong megathrust Kamchatka earthquake and its aftershocks over a thousand km from the observation stations. The recorded anomalous geomagnetic and electron density variations are interpreted as resulting from the propagation of three types of earthquake-induced waves: seismic Rayleigh waves, atmospheric internal waves originated at the earthquake epicenter, and slow magnetohydrodynamic waves generated via the transformation of atmospheric waves in the lower ionosphere.