Sonnet
Senior Member
- Oct 22, 2013
- 170
- 130
Lake Nyos Disaster
The sun dawned on August 22, 1986 much as it did every morning previous in Cameroon. A man (unnamed) decided to take advantage of the daylight. He hopped on his bicycle and began the trip from his village, Wum, toward the village of Nyos.
On the way, he noticed an antelope lying dead along the side of the road. “Why let it go to waste?” he asked himself as he strapped it to his bicycle (somehow). He continued to Nyos, passing two dead rats, a dead dog, and other deceased animals.
He wondered if they had all been killed by lightning – when lightning strikes, it’s not uncommon for nearby animals to die of the shock. He pulled into a group of huts, planning on asking the locals if they knew anything, but as he drew closer he saw dead bodies strewn everywhere. He checked the huts – there wasn’t a living soul in sight.
The man tossed his bicycle aside and ran all the way back to Wum.
When he arrived, the survivors of whatever had decimated Nyos and the surrounding villages were staggering into Wum. With them came strange tales of an explosion, rumbling noises, strange smells, and passing out only to wake up 36 hours later and find everyone around them dead.
When medical teams arrived two days later (Wum and Nyos exist in a very remote part of Cameroon), they discovered that in the course of one night, something had killed nearly 1,800 people, in addition to more than 3,000 cattle and numberless others creature – essentially, every living thing for miles around.
And by all appearances, the killer had disappeared as suddenly as it had come.
Scientists from all over the world traveled to Cameroon to assist in the sleuthing. The remains of the victims were of little help. There were no signs of bleeding, physical trauma, or disease, and no evidence of exposure to radiation, chemical weapons, or poison gas. And none of them showed signs of suffering or “death agony.” Apparently, they all just fell over and died.
The distribution of death gave the scientists their first clue – they had all died within 12 miles of Lake Nyos. Some local tribes refer to the lake as the “bad lake.” A legend exists which says that years ago, an evil spirit had risen out of the lake and killed all the people living at the water’s edge.
The lake itself gave scientists their next big, but perplexing, clue. The water, which was normally a pure blue, had transformed into deep, murky red. Apparently, there was more to the legend of the “bad lake” than anyone had realized.
Lake Nyos is a “crater lake” – it formed when the crater of an extinct volcano filled with water. But was the volcano really extinct? Maybe it had come back to life and released enough poison gas to kill every living thing in the area.
As compelling as that theory was, an eruption of that magnitude would have been accompanied by major seismic activity. None of the eyewitnesses mentioned earthquakes and nearest seismic recording station reporting nothing of interest happening that night.
This was backed up by the fact that in all of villages, goods were still piled neatly in homes where every living thing had been killed. The houses also offered one more interesting clue: The oil lamps had all be extinguished, even the ones still full of oil......
Scientists began testing water samples taken from different depths of the lake. The murky red color turned out to be dissolved iron, normally found at the bottom of the lake. Somehow, sediment from the bottom had been churned up to the top, where the iron turned red after coming in contact with oxygen.
Scientists also found unusually high levels of CO2 dissolved in the water. As they took samples from deeper and deeper, the CO2 levels steadily increased. At 600 feet, the levels suddenly shot off the charts. Beyond that depth, the containers burst from the pressure of the gas contained within them.
The theory formed that though the volcano had long since gone extinct, the magma chamber still simmered deep below the surface of the Earth and was still released carbon dioxide into the lake and the surrounding environment.
CO2 shows up in lakes all over the world. The CO2 in Lake Nyos, however, instead of floating to the surface and evaporating into the air, was accumulating at the bottom of the lake.
Normally lakes and other water bodies convect: the surface layers cools because of rain or wind, it becomes denser than the warmer water below, sinks, and displaces the warmer, CO2 rich layers at the bottom, which then move high enough for the CO2 to bubble to the surface and disappear.
Convection example. Pretend it's a lake.
Lake Nyos is one of the stillest lakes in the world. It is surrounded by tall hills that block the wind and because it is in a tropical climate, the water temperature stays consistent throughout the whole year. Also, because the lake is so deep (690 ft), when the surface is agitated, very little disturbance reaches its depths. The unusual stillness of the lake is what made it so deadly.
