March 9, 2011

• I will be able to identify what makes ________
_____________________________________
_
• I will be able to compare _________________ that come out of a volcano.
• I will be able to compare the different
_____________________________________
_

• A magma’s viscosity is directly related to its silica content.
• A lava flow with a surface of rough, jagged blocks and sharp, angular projections is called aa flow.
• As the temperature of lava increases, the viscocity decreases.
• Highly explosive volcanoes tend to have magma with high silica, high viscosity, and higher gas content.
• The particles produced in volcanic eruptions are called pyroclastic material.
• Pyroclastic materials include ash, cinders and lapili.
• The most abundant gas associated with volcanic activity is water vapor.
• A cinder cone is a type of volcano that is built almost entirely from ejected lava fragments.
• The pipe is the hollow center of the volcano.

• Volcanoes can erupt explosively or mildly.
They can erupt with lots of lava spewing out or slowly oozing out of the mouth. Some volcanoes erupt ash and dust with no lava at all. So what makes all of them so unique?
• Let's watch!
• Let’s take a look at the factors that affect the eruption of a volcano.

Viscosity - _____________________________
____________________________________.
– This means that something that has a high viscosity does not flow easily. A substance with a high viscosity would be honey. A substance with a low viscosity would be water.
– If the lava of a volcano has _________________
_____________________, the ______________ of a volcano will be _______________________.
– There are three factors that affect the viscosity of lava: ___________________, ______content, and _____________________.

1. Silica – the more silica in lava, the more
______________ it has. A magma’s viscosity is directly related to its silica content.
2. Gas content - the more _____________ in lava, the ____________viscocity it has.
3. Temperature – as temperature in lava increases,
______________________________.
• Example: heating up syrup.
***Bottom line: _____________________________ volcanoes tend to have magma with high
_________, _________viscosity, and higher
___________content.

There are three main types of materials that come out of volcanoes: ________________________, _________, and
_________________________________.
Lava flows:
1.aa flow (AH ah): A lava flow with a surface of _________, jagged ___________and sharp, angular _______________. view here!
Think “ow!” it hurts to step on!
1.pahoehoe flow: lava flows that flow ______________ forming flows that look like twisted braids in ropes.
view here!
Gases:
The most abundant gas associated with volcanic activity is
______________________.

Pyroclastic Material – _____________________
_____________________________________
_
• Pyroclastic materials include _______,
____________ and __________.
• These particles can range in __________ from fine dust to pieces that weigh several tons!

Anatomy of a volcano
• While there are several different types of volcanoes, each have a “typical” anatomy with the following parts:
A. ____________
B. ____________
C. ____________
D.____________

• The three main types of volcanoes are
_____________cones, ___________volcanoes and ________________cones.
• ________________________ plays a major part in determining the __________of a volcano.

• When you think about a typical volcano, what do you see?
• Usually a cinder cone – highly explosive lava.
1.A cinder cone is a type of volcano that is built almost entirely from _______________
___________.
– This give it a cone shape over time.
– Learn more here!

Cinder Cone from Pu'u'O'o eruption of Mount Kilauea

2. Composite Cones – a
___________________, symmetrical volcano composed of both _______ and
__________________deposits.
About Composite Cone Volcanoes

Mt. Shasta

3. Shield Volcano – have the shape of a broad, slightly _____________structure.
• Most shield volcanoes grow up from the
____________________– like the islands of
Hawaii or Iceland.
More about shield volcanoes

Iceland

1. What is the viscosity of a lava/magma?
2. How does silica content affect viscosity?
3. How does gas content affect viscosity?
4. How does temperature affect viscosity?
5. What are the particles produced in volcanic eruptions called?
6. Name and describe the 2 types of lava flows.

• I will be able to relate plate tectonics to volcanoes by describing where magma comes from, the types of boundaries that produce volcanoes.
• I will be able to graph the locations of volcanoes on a map and compare patterns of volcanoes to plate tectonics.

• Magma composition plays a major part in determining the form of a volcano.
• Magma forms when solid rock in the crust and upper mantle melts.
• The composition of the material, water content and confining pressure are factors that affect the melting point of rock.
• Magma tends to rise towards Earth’s surface primarily because rocks become less dense when they melt.
• Most of the active volcanoes on Earth are located in a belt known as the ring of fire.
• Identify an O-C plate boundary creating a volcano.

• How Volcanoes Form Video

• As we know, __________________________ plays a major part in determining the form of a volcano.
• But where does magma come from?
• Magma forms when solid rock in the crust and upper mantle melts.

• How does rock melt?
– There are three factors that contribute to rocks melting, or the formation of magma.
1. _______________
– As you go ___________ in the earth, the temperature
___________.
– Subduction creates ______________and causing heat
– As magma rises, it heats rocks closer to the earth’s surface.
• But this alone is not enough to create all of the magma that we know exists below the earth’s crust…

2. Confining Pressure
– As confining pressure is __________________, the melting temperature of rocks is __________.
– This means that as rocks can melt easier as they are released from the confining pressure deep within the earth.
– This process is called
_______________________.

3. ________________
– ____________in rocks can cause a rock to melt at
_________________________________.
– Rocks with more water in them melt easier than rocks that are “dry”.
• BOTTOM LINE: The __________________ of the material, _______________content and confining ________________are factors that affect the melting point of rock.

• Now that we know how magma forms, why does it come to the surface of the planet?
• Let’s discuss.
• Write down what you think:
__________________________________
__________________________________

• Magma tends to rise towards Earth’s surface primarily because _______________________
______________________________________
• What does that mean? When rocks change from a solid state to a liquid state, they become lighter!
• What is lighter will rise, just like heavy things sink!

• Most of the active volcanoes on Earth are located in a belt known as “______________
______________________”.
• Others are located seemingly sporadically around the globe.
• Scientists could not explain the worldwide distribution of volcanoes until the introduction of the theory of Plate Tectonics.

• Watch a slideshow of the Volcanoes on the
Ring of Fire HERE !

• Plate movement forms volcanoes in three zones:
1.Convergent Plates
– Ocean – Ocean
• Rising magma can form ____________________ in an ocean (Aleutian Islands).
– Ocean – Continent
• Rising magma can form
__________________________________________
(Andes Mountains).

Was type of convergent boundary caused Mt. St.
Helens?
How do you know?
Mount St. Helens emitting volcanic ash 2 months after it’s May eruption in 1980.

2. Divergent Plate Boundaries
– When plates pull apart, there is less pressure on the rocks below.
– _______________________________________
________________________________________.

3. Intraplate Igneous Activity
– Intraplate means activity __________a tectonic plate
_____________from plate boundaries.
– This is caused by Hot spots.
– Examples of this are the ____________________

Follow the directions on the handout to map volcanoes around the world.
After you finish plotting the volcanoes, answer the questions in complete sentences.

• You will be working in pairs to investigate viscosity today.
• 1 partner and ONLY 1 partner will need his or her laptop out.
• Once you are in your groups go to the following web address (also linked on the wiki)
• http://www.seed.slb.com/flash/science/lab/li quids/visco_exp/en/viscosity.htm?width=620
&height=500&popup=true
• You will have 20 minutes to complete this- work efficiently!