Radiation mechanism of generation of geomagnetic signals from underground and contact explosions

A mechanism is proposed for the generation of geomagnetic perturbations by an atmospheric electrical dipole formed by the gamma radiation from contact and underground explosions accompanied by formation of a ground dome and escape of explosion products into the atmosphere. The gyrotropic $E$-layer of the ionosphere plays a determining role in the generation of geomagnetic fluctuations at long epicentral distances. The amplitude-frequency parameters of a geomagnetic signal at 1000 km from a contact explosion with an energy of 150 ktons are estimated. The possibility of recording such geomagnetic signals from explosions with emission of gamma radiation into the atmosphere is shown.