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Name _______________________________________ Date _______________ Core _________
3.1 VOLCANOES AND PLATE TECTONICS
Key Concepts: Where are Earth’s volcanoes found?
How do hot spot volcanoes form?
1. Definitions:
 ____________________________________ a weak spot in the Earth’s crust where molten
material (magma) comes to the surface
 _____________________________________ a molten mixture of rock forming substances,
gases and water from the earth’s mantle.
 ______________________________________ when magma reaches the Earth’s surface.
2. Volcanoes & Plate Boundaries
•600 _______________________________ on land, many more under the sea.
•Volcanoes occur in __________________ that extend across continents and oceans.
•_______________________________ - major volcanic belt formed by the many volcanoes
that rim the Pacific Ocean.
•Volcanic belts form along the ____________________________________.
•Diverging ________________________and converging_____________ occur.
•Results in ______________________________________
•Magma reaches the _____________________.
Most volcanoes occur at:
a. ___________________________________
–Mid Ocean Ridge
b._____________________________________
Points of subduction
ex. Mount Etna – Eurasian and African plates
3. Volcanoes on Divergent Boundaries
a. _____________________________________ point of Mid ocean ridges occurring ( long
underwater mountain ranges)
b. Many have __________________________ down the center
c. Lava pours out of rift valley – __________________________________.
d. ______________________________ Great Rift Valley in East Africa
4. Volcanoes on Convergent Boundaries
a. Volcanoes form when:
_____________________________________
_____________________________________
.
b. In both situations, ________________________________________________
c. Rock above the plate melts to __________________________________.
d. Erupts to the surface as ______________________.
5. Volcanoes on Convergent Boundaries
a. ______________________________ – less dense than the surrounding rock
Magma rises to the surface and breaks through the ocean floor
___________________________________.
–String of islands formed:
________________________________________
b. Examples: Japan, New Zealand, Indonesia, the Philippines
6. Hot Spot Volcanoes
a. ___________________________________________ – an area where material from
deep within the mantle rises and melts forming magma
b.
c. ____________________________________above a hot spot when magma erupts
through the crust and reaches the surface.
d. Some hot spots lie in the middle of plates _____________________________.
e. Others occur _______________________________________.
f. A hot spot in the ocean floor can gradually form a series of _______________.
Ex. The Hawaiian islands
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A hot spot can also form __________________________________
Ex. Yellowstone National Park, WY
Chapter 3.1 Assessment Questions:
1. What is a volcano?
2. Where are most volcanoes located? Pg 83
3. What causes volcanoes to form at a diverging plate boundary? Pg 83.
4. What is a hot spot? Pg 85
5. How does a hot spot volcano form? Pg 85
6. What features form as an oceanic plate moves across a hot spot? Pg 85
Chapter 3.2 Guided Notes
3.2 PROPERTIES OF MAGMA (Reference pgs. 87-90) Notes
1. Introduction
a. Measured from the bottom of the Pacific Ocean, the Big Island of Hawaii is
the ___________________ mountain on Earth.
b. This island is made up of __________________ ___________________.
c. One of these volcanoes, ___________________________ erupts frequently
and produces huge amounts of __________________.
2. Physical and Chemical properties
a. Magma and lava are made up of ___________________ and _____________
- ______________________ - a substance that cannot be broken down
into other substances.
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Examples: ________________________________________
-. ______________________ - a substance made of two or more
elements that have been chemically combined.
Examples: ____________________________________
b. Each substance has a particular set of _______________________ and
_______________________ properties.
c. These properties can be used to ___________________ a substance or
__________________________ how it will behave.
d. Physical Property – is any characteristic of a substance that ca be observed or
measured_________________________________________________________.
Examples: _________________________________________________
e. Chemical property – is any property that
_________________________________________________________________.
Examples: ______________________________________________
*You can often tell that one substance has reacted with another if:
1)
2)
3)
3. What is viscosity?
a. A familiar physical property of liquids is that the __________________ in a
liquid
are ______________________ one another and a liquid can ________________
from place to place.
b. __________________________ - the resistance of a liquid to flowing.
c. Because liquids differ is _____________________, some flow
_________________________ than others.
- the greater the viscosity of a liquid the ____________ it flows.
Example: _____________________________
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d. the lower the viscosity of a liquid the ___________________ it flows.
Example: ______________________________
e. Liquids that have a _______________ degree of ______________ among the
particles have a ________________ viscosity.
4. Magma Composition (top of page 89)
Magma varies in _____________________ and is classified according to the amount
of _____________ it contains.
