Deadly Exploding Lakes
There was an awesome documentary last night on the Discovery Channel about a Lake Nyos in Cameroon that was fed carbon dioxide via carbonic acid springs. Approximately 50 miles directly below the lake resides a pool of magma, which lets off carbon dioxide and other gases; the gasses then travel upward through the earth. The fumes are then ensnared by the natural springs encircling the lake, ultimately rising to the surface of the water and leading into the lake. This was the cause for the presence of carbon dioxide and other gases contained within the lake. Lake Monoun, and Lake Kivu in Rwanda are the only 2 other lakes saturated in carbon dioxide this way.
The carbon dioxide is dissolved in a supersaturated bottom pocket of the lake and sits under pressure much like carbonated soda in a bottle.
On August 21, 1986, a land slide caused a Limnic reaction in which the lake literally exploded and emitted 1.6 million tonnes of Carbon Dioxide. This cloud rose at nearly 100 kilometres (62 mi) per hour. The gas spilled over the northern lip of the lake into a valley running roughly east-west, and then rushed down two valleys branching off it to the north, displacing all the air and suffocating some 1,700 people within 20 kilometres (12 mi) of the lake, mostly rural villagers, as well as 3,500 livestock.
Scientists concluded from evidence that a 300-foot (91 m) fountain of water and foam formed at the surface of the lake. The sudden amount of water rising caused much turbulence in the water, spanning a wave of at least 80 feet that would scour the shore of one side.
One survivor described himself when he awoke after the gases had struck:
"I could not speak. I became unconscious. I could not open my mouth because then I smelled something terrible . . . I heard my daughter snoring in a terrible way, very abnormal . . . When crossing to my daughter's bed . . . I collapsed and fell. I was there till nine o'clock in the (Friday) morning . . . until a friend of mine came and knocked at my door . . . I was surprised to see that my trousers were red, had some stains like honey. I saw some . . . starchy mess on my body. My arms had some wounds . . . I didn't really know how I got these wounds . . .I opened the door . . . I wanted to speak, my breath would not come out . . . My daughter was already dead . . . I went into my daughter's bed, thinking that she was still sleeping. I slept till it was 4:30 p.m. in the afternoon . . . on Friday. (Then) I managed to go over to my neighbors' houses. They were all dead . . . I decided to leave . . . . (because) most of my family was in Wum . . . I got my motorcycle . . . A friend whose father had died left with me (for) Wum . . . As I rode . . . through Nyos I didn't see any sign of any living thing . . . (When I got to Wum), I was unable to walk, even to talk . . . my body was completely weak."
Carbon dioxide, being about 1.5 times as dense as air, caused the cloud to "hug" the ground and descend down the valleys where various villages were located. The mass was about 50 metres (164 ft) thick and it traveled downward at a rate of 20-50 kilometres (12-31 mi) per hour. For roughly 23 kilometres (14 mi) the cloud remained condensed and dangerous, suffocating many of the people sleeping in Nyos, Kam, Cha, and Subum. About 4,000 inhabitants fled the area, and many of these developed respiratory problems, lesions, and paralysis as a result of the gases.
It is believed that up to a cubic kilometre of gas was released. The normally blue waters of the lake turned a deep red after the outgassing, due to iron-rich water from the deep rising to the surface and being oxidised by the air. The level of the lake dropped by about a metre, representing the volume of gas released. The outgassing probably also caused an overflow of the waters of the lake. Trees near the lake were knocked down.
Following the eruption, many survivors were treated at the main hospital in Yaoundé, the country's capital. Doctors found that many of the victims had been partially poisoned by the mixture of such gases as hydrogen and sulfur. He described that poisoning by these gases would lead to burning pains in the eyes and nose, coughing and signs of asphyxiation similar to being strangled, as like "being gassed by a kitchen stove"
At an explosion at lake Manoun:
A physician who examined the bodies concluded that the people who had been traveling to market in the open air before dawn had died of asphyxia. Bata, now at Tulane University Medical Center in New Orleans, told SCIENCE NEWS that mucus and blood had oozed as foam from the victims' noses and mouths, and their bodies were rigid from seizure. They also had first-degree chemical burns on their skin, though their clothes were unaffected.
