1. EARTH SCIENCE Mrs. Baker cjcb2015
VOLCANOES
EARTH SCIENCE
Mrs. Baker
cjcb2015

2. Volcanoes
An opening in the Earth’s crust that erupts gases, ash, and lava (pyroclastic material).
There are more than 600 active volcanoes on Earth!
Mt. Kilauea in Hawaii is the most active volcano!

3. Vocabulary

4. Parts of a Volcano A Magma Reservoir B Flank C Conduit D Crater
E Solidified Lava
F Dike
G Ash
H Vent
I Sill
INTERACTIVE WEBSITES (GO TO “LAUNCH”):
(images)
(LOTS of information)

5. Viscosity The ability of a substance to resist flowing.
Materials that flow quickly have a low viscosity. Examples: water, basaltic magma
Materials that flow slowly have a
high viscosity. Examples:
syrup, Rhyolitic magma

6. Types of Magma
Temperature, pressure, and amount of water affect the formation of magma.

7. Explosiveness of a Volcano
The explosiveness of a volcano depends on the viscosity of the magma within it.
High in silica, low in water vapor = High viscosity.
The magma will clog the main vent, build up pressure and result in an explosion.

8. Life of a Volcano Extinct- has not erupted in recorded history
Dormant- has erupted in recorded history, not currently erupting
Active- is currently erupting

9. Batholith: Large igneous rock mass underneath mountains
Dike: Magma that cuts across preexisting rock
Laccolith: small pool of magma that collects just under Earth’s surface
Pluton: Intrusive igneous rocks formed by converging plates
Sill: Pool of solidified magma in between rock layers
Stock: Small batholith

10. Caldera: large crater formed from volcano collapse during or after it
erupts
Crater: depression at volcano’s
Summit
Hot Spot: Hot area of a tectonic plate not along plate boundary
Tephra: Rock fragments thrown into the air during a volcanic eruption
Vent: Opening in Earth’s crust where lava erupts and flows outward
Pyroclastic Flow: Fast-moving cloud of ash, gas, and volcanic material after an eruption

12. Types of Volcanoes
Cinder Cone
Composite
Shield

13. Composite Volcanoes
Pyroclastic
material
Solidified
Lava
Composed of alternating bands of pyroclastic material (volcanic fragments) and lava.
Explosive eruptions
Andesitic magma (high silica)
Example: Mt St Helens and Mt. Rainier in the Cascade Range
Mt St Helens

14. Mt. Rainier

15. Shield Volcanoes Wide volcanoes, gentle slope
Composed of layers of solidified magma
Calm lava eruptions
Basaltic Magma (low silica)
Example: Hawaiian Islands
Solidified lava

16. Cinder Cone
Composed of pyroclastic material (Tephra- volcanic fragments)
Small and steep
Explosive eruptions (high silica)
Example: Paricutin in Mexico
Pyroclastic
Materials

17. -due to the subduction of the Pacific Plate.
Volcanoes
The majority of Earth’s surface volcanoes are found along the Pacific Plate Boundary- Ring of Fire.
-due to the subduction of the Pacific Plate.

18. Volcano Formation at Convergent Boundaries

19. Volcano Formation at Convergent Boundaries
Mt St. Helens
Mt. Pinatubo
Aleutian Islands

20. Volcanoes also form along the mid-ocean ridges
-due to upwelling
of magma
- long fissures in
places

21. Volcano Formation at Divergent Boundaries

22. Volcano Formation at Divergent Boundaries
Iceland Volcanic Activity
Black Smoker,
Mid-Atlantic Ridge
Pillow Basalts,
South Pacific

23. Volcano Formation NOT at Plate Boundaries: Hot Spot Volcanoes

24. The Islands of Hawaii
These islands formed over a period of 5 million years.
The islands are slowly moving to the northwest with a active hot spot currently under the island of Hawaii.
Plate Movement
Hot Spot

25. The Yellowstone Caldera is the volcanic caldera located in Yellowstone National Park in the United States, sometimes referred to as the Yellowstone Supervolcano

26. Volcanic Hazards Lava Flows Pyroclastic Flows Lahars Earthquakes
Tsunamis
Toxic Gases
Volcanic Bombs
Ash Falls
More…