To catch a volcano
Posted: Monday, November 05, 2007 7:56 PM by Alan Boyle
GeoEye via NASA |
This view of Indonesia's Anak Krakatao volcano was
captured by the Ikonos satellite in 2005.
|
Catching a volcano just before it explodes isn't always as easy as, say, predicting the weather. And that's a problem for scientists as they gauge the current upswing of activity going on within Indonesia's volcanoes.
Mount Kelud is already pushing out magma and thick steam - while an island volcano called Anak Krakatao ("Child of Krakatoa") is reminding experts about a famous blast from the past.
Tens of thousands of people living around the flanks of the Kelud volcano are wondering whether they should heed the evacuation orders - and based on the strong uptick in temperature as well as seismic activity, the big blast could come at any time. Or not. The uncertainty points to gaps in our understanding of how volcanoes work - gaps that could be filled if only scientists had more data.
"It requires some forethought and resources to have instruments in the ground, and have the information that you need to have," said John Ewert of the Volcano Disaster Assistance Program, based at the U.S. Geological Survey's Cascades Volcano Observatory in Washington state.
The ideal would be to give potentially threatening volcanoes a thorough checkup every once in a while, so that scientists can get a fix on what represents normal activity. Ewert drew an analogy to getting an annual physical.
"Often what happens is that you see the patient with really bad pain in his abdomen," he told me. "It's a lot better if you know the history of the patient."
Slow burn vs. fast blast
When it comes to Mount Kelud, volcanologists know the patient is in a bad way. They just don't know how much worse it's going to get. In 1990, Kelud erupted explosively, killing more than 30 people. Since then, however, it's been relatively dormant, which makes it hard to determine exactly where the volcano is in its eruptive cycle.
"We're at the point now where it could be basically hanging fire for days, or a week or two," Ewert said.
If Mount Kelud doesn't erupt sometime in the next two weeks, that would be a good sign, even though the magma has risen, Ewert said. He explained that the key to an explosive eruption is the gases within the magma: water vapor, carbon dioxide, sulfur dioxide and the like. Those gases are what give an eruption its pop - and if you give the magma enough time, the gases will dissipate and the molten rock will go flat.
"It's a little bit like ripping the top off a champagne bottle because you won the World Series, or slowwwwwwly easing the top off because you paid 50 bucks for the bottle," Ewert explained.
The good news is that catching a volcano becomes easier once it shows what it's made of. "Typically what happens is, once you get into the eruptive cycle of a volcano, real predictions become easier to obtain," Ewert said.
Revolution in volcano science
And that demonstrates how far volcano science has come since Mount St. Helens erupted 27 years ago - which was just about the time Ewert began his work at the Cascades Volcano Laboratory. Back then, scientists were lucky to have a few spectrometers, seismometers and early tiltmeters on the ground.
"It's funny to look back at the systems and where they were, " Ewert said. "This was a time when a megabyte was a vast amount of memory. St. Helens happened right on the cusp of the computer revoluton and the digital age. We still relied pretty heavily on direct observation and direct measurements."
Today, Indonesian scientists can draw upon the new tools that have been developed since then. Mount Kelud has been watched particularly closely because it has killed before, back in 1990. Those tools include a variety of eyes in the sky:
- Locator devices on the ground that can provide real-time readings on ground deformation, using the Global Positioning System. Radar-sounding satellites can also look for the signs of rising ground that often precede an eruption.
- Infrared satellite imagery that can detect telltale variations in temperature variations.
- Orbiting sensors that essentially sniff the air below for the signs of volcanic sulfur dioxide emissions - another precursor of an eruption.
Indonesian scientists are doing what they can to keep track of Mount Kelud. "At Kelud, they have more sensors than they have at many of their other volcanoes. ... They had a system in the [crater] lake that was monitoring chemistry and temperature," Ewert said.
But Ewert said much more could be done to keep tabs on killer volcanoes - in Indonesia, and even in the United States.
"A lot's been learned in the last 27 years," he said. "Unfortunately, it's not enough to allow us to make predictions in every case. And a lot of that is because we don't have all the monitoring history that we'd like to."
Wanted: Early warning system
In 2005, a National Research Council committee report called for the development of a new generation of Earth-observing satellites - including a radar satellite that Ewert said could help with eruption prediction as well as other scientific tasks. "The Canadians have one. The Europeans have one. The Japanese have one. The U.S. does not have one," Ewert said.
Just last year, Ewert and some of his colleagues put out their own report for a National Volcano Early Warning System. The report said that just three of the United States' 18 most dangerous volcanoes - Kilauea in Hawaii, California's Long Valley caldera and Mount St. Helens - were being monitored adequately.
"There's a lot of unmet need on the part of the scientific community to have better monitoring on a large number of volcanoes," Ewert said.
To learn more about a volcano's inner workings, check out our interactive "Anatomy of a Volcano." For NBC's take on the current Indonesian cliffhanger, check out Ian Williams' posting on the World Blog. Find out more about the "Ring of Fire" that includes Indonesia's volcanoes as well as Mount St. Helens by clicking onto this archived article. And for the personal touch, read about my very own Mount St. Helens adventure 27 years ago.