When Bata and a police commandant first neared the area at 6:30 that morning, they saw the smokelike cloud coming from the direction of the lake. The cloud reportedly tasted bitter and made them nauseated, dizzy and weak, so they retreated until 10:30 a.m., when it had dissipated. Between the lake and road, animals, grasses and shrubs had been killed, and plants on the shore had been flattened. Njindoun villagers also reported hearing a loud explosion from the lake about 11:30 the night before. And on Aug. 17, authorities noted that Lake Monoun was reddish brown, indicating that the normally placid waters had been stirred up.
Following the Lake Nyos tragedy, scientists investigated other African lakes to see if a similar phenomenon could happen elsewhere. Lake Kivu in Rwanda, 2,000 times larger than Lake Nyos, was found also to be supersaturated, and geologists found evidence for outgassing events around the lake about every thousand years. The eruption of nearby Mount Nyiragongo in 2002 sent lava flowing into the lake, raising fears that a gas eruption could be triggered, but fortunately it was not, as the flow of lava stopped well before it got near the bottom layers of the lake where the gas is.
The scale of the disaster led to much study on how a recurrence could be prevented. Estimates of the rate of carbon dioxide entering the lake suggested that outgassings could occur every 10-30 years, though a recent study shows that release of water from the lake, caused by erosion of the natural barrier that keeps in the lake's water, could in turn reduce pressure on the lake's carbon dioxide and cause a gas escape much sooner.
Several researchers independently proposed the installation of degassing columns from rafts in the lake. The principle is simple: a pump lifts water from the bottom of the lake, heavily saturated with CO2, until the loss of pressure begins releasing the gas and thus makes the process self-powered. In 1992 at Monoun, and in 1995 at Nyos, a French team demonstrated the feasibility of this approach. In 2001, the US Office of Foreign Disaster Assistance funded a permanent installation at Nyos.
en.wikipedia.org/wiki/Lake_Nyos
pagesperso-orange.fr/mhalb/nyos/indexwebcam.htm - heres a cool webcam that shows the self-sustaining degassing "soda fountain" at Nyos
www.thefreelibrary.com/The+%27killer+lake%27+of+Cameroon-a04053108
.
The carbon dioxide is dissolved in a supersaturated bottom pocket of the lake and sits under pressure much like carbonated soda in a bottle.
On August 21, 1986, a land slide caused a Limnic reaction in which the lake literally exploded and emitted 1.6 million tonnes of Carbon Dioxide. This cloud rose at nearly 100 kilometres (62 mi) per hour. The gas spilled over the northern lip of the lake into a valley running roughly east-west, and then rushed down two valleys branching off it to the north, displacing all the air and suffocating some 1,700 people within 20 kilometres (12 mi) of the lake, mostly rural villagers, as well as 3,500 livestock.
Scientists concluded from evidence that a 300-foot (91 m) fountain of water and foam formed at the surface of the lake. The sudden amount of water rising caused much turbulence in the water, spanning a wave of at least 80 feet that would scour the shore of one side.
One survivor described himself when he awoke after the gases had struck:
"I could not speak. I became unconscious. I could not open my mouth because then I smelled something terrible . . . I heard my daughter snoring in a terrible way, very abnormal . . . When crossing to my daughter's bed . . . I collapsed and fell. I was there till nine o'clock in the (Friday) morning . . . until a friend of mine came and knocked at my door . . . I was surprised to see that my trousers were red, had some stains like honey. I saw some . . . starchy mess on my body. My arms had some wounds . . . I didn't really know how I got these wounds . . .I opened the door . . . I wanted to speak, my breath would not come out . . . My daughter was already dead . . . I went into my daughter's bed, thinking that she was still sleeping. I slept till it was 4:30 p.m. in the afternoon . . . on Friday. (Then) I managed to go over to my neighbors' houses. They were all dead . . . I decided to leave . . . . (because) most of my family was in Wum . . . I got my motorcycle . . . A friend whose father had died left with me (for) Wum . . . As I rode . . . through Nyos I didn't see any sign of any living thing . . . (When I got to Wum), I was unable to walk, even to talk . . . my body was completely weak."
