Unit 9: Volcanoes and Earthquakes
10. Volcanic eruptions can cause some of the most dramatic changes to Earth’s surface.
I can…
a. Describe the anatomy of a volcano.
b. Name the locations in which volcanoes form (Pacific Ring of Fire, subduction zones, mid-ocean ridges and hot
spots) as well as describe how they form here.
11. Volcanoes can be thought of as windows into Earth’s interior. By studying volcanic eruptions, Geologists have
determined that there are two general types of magma.
I can…
a. Name and describe the two types of magma mafic and felsic.
b. Describe how magma’s viscosity relates to the amount of dissolved gases present and the type of eruption that
occurs (quiet or explosive).
c. Compare and contrast characteristics of quiet vs. explosive volcanic eruptions.
d. Describe what pyroclastic material is and list various types.
12. Three major types of volcanoes exist, each having their own characteristic features.
I can…
a. Name the three types of volcanoes: shield, composite and cinder.
b. Describe the features of each type of volcano including shape/structure, how they form, type of lava present,
type of eruption, and where they are found/common examples.
Volcano Basics
are __________________ in the
Earth’s surface. When they are active they can let _______, ________ and
hot ________________ escape in spectacular eruptions.
ash cloud - cloud of ash that forms in the air after some volcanic
eruptions.
conduit - a conduit is a passage through which magma (molten rock)
flows in a volcano.
crust - the crust is Earth's outermost, rocky layer.
lava - lava is molten rock; it usually comes out of erupting volcanoes.
magma chamber - a magma chamber contains magma (molten rock)
deep within the Earth's crust.
side vent - a side vent is a vent in the side of a volcano.
vent - a vent is an opening in the Earth's surface through which
volcanic materials erupt.
Volcanoes are usually
where
tectonic ______________ meet (convergent, divergent and
subduction zones). This is especially true for the Pacific
_________________________, an area around the
_______________ Ocean where over ________ of the volcanoes on
Earth are found.
When an oceanic and continental plate
converge, the more _____________, oceanic plate moves ______________
the continental plate. When this occurs, fluids like _____________ combine
with crust and mantle material. This ______________ the melting point of
the rock and causes it to melt and form _______________. Because magma
is ________________________ than the surrounding rock, it will _________
and erupt on Earth’s surface forming a ____________________.
Volcanoes can also form in areas that contain abnormally hot rock
inside the Earth. Known as ______________ plumes, these
are found at a number of locations
around the globe with the most notable being in ______________.
As a __________________ plate moves over a __________________
mantle plume, _________________ mountains (like the Hawaiian
Islands) form. The activity of the volcano stops because it has moved
away from the hot spot that supplied it with magma.
______________________, like the Hawaiian Islands, is believed to
lie on top of one of the planet's few dozen _________________
where light hot molten mantle rock rises towards the surface.
In addition to subduction and hotspots, _______________
along two ________________ oceanic plates (mid-ocean
ridge) can create submarine volcanoes.
http://www.pbs.org/wgbh/nova/earth/meet-volcanoes.html types of volcanoes
www.maryputra.weebly.com
There are two factors that affect the size of a volcanic eruption:
1. The amount of dissolved gases (carbon dioxide and water vapor)-during eruptions gases provide the force to
propel magma through the vent.
2. Viscosity-is a substance’s resistance to flow. Magma’s viscosity, whether thick, runny or sticky affects the type of
eruption.
Questions:
1. There are two types of magma: mafic and felsic. Fill in the missing information in the chart below:
Magma
Type
Composition
Color
Where it is found
Temperature-fill in the
bottom box on
viscosity and then
come back to this one
Amount of dissolved
gases-read through
the two main types of
eruptions then come
back to this one
Mafic
Felsic
Compare the viscosity of mafic and felsic magma: which one is more viscous? What does this mean in terms of flow?
2. Volcanic Eruptions can be categorized as either quiet or explosive, compare these in the venn diagram below and
include the following: the type of magma (mafic/felsic), a description of how it flows, for quiet-the type of lava and
what it looks like when it cools (Pahoehoe, Aa and blocky lava).
Quiet
Explosive
Similarities
3. What is pyroclastic material? What are two ways in which it forms?
Definition:
Ways it forms:
1.
2.
4.List the five types of pyroclastic material and give a brief description (you do not need to write everything!!)
1.
2.
3.
4.
5.
5.Predicting Eruptions: read through “Can Scientists Predict a Volcanic Eruption” and list at least 4 indicators of a
POTENTIAL blast.
1.
2.
3.
4.
Analysis Questions:
1. Why does felsic lava produce explosive eruptions more often than mafic lava does?
2.
Give one similarity and one difference between lapilli and volcanic blocks.
3. Which would be more likely to increase the steepness of a volcanic cone—a quiet eruption or an explosive eruption?
Explain your answer.