Limnic Eruptions

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Limnic Eruptions

• By Corney Crumbley
• Denisse Iacobucci
• April Williams

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Limnic Eruption

• When CO2 builds up in the bottom of a lake.
• The water becomes saturated with CO2.
• Require trigger such as a landslide, volcanic
  eruption, explosion, and even a rain storm to
  create an eruption.
• followed by a release of CO2 into the air causing
  death by asphyxiation.

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Very Rare

• Though very dangerous there are only two know
  cases.
• One was in Cameroon, Africa at Lake Monoun in
  1984, which killed 37 people.

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Second known event

• At Lake Nyos in Cameroon as well. It erupted in
  1986, and was larger in size killing 1700 to 1800
  people!!!
• Released 80 million cubic meters of CO2
• Most wildlife was killed, including fish in the
  eruptions.

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Third possible Eruption

• Another lake is showing signs of a possible
  Limnic Eruption!
• Lake Kivu in Africa has been known for violent
  lake overturns in the past.
• There is evidence of massive biological
  extinction happening every 1,000 years
• These three lakes have been called exploding
  lakes!!!
• Lake Kivu is the largest of the three lakes and
  near the most populated area!!!

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Why?

• Why do you think that Limnic Eruption are so
  rare?
• Specific conditions need to be met.
• Most temperate lakes turn over yearly causing
  water temperature to change in each layer.
• Dont worry the Great Lakes or Lake Altoona will
  never do this!
• Soon you will see how Temperature effects this
  process

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Conditions for an Eruption

• Conditions for CO2 accumulation must be met
  first.

• The conditions for a Limnic eruption are
• Need a CO2 source. Can be volcanic activity or
  organic degradation
• Degradation only contributes not really a cause
  (Volcanic activity).
• Need high amount of pressure present.
• CO2 dissolves at higher pressure and lower Temp,
  such as the bottom of a deep lake.

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Eruption

• Once the conditions are met, the possibility for
  an eruption greatly increase.
• What happens is similar to opening a shaken can
  of soda on a horribly large scale.
• An Eruption causes a violent displacement of
  water and could cause a Tsunami!
• An Eruption can be looked at in step ward
  fashion.
• 7 steps of an Limnic Eruption

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Eruption Cont.

• Once the water becomes saturated with CO2 due to
  mostly volcanic activity,
• a trigger causes saturated water to rise.
• As the water rises, less dense water cause
  dissolved CO2 to become released in the form of
  bubbles.
• The bubbles natural buoyancy causes more
  saturated water to rise to the surface.
• CO2 bubbles start being released more rapidly and
  cause more saturated water to rise faster.
• Soon a huge displacement of water takes place
  releasing CO2 into the air.
• The water displacement can cause Tsunami!

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Aftermath

• Once an eruption takes place so much CO2 is
  released that a CO2 cloud sits over the land.
• This cloud does not rise!
• The reason the cloud does not rise is due to the
  density of CO2. CO2 is 1.98 g/L at stp which is
  greater than oxygen which is 1.43 g/L at stp.
  Thus, CO2 sinks to the ground.

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Aftermath cont..

• The CO2 that is released kills wildlife and
  people in the area. The speed of this natural
  disaster makes it so dangerous.
• Most things caught in wake of a Limnic eruption
  is killed by asphyxiation.
• Surviving a Limnic eruption is possible but
  causes many problems.
• Brain damage and breathing problems occurs
  because of the large amounts of CO2 and other
  gases.

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Tsunami

• A Tsunami happens when a huge body of water is
  rapidly displaced.
• A Limnic eruption is a perfect example.
• Imagine a huge rock being dropped into a puddle
  and how huge water ripples move toward the
  outside.
• A 5-meter Tsunami was reported after the Eruption
  at Lake Nyos.

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Human Reaction

• CO2 reacts with water molecules in the blood to
  form H2CO3. Then HCO3- and H are formed. The H
  ion increases the acidity of the blood. This
  increase in acidity harms a persons ability to
  further take up oxygen, which can lead to death.
  
• Reaction
• CO2 H2O ? H2CO3? H (acidic) HCO3-

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Human reaction

• The human body undergoes a state of hypercapnia
  (a condition in which too much CO2 is in the
  blood) otherwise known as CO2 poisoning.
• Symptoms include rapid breathing, flushness of
  the skin, raised blood pressure, and
  unconsciousness followed by death!

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No Oxygen

• Dynamics within the human body change overtime
  and quickly with the loss of oxygen

 
The following symptoms take place within 6
Minutes !!
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Other Symptoms

• Some believe that there are other gases that
  cause further damage to people caught in Limnic
  eruptions.
• Hydrogen Chloride (HCL) - was also thought to be
  released because of change in skin color.
• Most depute this claim and believe other
  environmental factors are the cause.
• Carbon monoxide (CO) - which was blamed for
  blisters on patients skin caused by poor oxygen
  levels.

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Carbon Monoxide

• Know as carbon monoxide poisoning
• Due the inhalation of carbon monoxide.
• Flu like symptoms, vertigo, headache, and
  blisters on skin.
• Long term effects cause problems to the central
  nervous system, heart, and the fetus. If not
  treated quickly death is certain.
• Treatment involves the use of 100 pure oxygen or
  hyperbaric treatment.

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Prevention Methods

• Limnic Eruptions in a highly populated area could
  be a catastrophe.
• In January 2001, Cameroonian and French
  scientists installed a pipe in Lake Nyos to
  release the gas in safe amounts.
• Makes Cool Fountains ?
• Comes with a threat.

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Degassing

• The process of removing CO2 threatens lakes.
• Very effective process (on small lakes)!
• A siphon is used to pump water from the bottom of
  the lake to the top to remove CO2.
• Requires little energy
• Process requires little energy because as the CO2
  saturated water rises bubbles are formed.
• These bubbles natural buoyancy causes water to
  rush out in a rapid fashion forming a fountain.

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Drawbacks

• A Thin layer of CO2 could be released above the
  lake.
• A thin layer would be a biological disaster,
  killing all life within the lake.
• Would be a mini Limnic eruption.

• This process is good on small lakes only.
• Larger lakes could cost millions to degas.
• Pipes and electronics need constant maintenance
  due to the acidic water.
• Caused by dissolved CO2

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Pipe Corrosion

• CO2 reacts with H2O to form Carbonic acid (H2CO3)
• CO2 H2O ? H2CO3 ? H HCO32-
• When Carbonic Acid comes in contact with steel
  (Fe), the following corrosion reaction occurs.
• Fe 2H2CO3 ? Fe(HCO3)2 H2
• 2Fe(HCO3)2 ½ O2 ? Fe2O3 4CO2 2H2O

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Next possible threat

• Lake Kivu meets the condition for a Limnic
  eruption
• Has shown to erupt in the past
• 2,000 times bigger than Lake Nyos
• Over 2 million people live off the shores
• Lake contains methane. An eruption would mean a
  huge release of explosive gas.
• Too expensive for the local economy to degas
• Remember expensive to degas large lakes plus all
  draw backs increase!

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Recap

• Limnic eruption is when CO2 suddenly rises from a
  lake.
• Rare needs specific set of conditions
• Eruption causes huge displacement of water.
• Tsunamis
• CO2 cloud sits over lake killing surrounding area
  by CO2 poisoning.
• Due to density
• The human body can survive without oxygen for
  about 6 minutes.
• Degassing is the method of prevention.
• Many draw backs
• Lake Kivu is the next possible disaster.
• 2,000 times larger than Lake Nyos and 2 million
  people live around it.

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Thanks For Your Time Any Questions?