Published: April 2011

Nyiragongo Volcano

Nyiragongo Volcano Lava Lake

The Volcano Next Door

Scientists descend to a fiery lava lake to protect a Congolese city in its path.

By Michael Finkel
Photograph by Carsten Peter

When? This is the question that has brought two of the world's leading volcano scientists to the center of Africa; it's the question that haunts a team of Congolese seismologists; it's the question that may determine the fate of close to one million people. When will Nyiragongo erupt?

Nyiragongo is a two-mile-high volcano towering over the eastern edge of the Democratic Republic of the Congo (DRC)—one of the most active volcanoes on the planet and also one of the least studied. The chief reason for the lack of research is that for the past 20 years the eastern DRC has seen nearly constant warfare, including a spillover of the massacres in neighboring Rwanda. One of the largest United Nations forces in the world, some 20,000 troops, currently maintains a fragile, and often broken, peace.

At the base of the volcano sprawls the city of Goma, growing by the day as villagers from the countryside seek refuge from rebel and government forces. An estimated million people are now crammed into Goma. Twice in recent years Nyiragongo's eruptions have sent molten rock flowing toward the city. In 1977 lava raced down the mountain at more than 60 miles an hour, the fastest ever observed. Several hundred people died, even though the flow had hardened before it reached the main part of the city. In 2002 the volcano shot more than 15 million cubic yards of lava into downtown Goma, destroying 14,000 homes, burying buildings to the top of the first floor, and forcing 350,000 citizens to flee. Both eruptions were mere grumbles, though, compared with the fury Nyiragongo is thought capable of unleashing.

Part of Dario Tedesco's job is to envision that possibility. For much of the past 15 years, with funding from the European Union, the Italian volcanologist has struggled to focus the scientific community's attention on Nyiragongo. According to Tedesco, there is no question the volcano will erupt again, potentially transforming Goma into a modern Pompeii.

"Goma," he says, "is the most dangerous city in the world."

Last July, Tedesco headed to Nyiragongo with U.S. volcanologist Ken Sims, a team of younger scientists, and a support crew, including six Kalashnikov-toting guards. Their three-week mission was akin to that of a doctor giving a patient a long-overdue physical exam. They wanted to take the measure of the mountain, to study its rocks and sample its gases, to decipher its methods and moods. They hoped to transform the question of when into the beginnings of an answer.

Reaching the summit rim of Nyiragongo was straightforward: Sims and Tedesco followed the lava. The recent eruptions hadn't been classic, spouting-out-the-top types, so-called Plinian eruptions, but rather fissure eruptions, like bursting pipes. In 2002 the rupture happened a few hundred feet below the 11,385-foot peak. Nyiragongo has an intricate plumbing system, widespread as the roots of a tree, and once the initial seam opened, the pressure blew open vents systemwide, shooting out fountains of molten rock, including in the very center of town. The risk, it turns out, is not just near the city of Goma, but directly beneath it.

The lava had steamrolled through forests and neighborhoods. It looked as if a ten-lane highway had been dropped down the mountain's flanks, right across the city. Though the next eruption will likely follow a similar path, thousands of homes, shacks of hand-hewn eucalyptus boards and sheet-metal roofs, have been built directly atop the old flow. Real estate brokers sell tiny lots consisting of nothing but lava rocks enclosed by lava walls for as much as $1,500. And if Goma doesn't have enough to worry about, the thousand-square-mile Lake Kivu conceals an enormous underwater concentration of carbon dioxide and methane. The theory is that a major eruption could release it, spreading a lethal cloud across the city that would spare no one.

After a full day of hiking, Sims and Tedesco reached the barren, wind-wracked summit rim. A long line of porters hauled camping gear, climbing equipment, scientific instruments, food, and water. From here, the scientists looked into the mouth of the volcano. Crumbly sheer walls ringed by ledges dropped a quarter mile down to a vast, flat floor, black with hardened lava. In the middle, contained in a giant soup-bowl-shaped spatter cone, was a stunning sight: a lake of lava.

The lake was 700 feet across—one of the largest in the world—with a mesmerizing kaleidoscopic surface. Black plates were cut by jagged cracks of orange, violently shifting and roiling. One moment the crust took the form of a shattered windshield, then it coalesced into a jigsaw puzzle, then a ragged map of the world. The lake roared like a jet plane taking off and emitted a thick white plume of dozens of deadly gases. "The whole periodic table is churning in there," Sims said.

Even from the rim the scientists could feel the heat. The 1800°F lava exploded from the lake in electric orange geysers, several every minute—25 feet high, 50 feet, 100 feet, bursting into evanescent arches of liquid rock morphing from orange to black in midair as they cooled. The lake seemed to breathe, expanding and contracting, rising and falling, its surface level changing several feet in a matter of minutes, spectacular and terrifying at once.

Sims was awestruck. "There," he said after a long silence, pointing down at the lake, "is where I'd really love to get a sample."

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