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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
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
Volcanos – explosive eruptions
• Explosive eruptions are characterized by violent eruptions of gasses and ash
Volcanos – explosive eruptions
• Explosive eruptions are characterized by violent eruptions of gasses and ash
• These eruptions produce “glowing clouds”
“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
“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
Vesuvius – 79 A.D.
• The “type” example of a Plinian eruption
• Pliny the Younger’s account of the eruption
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?
Other areas of Plinian risk
• Long Valley Caldera, California
• Valles, New Mexico
• Yellowstone National Park
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