Ron Thomas and Paul Krehbiel

Right: Tech professors Ron Thomas and Paul Krehbiel set up a lightning sensing station in Kenai, Alaska, across Cook Inlet from the rumbling Mount Redoubt volcano.

By Thomas Guengerich

SOCORRO, N.M., Feb. 5, 2009 – Two New Mexico Tech professors and a graduate student spent three days last week near Mount Redoubt in south central Alaska, setting up monitors in anticipation of an upcoming eruption.

Electrical engineering professor Dr. Ron Thomas, physics professor Dr. Paul Krehbiel and physics graduate student Sonja Behnke set up four sensing stations around the active volcano, along with a colleague from the University of Alaska-Fairbanks and others from the Alaska Volcano Observatory.

The New Mexico Tech researchers are investigating the little-studied phenomenon of lightning produced by volcanoes. Using instruments developed at Tech, the scientists will be able to map the lightning throughout the various phases of volcanic activity.

Behnke earned a bachelor’s at New Mexico Tech in physics and is now working on her doctorate in physics. She said the excursion to Alaska fits nicely with her research.

“Hopefully the volcano erupts like it has in the past while all the stations are operating,” she said. “It's great that we have antennae there now because we will be able to see the first part of an explosive eruption. I think that by studying different types of electric discharges we can gain a greater understanding of lightning.”

Map of area around Cook Inlet

The area around Cook Inlet, including active volcano Mount Redoubt. Image by Janet Schaefer/Courtesy of Alaska Volcano Observatory and the Alaska Division of Geological and Geophysical Surveys.

Mount Redoubt has been active for centuries, with major eruptions in 1902 and 1989. Seismology studies indicate the volcano will erupt again – probably before the end of February.

“Our colleagues in Alaska expect Mount Redoubt to act like it did in 1989, with pretty major eruptions,” Thomas said. “Seismic activity is lasting longer this time than it did last time. It could happen any day, but it could be another week or more.”

Thomas said every volcano has its own personality; meaning, each eruption is similar in nature to previous eruptions.

“All that volcanic material coming out charged from the volcano and being injected into the atmosphere during an eruption creates something like a thunderstorm,” Krehbiel said. “Some scientists have even coined the term ‘dirty thunderstorm’ to describe this effect.”

The New Mexico Tech researchers haven’t pinpointed the mechanism that triggers volcanic lightning, but they have discovered a different kind of volcanic electrical discharge, which seemed to emanate from the mouth of the volcano during the violently explosive, eruptive phases.

Mt. Redoubt

Right: An aerial photo of Mount Redoubt taken from the west. The visible steam is evidence of volcanic activity brewing beneath the volcano. Photo by Kristi Wallace/Courtesy of Alaska Volcano Observatory / U.S. Geological Survey.

The trio – along with other lightning researchers at New Mexico Tech – will gather and analyze the data in an effort to better understand lightning, its genesis and its effects.

Scientists at the Alaska Volcano Observatory on January 30, 2009, warned that an eruption was imminent. The next day, volcanic earthquakes increased to several per hour and a large hole in the glacier on the side of the mountain was spotted. The Anchorage Daily News has published regular updates about Mount Redoubt for the past 10 days.

The headlines tracked the volcano’s progress:

“Mount Redoubt rumbles: eruption possible,” Jan. 25
“Redoubt huffs and puffs,” Jan. 26
“Redoubt history points to likely eruption,” Jan. 31
“Evidence of eruption continues to mount,” Feb. 1

The newspaper has also published articles advising readers how to protect pets, how to protect themselves and their property and about the potential hazards to the oil terminal just north of the volcano.

Chasing volcanic lightning is akin to chasing tornadoes; it’s all about being in the right place at the right time. The New Mexico Tech contingent acted quickly. After news broke about the seismic activity on Sunday, Jan. 25, the team met Monday, Jan. 26, and decided to go to Alaska. Three researchers flew to Alaska on Tuesday, Jan. 27, and had the sensors in place by Friday, Jan. 30.

Each of the four Lightning Mapping Array stations weighs about 40 pounds and is contained within a modified picnic cooler. The sensing stations can store up to three months of radio wave information and are capable of running unattended.

