These opening images depict the eruption of Chile’s Chaiten volcano, which last year unexpectedly began to vent its volcanic fury for the first time in over nine thousand years. With volcanic lightning getting in on the act, from a purely photographic point of view it was worth the wait. The awesome power of charged electricity violently grabbing hold of and coursing through the plume of volcanic smoke and ash leaves one breathless.
However, there was a more ominous side to this geologically explosive incident, likewise brilliantly captured by these apocalyptic looking shots. Once it had escaped the grip of the lightning, Chaiten’s eruption column rose to an estimated height of over 98,000 feet (30,000 m), prompting the evacuation of its nearby village and surrounding areas, and sending out dense ash clouds that contaminated water supplies and coated one town 30 cm deep.
But let’s concentrate on the volcanic lightning itself, shown here in the form of a bolt looking to lock horns with lava issuing from Mount Rinjani in Indonesia. When volcanic gasses and materials are thrust high into the air, lightning can be triggered inside the ash clouds. Yet despite the fact that such electrical activity frequently accompanies large eruptions, and have done so at least 150 times in the past two centuries, these spectacular natural light shows are not clearly understood.
For years geologists talked about dry volcanic dust particles colliding with one another and building up enough static charge to cause sparks in an attempt to explain volcanic lighting. However, a new theory focuses on the surprising water content of magma and volcanic debris, which would make this rogue phenomenon more like a typical thunderstorm. Before the recent eruption of Alaska’s Mount Redoubt – pictured above with fingers of lightning clutching at an ash cloud – scientists daringly set up mapping gear to try and see how lightning is born and spreads through the volcanic plumes.
Curiously, some volcanoes with large plumes generate little or no lightning, while those whose clouds are smaller produce a lot more. This suggests that while all volcanoes have electric potential, lightning only occurs when there is high resistance to the volcanic current in the air. Size isn’t everything – and yet a large show of volcanic and electrical force can be a warning to expect a pretty major event. The massive 1982 eruption of Indonesia’s Galunggung – shown in the incredible shot above beset by lightning strikes – resulted in 68 deaths, and its ash column forced two Boeing 747s to make emergency landings.
The branching of lightning in this image of Sakurajima volcano in Japan is just one example of the types of lightning known to take place over volcanoes. According to one source: “The 1981 eruption of Mt St Helens featured a spectacular display of sheet lightning, with truck-sized balls of St Elmo’s fire seen rolling along the ground 29 miles north of the mountain.” Volcanic lightning surely is one of nature’s most powerful and awe-inspiring pyrotechnic exhibitions, yet mystery still shrouds its origins.