Ramp of Terror:

The Amazing CO2 Fire Extinguisher

	In this experiment students learn that carbon dioxide gas is denser than air and can be poured down a ramp like a liquid. The large ramp in the picture to the left has candles every so often. As the gas was poured down the ramp each candle goes out as the carbon dioxide gas smothers the candle's flame. This experiment was done as a demo for the class first and then each lab group had a chance to try it out themselves.
	Each lab group mixes vinegar and baking soda to create the carbon dioxide gas. They then carefully reach down in the bowl to gather the invisible dense CO2 gas in a cup.
	Students then pour the invisible gas down a ramp. The candle at the bottom goes out when the CO2 reaches it. Some students commented "You feel kinda dumb because you can't see what you are scooping up and pouring out. It is like make-believe or pretending.
http://news.bbc.co.uk/1/hi/sci/tech/4285878.stm
Zoom In Animation Lake Nyos (CO2) Density Disaster On August 21,1986, a cloud of carbon dioxide gas was released from the lake. Because carbon dioxide is more dense than air it hugged the ground and flowed down valleys. The cloud traveled as far as 15 miles (25 km) from the lake. It was moving fast enough to flatten vegetation, including a few trees. 1,700 deaths were caused by suffocation. 845 people were hospitalized. Photo by Jack Lockwood, U.S. Geological Survey.	Lake Nyos (CO2) Density Disaster  http://news.bbc.co.uk/onthisday/hi/dates/stories/august/21/newsid_3380000/3380803.stm This link above has two video news reports about the disaster just after it happened. Very interesting!
At least 1,200 people are feared dead in Cameroon, West Africa, after a cloud of lethal gas escaped from a volcanic lake. The tragedy happened at Lake Nyos, about 200 miles (322 km) northwest of the capital, Yaoundé, during the night. Most of the victims died in their sleep. The gas killed all living things within a 15-mile (25km) radius of the lake, and the area is still highly contaminated. Cause unknown It is not yet known what caused the gas to escape the lake, which lies in a volcanic crater. Government officials say the most likely cause is a volcanic eruption in Lake Nyos which created a fissure, leaking gas into the atmosphere. But independent scientists say this is unlikely, as the volcano is believed to be extinct. Cameroon radio is reporting that gases are continuing to escape from the lake. Rescue teams wearing gas masks have been rushing cylinders of oxygen to the remote area to help any who may have survived.   Victims 'poisoned' Hundreds of people have been arriving in the main hospital in Yaoundé for treatment. A doctor there said they had been poisoned by a mixture of gases including hydrogen and sulphur. He described the symptoms, including burning pains in the eyes and nose, coughing and signs of asphyxiation similar to strangulation, as like being gassed by a kitchen stove. Eyewitnesses described how the normally clear waters of the lake turned a reddish brown, while a sudden wind arose and whipped up huge waves. The gas is believed to have overwhelmed at least three villages. The entire population of one of the villages is thought to have been killed.	1986: Hundreds gassed in Cameroon lake disaster   VIDEO : BBC's Triona Holden: "Priests say few people in the path of the gas survived"   VIDEO : BBC's Mike Donkin: "Many children saw their mother, father, uncles and aunts die around them"     Lake Nyos Video Clips Mystery There was a similar escape of toxic gases at a nearby lake in the same volcanic crater two years ago which killed 37 people. The cause of that disaster, too, remains a mystery. Scientists from the United States and France are on their way to investigate the lake. They will bring with them rescue teams and emergency aid to help the survivors. The US has pledged $25,000 in immediate aid, while France, Britain and other Western European countries have promised logistical support. The Israeli Prime Minister, Shimon Peres, has said he will not cancel his state visit to Cameroon, due to start on Monday. He said he would be bringing a medical team and equipment for treating the victims.   In Context The eventual number of people who died in the Lake Nyos gas leak was put at more than 1,700. Scientists debated the cause of the disaster for some time afterwards. It was finally concluded that the lake's lower levels had become saturated by carbon dioxide gas (CO2) due to gaseous springs which bubbled up from the extinct volcano beneath. It is thought that recent high rainfall had displaced the CO2-rich water at the bottom, releasing a massive bubble of carbon dioxide gas from the lake in a natural phenomenon now referred to as "lake overturn". The heavy gas then sank to the ground and rolled in a cloud several tens of metres deep across the surrounding countryside. Pipes have now been put in place in Lake Nyos and nearby Lake Monoun to siphon water from the lower layers up to the surface and allow the CO2 at the bottom of the lake to slowly bubble out, preventing a repeat of 1986 tragedy. Following the Nyos tragedy, a survey was carried out into the CO2 content of other African lakes. It revealed that Lake Kivu, in Rwanda, is becoming saturated with carbon dioxide just as Lake Nyos was, and is seriously at risk of lake overturn. Scientists have warned that if nothing is done, millions of people living around Lake Kivu are in danger.
	RESEARCH ON LAKE NYOS West Africa

