VOLCANOES

EARTH SCIENCE

Mrs. Bakercjcb2015

Volcanoes

• An opening in the Earth’s crust that erupts gases, ash, and lava (pyroclastic material).

There are more than 600 active volcanoes on Earth!

Mt. Kilauea in Hawaii is the most active volcano!

Vocabulary

Parts of a Volcano• A Magma Reservoir• B Flank• C Conduit• D Crater• E Solidified Lava• F Dike• G Ash• H Vent• I Sill

• INTERACTIVE WEBSITES (GO TO “LAUNCH”):• http

://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.nyiragongo/anatomy-of-a-volcano/ (images)

• http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.volcanintro/volcanism/ (LOTS of information)

ViscosityMaterials that flow quickly have a

low viscosity. Examples: water, basaltic magma

The ability of a substance to resist flowing.

Materials that flow slowly have a high viscosity. Examples: syrup, Rhyolitic magma

Types of Magma

• Temperature, pressure, and amount of water affect the formation of magma.

Explosiveness of a Volcano

• The explosiveness of a volcano depends on the viscosity of the magma within it.

• High in silica, low in water vapor = High viscosity.

• The magma will clog the main vent, build up pressure and result in an explosion.

Life of a Volcano

• Extinct- has not erupted in recorded history

• Dormant- has erupted in recorded history, not currently erupting

• Active- is currently erupting

Batholith: Large igneous rock mass underneath mountains

Dike: Magma that cuts across preexisting rock

Laccolith: small pool of magma that collects just under Earth’s surface

Pluton: Intrusive igneous rocks formed by converging plates

Sill: Pool of solidified magma in between rock layers

Stock: Small batholith

Caldera: large crater formed from volcano collapse during or after it erupts

Crater: depression at volcano’s Summithttp://www.boston.com/bigpicture/2011/02/nyiragongo_crater_journey_to_t.html

Hot Spot: Hot area of a tectonic plate not along plate boundary

Tephra: Rock fragments thrown into the air during a volcanic eruption

Vent: Opening in Earth’s crust where lava erupts and flows outward

Pyroclastic Flow: Fast-moving cloud of ash, gas, and volcanic material after an eruption

Types of Volcanoes

• Cinder Cone

• Composite

• Shield

Composite Volcanoes

• Composed of alternating bands of pyroclastic material (volcanic fragments) and lava.

• Explosive eruptions• Andesitic magma (high

silica)• Example: Mt St Helens

and Mt. Rainier in the Cascade Range Mt St Helens

Pyroclasticmaterial

SolidifiedLava

Mt. Rainier

Shield Volcanoes

• Wide volcanoes, gentle slope

• Composed of layers of solidified magma

• Calm lava eruptions• Basaltic Magma (low

silica)• Example: Hawaiian

Islands

Solidified lava

Cinder Cone

• Composed of pyroclastic material (Tephra- volcanic fragments)

• Small and steep• Explosive eruptions (high silica)• Example: Paricutin in Mexico

PyroclasticMaterials

Volcanoes

• The majority of Earth’s surface

volcanoes are found along the Pacific

Plate Boundary- Ring of Fire.

-due to the subduction of the Pacific Plate.

Volcano Formation at Convergent Boundaries

Volcano Formation at Convergent Boundaries

Mt St. Helens

Mt. Pinatubo

Aleutian Islands

Volcanoes• Volcanoes also

form along the mid-ocean ridges

-due to upwelling of magma- long fissures in places

Volcano Formation at Divergent Boundaries

Volcano Formation at Divergent Boundaries

Iceland Volcanic ActivityBlack Smoker,Mid-Atlantic Ridge

Pillow Basalts,South Pacific

Volcano Formation NOT at Plate Boundaries: Hot Spot Volcanoes

The Islands of Hawaii

• These islands formed over a period of 5 million years.

• The islands are slowly moving to the northwest with a active hot spot currently under the island of Hawaii.

Plate Movement

Hot Spot

The Yellowstone Caldera is the volcanic caldera located in Yellowstone National Park in the United States, sometimes referred to

as the Yellowstone Supervolcano

Volcanic Hazards

• Lava Flows• Pyroclastic Flows• Lahars• Earthquakes• Tsunamis• Toxic Gases• Volcanic Bombs• Ash Falls• More…