D.O. Crash = lake nyos in camaroon???

I was watching a documentry this evening on national geograpic channel titled "death fog". It was talking about lake nyos in camaroon africa. Would this be considered an extra leage form of a do crash?

Chemicals?

No chemicals. A researcher stated the lake flipped due to an huge rock slide.
The lake was 300m+ deep, an old volcano (some thought it was an eruption but it was not)
The water was a deep blue then after the slide/fog it turned orange/bright orange. Upon arriving the water was tested at different depths and when the water container came fron the bottom
Co2 was trapped in the container. Water temps were normal which would indicate no eruption. As it neared the surface the Co2 expanded and popped open the container releasing mass amounts of the gas that was odorless. Stated that the buildup of muck on the bottom was so much that the shear weight of the rockslide pushing/rolling down in the water had the effect of a blender. Similar to taking an oversized aerator and dropping it to the deepest part of a very old lake that never had been aerated. No mention was made as to weither there was a fish kill. The slide happened after dark and the lake is at a higher elevation than
the surrounding villages. The Co2 fog cloud being heavier than air sank down the valley displacing
oxygen and suffercating all of the people in the valley that night along with animals.

bump

Wiki

"Lake Nyos is a crater lake in the Northwest Region of Cameroon, located about 200 miles (322 km) northwest of Yaound�.[1] Nyos is a deep lake high on the flank of an inactive volcano in the Oku volcanic plain along the Cameroon line of volcanic activity. A natural dam of volcanic rock hems in the lake waters.

A pocket of magma lies beneath the lake and leaks carbon dioxide (CO2) into the water, changing it into carbonic acid. Nyos is one of only three known lakes to be saturated with carbon dioxide in this way, the others being Lake Monoun, 100 km (62 mi) away SSE, and Lake Kivu in Rwanda. On August 21, 1986, possibly triggered by a landslide, Lake Nyos suddenly emitted a large cloud of CO2, which suffocated 1,700 people and 3,500 livestock in nearby villages.[2] Though not completely unprecedented, it was the first known large-scale asphyxiation caused by a natural event. To prevent a repetition, a degassing tube that syphons water from the bottom layers of water to the top allowing the carbon dioxide to leak in safe quantities was installed in 2001, though additional tubes are needed to make the lake safe.[3]

Today, the lake also poses a threat due to its weakening natural wall. A geological tremor could cause this natural dike to give way, allowing water to rush into downstream villages all the way into Nigeria and allowing much carbon dioxide to escape."

Ewest, In your opinion is this similar to what we talk about when we say a lake has flipped? Only on a larger scale? Or would this be considered a totally different thing. Thanks for the insight.

The conditions at Nyos and some of Africa's killer lakes are such that lake turnover rarely ever occurs, thus the build up of dissolved CO2 at the bottom of the lake over long periods of time.

Part of this is from the lakes location on the equator that leaves surface temps very stable year round, there are no cold fronts to cool the top layer of water to make it sink.

Another condition are the high walls characteristic of volcanic lakes that keep keep the wind off the surface of the lake and thus from turning the water. The last condition is the extreme depth of the lakes which allows for large amounts of dissolved CO2 to accumulate and remain "bottled" up under pressure.

Every once in a while a landslide into the lake or something else triggers a lake turnover and huge amounts of CO2 are brought to the surface. CO2 is denser than air so it travels along the lowest points through valleys away from lake.

http://www.geology.sdsu.edu/how_volcanoes_work/Nyos.html

Quote:

It had been known for years that the water in Lake Nyos was extremely enriched in dissolved CO2. The lake overlies a volcanic source, which appears to release CO2 and other gases. However, most of this gas does not escape into the atmosphere, but rather dissolves into the bottom waters of the lake. At a depth of over 200 meter, the sheer weight of the upper lake levels exerts considerable pressures on the bottom waters. This confining pressure allows CO2 to dissolve into the bottom waters without escaping to the surface, in much the same way that the cap on a carbonated beverage prevents CO2 from bubbling out of its container. At a depth of 200 meters, water can hold 15 times its own volume in CO2. It has been estimated that every liter of water in the lower part of the lake may have contained between 1 to 5 liters of CO2!

Thanks shorty!