“…After about 10 s, however, the ionization begins to subside, and diffusion permits the amplitude of E3A geomagnetic field variation to increase at the Earth's surface. During the second part, E3B, the ionized and heated atmosphere below the explosion buoyantly rises, a heaving that brings the field lines beneath the explosion hypocenter back together (e.g., Gombosi et al., 2017; Legro et al., 1985; Rivera et al., 2016). E3 geomagnetic disturbance induces geoelectric fields in the electrically conducting solid Earth, and these, in turn, drive uncontrolled currents in grounded electric‐power grids that can interfere with transmission operations and damage high‐voltage transformers (e.g., Electric Power Research Institute, 2019; Tesche et al., 1991).…”