Infrared Technology Reveals Volcanoes' Secrets

Gretchen Peters
for National Geographic magazine

November 20, 2008

What are the secrets of a volcanic eruption? A few hundred courageous scientists around the world are trying to figure out the answers, often at great personal risk.

One of them, geologist Michael Ramsey, has spent 12 years investigating volcanic behavior, and is now using thermal infrared technology and data from NASA and weather satellites to determine when and how violently volcanoes will erupt—research that will help to save lives.

Thermal infrared imaging, which captures pictures of radiated energy invisible to the human eye, helps scientists like Ramsey track potentially deadly patterns of heat in and around some of the world's 1,500 active volcanoes.

(See more photos of volcanoes.)

Data gleaned from these images can already alert them to volcanic activity before it becomes dangerous, and may one day help them better forecast eruptions.

"Ten percent of the global population lives underneath active volcanoes," says Ramsey, an associate professor at the University of Pittsburgh. "This is an issue that affects people around the world."

The View From Space

On high-resolution images shot by satellites circling our planet, active volcanoes stand out like lights on a Christmas tree. They glow bright white as they ramp up for an eruption, and the speed with which they cool down can tell scientists much about their geological composition, which in turn helps them predict whether the volcanoes will erupt violently.

With funding from the National Geographic Society's Committee for Research and Exploration, Ramsey and his research partner, geologist Adam Carter, were able to fine-tune information they received from the Earth-imaging ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) sensor on NASA's Terra satellite by cross-referencing it with ground samples and images Carter collected at one of 29 active volcanoes on the Kamchatka Peninsula, in far eastern Russia.

In the days leading up to an eruption, Carter used a handheld infrared camera known as the FLIR (Forward Looking Infrared Radiometer) to capture color images of the Bezymianny volcano's lava dome and ash deposits on its flank, as well as record their surface temperatures.

"Bezymianny is remarkably punctual," Carter says. "It typically erupts twice a year. We wanted to track it and see if there were any warning signs."

As it turned out, there were. Poring over their data, Carter and Ramsey were able to identify a thermal precursor signal—a crucial moment four days before a December 2006 eruption when ASTER's data showed the temperature in the lava dome had shot up by at least 68 degrees Fahrenheit (20 degrees Celsius).

Because the satellite images capture an average temperature reading for the entire volcano at a given moment, the scientists knew the reading in some areas was probably many times higher.

The data also allowed their team, which included U.S. scientists at the University of Alaska/Fairbanks and Russian experts at Kamchatka's Institute of Volcanology and Seismology, to identify subtle geological changes, including lava, rock, and ash flows, that preceded Bezymianny's explosion.

Predicting Eruptions

Scientists already know that volcanoes erupt because of density and pressure. The magma, or molten rock in the Earth's upper mantle, is less dense than rock and rises to the surface at weak points in the planet's crust.

As the magma rises, water and gases dissolved in it expand rapidly, often causing violent explosions—or volcanic eruptions. Volcanoes with a high silica content are of particular interest, because they tend to produce more viscous lava, which traps gas bubbles. As the pressure from the bubbles builds inside the volcano, so does the potential for a powerful and dangerous eruption.

But it's difficult for scientists to observe these processes in real time and in living color.

The changes Ramsey and Carter documented at Bezymianny were a sign that the volcano was about to blow, and further research like theirs could help scientists pinpoint the timing of explosive eruptions.

Air Traffic Hazards

The population around Bezymianny is sparse, but even in remote areas volcanoes can pose a significant threat.

The Federal Aviation Administration (FAA) considers it critical that scientists plot volcanic activity in the Kamchatka Peninsula because of the hazard to air travelers.

Every day hundreds of flights between the U.S., Europe, and Asia pass over volcanoes on Kamchatka and in Alaska, which can spew ash into the stratosphere and hundreds of miles downwind after a major eruption.

Some planes that have flown into these ash plumes have suffered a dangerous altitude loss because their engines cut out, and several nearly had accidents. "This is something the FAA is very worried about," says Ramsey. Indeed, the FAA says at least 15 planes have been damaged by volcanic ash in the North Pacific since 1980, although no lives have been lost. Airlines often have to redirect or cancel flights because of volcanic eruptions, and the rerouting and additional fuel have cost millions of dollars.

The most serious near miss occurred in 1989, when all four engines of a KLM 747 traveling from the Netherlands to Anchorage lost power after the jet flew into an ash cloud spewed by Alaska's Redoubt Volcano. The plane dropped 15,000 feet (4,500 meters) before pilots managed to restart the engines and land all 245 passengers safely in Anchorage.

"Ash clouds are not visible on air traffic control or aircraft radar systems, and it's often hard to distinguish between a weather cloud and an ash cloud in flight. At night the pilot often can't see them at all," says Gail Ferguson, system operations manager for traffic management at the FAA's Anchorage Air Route Traffic Control Center.

"Ash is basically pulverized rock, so when it enters the hot jet engines, it melts and adheres to critical engine surfaces, resulting in degraded engine performance—or failure."

Weather satellites have monitored Pacific Rim volcanoes for years, but they have a difficult time spotting volcanic activity until after a major eruption has already occurred.

"By then we must work quickly to warn planes in the sky," says geophysicist Rick Wessels of the U.S. Geological Survey's Alaska Volcano Observatory (AVO), which uses data on seismic and volcanic activity from weather satellites to provide volcano warnings and hazard assessments to airlines, the public, and the FAA.

Solutions

Officials at the AVO and the FAA believe new-generation satellites with higher resolution thermal infrared images will someday allow them to spot subtle temperature changes more precisely, along with temperature spikes that may precede eruptions.

Infrared technology has other important benefits too. It allows volcanologists to keep a safe distance—as much as 2.5 miles (4 kilometers)—from eruptions.

As technology improves and the price of infrared cameras drops, scientists around the globe are finding creative ways to perch the cameras near volcanoes, even setting them inside thick cases so they can continue sending images during major eruptions.

That's a critical development in a field where about 10 percent of the scientists have been killed or severely injured in the course of their work. "This is unlike any other profession—even storm chasers," says Ramsey, who narrowly escaped with his life during a 2000 eruption at Indonesia's Mount Semeru that killed two other scientists.

Ramsey and his colleagues hope the next generation of satellites will provide a steadier stream of high-resolution images, allowing them to routinely spot precursor signals indicating a volcano is about to blow.

"We'd like to get two high-resolution shots a day," says Wessels. "Boy, if we had that, it would be easy to put this all together."

In the meantime, scientists will continue to use all the tools they have to decipher volcanoes' secrets. The safety of air travelers and millions of people living in the shadow of active volcanoes depends on it.

For Ramsey and his colleagues, that's reason enough to continue their high-risk work.