EARTH SCIENCE Mrs. Baker cjcb2015 VOLCANOES EARTH SCIENCE Mrs. Baker cjcb2015

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)

Viscosity The ability of a substance to resist flowing. Materials that flow quickly have a low viscosity. Examples: water, basaltic magma 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 Summit http://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 Pyroclastic material Solidified Lava 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

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 Pyroclastic Materials

-due to the subduction of the Pacific Plate. 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 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 Activity Black 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…