The graphs to the right show
the average composition of the
two types of magma. Use the
graphs to answer the
questions.
a. What materials make up both types of magma?
b. Which type of magma has more silica? About how much silica does this type of magma contain?
c. A third type of magma has a silica content that is halfway between that of the other two types.
About how much silica does this type of magma contain?
d. What type of magma would have a higher viscosity? Explain.
5. Viscosity of Magma
-Inside the Earth, the extremely high temperature and pressure causes the mantle
_______________ and form __________________.
rock to
-Not all types of ________________ have the same ________________.
-The ___________________ of magma depends upon its _________________
___________________________________.
content and
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A. Silica content
1) Magma is a complex mixture but its major ingredient is _______________.
2) ______________________ - is made up of particles of the
elements oxygen and silicon.
3) Silica is one of the most abundant materials in the _________________________.
4) The silica content of magma ranges from _________________________.
5) The more silica magma contains --- __________ viscosity.
a) High silica = _______ colored lava, slow flowing.
b) When it cools, this lava forms - ____________________
(Similar to granite)
6) The less silica magma contains ----- ____________ viscosity
a) Low silica - __________ colored lava, flows readily.
b) When it cools, this lava forms - __________________
B. Temperature
1) Viscosity increases as __________________ decreases.
2) the temperature of magma and lava can range from ___________ to
________________ degrees Celsius.
3) _______________________ differences produce different
types of lava.
a) ________________________ - is fast moving, hot lava that has a
________________ viscosity.
i) the surface of this lava when it cools looks like:
________________________________.
b) ____________ - has a higher _______________ than pahoehoe.
i) when this type of lava cools, it forms: ___________________________
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Chapter 3.2 Assessment Questions:
1. What is a physical property?
2. What is a chemical property?
3. Magma is a hot, liquid mixture that changes to solid rock when it cools and hardens.
Which of these characteristics are physical properties?
4. What is viscosity?
5. Which has a higher viscosity, a fast-flowing liquid or a slow-flowing liquid?
6. What can you infer about the amount of friction among the particles of a liquid that has
low viscosity?
7. What two main factors affect magma’s viscosity?
8. A lava flow cools as it moves away from the vent. How would this affect the surface
appearance of the lava flow?
VOLCANIC ERUPTIONS 3.3
Objectives:
Explain what happens when a volcano erupts.
Describe 2 types of volcanic eruptions
Identify stages of volcanic activity
1. What comes out of volcanic explosions?
a. ______________________________________________
b. Magma forms in the ______________________________
c. ________________ currents in the mantle bring magma towards the surface
d. Magma tries to flow into any ___________________
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e. When magma reaches a _______________spot in the crust, a ___________________
forms
f.
____________ is magma that has reached the surface
2. Magma Reaches Earth’s Surface
a. Volcanoes are __________________________________ through which magma moves.
b. Inside a Volcano
c. Magma collects below the volcano in the _________________________
d. Magma flows upward through a tube (______________) that connects the magma chamber
to the surface.
e. __________________________ leave through vents
f. Central vent is the opening at the top
g. Side vent anywhere along the side of the volcano
h. Lava pours out of the vents and creates a __________________________
i.
A ________________________ area called a crater may form around the central vent
3. A Volcanic Eruption
a. Dissolved ________ are trapped in magma under extreme _____________
b. as magma flows_____ , pressure ______ because there is less rock on top of it.
c. the dissolved gases expand and form bubbles
d. When a volcano erupts, the ____________________________________ forces magma up
the pipe until it explodes out the vent
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4. Kinds of Volcanic Eruptions
-Volcanic eruptions can be __________________________________________.
-Eruptions depend on the properties of magma: 1) __________________ 2)______________
a. Quiet Eruptions
-Magma has ______ silica content = low _____________
-Magma flows easier so gases bubble out gently
-Lava can flow __________________________ from the vent
-Produce both pahoehoe and aa lava
-Example: _____________________________
b. Explosive Eruptions
-Magma has high ____________ content = ______________ viscosity
-Magma doesn’t always flow out of vent and so it builds up (like a cork in a bottle)
-Trapped _______________ build up ____________________ until they explode
-Magma is pushed out of the vent with incredible force
-Lava breaks into fragments that cool quickly and harden into different sizes
-____________ – fine, dust sized particles of lava
-Cinders – ___________________________________________
-______________ – baseball to car sized chunks of lava
-__________________________: when an explosive eruption hurls out gases, ash, cinders
and bombs.
