Tungerahua Volcano, Ecuador Photo by Alcinoe Calahorrano

Volcanoes

By Jeanie Lacob 2013

Volcano StatsVolcano Stats

• Definition of Volcano– Mountain that forms when molten rock

(magma) is forced to the Earth’s surface

• Number of active volcanos = ? – 20 erupting right now

(50-60/year) (160/decade)

Volcanic Eruptions

• Nonexplosive Eruptions

• Explosive Eruptions

What is magma that flows onto the Earth’s surface?

Lava fountain

Lava flow

Click here to see what a volcano is

1. What did you learn?Write/draw this in your

science journal.

Volcanoes form around

vents that release magma onto the Earth’s surface.

VentsLava

Magma chamber

The Composition of Magma Determines whether it is explosive or not!

• High water content– More likely to be !!!

• High content– More likely to be !!!

Why? Silica has a thick, stiff consistencyFlows slowlyTends to Harden in the volcano’s vent

Explosive Eruptions Lava fountain

Choose high or low

Explosive Eruptions Lava fountain

Mount Saint Helens explosive eruption on

July 22, 1980

Volcanic explosion from space

Mt. Saint Helens May 1980

Before eruption

Mt. Saint Helens Sept. 1980

After eruption

The explosive eruption blew off a large portion of the mountain and significantly changed the surrounding landscape.

1822 artist rendition of the eruption of Vesuvius, depicting what the AD 79

eruption may have looked like.

April 21, 1990 eruption cloud from Redoubt Volcano as

viewed to the west from the Kenai Peninsula

http://www.photovolcanica.com/VolcanoInfo/Fuego/Fuego.html

Strong explosive eruption of Fuego volcano, Guatemala with associated rockfalls, Dec. 2007

SODA BOTTLE VOLCANO

• MATERIALS:

• roll of mint Mentos (type of candy)

• clear 2-liter bottle of Coke (diet works better)

• PROCESS:

• Go outside to an area where you have a lot of room. This experiment is messy!

• Open the bottle of soda carefully. Position the bottle on the ground, so that it will not tip over.

• *Diet soda works better than regular soda. Plus, diet doesn't leave a sticky mess.

• Unwrap the roll of Mentos. The goal is to drop the Mentos into the bottle at the same time, which is very tricky. One method is to roll a piece of paper into a tube just big enough to hold the loose Mentos. Put a card under the roll and on top of the bottle top, so you can pull the card and the candies will just drop in at once.

• Drop all of the Mentos into the bottle at the same time and then move out of the way just as quick as you can.

• Watch the eruption!

•

http://www.weatherwizkids.com/experiments-volcano-soda-bottle.htm

Comparing EruptionsYou can further your project by using all the different kinds of "lava," vinegar/baking soda, hydrogen peroxide/yeast and baking soda/lemon juice. Keep a record of how much of each substance you use in your project. Record observations on the various reactions. Record which combination makes the most foam, which one reaches farthest down the side of the volcano, and which, if any, gives off an odor. You will need to reuse your volcano for multiple eruptions, so make sure to use a clay that you can clean off.Dry IceFor a visual effect using dry ice, place a container of hot water inside your volcano -- the hotter the better. To make sure no smoke seeps out, seal around the bottom of the mountain. Using gloves, put small pieces of dry ice in the hot water. The dry ice fog will come out the top of the volcano and seep down the sides.

Read more: http://www.ehow.com/info_8780397_erupting-volcanoes-school-projects.html#ixzz2igt76FWI

a. What physical event causes explosive eruptions?

b. Would high water content increase the likelihood of having an explosive eruption?

c. Would high silica content increase the likelihood of having an explosive eruption?

2. What did you learn?Write/draw this in your

science journal.

Study Magma MovementGather a 1 oz. box of unflavored gelatin, red food coloring, a plastic syringe, a 40-by-60 pegboard with 5 mm-diameter holes spaced 2.5 cm apart, two 30 cm high bricks, a knife and tray. Mix four packets of gelatin and 6 cups of boiling water. Pour gelatin into the 2-liter bowl and refrigerate until the mix firms. Mix red food coloring and water in a glass to create a dark solution. Dip the chilled bowl of gelatin in a bowl of hot water to loosen, and then turn it upside-down onto the pegboard. Place the board on top of the bricks. Pour the red water into the syringe. Write down students' predictions of what may occur after the red water has been injected into the mold. Poke the syringe through a hole in the board and into the middle of the mold. Inject the red water at about 20 cc per minute. Have students sketch the movement of the red water or magma. Refill the syringe and repeat the injection several times.gelatin volcanoes

Read more: http://www.ehow.com/info_8204410_volcano-classroom-experiments.html#ixzz2igrWKF1x

1. Loosen the gelatin volcano from the cups by dipping the cups briefly in the bowl of hot water.

2. Lay the pegboard on top of a food serving tray to collect drips. 3. Weave the airline tubing into the pegboard from the top and back up

through the bottom so that 2” or so of tubing is sticking up out of the pegboard. Remove the plunger.

