Images of volcanoes and lightning can be quite impressive on their own, but when the two mix, the results are nothing short of epic. These images, taken in Indonesia and Iceland, reveal both the beauty and sheer power of nature.
CAPTION: A giant bolt of lightning strikes Indonesia's Mount Merapi in 2010. (Photos: Merapi Volcano Ash Smothers Indonesian Villages.) "We sometimes refer to [volcanic plumes] as dirty thunderstorms," Stephen McNutt said. But, he added, there's a lot more lightning in the ash plumes than is visible in the pictures. "That's because ash clouds are opaque."
(More pictures from National Geographic magazine: living with volcanoes in Indonesia.)
CAPTION: It wasn't the lightning but rather the widespread ash clouds from the April 2010 eruption of Iceland's Eyjafjallajökull volcano (pictured) that eventually grounded a hundred thousand flights.
Particles of rock, glass, and sand in volcanic plumes can jam jet engines, as happened in 1982 when a British Airways 747 lost all four engines over Indonesia before recovering in the nick of time. (Read more about why ash is so dangerous to airplanes.)
Radio emissions from volcanic lightning might provide a tool for quickly assessing the amount of ash in a volcanic plume occurring at night or in inclement weather, when neither satellites nor ground-based observers can see exactly what is happening, according to the new volcanic-lightning research, published in the journal Eos.
Other methods, such as seismometers or sound detectors, can't distinguish ash-producing eruptions from eruptions that pose no risk to air traffic, said report coauthor McNutt, a volcanologist at the University of Alaska, Fairbanks.
CAPTION: Iceland's Eyjafjallajökull volcano erupts with flash and ash in 2010. (Related pictures: "Iceland Volcano Spews Giant Ash Clouds [April 2010].")
With the right instruments, McNutt said, "you can see electrical activity right at the onset of the eruption," inside the crater.
These otherwise invisible lightning bolts (not pictured) are produced by the other mechanism for static-charge generation: the shattering of rocks thrust skyward in an eruption.
The in-crater bolts aren't huge, but they can strike thousands of times a second, creating a nearly continuous radio signal that would instantly mark the onset of the eruption, he said.