Killer Lakes: III
In 1986, a huge carbon dioxide explosion triggered one of the world's most devastating natural disasters at Lake Nyos, West of Cameroon.
Part 1 * 2 * 3
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 final installment 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, for his book "Barren Lands"
Image Credit: Krajick
Lake Monoun sits in steamy low country, surrounded by dozens of miniature, dormant volcanic cones. The area was not evacuated after the disaster in 1984; the nearby village of Njindoun alone has 3,000 residents. Yet, as at Nyos, carbon dioxide levels have been building up for years. The U.S. OFDA and the French government have pledged money to vent the lake, and preparations for installing the first pipe were begun earlier this year, as I looked on this January.
Plans call for the installation of three pipes in Monoun, which could render the lake safe in only three years. The lake is smaller and shallower than Nyos, but continuing buildup had made Monoun more volatile. Some 210 feet down, carbon dioxide had reached 97 percent saturation. At that depth, says Kusakabe, if the layer were stirred up by only three feet, the water could start bubbling and trigger an explosion. His colleague, Bill Evans, advised caution: "Let's not go splashing around too much out there," he tells me.
Sections of pipe and other components were stacked by the lake and under military guard when photographer Louise Gubb and I arrived. A team headed by Kusakabe was eager to start, but locals made it clear that first it was necessary to contact the lake spirits. "Man can build machines, but machines can betray man," said Njindoun elder Mamar Ngouhou. "We must move slowly."
The next morning, a crowd assembled at the shore. Under a tree, several shamans stirred a blackish green paste in a ceremonial bowl and then, carrying cornstalks and an ancient wooden gong, led a solemn procession to the water. The head priest, Amadou Fakueoh Kouobouom, beat the gong while crying out to ancestors. On the lake, men in fishing canoes tossed offerings of fruit, salt and palm oil into the water. Kouobouom dipped his forefingers into the paste, and people lined up to lick it off. (The foreigners balked until a young man whispered, "This will prevent harm from coming to you on the lake.") Then came Muslim prayers; most villagers are also followers of Islam. A feast of rice and smoked fish ensued. Finally, a live ram was carried to the water; an Imam cut its throat and held the knife in the slit until the blood stopped flowing. Only after this four-hour ceremony was it time to proceed.
The Japanese technicians leaped up, wrenches and screwdrivers at the ready, and began fastening together two small rafts to support monitors and a vent pipe. A 15-man team wrestled the rafts into the water. Kling and Evans motored out in a dinghy and gingerly suspended instruments for measuring carbon dioxide and temperature. Later that day, the two American scientists drove to the spot where the first victims of the Monoun explosion had fallen. The team had installed a solar-powered carbon dioxide detector, equipped with a loud siren and marked with a hand-painted skull and crossbones sign and instructions to flee if the alarm sounded. They were pleased that it was still working. Three weeks later, engineers headed by Halbwachs finished installing the first pipe for Monoun. It has worked well so far.
Image Credit: Prentice Hall
The countryside around Lake Nyos was beautiful but eerie. At a nearby spring, one of several fed by deep lake waters, carbon dioxide bubbled up. A dead hawk lay in a mud puddle next to a dead mouse, both apparently asphyxiated. Out in the woods, white cattle appeared suddenly like ghosts, then melted into the bush silently, their owners nowhere to be seen. We slept on a lakeside promontory, millions of stars overhead, amid cricket songs and the barks of baboons. It was the dry season; farmers on the heights were torching the bush to prepare for planting. At night great rings of land-clearing fires burned above the lake.
One morning we visited what was left of Lower Nyos, now mostly impenetrable brush. Along the dirt road, the foundations of a few mud-brick houses were still visible. Lines of trees marked the edges of what had once been yards. In the center of the former marketplace lay a large pile of rotting shoes. After the disaster, soldiers had buried the bodies in mass graves, whose locations were quickly lost in the rapidly revegetated bush country. That was a nearly unbearable loss: here, people routinely bury family members in the front yard so they can serve them meals, ask their advice and take comfort from their presence.
Survivors have overcome great challenges. On the day of the Nyos disaster, Mercy Bih was on her way to Wum, carrying about $100--a considerable sum in Cameroon--to buy supplies for her 26-member extended family. All her relatives were killed. She was 12. She returned the groceries and was reimbursed the $100, which she saved. Now 29 and the mother of two, she's the proprietor of the Lake Nyos Survival Good Faith Club, a four-table restaurant in Wum serving cold beer and the best grilled mackerel for miles. "I was lucky," she says. "Some people got left with nothing."
|"Planetary biospheres are complex entities whose histories are fraught with contingency, accident, and luck." -David Grinspoon
Image Credit: NASA
Though the Cameroon military had driven out most of those who had not fled the area on their own, Che, living on high ground, was allowed to remain, along with his wife and children, who had also survived. However, his uncle's seven children had been orphaned by the disaster, and tradition required Che to adopt them all, bringing his brood to 11. Che's income has been boosted by the foreign scientists working in the area, who pay him to measure lake levels and guard equipment, among other things.
As for Halima Suley, she and her husband now have five youngsters born to them since the tragedy. Just before dawn one morning, we hiked up to Suley and Ahmadou's new compound, located in a narrow pass above the lake. As a cooling breeze sprang up, we glimpsed thatched huts and cattle fencing coming into view. Out back, Ahmadou milked the cows; the herd numbers only 40 now. Suley greeted us in the family's perfectly swept yard with her children--from 15-year-old Ahmadou to 2-year-old Nafih. Suley made sweet tea with fresh milk and cradled the little one. "I'm no more thinking about the disaster," she says. "I have more children. I'm thinking about the children I have now." She smiled. "The only problem is a lack of cattle to feed them and to pay for them to go to school."
Ahmadou says, "If I think about what I was, what the family was, I can go crazy. So I try not to. We are believers. Your children can survive you, or you can survive your children--it is all in the hands of God." He says he appreciates the scientists' work. "When we feel their presence, we are much more peaceful, because we think something is being done." But, he admits, "When they leave, we live in fear."
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