4. Fill the syringe with your prepared “magma.” Remove any air bubbles from the syringe and tubing by holding the syringe upright and squirting out a small amount of the liquid. Air tends to fracture the gelatin.

5. Unmold the gelatin by tipping the bowl over onto the center of the pegboard on top of the tubing and lifting the bowl. Do this VERY CAREFULLY so that the gelatin cast won’t develop cracks; a few small cracks are acceptable. The gelatin cast will spread and settle. It should resemble a colorless to milky volcano.

6. Inject the red water VERY SLOWLY, at a rate of about 20 ml/min. Each student should inject about 10mL into the volcano with the other students watching carefully.

7. What do you observe? 8. Use a plastic knife to slice open the volcano, and view the cross-

section.

Gelatin volcanoes

a. Where did the lava flow in your model?

b. Did the lava choose the path of least resistance (weakest places), like cracks?

c. Did the lava deepen the existing cracks or make new cracks?

3. What did you learn?Write/draw this in your

science journal.

What Erupts from a Volcano?

Pyroclastic material• Rock fragments created by eruptions

•magma explodes from volcano and solidifies in the air•existing rock is shattered by powerful eruptions

Volcanic blocks

Volcanic bombs

Lapilli

Volcanic ash

There are 2 kinds of lava:

pahoehoe 'a'a• stiff, rough and jagged. • This Hawaiian name means " a

painful surface for walking.”

Pahoehoe lava flow, showing well-developed flow structures at La'epuki, Hawaii Volcanoes National Park: Photo by Donald B MacGowan

• smooth, with a twisted, or ropy texture

Watch this video.

A

B

What kind of lava do you see?

http://www.learner.org/interactives/volcanoes/

Types of Volcanoes

Shield volcano

Cinder cone volcano

Composite volcano

Volcano Types:

Volcanoes – Bill Nye Volcano

Cinder Cone Volcanoes

Formed by a single eruption piling ashes into a cone shape

Shield volcanoes, - built of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior's shield. Some of the largest volcanoes in the world are shield volcanoes.   

Examples: Kilauea and Mauna Loa (above) -on the island of Hawaii-- two of the world's most active volcanoes.

Mauna Loa, the largest of the shield volcanoes is over 28,000 feet above the deep ocean floor.

Can you notice the profile of an upside-down warrior's shield?

Anatomy of a Shield Volcano: Quiet "Hawaiian Style" Eruption

Mount Kilauea, Hawaii

A shield volcano is a type of volcano usually built almost entirely of fluid lava flows. They are named for their large size and low profile, resembling a warrior's shield lying on the ground.

Example: Mount Fuji in Japan,

Click here for volcano eruption

 Another example of a composite volcano:

Mount St. Helens in Washington

before after

1980 The Mount Saint Helens Eruption Click for the

This dome is inside Mt. St. Helens

Volcanic Dome: form when very thick, rubbly lava is squeezed out of a vent without exploding. The lava piles up into a dome, which may grow by inflating from the inside

Caldera- a large, cauldron-like a large, cauldron-like volcanic depression that depression that forms when a magma chamber empties and it’s roof collapses forms when a magma chamber empties and it’s roof collapses usually following an explosive volcanic eruptionusually following an explosive volcanic eruption. The word comes from Latin CALDARIA, meaning "cooking pot". 

Caldera: Crater Formed by Volcanic Collapse or Explosion

Aniakchak Caldera, Alaska

Caldera

The current caldera at Yellowstone is the most recent in a series of eruptions that span millions of years. The North American Plate is moving west over a stationary hot spot. As the plate moves the hotspot produces an enormous eruption (and a large caldera) every few million years.    

Do you think this was an explosive or non-explosive eruption? Why?

The rim of the Yellowstone Caldera.

How large is it?

Steps in the formation of Crater Lake Caldera

Simulation of super-eruption resulting in Yellowstone Caldera

Caldera- is a cauldron-like volcanic feature usually formed by the collapse of land following an explosive volcanic eruption. The word comes from Latin CALDARIA, meaning "cooking pot". 

Caldera: Crater Formed by Volcanic Collapse or Explosion

Caldera demonstration

Aniakchak Caldera, Alaska

Crater lakes are formed when a caldera becomes filled with water sometime after it is formed.  An example is the Crater Lake in Oregon, America.  It is 9 kilometers in diameter whose floor is 600 meters in depth, while the surrounding 6800-year-old caldera walls rise steeply 600 meters above it.

Crater Lake, Oregon

What causes volcanoes?

The Formation of Magma• Mantle rock melts when the temperature increases or the pressure decreases.

How volcanoes erupt - animation

Magma rises to the surface because it is LESS dense than the solid rock around it.

