TY JOUR TI Coseismic Effect of the 2025 Kamchatka Earthquakes KW Remote earthquakes KW magnetic observatory KW coseismic electromagnetic effect KW 1-second magnetic data KW INTERMAGNET KW Kamchatka megathrust earthquake JO Russian Journal of Earth Sciences AU Aleshin, I.M. AU Soloviev, A.A. AU Goev, A.G. AU Kudin, D.V. PY 2026 IS 26 PB Geophysical Center of the Russian Academy of Sciences