Volcanos Cradle of life Hazards to life Volcanos

Volcanos Cradle of life, Hazards to life

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

Hawaiian lava flow and power lines

Truck – burned by lava, then encased in igneous rock

Lava flow crosses road

Hawaiian lava flow and house fire

Lava flow and church fire

Trying to stop the lava

Volcanos – explosive eruptions • Explosive eruptions are characterized by violent eruptions of gasses and ash

Explosive or “Plinian” Eruptions

Volcanos – explosive eruptions • Explosive eruptions are characterized by violent eruptions of gasses and ash • These eruptions produce “glowing clouds”

Explosive eruption and “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 Cloud on Mt. St. Helens

“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

Vesuvius – 79 A. D. • The “type” example of a Plinian eruption • Pliny the Younger’s account of the eruption

Pompeii – 79 A. D.

Herculaneum – 79 A. D.

Casts from Herculaneum

Citizens of Herculaneum

Vesuvius Today – Naples and vicinity

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

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