I think there is a pretty good consensus as to what happened at Lake Nyos (in 1986, by the way). A few folks disagree on the details, but the main event was the sudden release of a large cloud of carbon dioxide gas from the lake. Lake Nyos is a water-filled throat of an old volcano and it is deep and funnel-shaped. Although no longer erupting, there is still gas being released by the old plumbing system under the lake. Carbon dioxide gas was released directly into the deepest waters of the lake, where it could remain in solution (the way that carbon dioxide stays in solution in an un-opened soda or beer). In this situation the lake could build up a large amount of carbon dioxide dissolved in the deeper water. This was a stable situation. The carbon-dioxide charged water was slightly denser than the normal water in the upper levels of the lake, and the weight of the overlying water kept the carbon dioxide in solution in the deeper parts of the lake. However, nature decided to unbalance the situation. This is where the disagreement among volcanologists comes in. It is agreed that somehow some of that carbon dioxide-rich water was displaced upward into shallower depths to the point where the overlying water pressure was lower and carbon dioxide bubbles could start to form (like when you lower the pressure on a soda by opening the bottle and suddenly bubbles start to form). At Lake Nyos, once these bubbles started to form they wanted to rise to the top, this brought up more carbon dioxide-rich water which then also started to develop bubbles, and pretty soon there was a big rush of carbon dioxide bubbles to the surface. What people don't agree on is what the trigger for this unbalancing event was. Most people, I think, feel that there was some sort of landslide into the lake that stirred up the water. There are a few volcanologists who think there was some type of eruption in the deeper part of the lake, but they are in the minority. That detail isn't really too important.

Once all this carbon dioxide reached the surface, it splashed some lake water out of the lake, like a big bubble bursting. Carbon dioxide is denser than air, so it hugged the ground and flowed down the stream valley that leads away from the lake. Unfortunately many homes and at least one town are also along this valley and the inhabitants were caught by this cloud of ground-hugging gas. Carbon dioxide usually kills people by displacing the air that they need to breathe, but in high-enough concentrations it is poisonous as well.

So you see that although volcanologists might disagree on the tectonic details underlying Camaroon and might even disagree on the triggering mechanism for the 1986 disaster, but the danger is pretty well understood. Obviously one way to minimize the chances of this happening again is to prevent the deep lake waters from becoming gas-charged. A program was started to have a pump running that brought up the deep water (in a small controlled way), where it was pumped into the air like a fountain. This allowed smaller amounts of deep water to lose their carbon dioxide gradually rather than having the potential of a big bubble occurring again. Another worry is that the lake walls themselves are not very strong (they are constructed of tuff, partially solidified ash). The problem is that there is this lake at an elevation higher than the main towns nearby, and if for any reason the walls of the lake were breached there would be a flood of water that could be just as dangerous as a flood of carbon dioxide. I'm not sure but I think there were plans to pump water out of the lake to try and keep the level and pressure down.

This has been kind of a long-winded explanation. One of the most important things that volcanologists need to do is to make sure the folks who are actually living in danger understand the dangers. Perhaps this has not happened in Camaroon. Often scientists are very good at talking amongst themselves in technical language but are not so good at explaining things to normal people. It is often a good idea to have local teachers, writers, and artists helping to prepare materials for educating the public.

Sincerely,

Scott Rowland

http://www.hindenburg.net/disaster.htm
http://hearitnow.umd.edu/1937.htm	Herb Morrison

http://www.vidicom-tv.com/tohiburg.htm

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