Volcanoes Intro-Complete

Volcano-Intro

By Restie Carullo

Where on Earth are volcanoes
located?

• Most active volcanoes on land are located along
the margins of the ocean basin-within the circum-
Pacific belt known as the Ring of Fire.
• Another group of volcanoes, seamounts form
along the crest of the mid-ocean ridges.
• Volcanic structures that comprise most of the
islands of deep ocean basins, including Hawaiian
Islands, Galapagos Island and Easter Island.

​Chemical Layers:

1. Crust-basaltic/granitic

2. Mantle-peridotite

3. Core-iron and nickel

​Layers of the Earth

Multiple Choice

Why does the Earth have layers?

• temperature

• mass

• volume

• density

​

1. Lithosphere

2. Asthenosphere

2. Mesosphere*

3. Outer Core

4. Inner Core

​Layers of the Earth

Multiple Choice

What's the difference between the crust and the lithosphere?

• crust and lithosphere are one and the same

• crust is primarily made up of granitic rocks while the lithosphere is primarily made up of peridotite

• crust is primarily made up of basaltic rocks while the lithosphere is primarily made up of granodiorite

• none of the choices

Let’s start with the layers of the earth. Why does Earth have layers?

Table 1. Layers of the earth and its chemical and physical properties.

Chemical Properties

Physical Properties

1. Crust-basaltic and granitic
1.1. oceanic – basaltic
1.2. continental – granitic

1. Lithosphere-cool rigid outer shell
(crust plus the upper mantle)

2. Mantle- peridotite

2. Asthenosphere-temperature and pressure
results in small amount of melting

3. Core- iron and nickel

3. Outer Core-liquid metallic iron

4. Inner Core-solid iron due to immense
pressure that exist in the center of the planet.

Multiple Choice

The core is made up of iron and nickel but why is the outer core liquid and the inner core solid?

• The inner core is experiencing extreme high pressure while the outer core is experiencing high pressure (not that extreme)

• The inner core is experiencing extreme high temperature while the outer core is experiencing high temperature (not that extreme)

• The inner core is experiencing extreme low pressure while the outer core is experiencing low pressure (not that extreme)

• The inner core is experiencing extreme low temperature while the outer core is experiencing low temperature(not that extreme)

Your familiar with the crust, mantle and the core. You are also familiar with
the Lithosphere, Asthenosphere, Mesosphere, Inner Core and Outer Core.
The first is known as the chemical layers of the earth (focusing on the
composition) while the second is known as the mechanical layers/physical
properties of the earth (focusing on the state of matter). With the given
information, can you tell why the earth has layers in the first place?

D

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S___

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S___

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R

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Why do volcanoes erupt? The reason why
earth have layers is the same reason why
volcanoes erupt. Better search and read
your textbook for this.

Convergent Plate Boundaries

Two plates move
toward each
other leads to the
formation of
Volcanoes.

Table 2. Boundaries and formation of volcanoes.

Type of
Boundary

Continental

Vs.

Continental

Continental

Vs.

Oceanic

Oceanic

Vs.

Oceanic

Convergent

Mountains

Continental Volcanic

Arcs

Volcanic Island/Island

Arcs

(Seamounts-
Archipelagos)

Multiple Choice

The following are products of convergent boundary EXCEPT...

• volcanic island arc

• continental volcanic arc

• mountain

• none of the choices

Multiple Choice

Why is there no volcano being formed within two continental lithosphere in a convergent boundary?

• Continental lithosphere resist subduction

• It’s impossible to have two continental plates in a convergent boundary

• Oceanic lithosphere resist subduction

• There’s subduction between two continental plates but magma cools eventually

plates pull apart example Mid-Atlantic/Oceanic
Ridge, creating new sea floor, equal amounts
are returned to the mantle along boundaries
when two plates converge

Table 3. Boundaries and formation of volcanoes.

Type of
Boundary

Continental

Vs.

Continental

Continental

Vs.

Oceanic

Oceanic

Vs.

Oceanic

Divergent

*Continental

Rift

N/A

Oceanic Ridges

*Rift Valley

Hotspots can occur in the middle of
plate boundaries. A column of hot,
buoyant mantle material rising and
breaking through the crust to form
a volcano forms the hotspots. As
the plate moves, the column of
mantle material stays in one place
and the magma from the mantle
must break through in another
place in the crust. As the plate
continues to move, a chain of
volcanoes is formed.

Table 4. Hotspots and formation of volcanoes.

Type of
Boundary

Continental

Vs.

Continental

Continental

Vs.

Oceanic

Oceanic

Vs.

Oceanic

Hotspots/ Hot
Spots

N/A

N/A

N/A

Multiple Choice

Which of the following is NOT true about hotspots?

• Hawaiian Islands are formed due to hot spots.

• It is also known as Intraplate Volcanism.

• It is located far from plate boundaries.

• It moves with the motions of plates.

Plate motions provide the
mechanisms by which mantle
rocks undergo partial melting to
generate magma.

Multiple Choice

Why can't it be possible that magma comes from the liquid outer core?

• These materials are very dense and remains deep within Earth.

• These materials are very less dense and remains deep within Earth.

• These materials are insulators instead of conductors of heat.

• These materials are NOT applicable for convection type of heat transfer.

•Plate motions generate magma.

• Locations of volcanoes

1. Subduction zones
2. Spreading centers
3. Hotspots

• Types of volcanoes

1. Shield volcanoes
2. Stratovolcanoes
3. Cinder cones