Why does lightning attract caves?

Are caves a safe place during a thunderstorm?

The likelihood of being injured by lightning in a cave is certainly less than if you were outdoors. However, one must take into account that rocky ground - and this is where the caves are usually located - is a bad earth for lightning current. In rocky areas in particular, lightning strikes can occur a few hundred meters away from the point of impact, e.g. due to step voltage. Therefore one should keep a distance from the walls in a cave - one meter, better 3 meters - and put the feet close together. In groups one should not touch.

Experience reports from Austria show that this risk is not only theoretical. A few years ago, a person was injured while being guided through a cave when lightning struck the earth during a thunderstorm on top of the mountain and jumped over the person who was holding onto a metal railing in the cave. A hole was even burned in the rain jacket.

Lightning phenomena are also known in the Eisriesenwelt Werfen (see photo above). The guides report that during thunderstorms glowing phenomena ("bluish light") were seen in the ice at 1 km depth of the cave, and that although there is 400 m of earth above this point. The lightning current probably uses more electrically conductive water veins, which over time have created deep crevices, holes and caves with a length of more than 40 km in the limestone of the Tennengebirge. Therefore, when there is a thunderstorm, visitors are asked not to touch the metal railings.