Carbon dioxide, being about 1.5 times as dense as air, caused the cloud to "hug" the ground and descend down the valleys where various villages were located. The mass was about 50 metres (164 ft) thick and it traveled downward at a rate of 20-50 kilometres (12-31 mi) per hour. For roughly 23 kilometres (14 mi) the cloud remained condensed and dangerous, suffocating many of the people sleeping in Nyos, Kam, Cha, and Subum. About 4,000 inhabitants fled the area, and many of these developed respiratory problems, lesions, and paralysis as a result of the gases.
It is believed that up to a cubic kilometre of gas was released. The normally blue waters of the lake turned a deep red after the outgassing, due to iron-rich water from the deep rising to the surface and being oxidised by the air. The level of the lake dropped by about a metre, representing the volume of gas released. The outgassing probably also caused an overflow of the waters of the lake. Trees near the lake were knocked down.
Following the eruption, many survivors were treated at the main hospital in Yaoundé, the country's capital. Doctors found that many of the victims had been partially poisoned by the mixture of such gases as hydrogen and sulfur. He described that poisoning by these gases would lead to burning pains in the eyes and nose, coughing and signs of asphyxiation similar to being strangled, as like "being gassed by a kitchen stove"
At an explosion at lake Manoun:
A physician who examined the bodies concluded that the people who had been traveling to market in the open air before dawn had died of asphyxia. Bata, now at Tulane University Medical Center in New Orleans, told SCIENCE NEWS that mucus and blood had oozed as foam from the victims' noses and mouths, and their bodies were rigid from seizure. They also had first-degree chemical burns on their skin, though their clothes were unaffected.
When Bata and a police commandant first neared the area at 6:30 that morning, they saw the smokelike cloud coming from the direction of the lake. The cloud reportedly tasted bitter and made them nauseated, dizzy and weak, so they retreated until 10:30 a.m., when it had dissipated. Between the lake and road, animals, grasses and shrubs had been killed, and plants on the shore had been flattened. Njindoun villagers also reported hearing a loud explosion from the lake about 11:30 the night before. And on Aug. 17, authorities noted that Lake Monoun was reddish brown, indicating that the normally placid waters had been stirred up.
Following the Lake Nyos tragedy, scientists investigated other African lakes to see if a similar phenomenon could happen elsewhere. Lake Kivu in Rwanda, 2,000 times larger than Lake Nyos, was found also to be supersaturated, and geologists found evidence for outgassing events around the lake about every thousand years. The eruption of nearby Mount Nyiragongo in 2002 sent lava flowing into the lake, raising fears that a gas eruption could be triggered, but fortunately it was not, as the flow of lava stopped well before it got near the bottom layers of the lake where the gas is.
The scale of the disaster led to much study on how a recurrence could be prevented. Estimates of the rate of carbon dioxide entering the lake suggested that outgassings could occur every 10-30 years, though a recent study shows that release of water from the lake, caused by erosion of the natural barrier that keeps in the lake's water, could in turn reduce pressure on the lake's carbon dioxide and cause a gas escape much sooner.
Several researchers independently proposed the installation of degassing columns from rafts in the lake. The principle is simple: a pump lifts water from the bottom of the lake, heavily saturated with CO2, until the loss of pressure begins releasing the gas and thus makes the process self-powered. In 1992 at Monoun, and in 1995 at Nyos, a French team demonstrated the feasibility of this approach. In 2001, the US Office of Foreign Disaster Assistance funded a permanent installation at Nyos.
en.wikipedia.org/wiki/Lake_Nyos
pagesperso-orange.fr/mhalb/nyos/indexwebcam.htm - heres a cool webcam that shows the self-sustaining degassing "soda fountain" at Nyos
www.thefreelibrary.com/The+%27killer+lake%27+of+Cameroon-a04053108
.