1. December 02, 2014 Agenda Roll PowerPoint: Volcanic Eruptions Part 1
Possible Video
Have your science notebook out and open to the next blank page.

2. Subject Area: Volcanic Eruptions
EQ: What are volcanoes?
Questions:
What is the difference between an explosive and a nonexplosive eruption?
How does the composition of the magma determine the type of eruption?
What are the main types of lava and volcanic debris?

3. Volcanic Eruptions
Think about the force of the explosion of an atomic bomb. Now imagine an explosion 10,000 times stronger. This is the possible power that can come from a volcanic explosion.

4. Nonexplosive Eruptions
Often people think of a river of red-hot lava when they think of a volcanic eruption. Lava flow is a river of hot lava. Lava flows are common in nonexplosive eruptions where the lava flows continually. Sometimes they will spray, they are not explosive.

5. Explosive Eruptions
In an explosive eruption, clouds of hot debris and gases shoot out from the volcano, often at supersonic speeds. Instead of lava these volcanoes blow molten rock into the air where it will harden. The larger pieces fall to the Earth and the smaller portions can circle the globe for years in the upper atmosphere.

6. Explosive Eruptions
An explosive volcano can also blast millions of tons of solid rock. This rock could have accumulated over millions of years. This means that a volcano can actually shrink after an eruption.
Movie

7. Cross Section of a Volcano
All volcanoes share the same basic features. They all have magma. Magma is the hot liquid material that is the driving force of creating volcanoes.

8. Cross Section of a Volcano
Magma rises through holes in the Earth’s crust called Vents.

9. Cross Section of a Volcano
Magma that erupts and flows onto the Earth’s surface is called Lava.

10. Cross Section of a Volcano
Magma that erupts as fragments of molten material that solidify in the air is called pyroclastic material.

11. Cross Section of a Volcano
A vent or a group of vents combined with the buildup of lava or pyroclastic material on the Earth’s surface is a volcano.

12. Magma
By comparing the composition of magma from different types of eruptions, scientists have discovered that the composition of magma determines whether a volcanic eruption is nonexplosive, explosive, or somewhere in between.

13. Magma
Water: A volcano is more likely to erupt explosively if its magma has a high water content. The effect of water on magma is similar to the effect of carbon dioxide gas on a can of soda when you shake it up.

14. Magma
Silica: Explosive eruptions are also caused by magma that contains a large percentage of silica. This type of magma tends to move slowly and harden in the volcanoes vent. This prevents water vapor and other gasses from escaping. It causes a build up of pressure and eventually a violent eruption will occur.
Partner Share:
If a volcano contained magma with portions of water and silica, would you predict a nonexplosive eruption or an explosive one? Why?
I Predict …Because…

15. The Story of a Volcano Questions for your Science Notebook
What did you know?
Skip 5 lines
What did you learn?
What do you want to know?
Why does the family choose to continue to live near a volcano?

16. What Erupts From a Volcano?
Nonexplosive eruptions produce mostly lava. Volcanoes can change and produce pyroclastic material. Explosive eruptions will produce both pyroclastic material and lava.
Partner Share:
Is a nonexplosive volcanic eruption more likely to produce lava or pyroclastic materials?
A nonexplosive volcano produces …

17. What Erupts From a Volcano?
Lava: Lava is magma that flows to the Earth’s surface. It can be thick and thin. Blocky lava is thick and barely moves along. Other lava such as pahoehoe, aa, and pillow lava, are thinner and produce faster lava flows.
movie

18. Blocky lava
Blocky lava is cool, stiff lava that cannot travel far from an erupting vent. Blocky lava forms in jumbled heaps of sharp-edge chunks.

19. Pahoehoe
Pahoehoe lava flows slowly, like wax dripping from a candle, forming a glassy surface with rounded wrinkles. Pahoehoe gets its name from the Hawaiian word for “ropy” because its surface resembles the coils of a rope.

20. Aa
Aa is a Hawaiian word that refers to a type of lava that has a jagged surface. Aa is named after the sound you would make if you were to walk across this type of lava barefoot.
Partner Share:
What is aa?
Aa is …

21. Pillow Lava
Pillow lava forms when lava erupts underwater. Pillow lava has a rounded shape because contact with water causes rapid cooling of the lava’s surface.

22. What Erupts From a Volcano?
Pyroclastic Material: Pyroclastic material is the rock fragments created by explosive volcanic eruptions. It comes in a variety of sizes, from boulders the size of a house to particles so small they can remain in the atmosphere for years. There are four major types of pyroclastic material: volcanic bombs, volcanic blocks, lapilli, and volcanic ash.

23. Volcanic Blocks
Volcanic blocks are the largest pieces of pyroclastic material, they consist of solid rock blasted out of a volcano.
Partner Share:
What is a volcanic block?
A volcanic block is …

24. Volcanic Bombs
Volcanic bombs are large blobs of magma that harden in the air.

25. Lapilli
Lapilli are pebble-like bits of pyroclastic material. They cool in the air and are solid when they hit the ground.

26. Volcanic Ash
Volcanic ash is small particles that are less than 2 mm in diameter. Volcanic ash forms when gases in stiff magma expand rapidly and the walls of the gas bubbles explode into tiny glasslike slivers.
Partner Share:
How is volcanic ash made?
Volcanic Ash is made by …

27. Summary Answer the essential question “What are Volcanoes?”
Your answer needs to be in complete sentences.
Place your answer at the bottom of the notes we did yesterday and today.
Make sure you use the definition of a volcano from your notes.
You may also write about the difference between explosive and nonexplosive volcanoes.
You can write about pyroclastic material and the different types of lava.

28. Into the Volcano Questions for your Science Notebook Into the Volcano
What did you know?
Skip 3 lines
What did you learn?
What do you want to know?

29. Objectives:
Distinguish between nonexplosive and explosive volcanic eruptions.
Explain how the composition of magma determines the type of volcanic eruption that will occur.
Classify the main type of lava and volcanic debris.