VOLCANOES
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VOLCANOES. What is a volcano?. A volcano is a weak spot in the crust where magma comes to the surface. Volcanoes are a constructive force (adds new rock to existing crust). http://gvc1007.gvc10.virtualclassroom.org/volcanoes.html. Where do volcanoes form?.

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VOLCANOES

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Volcanoes

VOLCANOES


What is a volcano

What is a volcano?

  • A volcano is a weak spot in the crust where magma comes to the surface.

  • Volcanoes are a constructive force (adds new rock to existing crust).

http://gvc1007.gvc10.virtualclassroom.org/volcanoes.html


Where do volcanoes form

Where do volcanoes form?

  • Volcanoes occur mostly along PLATE BOUNDARIES!

    • Divergent boundaries: volcanoes form along mid-ocean ridges and rift

      valleys

    • Convergent boundaries:

      volcanoes form at oceanic

      plate collisions


Where do volcanoes form1

Where do volcanoes form?

  • Volcanoes occur mostly along PLATE BOUNDARIES!

Ring of Fire:

Belt of volcanoes that surrounds the Pacific Plate (convergent boundaries)


Where do volcanoes form2

Where do volcanoes form?

  • Volcanoes also occur at hot spots!

    • a hot spotis an area where magma rises from deep in the mantle through the crust

    • stays in one place, creating a trail of volcanoes, as plate moves above it

    • oldest volcanoes

      are furthest from

      hot spot; newest

      volcanoes are

      closest

    • Example: Hawaii


Volcanoes

Parts of a volcano

crater

A bowl shaped area that may form at the top of a volcano.

Any opening in a volcano

pipe

A long tube connecting the magma chamber to the surface

Where magma collects beneath a volcano


Volcanoes

CRATER


What are the two types of eruptions

What are the two types of eruptions?

  • QUIET – mostly lava erupts

  • EXPLOSIVE – ash, cinders, and bombs erupt


Volcanoes

Explosive


Volcanoes

Quiet


What is a pyroclastic flow

What is a pyroclastic flow?

  • Pyroclastic flow occurs during an explosive eruption.

  • composed of ash, cinders, bombs, gases


Landforms created from lava

Landforms created from lava

  • SHIELD VOLCANO

  • CINDER CONE VOLCANO

  • COMPOSITE VOLCANO


Shield volcanoes

Shield volcanoes

  • Low and broad

  • Quiet eruptions with lava flows, little pyroclastics

    • Example:

      Mauna Loa


Volcanoes

Shield Volcano— low and broad in shape


Volcanoes

Mauna Loa—located on the big island of Hawaii, largest volcano on Earth


Volcanoes

Kilauea


Volcanoes

Surtsey, Iceland


Volcanoes

Cinder cone volcanoes

  • Small volcanoes with explosive pyroclastic eruptions from a single vent

  • Very steep “upside-down ice cream cone” slopes


Volcanoes

Sunset Crater(Arizona) — among the largest cinder cones in the world


Volcanoes

Composite Volcanoes

  • Formed by alternating layers of molten lava, volcanic rock and ash

  • Very steep and jagged

  • Can have both quiet and explosive eruptions

  • Example: Mt. Rainer


Volcanoes

Composite Volcano


Volcanoes

Mt. Rainer, Washington


Volcanoes

Mt. Rainer, Washington


Volcanoes

Mt. Fuji, Japan


Volcanoes

Mt. Rainer

Mt. Adams


Volcanoes

1980: Mt. St. Helens before the eruption.


Volcanoes

1982: Mt. St. Helens after the eruption.


Volcanoes

Mount St. Helens: May 19,1982

Elevation before eruption: 9,677ft.

Elevation after eruption: 8,377 ft.


Volcanoes

Mount Hood, Oregon: Elevation 11,239 ft.


Volcanoes

Mt. Lassen, California


Volcanoes

Mt. Shasta, California


Volcanoes

Mt Vesuvius


Profiles of volcano types

Profiles of Volcano Types


What are the stages of a volcano

What are the stages of a volcano?

  • An active volcano is currently erupting or showing signs of erupting in the future.

  • A dormant volcano is not showing signs of erupting but may erupt in the future.

  • An extinct volcano is not likely to erupt again.


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