1. E3.P3XC Unit: Volcanoes Powerpoint on the standards for Volcanoes

2. Volcanic Eruptions Volcano- mountain formed from molten magma forced through the Earth’s surface Magma- Molten rock material Do you think that most volcanoes have explosive or non-explosive eruptions? Why?

3. Most volcanic eruptions are Non-Explosive! Types of Eruptions – Non-Explosive Lava- magma that reaches Earth’s surface Lava flows happen with non-explosive eruptions – Explosive Shoots hot debris and gases No lava flows, but massive debris Dust clouds up the atmosphere

4. Explosive V. Non-Explosive List a few characteristics of each type of explosion. Be prepared to share!

5. Cross Section of a Volcano Volcanoes form around vents that release magma

6. Magma! Explosive Magma! – High water content – High silica content Creates an eruption with stiff magma and releases gases

7. What Erupts? Pyroclastic Material – – hot debris from the volcano Four types of Lava: 1.Blocky Lava 2.Pahoehoe 3.Aa 4.Pillow

8. 1. Blocky Lava – Cool, stiff lava – Doesn’t travel far 2. Pahoehoe – Slow flowing lava – Like dripping wax – Forms glassy surface

9. 3. Aa – Hawaiian for “Jagged Lava” – Forms jagged – Underneath continues to move 4. Pillow Lava – Forms underwater – Rounded, bubble lumps

10. Types of Pyroclastic Material 1.Volcanic Blocks -Largest pieces -Solid Rock 2.Volcanic Bombs - Blobs of magma that harden in the air

11. 3.Lapilli - Little stones -Pebbles 4. Volcanic Ash -gases expand rapidly and shoot hot ash Which type of Pyroclastic material is most harmful to the environment? Why?

12. Assignment 1.What are the four types of lava? 2.What are the types of pyroclastic material? 3.How is pyroclastic material categorized? 4.Why do you think that volcanic eruptions with water are explosive? 5.Draw a non-explosive erupting volcano including its vents.

13. What Causes Volcanoes Chapter 9 Sec 3

14. Formation of Volcanoes Volcanoes are formed by the build up of cooled lava and other pyroclastic materials Magma is a mixture of liquid and solid rock material at high temperatures A large number of volcanoes lie on the plate boundaries What are the three types of plate boundaries? Transform, Divergent, Convergent

15. Boundaries – Volcanoes form at boundaries where tectonic action is at – Ring of Fire! Area of immense volcanic activity Surrounding the Pacific Plate

16. When Plate Separate What boundary is associated with plate separation? Divergent! Magma rises through the rift in the ocean floor forming new crust Produce what underwater sea features? Mid-Ocean Ridges DID YOU KNOW…. Divergent boundaries can also be continental. It’s rare, but true!

17. When Plates Collide! Which boundary is associated with plate collision? Convergent! Common where oceanic subducts under continental crust Oceanic plate moves downward, melts in the mantle, forms magma Magma rises to the surface and forms volcano! Why do oceanic plates always subduct beneath continental? Oceanic is denser than continental!

18. Hot Spots Hot Spots- weak areas of crust where magma comes through – The Hawaiian islands are formed from volcanic activity, but are no where near a plate boundary!

19. Hot Spots often produce chains of volcanoes as the Hot Spot remains permanent and the plate moves over it. Is it possible to live on a previous hot spot? Yes! Hawaiians do so daily!

20. Predicting Extinct- A volcano that hasn’t erupted in recorded history Dormant- A volcano that has not erupted in some time Active- have shown signs up erupting Before become active, what type of volcano was Dante’s Peak? Dante’s Peak was dormant. Goes to show you, always proceed with caution!

21. Signs of Eruption 1.Eruptions are preceded by many small quakes 2.The Volcano’s slop may bulge indicating a build up in the magma chamber 3.Increase levels of volcanic gases 4.Infrared images from outer space show temperature changes What two gases did Pierce Brosnan detect on Dante’s Peak? Sulfur Dioxide and Carbon Dioxide, both are common volcanic gases used for detection today

22. Assignment 1.Please draw and label the convection currents of the mantle. 2.What are the four main predictions for volcanic activity? 3.Where are most divergent boundaries found? 4.Why do oceanic crusts always subduct under continental crust? 5.How do Hot Spots leave a string of volcanoes? 6.What is the difference between extinct and dormant volcanoes?