What comes to mind when you think of a lake? You probably imagine a pretty scene with
blue water,birds,and fish.For the people in the northwestern Cameroon,however, the image is
very different. For them,lakes may mean terrible disasters. In 1984,poisonous gases exploded
out of Lake Monoun and came down into the nearby villages,killing thirtyseven people.Two
years later,Lake Nyos erupted A cloud of gases rolled down the hills and into the valleys and
killed 1,700 people.
Lake Nyos and Lake Monoun are craterlakes They were formed when water
collected in the craters of old volcanoes The volcanoes under Lake Nyos and Lake Monoun are
not active anymore. However, poisonous gases from the center of the earth continue to flow up
through cracks in the bottom of the lake. This is normal in a crater lake. In most crater lakes,these
gases are released often because the waterturns overregularly.That is,the water from the
bottom of the lake rises and mixes with the water at the top,allowing the gases to escape slowly.
However,in Lakes Nyos and Monoun,there is no regular turning over.No one knows the
reason for this fact,but as a result,these lakes have more gases tapped at the bottom than other
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