Killer Lakes: I
In 1986, a huge carbon dioxide explosion triggered one of the world's most devastating natural disasters at Lake Nyos, West of Cameroon.
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The explosion killed more than 1700 people and reduced livestock herds up to 25 kilometers (15 miles) away. Many understood the disaster as something akin to shaking a carbonated bottle of water and then popping the shaken soda's cap. Dissolved carbon dioxide in Lake Nyos had become trapped in deep water because the lake bottom extended so far beneath the surface. Given the weight of water, the lake had to blow; its high hydrostatic pressure had capped this relentless buildup of carbonated water. But over time, bubbles started to appear until eventually the soda lake erupted, literally turning itself upside down in a few days of devastation.
To astrobiologists, the story of Lake Nyos offers a fascinating and modern look into a field called paleogeology--the combined records of climate with geology and their mutual influences on the history of Earth's life. A few theories have extended what happened in 1986 to our distant past, when global catastrophes altered the entire course of evolution. For instance, over two hundred million years ago, nearly 70 percent of land life and 95 percent of marine organisms suddenly and mysteriously disappeared. Did an asteroid strike? Did an ice age begin? Some suppose this event known as "The Great Dying" may share similarities to what happened on a much smaller scale at Lake Nyos. Was the Great Dying precipitated by dissolved gases such as poisonous methane building up in the world's oceans, only later to be released as explosive clouds of acid rain?
In this way, the modern soda fountain at Lake Nyos provides a case study for evaluating how biologically important theories in paleogeology might have worked. Astrobiology Magazine had the opportunity to sample ground truth about what happened at Lake Nyos from someone who visited the devastation afterwards. Cameroon became the destination for award-winning science journalist, Kevin Krajick.
Krajick's article, "Defusing Africa's Killer Lakes", first appeared in the September 2003 issue Smithsonian Magazine, and was subsequently honored by receiving the Walter Sullivan Award for Excellence in Science Journalism. His articles have appeared in National Geographic, Newsweek, The New York Times, Science, Discover, Audubon, Natural History, Smithsonian and many other publications. Krajick also authored "Barren Lands: An Epic Search for Diamonds in the North American Arctic". All publication rights and copyright remain with K. Krajick. This first of three installments is reprinted for the NASA-sponsored Astrobiology Magazine with author permission.
|Author Kevin Krajick went places in Cameroon many scientific groups and journalists alike have had difficulty getting to. Shown here in northern Canada, from his book "Barren Lands"
Image Credit: Krajick
On the night of the apocalypse, Ephriam Che was in his mud-brick house on a cliff above Nyos, a crater lake in the volcanic highlands of northwest Cameroon. A half-moon lit the water and the hills and valleys beyond. Around 9 p.m., Che, a subsistence farmer with four children, heard a rumbling that sounded like a rockslide. Then a strange white mist rose from the lake. He told his children that it looked as if rain were on the way and went to bed, feeling ill.
Down below, near the lake's shore, Halima Suley, a cowherd, and her four children had retired for the night. She also heard the rumbling; it sounded, she would recall, like "the shouting of many voices." A great wind roared through her extended family's small compound of thatched huts, and she promptly passed out--"like a dead person," she says.
At first light, Che headed downhill. Nyos, normally crystal blue, had turned a dull red. When he reached the lake's sole outlet, a waterfall cascading down from a low spot in the shore, he found the falls to be, uncharacteristically, dry. At this moment he noticed the silence; even the usual morning chorus of songbirds and insects was absent. So frightened his knees were shaking, he ran farther along the lake. Then he heard shrieking. It was Suley, who, in a frenzy of grief and horror, had torn off her clothing. "Ephriam!" she cried. "Come here! Why are these people lying here? Why won't they move again?"
Che tried to look away: scattered about lay the bodies of Suley's children, 31 other members of her family and their 400 cattle. Suley kept trying to shake her lifeless father awake. "On that day there were no flies on the dead," says Che. The flies were dead too.
|Self-sustained soda fountain (21 m height), Lake Nyos, Cameroon, Africa, is part of a project to degas gradually soda lakes.
Credit: Bernard Canet
He ran on downhill, to the village of Lower Nyos. There, nearly every one of the village's 1,000 residents was dead, including his parents, siblings, uncles and aunts. "I myself, I was crying, crying, crying," he says. It was August 21, 1986-- the end of the world, or so Che believed at the time.
