1. Volcanos Cradle of life, Hazards to life

2. 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

3. 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

4. Hawaiian lava flow and power lines

5. Truck – burned by lava, then encased in igneous rock

6. Lava flow crosses road

7. Hawaiian lava flow and house fire

8. Lava flow and church fire

9. Trying to stop the lava

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

11. Explosive or “Plinian” Eruptions

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

13. Explosive eruption and “glowing clouds”

14. “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

15. Glowing Cloud on Mt. St. Helens

16. “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

17. Vesuvius

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

19. Pompeii – 79 A.D.

20. Herculaneum – 79 A.D.

21. Casts from Herculaneum

22. Citizens of Herculaneum

23. Vesuvius Today – Naples and vicinity

24. 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?

25. Other areas of Plinian risk Long Valley Caldera, California Valles, New Mexico Yellowstone National Park

26. Additional Volcanic Hazards Associated earthquakes Mudflows Acid precipitation – major source of SO x Particulate matter – blocks sunlight Short-term changes in climate