Lake Nyos, Africa
DEAD COWS!!!
Spreading centers, the huge rifts
which expand oceans and break apart continents, have a three way split
when seen from orbit. They expand in three directions, usually at
angles similar to each other, until one or two of the rifts conquer
the other(s). This is the pattern responsible for Lake Nyos and Lake
Monoun in the African country of Cameroon. When South America and
Africa split apart millions of years ago, it was caused by the three way
split of a rift zone. Two arms of the split dominated to create the
coast lines where the two continents would fit together today. The
third, presently situated just off the coast of Africa and extending East
North-East through the country of Cameroon, failed to split the land but
has stayed an active hot spot of activity. These two lakes situated
along a line formed by the failed rift are a pair of volcanoes with large
craters on top. These craters have filled with water to create lakes
with beautiful clear blue lakes.
However, the volcano beneath
the waters was not dead. Over the years after its creation it constantly
fed the bottom of the lake with Volcanic Carbon dioxide and other gasses.
Normally a lake has a turn-over of waters, the warm on the top goes to
the bottom and the cooler waters below move to the surface, at least two
major movements a year during the shift of seasons. However Lake
Nyos did not have regular turn overs and the CO2 built up in waters of
the deep part of the lake. In 1986, August 21st at about 9:30 pm
something disturbed the lake. Most likely the result of some sort
of mild earthquake or volcanic tremor, the lake erupted in a cloud of CO2
which "sloshed" out of one side of the lake and down the slope of the mountain.
People in the area heard a low rumble as a huge cloud of gas 165 ft thick
swept as far as 16 miles away from the mountain as fast as 45 miles per
hour.
Those who lived through the incident
felt light-headed and warm before they passed out. When they awoke
they found they were some the the few things breathing. In the area
where the gas cloud passed, all of the oxygen was pushed out of the way
and all creatures which needed it to survive were asphyxiated. All
the plant life in the area was untouched but not a bug, bird or animal
survived. Those who walked through their once lively towns were surrounded
by the bodies of over 1700 people and 3000 DEAD COWS!!! The
eruption of all the volcanic gas turned the once clear blue waters into
a yellow sulfur smelling soup.
This is one of the most bizarre
deadly incidents caused by volcanic activity. It is unfortunate that
this is not a one time incident. In about 20 years Lake Nyos may
once again be over saturated with carbon dioxide. Lake Monoun, too,
was formed in the same way as Nyos and may in the future surprise the residents
of its base with a death cloud of its own.