All told, some 1,800 people perished at Lake Nyos. Many of the victims were found right where they'd normally be around 9 o'clock at night, suggesting they died on the spot. Bodies lay near cooking fires, clustered in doorways and in bed. Some people who had lain unconscious for more than a day finally awoke, saw their family members lying dead and then committed suicide.
Within days scientists from around the world converged on Nyos. At first, they assumed the long-dormant volcano under its crater had erupted, spewing out some kind of deadly fumes. Over months and years, however, the researchers uncovered a monstrous, far more insidious geologic disaster-- one thought to exist only in myth. Even worse, they realized, the catastrophe could recur, at Nyos and at least one additional lake nearby. Since then, a small band of dedicated scientists has returned here repeatedly in an attempt to head off tragedy. Their methods, remarkably low-tech and inexpensive, may very well work. "We are anxious to protect the people there," says Gregory Tanyileke, a Cameroonian hydrologist who coordinates experts from Japan, the United States and Europe.
It took me nearly 24 hours to fly from New York, via Paris, to Yaounde', Cameroon's sprawling capital. There I met photographer Louise Gubb, but this was just the start of our journey. Most people in Cameroon, a poor equatorial country the size of California, are subsistence farmers, cultivating yams, beans and other staples by hand. In a nation with 200 or more ethnic groups, languages change every few miles. Islam, Christianity and animist cults mix and recombine in peaceful confusion.
After a 12-hour overland journey northwest from Yaounde', we took the road to Lake Nyos, a washed-out dirt track winding through forested hills and passable only in a four-wheel drive vehicle. Electric power lines peter out at the dusty market town of Wum, 18 miles from the lake. As one approaches Nyos, grass grows in the road, indicating that few travelers come this way. After a final, mile-long climb through thinning bush, one emerges into an airy amphitheater of high cliffs carved into fantastical shapes surrounding the lake. At its north end, the crater's rim cants downward to a natural spillway, the waterfall Che found running dry that terrible morning. The lake is small, roughly half a square mile in area, now once again blue and tranquil. Black fishing eagles soar under a perfect sky. "Nyos," in the regional Mmen language, means "good," but in Itangikom, a related tongue, it means "to crush."
|Terrestrial options for early climate. Early earth, snowball, cauldron or temperate?Credit: NASA
Local mythology suggests that people around Nyos have long been aware that the lake harbored destruction. Indeed, Cameroonian myths reserve a special category for lakes, which are said to be the homes of ancestors and spirits and sometimes a source of death. According to legends documented by anthropologist Eugenia Shanklin of the College of New Jersey, in Ewing, a lake may rise, sink, explode or even change locations. Certain ethnic groups decree that houses near lakes be erected on high ground, perhaps, in the collective memory, as a defense against disaster. Che's people, the Bafmen, have lived here for hundreds of years and followed that tradition: they settled Upper Nyos. About 60 years ago, other groups began moving into the area, and they did not necessarily follow long-standing custom. Suley and her family, for instance, who are Muslims (Che is Christian), are Fulani; they settled on Nyos' lower slopes. By the 1980s, the population near the lake was several thousand and growing fast. Even some Bafmen relocated down there.
Che, an energetic man who never seems to stop smiling, walked with me around Nyos' rim, telling a story he had learned from his grandfather. Long ago, the story went, a group of villagers decided to cross Lake Nyos. One man parted the waters, much as God parted the Red Sea for the Israelites, but a mosquito bit the man on a testicle; when he swatted the insect, he lost his grip on the waters and every villager was drowned. Che pointed toward the lake with the homemade spear he often carries. "They're between those two rocks," he said, referring matter-of-factly to the ghosts of that catastrophe. "You hear them talking sometimes, but you do not see them."
The story falls under the rubric of what anthropologist Shanklin calls "geomythology"--in this case, an account of an actual disaster that would become more fantastic as it passed down the generations, eventually fading into legend. "Details shift over time, but these stories probably preserve real events," Shanklin says.
Related Web Pages
Methane: The Great Dying
Great Impact: Part I
Impact Hazards Website
NASA/JPL Near Earth Object Program
Do We Know What Killed the Dinosaurs?
Massive Volcanic Eruptions in Siberia Linked with Mass Extinction
Theories of Causes of the PT extinction