Volcano Pictures: First Descent Into a Magma Chamber

Into the Abyss
Photograph by Hans Strand
During the first ever scientific expedition into a volcanic magma chamber, climber Einar Stefánsson rappels into Iceland's dormant Thrihnukagigur volcano in October. Magma chambers supply the molten rock that oozes or bursts onto Earth's surface during an eruption.
Thrihnukagigur, which last erupted about 3,000 years ago, contains only ancient magma—though the volcano could come back to life at anytime, experts say. (See "'Sleeping' Volcanoes Can Wake Up Faster Than Thought.")
"Thrihnukagigur is unique. … It's like somebody came and pulled the plug and all the magma ran down out of it," said volcanologist Haraldur Sigurdsson, who appears in Into Iceland's Volcano, a new documentary featuring the expedition, airing Friday on the National Geographic Channel. (The channel is partly owned by the National Geographic Society, which owns National Geographic News.)
Thrihnukagigur is located about a hundred miles (160 kilometers) from Iceland's Eyjafjallajökull volcano, which blew last April and grounded airplanes for several days with its ash clouds.
While people have ventured inside the relatively shallow volcanic craters located close to Earth's surface, the 2010 expedition was the first to explore a volcano's deeper chambers.
"It was a really amazing experience—just unbelievable," Sigurdsson said.
ON TV: Into Iceland's Volcano airs Friday, April 8, at 8 p.m. ET/PT on the National Geographic Channel. Preview >>
—Ker Than
Published April 7, 2011
Hanging Out
Photograph by Hans Strand
Climber Björn Ólafsson descends into the 45-story magma chamber inside Iceland's Thrihnukagigur volcano in fall 2010.
To enter the magma chamber, the team jury-rigged a lowering system that involved placing a steel beam—similar to one used by construction cranes—across the volcano's surface opening.
"We then rigged up a basket that was suspended from the middle of the beam, and we put a winch on that, and we [lowered] ourselves up and down," explained Sigurdsson, of the University of Rhode Island.
The team was careful not to touch the walls as they descended. "We didn't want to damage anything, and it was also for our safety—we didn't want rocks falling down on us," said Sigurdsson, whose work has been funded by the National Geographic Expeditions Council.
(See "Scientists to Drill Earth's Mantle, Retrieve First Sample?")
Published April 7, 2011
Mantle Find
Photograph by Hans Strand
Sigurdsson (left) examines rock from inside Thrihnukagigur volcano's magma chamber with team member Freysteinn Sigmundsson, a volcanologist at the University of Iceland.
"Everywhere inside the chamber, you had a plastering of magma on the walls," Sigurdsson said.
"It looked like a beautiful plaster of Paris, and, in places that peeled off, you could see the geological makeup of the volcano underneath."
James Quick, a volcanologist at Southern Methodist University in Dallas, Texas, said the Thrihnukagigur expedition will provide a firsthand look into a part of Earth only roughly known before.
"We knew from geophysical tools what the plumbing system inside of a volcano looked like, but we only knew it in the crudest way," said Quick, who wasn't part of the expedition.
(Read more about Iceland's volcanoes.)
Published April 7, 2011
On Shaky Ground
Photograph by Hans Strand
Two expedition vehicles trundle across an ash-covered glacier about a mile (1.6 kilometers) from the opening of Iceland's Eyjafjallajökull volcano, which erupted last spring.
While inside the Thrihnukagigur magma chamber, about a hundred miles (160 kilometers) away, the expedition team's biggest risk was gas poisoning, SMU's Quick said.
"Whenever you go into magmatic systems like that, you run the risk of exposure to high levels of carbon dioxide" that can well up from Earth's interior, he said.
The University of Rhode Island's Sigurdsson—who was prepared for such a scenario—said the thought did occur to him during his descent.
"I sniffed the air as I went down to see if I felt light-headed at all," he said. "I had a [gas mask] in my backpack, but we didn't need it."
(See more pictures of Thrihnukagigur volcano on the National Geographic Channel website.)
Published April 7, 2011
Lavacicles
Photograph by Hans Strand
Inside Thrihnukagigur's volcano's magma chamber, Stefánsson and Ólafsson examine what Sigurdsson called "lava icicles"—magma that has solidified in mid-drip.
"When the magma in the chamber drained away," Sigurdsson said, "some of it was still hanging on the roof, and it dripped down to form delicate strings."
(See "'Magma 'Ocean' May Have Flowed Inside Early Earth.")
Published April 7, 2011
Lava Tube
Photograph by Hans Strand
Stefánsson and Ólafsson gaze up a magma shaft—an offshoot of the much larger magma chamber—inside Iceland's Thrihnukagigur volcano in autumn 2010.
The magma chamber itself is bottle shaped, Sigurdsson said. The bottom half is about a hundred feet (30 meters) across, while the "neck" that connects to the surface is only about 10 feet (3 meters) wide.
The entire chamber is about 450 feet (137 meters), from top to bottom.
Branching off from the main "bottle" are various veinlike vertical chutes and horizontal channels where magma once flowed.
"On the southwest side of the chamber, we went out of the bottle and into a lava tunnel," Sigurdsson said. "And on the opposite side, we found another lava tunnel, and we explored that a bit before it got too narrow to crawl through."
SMU's Quick said the magma channels the team discovered appear to be "beautiful textbook examples of how magma can be transported laterally in the Earth's surface and stored in shallow chambers."
(See "New Magma Layer Found Deep in Earth's Mantle?")
Published April 7, 2011
Flash and Ash
Photograph by Sigurdur Hrafn Stefnisson, National Geographic
Lightning pierces the erupting Eyjafjallajökull volcano's ash cloud in spring 2010. (See more pictures of lightning at Eyjafjallajökull volcano.)
While exploring Thrihnukagigur's interior might not shed much light on why Eyjafjallajökull erupted so violently in 2010, the knowledge gained from the expedition could help scientists understand volcanoes in general, scientists say.
"It could help us understand the plumbing systems in volcanoes," Sigurdsson said, "how the magma moves around, ... the conduits that magma travels along, and what it leaves behind when it's finished."
ON TV: Into Iceland's Volcano airs Friday, April 8, at 8 p.m. ET/PT on the National Geographic Channel. Preview >>
Published April 7, 2011