Volcanos

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Volcanos

• Cradle of life,
• Hazards to life

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Volcanos Cradle of Life

• We have already discussed the probable connection
  between volcanos and the origin of life
• Now we will examine the opposite situation
  volcanos as hazards to life and property

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Volcanos fluid eruptions

• Fluid eruptions are characterized by lava flows
• There is little ash produced in comparison to the
  lava
• Major threat is to property rather than life

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Hawaiian lava flowand power lines
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Truck burned by lava, then encased in igneous
rock
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Lava flow crosses road
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Hawaiian lava flowand house fire
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Lava flow and church fire
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Trying to stop the lava
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Volcanos explosive eruptions

• Explosive eruptions are characterized by violent
  eruptions of gasses and ash

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Explosive or Plinian Eruptions
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Volcanos explosive eruptions

• Explosive eruptions are characterized by violent
  eruptions of gasses and ash
• These eruptions produce glowing clouds

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Explosive eruptionand glowing clouds
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Glowing Clouds

• Columns of ash, drops of lava and gasses are shot
  into the air
• Column reaches a certain height and the upward
  force is balanced by gravity
• Gravity brings the ash and gasses back to the
  surface where they flow along the ground

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Glowing Cloud on Mt. St. Helens
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Glowing Clouds

• Glowing clouds range in temperature from about
  500 degrees (C) to nearly 1000 degrees
• Because they are more dense than air, they hug
  the ground and move at speeds from 100 to 200 mph

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Vesuvius
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Vesuvius 79 A.D.

• The type example of a Plinian eruption
• Pliny the Youngers account of the eruption

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Pompeii 79 A.D.
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Herculaneum 79 A.D.
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Casts from Herculaneum
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Citizens of Herculaneum
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Vesuvius Today Naples and vicinity
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Vesuvius Today

• Approximately 1 million people live in the shadow
  of Vesuvius
• Nearly 3 million people are nearby
• A glowing cloud from Vesuvius would reach the Bay
  of Naples in about 5 minutes
• Prediction of eruption is difficult
• A catastrophe waiting to happen?

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Other areas of Plinian risk

• Long Valley Caldera, California
• Valles, New Mexico
• Yellowstone National Park

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Additional Volcanic Hazards

• Associated earthquakes
• Mudflows
• Acid precipitation major source of SOx
• Particulate matter blocks sunlight
• Short-term changes in climate