Unit 1.5- Volcanoes

Introduction to Volcanoes

•Forces of Nature- National Geographic Video

Latitude and Longitude Review• Latitudes are imaginary lines to the north

and south of the equator (x- axis)• Longitudes are imaginary lines to the east

and west of the Prime Meridian (y-axis)Example: Plot the following Points (1, 4), (2, 3), and (5, 2)

Earthquake Locations

• Where did most of the Volcanoes occur?

• How is this similar to where earthquakes occur?

• How does plate tectonic movement effect the location of volcanoes?

Ring of Fire

• The volcanoes belt that

circles the Pacific Ocean is

called the Ring of Fire

Volcanoes at Subduction Zones

• Volcanoes Form at Subduction Zones Video• At CONVERGENT BOUNDARIES the denser

plate subducts below the less dense plate to form a trench. As this dense plate gets pulled into the mantle, it begins to melt• This melted rock rises toward the crust and

forms a volcano

How do Volcanoes form in the middle of a plate?

• Volcanoes that do not form on plate boundaries form over Hot Spots• Hot Spots Video• Hot magma from the core rises through the

mantle and heats the earth’s crust until it breaks through the crust. • As it breaks through the crust, lava is spewed

into the ocean and hardens into an island. • The oceanic crust moves like a conveyer belt and

forms a string of islands like the Hawaiian islands.

Anatomy of a Volcano

• Can we go inside a volcano and see what it looks like?

• How could we learn what the inside of a volcano is like?

What does the inside of a volcano look like?• In your notes, draw and label a picture of what you think the inside of

a volcano looks like.

Anatomy of a Volcano Vocabulary• Magma- Molten rock beneath the

surface• Lava- Molten rock on the surface• Magma Chamber- as magma rises to

the surface, it forms a large pocket beneath the surface that holds the magma• Pipe: a narrow crack in the crust

through which magma flows• Vent- central opening that allows the

flow of magma to the surface (where magma leaves the pipe)• Crater- the bowl-like depression over

the vent at the summit of the cone

Types of Volcanoes

• Cinder Cone

• Shield

• Composite

Cinder Cone Volcano

• A small, steep- sided volcano• Made mostly of cinders with lava flow

intermixed• Eruptions are small and often do not cause

damage

Shield Volcano

• Usually wider than it is tall• Made entirely of lava• Near oceans or on oceanic crust• Eruptions are quiet, but lava

causes significant damage

Composite Volcano

• A large, steep-sided volcano• Made of alternating layers of lava flow and pyroclastic debris

• Pyroclastic Debris: ash, lava and hot volcanic gas

• Erupt explosively or quietly

Life Cycle of Volcanoes

1. Active Volcanoes: a volcano that is erupting now, has erupted in the recent past, and shows signs of erupting in the near future

2. Dormant Volcano: a volcano that has not erupted recently, but has during recorded history. It is expected to erupt again in the future.

3. Extinct Volcano: has not erupted in recorded history and will not likely erupt again.