Hazards Case Studies - Yellowstone and Cameroon.

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  • Hazards Case Study -Cameroon and Yellowstone.
    • Yellowstone Caldera; Wyoming 82190, USA.
      • Volcanic activity began 2 million years ago when a giant caldera formed. Two further huge eruptions 1.3 million and 640,000 years ago in addition. dozens of smaller eruptions have also occurred.
      • Misconception.
        • Yellowstone is overdue a very high-magnitude event. Tectonic events do not follow a regular pattern, making accurate and reliable prediction impossible
        • "The Yellowstone magma chamber is growing." No evidence exists for growth in a near-surface chamber of the size required for a super-volcanic eruption.
        • When Yellowstone erupts it will have severe globalconsequences. The most probable eruption will be a lava flow or a hydrothermal event. These would have little if any impact outside of the Yellowstone region.
        • Earthquake data indicate magma is moving. Recentearthquakes are linked to fractures in brittle rocks. Even if long-period events (the type of earthquake usually associated with magma movements) are registered, this does not mean an eruption is imminent.Hazardous earth.
        • The caldera surface is rising.
          • Yellowstone last erupted about 70,000 years ago. Given that the hot spot under Yellowstone heats, stretches and weakens the crustal rocks, volcanic activity could occur at any time. However, the probability of a super-volcano style eruption is exceedingly low
          • Measurements have indicated both rises and falls in ground surfaces within the caldera. The latest research suggests that volcanoes can display quite rapid ground movements without necessarily erupting.
    • Lake Nyros, NW Cameroon, 315km from the capital (Yaounde).
      • Lake Nyos is one of a number of deep lakes that occupy volcanic craters in Cameroon in West Africa. It is 2 km wide and 200 m deep. 
      • August 1986, 1700 people and all animal life in the area around the volcano were asphyxiated due to  a leak of CO2 from a volcanic crater lake.       
      • gas had built up at the bottom of the lake after being emitted from the underlying magma chamber.   
      • Causes to carbon dioxide escaping the lake are uncertain however it could be due;
        • Magma Movement.
        • Changes in temperature of lake water.
        • Earthquake.
        • Strong winds stirring up the water.
  • The caldera surface is rising.
    • Yellowstone last erupted about 70,000 years ago. Given that the hot spot under Yellowstone heats, stretches and weakens the crustal rocks, volcanic activity could occur at any time. However, the probability of a super-volcano style eruption is exceedingly low
    • Measurements have indicated both rises and falls in ground surfaces within the caldera. The latest research suggests that volcanoes can display quite rapid ground movements without necessarily erupting.

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