-Pumice forms when lava _________________ and traps air bubbles inside
-_______________ forms when lava cools quick leaving the surface smooth and glass-like
5. Volcano Hazards
a. ___________ eruptions cause lava to flow far --- burning and burying everything in its path
b.Explosive eruptions can ________________________ in ash, cause landslides, avalanches,
cause damage from gases and cinders/bombs.
6. Stages of Volcanic Activity
a.Life Cycle of a Volcano
-Scientists use _____________________ and monitor volcanoes to determine what
____________ of activity a volcano is in
-A volcano can be _____________, ________________ or ___________________
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-An active volcano is erupting or showing ____________________________________
-A _________________ (sleeping) volcano can awaken in the future and become active
-An extinct (dead) volcano is ____________________ to erupt ever again
b.Monitoring Volcanoes
-Geologists use ______________________________ to detect slight changes in surface
elevation cause by _______________ moving underground
-They monitor __________________ escaping from a volcano
-Increase in _________________________ might mean magma is nearing the surface
-The changes detected may give a short warning time BUT
-We cannot be certain the _______________________ or how _____________ it will be
3.4 VOLCANIC LANDFORMS
-Volcanic activity on and beneath the surface has built up Earth’s land areas.
1. Landforms from Lava and Ash
-Volcanic eruptions create landforms made of lava, ash and other materials
__________________________
__________________________
__________________________
___________________________
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Another landform results from the collapse of a volcanic mountain
-_____________
a. Shield volcanoes
-___________________ sloping mountains
-Thin layers of ____________________________ lava
build up over time
-Ex) the Hawaiian Islands
b.________________________ volcanoes
-_____________________________ lava produces ash,
cinders and bombs
-Those materials build up around the vent in a
______________________________________
-Ex) Sunset Crater in Arizona
c._____________________ Volcanoes
-Form when volcanoes alternate between
_________________________________________ of
ash, cinders and bombs
-Tall, cone shaped mountain with
__________________________ layers of ash and lava
-Ex) Mt St. Helens, Washington and Mt. Fuji, Japan
d._______________________________
-Low viscosity lava flows out of ___________________________ and travels far before
cooling
-After millions of years a high plateau forms
-Ex) Columbia Plateau in Washington, Oregon and Idaho
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e. Calderas
-Huge hole left by the _____________________ of
composite volcanic mountains
-Filled with fallen pieces of the volcano, ash and lava
-Enormous eruptions may empty the
____________________________________
-There is only ___________________ space left that can’t support the weight and it
collapses on itself.
-Overtime water from rain and snow may fill the caldera
-Ex) Crater Lake, Oregon
f. _____________ from lava and ash
-People settle near volcanoes because of the _______________, _________________
soil
-At first, after volcanic eruptions the land is empty and barren
-Overtime the _____________________________________ and provides:
1. Potassium
2. Phosphorus
3. Other substances that plants need
2. Landforms from Magma
-Sometimes ______________ forces its way through cracks in the _______________
but never reaches the ____________________
-The magma cools and hardens within the rock layers
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-Overtime ____________, ______________, or ______________ erode away the
surrounding rock and expose the hardened magma
a. _________________________________
a. Forms when magma
1.__________________________________________
2. Overtime the __________________________ is
weathered away
3. Looks like a giant tooth
Ex) Ship Rock, New Mexico
b. Dikes and Sills
1. Dike: when magma forces its way ________________________ rock layers and
hardens
2. Sill: when magma squeezes ______________________________ layers of rock and
hardens
3. Ex) Palisades, NY
sill
&NJ
dike
c____________________________
1. Large ___________________________ that are formed
when a huge mass of ____________ cools inside the
Earth’s crust
2.The ________________ layers of rock erode away leaving
the hardened magma exposed
3. Ex) Sierra Nevada Batholiths
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d_______________ Mountains
1. Created by smaller bodies of magma
2. The hardened magma uplifts the surrounding rock and causes it to bend into a dome shape
3. Ex) Black Hills, South Dakota
e. Geothermal Activity
1. Geo = _______________, therme = ______________
2. _________________________ – when magma a few km beneath the surface heats
underground water.
3. Ex) hot springs and geysers found near past and present volcanic activity
a________________________
4. Forms when __________________________________ is heated by magma or hot
rock
5. The heated water _______________ and collects in pools
b_______________________
6. Fountains of water and steam that erupt from the ground
7. The heated water and steam __________________________________ until finally it
erupts
8. Ex) Old Faithful, Yellowstone National Park
c._____________________________________
9. Heated water can provide an energy source
10. Heated water can be used to power turbines and create electricity
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