by Thomas Guengerich
SOCORRO, N.M., May 19, 2008 -- A team of New Mexico Tech scientists is headed to the southern coast of Chile to study the bizarre lightning emanating from the Chaitén Volcano, which began erupting May 2.
Three professors hope to track the lightning in the ash plume that has resulted from continued volcanic activity.
After more than 9,000 years of silence, Chaitén Volcano exploded, sending a plume of ash and steam more than 35,000 feet into the atmosphere, according to the Smithsonian’s Global Volcanism Program.
The team will set up an array of four mapping sensors that were developed by New Mexico Tech professors and students over the past 13 years. Tech’s pioneering research into lightning – both volcanic and thunderstorm lightning – has led to a series of breakthroughs, including patented sensing technology that allows scientists, meteorologists and storm chasers to pierce the veil of clouds to “see” lightning as it occurs.
The team is using new technology developed by Dr. William Rison, professor of electrical engineering at New Mexico Tech.
“Our business is studying thunderstorms and how they produce lightning,” said physics professor Paul Krehbiel. “Volcanoes do the same thing, in essence. We call it a ‘dirty thunderstorm’ because the plume is full of dirt, rock, ash and other particles. The question is how the electrification occurs.”
By studying the path of lightning in a volcano’s plume, Tech scientists hope to gather an understanding of how electrical activity is transmitted from the Earth into the atmosphere.
“With each lightning flash, we’ll be able to monitor how it moves through the clouds and where it goes,” said professor Ron Thomas, professor of electrical engineering at New Mexico Tech. “If we take all our theories about lightning created in thunderstorms, we can learn about both types of lightning.”
The trick is to have the sensors in place as a volcano erupts. The New Mexico Tech team first deployed lightning sensors at Mount St. Augustine, which first erupted from December 2005 through February 2006 in southern Alaska.
“At Mount St. Augustine, we got lucky,” Krehbiel said. “We hurried up to Alaska after the first eruption and had our sensors in place for the second big eruption. We got spectacular data.”
When Mt. St. Augustine produced its second large eruption, the Tech team only had two sensors in Alaska and could not accurately map the lightning’s path in three-dimensions. In Chile, the Tech team will track lightning using four sensors.
“We’re anxious to get down there and take measurements while it’s still active,” said Ron Thomas. “The ash is coming out of the volcano at a very high velocity. The fracturing of the particles of ash and other materials appears to make them very electrified. The volcano is acting like a static electricity generator.”
The team will leave the sensors in place in Chile for as long as three months, then return to collect the data.
The first breakthrough was the initial sensing device, which was engineered by the three professors and a handful of electrical engineering and physics students at New Mexico Tech in 1995 and 1996.
The students helped show professors that it was feasible to build the system, Rison said. The team of Krehbiel, Rison and Thomas secured a National Science Foundation grant to build the sensor, then deployed the prototype in Oklahoma in 1998 and in western Kansas as part of the Severe Thunderstorm Electrification and Precipitation Study in 2000.
That initial test run produced the most detailed three-dimensional images of lightning to date. Since then, New Mexico Tech has provided lightning sensing systems to NASA, the National Severe Storm Laboratory and White Sands Missile Range. Tech also worked with NASA to deploy an array of sensors for the National Weather Service’s forecasting operation in Sterling, Va.
The sensing equipment has three proprietary systems developed at New Mexico Tech – the circuit boards, the firmware and the data analysis software, Rison said.
“The second significant breakthrough was designing sensors that are more compact,” Krehbiel said. “Just before the Mount St. Augustine explosion, we developed a portable station about the size of a lightweight picnic cooler that could be easily and quickly transported.”
The first system weighed more than 200 pounds and had only 2 gibabytes of memory, Rison said. He and other scientists had to download data from the sensors every two days. The new system weighs about 10 pounds and has more than 160 gigabytes of memory – enough to capture data continuously for more than three months.
New Mexico Tech Assistant Professor of Geophysics Jeffrey Johnson is an expert in studying sound waves created by volcanoes. His forte is the study of low frequency sound waves created by volcanoes. In Chile, Johnson will serve as logistic support to deploy the sensors and as translator. He will also conduct seismological research using low-frequency – or infrasound – sensors.
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,” Krehbiel said. “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 40 nanoseconds, the sensors will be able to pinpoint a three-dimensional location of lightning within about 40 feet, Krehbiel said.
“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.”
The sensing stations can store up to three months of radio wave information. After deployment, the sensing stations will run unattended. After learning of the Chaitén eruption and seeing spectacular images of lightning in the rising plume, Thomas, Krehbiel and Rison started working feverishly to prepare the sensors for deployment and making travel plans.
“One reason we’re rushing into this project is that it’s a great opportunity to study a very large eruption. These opportunities don’t come around that often,” Johnson said. “This volcano is explosive. We know from previous studies and from the past two weeks that these explosive volcanoes happen infrequently, but create tremendous activity.”
The remoteness of the region and the weather conditions create logistical challenges – and unique opportunities to study volcanic activity. The Chaitén Volcano sits along the coast of central Chile. The local volcano observatory is one of the only such facilities that is on a boat in Corvovado Bay and not on land, Johnson said. The Tech sensing equipment will be placed on Chiloe Island, across the bay from Chaitén and about 50 kilometers from Chaitén Volcano.
The Patagonia region of Chile is entering the rainy season and Chaitén Volcano is often shrouded in clouds. The radio-wave sensing equipment will lift the veil of clouds and allow scientists to “see” the lightning and the eruptions as they happen.
New Mexico Tech has been a leader in seismological research since the 1950s.
The university first began researching lightning in the 1930s, led by Dr. E.J. Workman. The university started the Langmuir Laboratory in 1963, the same year that Tech researchers Charlie Moore and Marx Brooks became the first researchers to observe and study volcanic lightning at the eruption of the Surtsey Volcano off the coast of Iceland.
Krehbiel joined the Tech faculty in 1966 and has been studying lightning ever since. In 1973, Moore and Brooks led another research expedition during the eruption of Heimaey Volcano on the mainland of Iceland.
According to news reports issued by the AFP news service, on May 2 ash blanketed the town of Chaitén, 10 kilometers away, forcing the town’s 4,000 people to evacuate by boat.
On May 3, ash and steam continued to billow from the volcano. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Terra satellite captured photo-like images of a long, cloud-like plume flowing southeast from the volcano’s summit on May 3 at 10:35 a.m. local time (14:35 UTC). The plume rises high over the Andes Mountains, drifts across Argentina, and dissipates over the Atlantic Ocean. Ash closed schools, roads, and an airport in Argentina, hundreds of kilometers away from the volcano, said AFP.
Radiocarbon dating of the last lava flow from Chaitén Volcano suggests that the volcano last erupted in 7420 BC, plus or minus 75 years, says the Global Volcanism Program. The volcano has a history of explosive eruptions with pyroclastic flows associated with dome collapse. During an eruption, some volcanoes build a dome of lava. Eventually, hot blocks of lava break away from the dome, triggering a fast-moving avalanche of hot volcanic ash, gas, and lava, called a pyroclastic flow. As of May 5, ash continued to rise from the volcano, but no pyroclastic flows had been reported.