November 14, 2011
Lightning network helps get a handle on volcanoes
Scientists in Alaska are using data from a worldwide lightning monitoring program at the University of Washington to keep tabs on a remote volcano that rumbled to life recently but is not equipped with monitors.
The real-time alert system has been operational for about a year as part of the World Wide Lightning Location Network, said Robert Holzworth, a UW professor of Earth and spaces sciences who manages the lightning network. In the past year, four or five eruptions worldwide have been detected within minutes, he said, faster than they could be confirmed using satellite images.
“Its had a good test, but there hasnt been a U.S. eruption or one particularly alarming to the U.S. that has occurred during that time,” Holzworth said.
The Anchorage Daily News recently cited work by Stephen McNutt, a research professor with the Alaska Volcano Observatory and the University of Alaska Fairbanks, who said that data from the lightning detection network could be the best way to confirm an explosive eruption at volcanoes that dont have sophisticated instruments.
That includes Cleveland Volcano in the Aleutian Islands, more than 900 miles from Anchorage and close enough to international air routes to cause concern. The volcano has been active lately, and McNutt said the closest seismometer to the volcano is 45 miles away and a larger network is 80 miles away. In the past some stronger eruptions have been recorded on those instruments, “but it hasnt been very consistent.”
Thats where the lightning detection network comes in. The network uses more than 50 sensors around the world to triangulate lightning strokes and provide a precise location. The network doesnt detect every lightning stroke, but it does pick up an average of five per second, or about 12 million to 13 million a month.
Each minute the network is looking for signs of eruption from more than 1,500 volcanoes, including some 250 in the “Ring of Fire” at the edges of the Pacific Ocean. The searches occur in two patterns, from the summit of the volcano out about 12 miles, and from 12 to 60 miles, Holzworth said.
“If the inner ring has more strokes than the outer ring, it starts a low-level alert,” he said, since volcanic ash in the atmosphere typically sparks more lightning.
Some of the data is available on the networks website and near-real-time lightning information is available for commercial use. Some airlines use the lightning data to plan routes, but so far none have requested the data specifically for volcano monitoring.
Aircraft face significant danger from volcanoes spewing ash clouds. In 1989, a Boeing 747 flown by KLM Royal Dutch Airlines flew into ash from Alaskas Mount Redoubt. All four engines failed at about 25,000 feet and the plane dropped more than 14,000 feet before the crew was able to restart the engines. The plane, which sustained more than $80 million damage, landed safely in Anchorage.
Similarly, in 1982 a British Airways flight experienced the failure of all four engines when it flew into an ash cloud from Indonesias Mount Galunggung. The crew was able to glide the plane out of the ash cloud, restart the engines and land safely in Jakarta.
Holzworth said the next step for him is to create a better alert system, with a higher confidence level.
“It takes interpretation at this point, but you can do that in a minute. However, its not a foolproof alert like youd need on a golf course to tell you to take shelter because theres lightning coming.”