06-12-2007, 12:56 AM
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Natural Disaster
From the FSM site...
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Originally Posted by ****
http://www.neatorama.com/2007/05/21/...-20th-century/
Very interesting account about the mysterious death of 1800 people around lake Nyos in Cameroon.
Apparently the depth, stillness, and constant temperature of the lake allowed it to store a lot of soluble CO2. Something triggered the sudden release of the CO2, essentially causing a "Lake Eruption" bigger than of Mt. St. Helens! All the people and wildlife surrounding the lake died of suffocation.
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As the scientists took samples from deeper and deeper in Lake Nyos, the
already high carbon dioxide (CO2) levels climbed steadily higher. At the 600 foot depth, the levels suddenly shot off the charts. Beyond that depth, the CO2 levels were so high that when the scientists tried to pull the samples to the surface, the containers burst from the pressure of all the gas that came out of solution. The scientists had to switch to pressurized containers to collect their samples, and when they did they were stunned to find that the water at the bottom of the lake contained five gallons of dissolved CO2 for every gallon of water.
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There is a physical limit to how much CO2 water can absorb, even under the tremendous pressured that exist at the bottom of a 690 foot deep lake. As the bottom layers become saturated, the CO2 is pushed up to where the pressure is low enough for it to start coming out of solution. At this point any little disturbance—a landslide, stormy weather, or even high winds or just a cold snap—can cause the CO2 to begin bubbling to the surface. And when the bubbles start rising, they can cause a siphoning or “chimney” effect, triggering a chain reaction that in one giant upheaval can cause the lake to disgorge CO2 that has been accumulating in the lake for decades.
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In the months following the disaster at Lake Nyos, the scientists continued to monitor the lake’s CO2 levels. When the levels began to increase again, they concluded that their theory was correct.
In the meantime, they had also come up with an estimate of just how much CO2 had escaped from the lake on August 22—and were stunned by what they found. Eyewitness accounts from people who were high enough in the hills above the lake to survive the eruption described how the lake began bubbling strangely on August 17, causing a misty cloud to form above the surface of the water. Then without warning, on August 22, the lake suddenly exploded; water and gas shot a couple of hundred feet into the air. The CO2 had taken up so much space in the lake that when it was finally released 1.2 cubic kilometers of CO2—enough to fill 10 football stadiums—in as little as 20 seconds. (Are you old enough to remember the huge volume of ash that Mt. Saint Helens released when it erupted in 1980? That eruption released only 1/3 of one cubic kilometer of ash—a quarter of Lake Nyos’s emission.)
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Crazy!
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