There is a physical limit to the amount of CO2 water can absorb. As the bottom layers become saturated, the CO2 is pushed upward to where the pressure is low enough for it to start coming out of solution. At this point, a disturbance such as an earthquake or a landslide can cause the CO2 to bubble to the top.
These bubbles cause a “chimney” effect – basically, they create a tube through which the lake can disgorge all of the CO2 that has been accumulating at its bottom for decades.
CO2 is odorless, colorless, and non-toxic; your body produces it and you exhale some every time you breathe. The air you breathe consists of about 0.05% CO2. What makes it deadly (in some circumstances) is that it is heavier than air: if too much is released at once, it displaces the air on the ground, suffocating everything in the area. 10% CO2 in the air can be fatal – as little as 5% can smother a flame…which is why the lamps were snuffed out.
As they monitored the lake, the scientists came up with an estimate of how much CO2 was released. On August 17, eyewitnesses said the lake began bubbling strangely, causing a misty cloud to form over the surface. Then on August 22, the lake exploded; water and gas shot a couple of hundred feet into the air.
The lake ejected 1.2 cubic kilometers into the air – enough to fill 10 football stadiums – in as little as 20 seconds. (If you know anything about the 1980 eruption of Mount Saint Helens, you remember the ash that circled the planet. That was only 1/3 of one kilometer of ash – a mere quarter of the CO2 released by Lake Nyos).
Dead cattle were found as high as 300 feet above the lake, indicating the gas had reached at least that high below settling down to suffocate everything at ground level.
Some survivors said it sounded like a gunshot or an explosion; other described it as a rumble. Those who ignored it and stayed in their houses were generally safe, but those who went outside to find the source quickly died on their front doorstep. The sight of these victims brought their family members to the doors and they too passed out and were killed.
Shut doors and windows offered the most safety, but there were still cases of CO2 seeping into homes through the floors and walls and smothering those who had laid down to sleep, but those who stood with their heads above the gas survived.
So what exactly happened and can it happen elsewhere, like in Tanzania? How were they poisoned? Did they really die from carbon dioxide emitted from the lake?
The sun dawned on August 22, 1986 much as it did every morning previous in Cameroon. A man (unnamed) decided to take advantage of the daylight. He hopped on his bicycle and began the trip from his village, Wum, toward the village of Nyos.
On the way, he noticed an antelope lying dead along the side of the road. “Why let it go to waste?” he asked himself as he strapped it to his bicycle (somehow). He continued to Nyos, passing two dead rats, a dead dog, and other deceased animals.
He wondered if they had all been killed by lightning – when lightning strikes, it’s not uncommon for nearby animals to die of the shock. He pulled into a group of huts, planning on asking the locals if they knew anything, but as he drew closer he saw dead bodies strewn everywhere. He checked the huts – there wasn’t a living soul in sight.
The man tossed his bicycle aside and ran all the way back to Wum.
When he arrived, the survivors of whatever had decimated Nyos and the surrounding villages were staggering into Wum. With them came strange tales of an explosion, rumbling noises, strange smells, and passing out only to wake up 36 hours later and find everyone around them dead.
When medical teams arrived two days later (Wum and Nyos exist in a very remote part of Cameroon), they discovered that in the course of one night, something had killed nearly 1,800 people, in addition to more than 3,000 cattle and numberless others creature – essentially, every living thing for miles around.
And by all appearances, the killer had disappeared as suddenly as it had come.
Scientists from all over the world traveled to Cameroon to assist in the sleuthing. The remains of the victims were of little help. There were no signs of bleeding, physical trauma, or disease, and no evidence of exposure to radiation, chemical weapons, or poison gas. And none of them showed signs of suffering or “death agony.” Apparently, they all just fell over and died.
The distribution of death gave the scientists their first clue – they had all died within 12 miles of Lake Nyos. Some local tribes refer to the lake as the “bad lake.” A legend exists which says that years ago, an evil spirit had risen out of the lake and killed all the people living at the water’s edge.
The lake itself gave scientists their next big, but perplexing, clue. The water, which was normally a pure blue, had transformed into deep, murky red. Apparently, there was more to the legend of the “bad lake” than anyone had realized.
