- Short, quick bursts of lightning were detected when Alaska's Redoubt Volcano erupted last year.
- Some volcanoes spark huge lightning displays, while others have none.
- In total, three types of lightning are now tied to volcanoes.
When Alaska's Redoubt Volcano erupted last year, ash, gases and steam weren't the only things filling the air. The eruption also produced a new type of lighting -- small, quick sparks right at the start.
"We long suspected that the first eruption might be different -- and it was," University of Alaska volcano seismologist Stephen McNutt, told Discovery News.
By monitoring seismic data, researchers were able to get a jump on Redoubt and set up lightning detectors in the area two months before the volcano blew. Three-dimensional pictures produced from the arrays showed -- for the first time -- tiny sparks of lighting lasting just a millisecond or two inside the volcano's ash plume at the start of the eruption.
The team also mapped two other types of previously documented, though poorly understood, volcanic lighting: large bolts, stretching for several miles, which are similar to what is produced during thunderstorms; and intermediate-sized bolts up to about two miles in length that blast out of volcanic vents.
Scientists don't know why some volcanoes spark huge lightning displays, while others have none. However, they did notice a relationship between the amount of lightning from a volcano and the size of its plume.
Redoubt had a series of more than 20 eruptions over 13 days last March, all of which were accompanied by lighting flashes.
"In general, the higher the plume went, the more lightning we got," said Ronald Thomas, a physicist and electrical engineer at the New Mexico Institute of Mining and Technology.
The physics of what's happening are still to be determined, but scientists are hopeful the research will lead to new ways to monitor and assess volcanic eruptions.
Volcanic ash plumes can reach the altitude of commercial jetliners in minutes and be dispersed by winds over thousands of miles.
"Modern jet engines are very susceptive to the mechanics of volcanic ash," McNutt said.
The team hopes to follow up the Redoubt Volcano studies by mapping lighting at other erupting volcanoes. So far, though, the 30 possible contenders have been relatively quiet.
"We have instruments ready and travel money," McNutt said. "We just keep track and monitor on an ongoing basis. When we see signs of life, we review the data and see if it's worth the financial and logistics effort to put out the instruments."
A research paper detailing the Redoubt Volcano lightning is pending.