1. Don’t get all steamed about it…
Volcanoes:
Don’t get all steamed about it…

2. A: Main Concept #3: Any place where heat and “molten material”
From deep in the earth reaches the surface of the crust!!!
Magma Chamber
Lava
Vent
Lava Flow
Pyroclastic Flow
The basic process of an eruption is listed here:
4. Lava and other super hot
material flow out of the
volcano and onto the sides
3. When it breaks through
the surface, we get a
volcanic eruption!
2. Molten material
fills up every
crack it can find
Q: What is a Volcano?
1. Pressure increases
as molten material fills
up the “magma chamber”

3. Where you’ll likely find a Volcano
Convergent plate boundary (large volcanoes)
Divergent plate boundary (small volcanoes)
“Hot spot” (various sizes but can be the biggest by far. This includes SUPERVOLCANOES!!!!)

4. Volcanoes & Plate Boundaries
Divergent & Convergent Plate Boundaries
As the crust goes deeper, it gets melted!
As we have learned, hot stuff goes up!
If the melted crust (magma) gets to the surface…we get a volcano!
You can see that volcanoes are forming where ocean crust dives under other crust

5. Hot Spots A hot spot is where a large amount of molten material
Is trying to push it’s way up to the surface FAR FROM
A PLATE BOUNDARY!!!
Hawaii is a CLASSIC
example of a hot spot
We are not sure
why they occur…
Why do volcanoes form at hot spots?
Because there is hot material that wants to move up!
Why do hot spots form?
Now that’s a good question!

6. You can identify hot spots in two ways:
We can learn a lot from hot spots!
Volcanoes in the middle of nowhere (not near a plate boundary)
We can see the direction a plate is
moving by the line of volcanoes!
Older
Younger
A long line of volcanoes that get older in one direction
Plate Boundary
You can see that the Pacific plate has changed
it’s direction of travel sometime in the past!!!
Hot spot

7. Volcanic Hazards
Hey! Where did my car go?!

8. Volcanic Hazards Quiet Eruptions
Lava flows from vents, setting fire and burying everything in its path.
Covers large areas with a thick layer of lava.
Great.
Now how are we gonna get home?

9. Volcanic Hazards Quiet Eruptions
Fig. 7.23a *
Teachers, Please don’t mark your students tardy – we have a bus that’s running late.
Stephen Marshak

10. Mt. Saint Helens

11. Mt. Saint Helens

12. Mt. Saint Helens

13. Mt. Saint Helens

14. Mt. Saint Helens

15. The Aftermath You can see stumps that were trees sliced in half by the
force of the wind!

16. Here is an entire forest that was destroyed by the energy released
from the volcano!
Now we also have a river of
hot mud instead of water!

17. The Aftermath It wasn’t just a small section of
forest that was destroyed!

18. The Aftermath The air was so hot, these trees
just started to burn spontaneously!!!

19. The amount of ash the volcano expelled almost covered this house!
Rabaul Caldera on September 19, 1994

20. The ash can travel 100’s of miles!!!
U.S. Clark Air Base, Philippines, about 25 km east of Mount Pinatubo

21. Pompeii was destroyed by Mt. Vesuvius in Italy
The people died before they could
run away and their bodies left a
body shaped hole in the ash.
If you fill in the hole with cement, and
then removed the ash, the cement
shows the person who died there!

22. There is volcanic danger in Utah!!!
Here is a map showing
the areas that are in
danger if Yellowstone
has a major
eruption again!!!
There are geysers…
What about Yellowstone National Park?
There are extinct
volcanoes all over Utah
There are hot springs
all over Utah
And lots of hot springs…
How do you explain all this if there isn’t hot
material under the ground?

23. Monitoring Volcanoes
Because volcanoes have a lot of energy, we can use instruments to detect that energy to determine when she’s gonna blow!
Tilt Meter
Seismograph
Measures the shaking
of the ground
If the ground begins to bulge

24. Volcanic Eruption Indicators
Bulging & Tilt
Increase in Earthquakes
Increase in Temperature from underground water
Out-gassing
Many other indicators…
Main Concept #4: We can use indicators to determine if a volcano is likely to erupt

25. Fig. 7.15abc W. W. Norton Dormant volcano (basically
no molten material at this time)
Notice a bulge forming
where the molten material
is trying to punch through
Fig. 7.15abc
Potentially active volcano
(Magma fills chamber,
signs of possible eruption)
W. W. Norton
Active volcano
(Molten material has
punched through)

26. Graphing the energy of a volcano
Energy builds up over time
Earthquakes release some
Eruption releases most
Volcanic Eruption
Earthquake 2
Earthquake 1