Influence of a single lightning discharge on the intensity of an air electric field and acoustic emission of near-surface rocks

The effect was observed as a sharp fall of the electric potential gradient from +80 V m 1 down to –21 V m 1. After that the field returned to its normal level according to the formula of the capacitor discharge with 17 s characteristic time. Simultaneously, the response of the acoustic emission of surface rocks in the range of frequencies between 6.5 kHz and 11 kHz was evaluated.