What causes volcanoes?

Where Volcanoes Form• Tectonic Plate Boundaries!!!

~75% world’s active volcanoes in Ring of Fire

What causes volcanoes?

Example: Cascade Range in California

Volcanoes often form where an oceanic plate collides with a continental plate.

The oceanic plate sinks through the trench.

Rock in the sinking plate melts, forming magma, which then erupts to the surface as lava.

Volcanoes can also form where two oceanic plates collide – forming an ISLAND ARC.

The oceanic plate sinks through the trench.

Rock in the sinking plate melts, forming magma, which then erupts to the surface as lava.

Island ArcA string of volcanic islands that form where two ocean plates

meet Aleutian Islands off of Alaska Islands of Japan

Form when two Oceanic plates meet.One plate is subducted under the other plate.The subducted plate melts as it is pushed downward, becoming magma.The resulting magma rises to the surface and erupts in volcanoes.

How Island Arcs form:

the Philippine Plate consists of several micro-plates - squeezed in between two convergent plate margins.

The subduction of the plates (at the lines with black triangles) result in the Philippine Island Arc

http://whatonearth.olehnielsen.dk/philippines.asp

What causes volcanoes?

Hot Spots

Hot spots are fixed places within the mantle or oceanic lithosphere, where rocks melt to generate magma. 

Plate movement over hot spot results in islands:

Active volcano = newest island = Hawaii

Previously over hot spot = oldest island = Kauai

Bill Nye Volcano hot spots

This view of the Hawaiian islands showing the youngest islands in the southeast and the oldest in the northwest. Kilauea volcano, which makes up the southeastern side of the Big Island of Hawaiian, is located above the Hawaiian hotspot.

Mapping of volcanoes along the ocean floor show that the age of the volcanoes increases as the distance from Hawaii increases.

Suiko Seamount is 65 million years old, Midway Islands are 27 million years old and the island of Hawaii is still forming.

The Hawaii-Emperor chain creates a large angular gash across the Pacific basin in this satellite image.

The bend in the chain is due to a change in the direction of motion of the Pacific plate 43 million years ago.

Hawaii

The Hawaiian chain continues into the Emperor Seamounts, which are so old they no longer reach above sea level. The oldest of the Emperor seamounts is about to subduct into the Aleutian trench off of Alaska

• Measuring Small Quakes– Before eruption, increase in number & intensity

• Measuring Slope– Bulges may form with magma (tiltmeter)

• Measuring Volcanic Gases– Outflow of volcanic gases

• Sulfur dioxide, carbon dioxide

• Measuring Temperature from Orbit– Measure changes in temperature over time

How do volcanologists predict eruptions?

1. Place 10mL of baking soda in center of a sheet of bathroom tissue. Fold the corners over the baking soda and crease the edges so that they stay in place. Place the tissue packet in the middle of a large disposable pan.

2. Put modeling clay around the top edge of a funnel. Turn the funnel upside down over the tissue packet. Press down to make a tight seal.

3. Put safety goggles on and add 50mL of vinegar and several drops of liquid dish soap to a 200mL beaker, and stir.

4. Predict how much time will elapse before your volcano erupts. WRITE THIS DOWN!

5. Pour the liquid into the upturned funnel. Using a stopwatch, record the time you began to pour and the time your volcano erupts.

6. How close was your prediction?

a. Was your time prediction close to the real time of eruption?

b. Are the eruption times similar for every group? If not, give at least one reason why this might be.

c. How is our experiment different from predicting the eruption of a real volcano?

4. What did you learn?Write/draw this in your

science journal.

Volcanic LightningA bright bolt of lightning crackles within the ash cloud from the eruption of the Eyjafjallajökull volcano in Iceland in April 2010.  Volcanic lightning occurs when roiling ash particles rub against each other and become electrically charged.

Photograph by Peter Vancoillie, Your Shot

Sakurajima Volcano with Lightning, Japan photo by: Martin Rietze (Alien Landscapes on Planet Earth)

Fun if we have time:

• Discovery Kids :: Games - Volcano Explorer:

National Geographic site on volcanoes with volcano builder

Epic footage of volcanoes erupting

Virtual Volcanoes :

• Cosmeo Virtual volcano explorer

Virtual Volcanoes :

• Volcano Lab - Scholastic

• Volcanoes- Glencoe

• BBC Animated guide to volcanoes

Review Questions

1. This volcano is formed by a single eruption piling ashes into a cone shape

Cinder cone volcano

2. A string of volcanic islands that form where two ocean plates meet

Island Arc

3. The Hawaiian islands are an example of ______ volcanoes.

shield

4. A large depression that forms when a magma chamber empties and its roof collapses

Caldera

Review Questions

Composite volcano

6. What is magma that flows onto the Earth’s surface?

lava

8. This is the largest caldera in the world

Yellowstone National Park