Ron Thomas and Paul Krehbiel

Left: Tech professors Ron Thomas (left) and Paul Krehbiel talk to Gary Katsion (right), owner of the Clam Gulch Lodge. The Tech scientists placed a sensing station at Katsion's business. Photo by Sonja Behnke/New Mexico Tech

By the time the Tech trio arrived, their colleagues in Alaska had found general areas to set up the sensing stations. Thomas said the four stations have been set up across Cook Inlet from the volcano. Thomas, Krehbiel and Behnke found four cooperative people in accessible locations to serve as caretakers for the stations.

The team endured 10 degree temperatures, snow and high winds while setting up the instruments; nevertheless, they successfully deployed the sensors along a roughly 60 mile stretch of coast on the east side of Cook Inlet. The northernmost sensor is in a school teacher’s house in Nikiski. The second station is in an architect’s office in Kenai. In Clam Gulch, Thomas is borrowing space at the Clam Gulch Lodge. The southernmost sensor is at a public school in Ninilchik.

The Tech team met dozens of local residents, all of whom were very receptive to the presence of scientists – and accustomed to living in volcano country.

“Everyone was so happy to have the building that got the antenna,” Behnke said. “We met a lady at the post office who was disappointed that she wasn’t the one to get a station. In that sense, this project was very easy.”

When Mount Redoubt erupts, Tech scientists and researchers will have their first ever data from an initial eruption of an explosive volcano. Three years ago, Thomas, Krehbiel and others arrived at Mount St. Augustine in Alaska a few days after the initial eruption. They captured data from subsequent eruptions, but with only two sensors, which weren’t enough data points to create three-dimensional images.

In May 2008, three Tech professors placed four sensing stations around the Chaiten Volcano in Chile. Although they arrived two weeks after the initial explosive eruptions, they still found lightning in the plume. The Tech professors presented preliminary findings at a conference of the American Geophysical Union in December 2008, but they are still analyzing and interpreting the data.

Behnke is currently assembling and analyzing data collected from the Mount St. Augustine eruptions in 2006. She jumped at the chance to get field experience back in Alaska.

Behnke, who graduated from Laytonville High School in northern California, earned her bachelor’s at New Mexico Tech in 2003. After graduation, she continued to work for Thomas studying lightning. She was the first author of a paper in the Journal of Geophysical Research in 2005. She returned to New Mexico Tech in 2007 to continue her research into lightning.

“I spend a lot of time working with Lightning Mapping Array data, but I hadn’t had a chance to get out in the field and work with the hardware,” she said. “Going to Alaska and setting up the stations was a good learning experience.”

With the pending activity at Mount Redoubt, New Mexico Tech scientists will be adding to their wealth of knowledge about lightning and volcanoes.

“We think it’s a good candidate for making lightning,” Thomas said. “Last time (in 1989), it had an explosive phase, a dome-building phase and pyroclastic flows, which are different aspects of eruption. It should have an explosive phase.”

During the strongest eruption at Mount St. Augustine in 2006, the New Mexico Tech lightning researchers observed more than 300 lightning discharges within the Augustine Volcano’s ash plume, a maelstrom of hot air, gases, moisture, dust and ashes which first floated upwards of 30,000 feet and then drifted across the line-of-sight of the two monitoring stations.

Tech electrical engineering professor Dr. Bill Rison designed the mapping sensors using field programmable gate arrays that determine the arrival time of radio waves with 40 nanosecond accuracy.

“We’ll measure the time the signals arrive at the four different stations,” said Krehbiel, who has conducted lightning research at New Mexico Tech since the 1960s. “From the four stations, we can determine the location and time of the lightning surges. It’s similar to triangulating.”

Radio waves created by lightning travel about one foot per nanosecond. With equipment that captures information every 10 microseconds, the sensors will be able to pinpoint a three-dimensional location of lightning within about 40 feet, Krehbiel said.

Up to thousands of individual segments of a single lightning stroke can be mapped with the Lightning Mapping Array and later analyzed on high-end computers to reveal how lightning initiates and spreads throughout a thunderstorm ... or within a volcanic plume.

“We receive radio bursts of noise generated from sparks of lightning, just like the static you hear on your car radio during a thunderstorm,” Thomas said. “We will use our sensing stations to locate the lightning and track its path.”

Tech’s pioneering research into lightning – both volcanic and thunderstorm lightning – has led to a series of scientific and technological breakthroughs, including proprietary sensing technology that allows scientists, meteorologists and storm chasers to pierce the veil of clouds to “see” lightning as it occurs.

“With each lightning flash, we’ll be able to monitor how it moves through the clouds and where it goes,” Thomas said. “If we take all our theories about lightning created in thunderstorms, we can learn about both types of lightning.”

– NMT –