Seismogenic Field in the Ionosphere before Two Powerful Earthquakes: Possible Magnitude and Observed Ionospheric Effects (Case Study)

A retrospective analysis of complex geophysical data around the time two most powerful earthquakes that occurred in Alaska and had magnitudes M = 8.2 (29 July 2021) 9.2 (28 March 1964), respectively, is carried out. The aim research to assess maximum possible magnitude electric field a seismogenic nature penetrated ionosphere/plasmasphere, which could cause ionospheric effects observed experimentally. Theoretical calculations have shown under conditions existed before these (favorable for penetration into ionosphere), value quasi-static ionosphere, perpendicular geomagnetic lines (tens hours/units days earthquake) with 8–9 reach 1–2 mV/m. Such values are sufficient formation plasmaspheric ULF-ELF-VLF-duct, formed vicinity field-line passing through epicenter earthquake influence ionosphere/plasmasphere. This leads an anomalous amplification captured ULF-ELF-VLF waves, ULF (DC-16 Hz), ELF (6 Hz–2.2 kHz), VLF (1.8–20 not only above future earthquake, but also at point magnetically conjugated testifying such duct, stretched along from one hemisphere another, on closed L-shells shortly earthquake. result confirmed by measurements mission CSES satellite (China-Seismo-Electromagnetic Satellite) 29 2021 8.2.