1. Chapter 10 Volcanoes

2. What is A Volcano?
A VOLCANO is an opening in Earth’s surface that often forms a mountain when layers of lava & ash erupt
After many thousands or even millions of years, magma reaches earth’s surface and flows out through an opening called a VENT.
The steep walled depression around a volcano’s vent is the CRATER.

3. Magma vs. Lava Magma – molten material inside a volcano
Lava – molten material on earth’s surface

4. Draw & Label the parts of a Volcano

5. Where do volcanoes occur?
Where plates move APART
AKA: Divergent plate boundaries
Where plates move TOGETHER
AKA: Convergent plate boundaries

6. Where do volcanoes occur?
3. HOT SPOTS
areas of earth that melt rock & force magma upward

7. Pacific Ring of Fire area around the pacific plate where earthquakes & volcanoes are common

8. Active vs. Dormant
Most of Earth’s volcanoes are DORMANT, which means they are not currently active
There are more than
600 active volcanoes
in the world
The most active volcano
in the world is Kilauea in Hawaii

9. VIDEO
how volcanoes form

10. Eruptions Eruptions can either be quiet or explosive.
Two factors to determine the type of eruption:
Amount of water vapor and other gases trapped in the magma.
Whether the magma is basaltic or granitic.

11. Trapped Gases
Gases like water vapor and carbon dioxide are trapped in magma by the pressure of the surrounding magma.
As magma nears the surface, pressure is reduced.
Gas escapes easily = quiet eruption
Gas trapped under high pressure = explosive eruption

12. Magma Composition
Basaltic Magma – contains less silica, very fluid, and produces quiet, nonexplosive eruptions.
Example: Kilauea, Hawaii
Granitic Magma – contains a lot of silica, very thick, and high water content. Gets trapped in vents causing pressure to build up resulting in explosive violent eruptions.
Example: Mount Saint Helens

13. VIDEOS
Kilauea Eruption
Mount Saint Helen Eruption

14. TYPE 1: SHIELD VOLCANO Broad volcano Gently sloping sides
Hawaiian Islands
Broad volcano
Gently sloping sides
Quiet Eruption

15. TYPE 2: CINDER CONE VOLCANO
Paricutin, Mexico
- steep, smooth sides
- loosely consolidated
Explosive eruptions throw lava into the air
Lava then cools & hardens into TEPHRA

16. TYPE 3: COMPOSITE VOLCANO
Mount Saint Helens
Vary between quiet & explosive eruptions
Lava & tephra is repeated over & over

17. Brain Pop