Lake Nyos is a “crater lake” – it formed when the crater of an extinct volcano filled with water. But was the volcano really extinct? Maybe it had come back to life and released enough poison gas to kill every living thing in the area.As compelling as that theory was, an eruption of that magnitude would have been accompanied by major seismic activity. None of the eyewitnesses mentioned earthquakes and nearest seismic recording station reporting nothing of interest happening that night.
This was backed up by the fact that in all of villages, goods were still piled neatly in homes where every living thing had been killed. The houses also offered one more interesting clue: The oil lamps had all be extinguished, even the ones still full of oil......
Scientists began testing water samples taken from different depths of the lake. The murky red color turned out to be dissolved iron, normally found at the bottom of the lake. Somehow, sediment from the bottom had been churned up to the top, where the iron turned red after coming in contact with oxygen.
Scientists also found unusually high levels of CO2 dissolved in the water. As they took samples from deeper and deeper, the CO2 levels steadily increased. At 600 feet, the levels suddenly shot off the charts. Beyond that depth, the containers burst from the pressure of the gas contained within them.
The theory formed that though the volcano had long since gone extinct, the magma chamber still simmered deep below the surface of the Earth and was still released carbon dioxide into the lake and the surrounding environment.
CO2 shows up in lakes all over the world. The CO2 in Lake Nyos, however, instead of floating to the surface and evaporating into the air, was accumulating at the bottom of the lake.
Normally lakes and other water bodies convect: the surface layers cools because of rain or wind, it becomes denser than the warmer water below, sinks, and displaces the warmer, CO2 rich layers at the bottom, which then move high enough for the CO2 to bubble to the surface and disappear.
Convection example. Pretend it's a lake.
Lake Nyos is one of the stillest lakes in the world. It is surrounded by tall hills that block the wind and because it is in a tropical climate, the water temperature stays consistent throughout the whole year. Also, because the lake is so deep (690 ft), when the surface is agitated, very little disturbance reaches its depths. The unusual stillness of the lake is what made it so deadly.
There is a physical limit to the amount of CO2 water can absorb. As the bottom layers become saturated, the CO2 is pushed upward to where the pressure is low enough for it to start coming out of solution. At this point, a disturbance such as an earthquake or a landslide can cause the CO2 to bubble to the top.
These bubbles cause a “chimney” effect – basically, they create a tube through which the lake can disgorge all of the CO2 that has been accumulating at its bottom for decades.
CO2 is odorless, colorless, and non-toxic; your body produces it and you exhale some every time you breathe. The air you breathe consists of about 0.05% CO2. What makes it deadly (in some circumstances) is that it is heavier than air: if too much is released at once, it displaces the air on the ground, suffocating everything in the area. 10% CO2 in the air can be fatal – as little as 5% can smother a flame…which is why the lamps were snuffed out.
As they monitored the lake, the scientists came up with an estimate of how much CO2 was released. On August 17, eyewitnesses said the lake began bubbling strangely, causing a misty cloud to form over the surface. Then on August 22, the lake exploded; water and gas shot a couple of hundred feet into the air.
The lake ejected 1.2 cubic kilometers into the air – enough to fill 10 football stadiums – in as little as 20 seconds. (If you know anything about the 1980 eruption of Mount Saint Helens, you remember the ash that circled the planet. That was only 1/3 of one kilometer of ash – a mere quarter of the CO2 released by Lake Nyos).
Dead cattle were found as high as 300 feet above the lake, indicating the gas had reached at least that high below settling down to suffocate everything at ground level.
Some survivors said it sounded like a gunshot or an explosion; other described it as a rumble. Those who ignored it and stayed in their houses were generally safe, but those who went outside to find the source quickly died on their front doorstep. The sight of these victims brought their family members to the doors and they too passed out and were killed.
Shut doors and windows offered the most safety, but there were still cases of CO2 seeping into homes through the floors and walls and smothering those who had laid down to sleep, but those who stood with their heads above the gas survived.
So what exactly happened and can it happen elsewhere, like in Tanzania? How were they poisoned? Did they really die from carbon dioxide emitted from the lake?
